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Service Manual - Test Equipment Depot

1. 0 3 4 FIGURE NO 3 3 8 3 9 3 10 3 11 3 12 3 13 3 14 3 15 TABLE OF CONTENTS LIST OF ILLUSTRATIONS Cont TITLE Page No Scale drawing of Discovery Balance Display Parts c sssccecesseeeeeeseeeeeeseeees 3 5 Removing screws to separate Display Housing from bottom of balance 3 6 Display Balance Load Cell COver ccccccecccccceseeeeeeeeeeeeeaeeeeeesaeeeeesseeeeeesseeeeeeeas 3 7 Discovery Balance Printed Circuit Board PCB ccccccseeeeeeseeeeeeeeeeeseeeeeeaaeees 3 8 EEProm chip next to battery on main PCB cece ceseeececeeeeeeeeeeeeaeeeeesaeeeesaeeeeees 3 8 PCB Cover has alternating teeth to secure it to the Mounting Plate 3 9 Removing Display Cable Shield Plate ccccccccccecssseeeeseeeeeesseeeeeesseeeeeeesaaees 3 10 The InCal Weight Cover sits beneath the Display Cable Shield Plate 3 11 Weights and Weight Holders can be removed but should only be handled while wearing a clean glove ccccecceeeeeeeeeeeeeees 3 11 InCal Weight hardware with Weights and Weight Holders removed Weight Arms with black tips are on either side of the Cantilever Arm 3 12 Calibration Motor Assembly installed to the right of the Load Cell 3 13 Calibration Motor Assembly closeup showing screws that secure It 3 13 Calibration Motor Assembly cessctec acess cascuiseaesacubedsnndedinus
2. 3 Remove the Breeze Ring Pan Breeze Ring Base and Grommet See Figure 3 1 Figure 3 1 Breeze Ring Breeze Ring Base Grommet and Pan removed from Discovery Balance CHAPTER 3 REPAIR PROCEDURES 3 1 1 Housing Disassembly Opening the Balance 1 Remove the two screws shown and then the third one on the bottom Figure 3 2 Removing back cover 2 Remove the back cover iia Back Screw Figure 3 3 Balance with Back Cover removed CHAPTER 3 REPAIR PROCEDURES 3 1 1 Housing Disassembly Opening the Balance 3 Tip the balance on its back 4 Locate the screw shown in Figure 3 4 5 Turn the screw counterclockwise four to five turns Figure 3 4 Scale bottom showing Draft Shield Assembly 6 Set the balance back on its feet 7 The Draft Shield Assembly should slide back approximately one quarter inch If not turn the screw one more turn 8 Slide the Draft Shield Assembly toward the back and lift to remove tt CHAPTER 3 REPAIR PROCEDURES 3 1 1 Housing Disassembly Opening the Balance Figure 3 5 Discovery Balance with cover removed and also cover of main Printed Circuit Board removed NOTE When replacing cover place keyway holes over cone shaped brass screw heads Keyway hole on Balance cover _ i Figure 3 6 Keyway hole on cover guided over cone shaped brass screw heads CHAPTER 3 REPAIR PROCEDURES 3 1 2 Display PCB Removal amp Replacement If the Display
3. Figure 5 2 Discovery Balance Display Assembly CHAPTER 5 PARTS LISTS amp DIAGRAMS 5 3 DISCOVERY INTERNAL PARTS OUTSIDE LOAD CELL TABLE 5 3 LIST OF INTERNAL PARTS OUTSIDE LOAD CELL Printed Circuit Board PCB Mounting Plate Main Printed Circuit Board PCB w EEROM Battery 6 Leveling Foot S O gt 8 Calibration Weight Arm 9 Calibration Weight Holder _ _ Internal Parts Outside Load Cell Figure 5 3 Internal Parts Outside Load Cell CHAPTER 5 PARTS LIST amp DIAGRAMS 5 4 DISCOVERY LOAD CELL PARTS TABLE 5 4 LIST OF DISCOVERY LOAD CELL PARTS Ratio Beam Assembly Printed Circuit Board PCB Load Cell Figure 5 4 Discovery Balance Load Cell Parts NOTE For Part Numbers for specific Discovery Models see specific parts lists APPENDIX A STANDARD CALIBRATION APPENDIX A STANDARD CALIBRATION Standard Calibration is performed by one of four methods Automatic Internal Calibration Advanced AutoCal Span Calibration Calibration Test and Calibration Adjustment A 1 Automatic Internal Calibration Advanced AutoCal Two internal masses are used with three weight values zero a weight value at or near midpoint of the Load Cell s weighing range and a weight value at or near the Load Cell s specified capacity A 2 Span Calibration Span Span calibration resets the balance s weighing range using two weight values zero and a value betw
4. NOTE The smooth arc of the connecting wires is critical for the balance to function properly Carefully observe this arc and be sure to replicate it when re soldering the wires Solder points na r W Figure 3 45 Solder points on either side of set screw connecting fine wire to Load Cell PCB CHAPTER 3 REPAIR PROCEDURES 3 2 2 Load Cell Disassembly Before proceeding with Load Cell disassembly secure the Ratio Beam with stabilizing rods from the Service Toolset in the front and rear This will lock Ratio Beam to the yoke and prevent it from falling down when the Up Down Stop Plate is removed Proceed as follows 15 On the back of the Load Cell lift the Ratio Beam and insert the brass rod under it Figure 3 46 Lifting Ratio Beam to Figure 3 47 Brass Rod installed insert Brass Rod 16 On the front of the Load Cell screw in the Threaded Rod until it touches the Ratio Beam Figure 3 48 Screwing in Threaded Rod on front of Load Cell CHAPTER 3 REPAIR PROCEDURES 3 2 2 Load Cell Disassembly 17 Remove the two screws on the top of the Load Cell PCB Carefully remove stepped washer from rear screw hole and lift off the PCB 1 E TA Bod afar a t M ee Figure 3 49 Removing screws from PCB Figure 3 50 Magnet Cover without PCB Note stepped washer under rear screw NOTE Ifthe Load Cell PCB has to be replaced for example if Ramp does not give a reading after removing the PCB unsolder the two Te
5. Screw holding yoke to frame Screw holding yoke to frame Figure 3 59 Screws on each side of yoke holding Ratio Beam must be removed CHAPTER 3 REPAIR PROCEDURES 3 2 2 Load Cell Disassembly 23 Gently lift the Ratio Beam out of the Load Cell Note The Ratio Beam is a critical part handle with care Figure 3 60 Ratio Beam removed from Load Cell 3 2 3 Load Cell Cleaning All parts should be inspected and cleaned Pay special attention to the Magnet gap and Coil the Weights and Holders the Up Down Stop Plate and the Temperature Sensor Tube d d a i Figure 3 62 Coil Assembly should be o carefully examined and cleaned Figure 3 61 Magnet gap and Temperature Sensor Tube should be carefully examined for dust and debris AN NOTE Use Sticky Notes to clean the Magnet gap DO NOT touch it with a cloth and DO NOT use a cleaning solution For best viewing use a fluorescent light with magnifier lens Check to see if Flexures are bent or broken Place the Flexure on a clean flat surface and check that both sides rest evenly on the surface CHAPTER 3 REPAIR PROCEDURES 3 2 4 Load Cell Assembly The first several steps of Load Cell assembly are critical Check at each step that parts are correctly aligned in order to ensure the balance will function properly 1 Set the Ratio Beam assembly in place and loosely install the 2 screws on left and right sides of the yoke Check that both front sides of t
6. 100 counts Note Before making a calibration adjustment perform an internal calibration To verify whether an adjustment is needed place a test mass on the Pan and note the difference in counts between the nominal mass value and the actual reading Refer to Table 1 1 Masses Used To Test Discovery Balances and use the highest value from the Span Calibration Points column as the test mass lf the difference is within XX count calibration adjustment is not required If the difference exceeds XX count calibration adjustment is recommended INFO TO COME Following a calibration adjustment repeat the internal calibration and verification procedures With the balance on press and hold Cal Menu until Menu Calibrate is displayed with CALIBRATE blinking then release the button Press Yes to enter calibration CAL AUTOCAL is displayed Press No CAL SPAN is displayed Press No CAL TEST is displayed Press No Press Yes to enter the CAL ADJ sub menu and view the current setting There will be a number value with d in the sub menu lf the actual reading is less than the nominal mass value a positive adjustment is required Press No to increase the d value Press it until the setting matches the desired d value Press Back to decrease the d value until the setting matches the desired d value Press Yes to accept and store the setting TABLE A 1 CALIBRATION MASSES FOR DISCOVERY BALANCE MODELS Model Span Calibra
7. 4 shows the front part of the scale with the Allen Keys sticking out in the back The arrows show the key rotation directions required to bring the weight within tolerance specification See Table 1 2 Discovery Balance Model Specifications Figure 4 4 Allen key rotation directions needed for back edge heavy back edge light right edge heavy and right edge light conditions The sign depicts the part of the Pan that is heavy It is a positive value that is greater than the tolerance specification The opposite side of the Pan which is lighter has a negative value that is less then the tolerance specification When moving the weights observe the Display value readings to see if they have positive or negative values In Figure 4 4 the top left graphic shows the key rotation direction needed if the back edge of the scale Pan has a heavy positive value greater then the tolerance specification The top right graphic shows the key rotation direction needed if the back edge has a lighter negative value less than the tolerance specification The graphics in bottom left and bottom right show key rotation directions for right edge heavy and right edge light conditions The purpose of these adjustments is to ensure that weight reading discrepancies on the Pan are diminished to close to zero and within tolerance specification CHAPTER 4 TESTING 4 2 2 Adjusting Off Center Load 6 Adjust as s
8. Circuit Board is suspected of being faulty it should be replaced Table 3 1 Display Assembly Parts List 1 In Use Cover Function Label Display Housing Upper Discovery Display Assembly Figure 3 7 Scale drawing of Discovery Balance Display Parts CHAPTER 3 REPAIR PROCEDURES 3 1 2 Display PCB Removal amp Replacement To remove the Display Printed Circuit Board PCB proceed as follows 1 Open the Housing as explained in Section 3 1 1 2 Tip balance onto back Remove the 2 screws holding Display Housing assembly to back plate of balance Figure 3 8 Removing screws to separate Display Housing from bottom of balance Display Housing will still be connected by a cable to the balance assembly Remove the 4 screws on the bottom of the Display Housing and remove the cover of the Display Disconnect the interconnecting cable from the Display PCB Remove the 6 screws securing the Display PCB and lift out the PCB CAUTION WHEN HANDLING THE PRINTED CIRCUIT BOARD HANDLE BY EDGES ONLY DO NOT TOUCH FOIL SIDE OF BOARD STATIC DISCHARGE MAY DAMAGE SOME COMPONENTS To replace the Display Circuit Board proceed as follows 6 7 8 9 Replace the Display PCB with a new board and install the 6 securing screws Re connect the interconnecting cable to the replacement Display PCB Replace the housing cover of the Display and insert the 4 screws on the bottom Install Display assembly t
9. IMMEDIATELY to avoid bending or breaking the Flexure If Flexure bends replace it CHAPTER 3 REPAIR PROCEDURES 3 2 4 Load Cell Assembly 23 Remove the thumb screws from the top of the Hanger ee Thumb screw holes Figure 3 82 Hanger with Thumb screws removed 24 Push the Brass Fixture from the grooved side then pull it out from the square side Figure 3 83 Pushing Brass Fixture from grooved side Figure 3 84 Pulling Brass Fixture out from square side CHAPTER 3 REPAIR PROCEDURES 3 2 4 Load Cell Assembly 25 Install the bottom Load Cell cover push it to the stops then insert and tighten screws on both sides Stops on sides of bottom Load Cell cover Figure 3 86 Tightening screws on bottom Load Cell Cover CHAPTER 3 REPAIR PROCEDURES 3 2 4 Load Cell Assembly 26 Set the top Load Cell Cover in place Press evenly against the bottom cover NOTE Make sure the cover does not touch any screws Figure 3 88 Tightening screws on top Load Cell Cover CHAPTER 3 REPAIR PROCEDURES 3 2 4 Load Cell Assembly 28 Gently push on the Hanger to make sure it moves freely and smoothly Figure 3 89 Hanger should move smoothly when touched CHAPTER 3 REPAIR PROCEDURES 3 2 5 Installing the Load Cell 1 Place Load Cell in the Chassis Make sure to set the front foot in the keyway See Figure 3 90 Install 3 screws in bottom of Chassis Do NOT tighten the 3 screws iE E
10. Motor Anan installed to the right of the Load Cell Screws securing Calibration Motor Assembly to Balance chassis ures 3 18 Calibration Motor Assembly closeup Note screws on right securing it to balance chassis 2 Remove the screws on the Calibration Motor Assembly and gently lift it out CHAPTER 3 REPAIR PROCEDURES Removing and Replacing Calibration Assembly Note Observe the cam position as in Figure 3 20 This is the rest position Replicating this position when installing the new Calibration Motor Assembly will make installation easier C L o u T x U i od i ITT a Meerecig Figure 3 20 Calibration Motor close up showing cam in rest position Figure 3 19 Calibration Motor Assembly Install new the Calibration Motor Assembly Re insert the 2 screws previously 3 removed 4 Replace Load Cell Cover following Section 3 2 1 in reverse order CHAPTER 3 REPAIR PROCEDURES 3 2 Load Cell Removal and Disassembly The Load Cell may need to be removed and repaired because of balance instability or because the balance does not calibrate or repeat or because the balance is physically broken or displays an error code Possible causes include e Parts being misaligned e Bent or broken Flexures e Contamination or debris in the Magnet area or in any moving part A N NOTE The Load Cell mechanism is extremely delicate and must be handled very gently in a dust free environment after
11. PCB cc ccecccccccccceseseeeeeeeeeeeeeseeeeeeseeeeeeeeas 3 27 FIGURE NO 3 52 3 53 3 54 3 55 3 56 3 57 3 58 3 59 3 60 3 61 3 62 3 63 3 64 3 65 3 66 3 67 3 68 3 69 3 70 3 71 3 2 3 73 3 74 3 75 3 76 3 7 7 3 78 3 79 3 80 3 81 3 82 3 83 3 84 3 85 3 86 3 87 3 88 3 89 3 90 3 91 3 92 3 93 3 94 3 95 3 96 3 97 TABLE OF CONTENTS LIST OF ILLUSTRATIONS Cont TITLE Page No Solder points on bottom of Load Cell PCB cccceccccssecceceeeeeseeeeeeseeeeesseeeeees 3 27 WPMD OWN SOA PF lAlC ges teen coiete intel a a hong bobs ool e 3 28 Removing Temperature Conductor ccccceccceceeeeceeceeeeeeeeaeeceesaeeeeeeesuaaeeeesaaees 3 28 Removing screws that secure the Magnet Covelr ccccsseccessseeeseeeeeseeseeeeenes 3 28 Lifting off the Magnet COVE ccccccccccecesseeeeseeeeeeeseeeeceeeseeeeeeeseaeeeesseeeeeseseeeees 3 28 Removing Thumb screws that hold Hanger in place cccccccseeceeeseeeeeeeeaeees 3 29 Load Cell without Hanger and Brass Fixture ccccecceceeeeeeeeeeceeeeeeeeeseeeeeanees 3 29 Screws on each side of yoke holding Ratio Beam must be removed 3 29 Ratio Beam removed from Load Cell ccc eccececcecceeeeceeeeeeeeeeseeeeeeeeeeeeeeeeneenenes 3 30 Magnet gap and Temperature Sensor Tube should be carefully examined for dust and CEDIIS cccccecseeeeeeeeeeeeeeeseeeeeeeeeeeeeeeseneeeeeas 3 30 Coil Assembl
12. Repeat process as necessary NOTE The Hanger should be positioned evenly around the Ratio Beam The Hangers left and right gap areas should be even when it is installed correctly sem Right gap area Left gap area i A Right side Bracket Left side Bracket Brass Fixture Hanger and Brass Brackets CHAPTER 3 REPAIR PROCEDURES 3 2 4 Load Cell Assembly 11 Set the Magnet Cover in place with its rear hole clearing the Ratio Beam s stop tab fm Figure 3 68 Magnet Cover has oblong hole Figure 3 69 Inserting screws to secure that clears Ratio Beam s stop tab the Magnet Cover 12 Insert the 2 screws on either side of the Magnet Cover as in Figure 3 65 Figure 3 70 Inserting the Temperature Figure 3 71 The Temperature Conductor Conductor in the middle of the Magnet Cover groove should line up with the two Screws 13 Insert the Temperature Conductor in the middle of the Magnet Cover NOTE The Temperature Conductor conducts heat from the Magnet to a small PCB on the Ratio Beam under the Load Cell s main PCB The small PCB communicates the heat reading to the balance s calibration system which adjusts the balance to compensate for temperature variations CHAPTER 3 REPAIR PROCEDURES 3 2 4 Load Cell Assembly 14 Inspect the Up Down Stop Plate for dust or signs of corrosion and clean it Figure 3 72 Up Down Stop Plate Figure 3 73 Up Down Stop Plate inserted over which rests on Magnet Cove
13. chip next to battery on main PCB AN NOTE Be extremely careful to avoid bending the chip s pins when removing and replacing the EEProm chip CHAPTER 3 REPAIR PROCEDURES 3 1 3 Main Printed Circuit Board PCB Removal amp Replacement 8 Install the replacement PCB carefully aligning the 3 screw holes and the RS232 screw holes 9 Install the 2 screws that secure the RS232 connector 10 Install the 3 screws that secure the PCB 11 Insert the 2 small cables through the small rectangular slot on the side of the PCB mounting plate Connect the 3 cables back to the PCB Be sure all 3 cables are secured properly 12 Re assemble balance Follow Sections 3 1 2 and 3 1 3 in reverse order NOTE AN Be careful when replacing the PCB Cover to avoid bending the teeth that secure the Cover to the Mounting Plate The Cover should rest on the inside of the rear Mounting Plate as shown in Figure 3 12 below 4 i E f Figure 3 12 The PCB Cover has alternating teeth to secure it to the Mounting Plate 13 Use the Discovery Service Tool Software to electronically install the new main PCB See Appendix C 3 14 Perform two calibrations first Service Calibration see Appendix B then Span Calibration See Appendix A 2 15 Check functioning of the balance CHAPTER 3 REPAIR PROCEDURES 3 1 4 InCal Weight Hardware Disassembly amp Testing If the Weight Mechanism appears to be unstable the first remedy should be
14. meet the balance specifications for temperature environmental requirements See specifications for temperature ranges of the various models e Must be free of vibrations such as fork lift trucks close by large motors etc e Must be free of air currents or drafts from air conditioning heating ducts opens windows people walking by fans etc e Area must be clean and air must not contain excessive dust particles e Work surface must be stable and level e Work surface must not be exposed to direct sunlight or radiating heat sources e Use an approved Electro Static Device CHAPTER 1 INTRODUCTION 1 3 SPECIAL TOOLS AND TEST EQUIPMENT REQUIRED To properly service the Discovery Balances certain Ohaus special tools and test items are required in addition to standard electronic tool kits These items are listed as follows 1 Alternate voltage Power Adapter if local power requirements do not match balance Adapter voltage ratings 2 APC running Microsoft Windows NT 4 0 or later or Microsoft Windows 98 or later 3 Discovery Instruction Manual Part No 80104130 4 MFR Service Toolset Part No 80030340 Figure 1 1 Service Toolset Part No 80030340 5 RS232 Cable Balance to PC P N 80500525 6 Standard Electronics Tool Kit 7 Digital Voltmeter DVM Input impedance of at least 10 megohms in the 1 Volt DC position 8 Masses as shown in Table 1 4 These masses are available from any Ohaus dealer 9 Discovery So
15. not center properly over the Magnet and Temperature Sensor Tube the Ratio Beam Flexures must be checked to see if they are bent Place each Flexure on a clean flat surface and check that both sides rest evenly on the surface If they don t replace them 3 2 5 1 Ratio Beam Flexure Replacement 5 1 Ensure yoke is aligned evenly side to side with frame and flush with frame on front Ratio Beam Flexures Figure 3 65 Yoke aligned with frame side to side and flush with frame on front 5 2 Re install Hanger with Brass Fixture and Thumb screws 5 3 Insert Brass Brackets on both sides See Figure 3 66 next page 5 4 Press Brackets from each side and Brass Fixture from below to ensure that Brackets are snug against yoke so that if Brackets are pulled there is resistance CHAPTER 3 REPAIR PROCEDURES 3 2 4 Load Cell Assembly 5 5 5 6 9 7 5 8 5 9 5 10 5 11 5 12 5 13 5 14 5 15 5 16 5 17 5 18 5 19 Loosen top 2 Flexure screws Screw in the Threaded Rod to snugly hit the Ratio Beam Remove Flexure screws and Flexures Examine Flexures If they are bent replace them Loosen Threaded Rod and insert Centering Pin in Temperature Sensor Tube Temperature Sensor Tube Figure 3 66 Centering Pin from Service Toolset goes into Temperature Sensor Tube in middle of Magnet Insert Brass Rod in rear Screw Threaded Rod back in Remove Brass Brackets and ensure that Ratio Beam is visually cen
16. the PCB and its Mounting Plate as shown in Figure 3 24 Figure 3 24 Lifting off the PCB and its Mounting Plate from the Load Cell 10 Lift off the Load Cell Cover It has no screws Figure 3 25 Lifting off Load Cell Cover CHAPTER 3 REPAIR PROCEDURES 3 2 1 Load Cell Removal i ah Figure 3 26 Load Cell with cover removed 11 Remove the Cantilever Arm by applying slight downward pressure with the fingers and press upward with the thumb then sliding away from the Load Cell Cantilever Arm l 4 mi p 3 ki i i A A 3 in m y a r 3 s e e y Shs A k h G Pr ge n x 7 y B TEF Pe Figure 3 27 Removing Cantilever Arm from Load Cell 12 Tilt the balance onto its back and remove the 3 screws that secure the Load Cell to the Bottom Housing Screws securing Load Cell to Bottom Housing Figure 3 28 Bottom Housing of Load Cell CHAPTER 3 REPAIR PROCEDURES 3 2 1 Load Cell Removal 13 Remove the Load Cell jostling it away from keyway which faces towards the front of the balance See Figure 3 29 Load Cell keyway inside chassis Figure 3 29 Load Cell chassis Note position of keyway facing towards front of balance 14 Disconnect the cable from the Load Cell by pulling it downward Figure 3 30 Load Cell removed CHAPTER 3 REPAIR PROCEDURES 3 2 2 Load Cell Disassembly 1 First follow procedures for Load Ce
17. 1 3 Main Printed Circuit Board PCB Removal amp Replacement c ccccceeeees 3 8 3 1 4 Incal Weight Hardware DISASSEMDIY ccccceeecceeeeceeeeeseeeeseeeeeeeeeesaeeeseeeesaes 3 10 3 1 5 Removing and Replacing Calibration Motor Assembly ccccsseeeeeeeeeeeees 3 13 3 2 Load Cell Cover Removal and Disassembly cc cccceeeeeeeeeeeeeeeeeeeeeeeeeeeseeeeeesens 3 15 3al Load Removal ma a RC a Me eRe er anne EE 3 15 322 Load GellDISASSEMDIY erria nude iaasnunssbousnnes 3 20 329 Load Gell GIG AMIN Gtarseseuae enee aE EAT eSa 3 30 Se EoadiCelASSSmDIY aratura a E Nde ee tal 3 31 325 INSANO Eoad elliri E E sa ata ea 3 45 CHAPTER 4 TESTING Alc VESUNG ereraa EO E 4 1 41 1 Operational TeSt acssriinisa e a a 4 1 4 1 2 Models Segment Display TeSt ccccceccccssseceeeeeeeceesaeeeeeesseeeeeeseeeeeeeseeeeeeneas 4 1 42 Load Cel Perormance Tesis ennn tel onre diem ee damerhn aera easel aaa atel eaten lae 4 1 22 Off Center Load Testyn i sesencdaceda tee sesueck A OA 4 1 4 22 Ad s ng Ol Center Load xi cevetiacioss ecrevasectervindenincehe a a 4 2 4 23 Repeatability VCS renen e a ai aaia 4 4 424 RemedidtONM sorssnsansee a tenet boaueriaeedeoleaeniws 4 4 425 WANN IY TES ises a iis wen enn alaseds 4 5 ASS Ro232 IME Mace TeS leei isons kaon ate asia ia toni R 4 6 Aa R9232 CONNECCION anneren R 4 6 4 4 1 Connecting the RS232 Interface cc ceccccceseeeeeeeeeeeeeaeeeeeesseeeeeeseeeeeess
18. 4 4 Com 1 Connector as it appears on balance s back COVE ccccccsseeeeeeeeeeeaees 4 7 AG Adapter CONG sateucsaactaccuesntndacddeuuaetnctu Sabie oi 4 9 Discovey Balanco HOUSING tcctetetisnctiedcaesetnsuswiandaitatnia N 5 1 Discovery Balance Display Assembly ccccsecccseeeceeeeceeeeseeseeceeseseeeesseeesseeeens 5 2 Internal Parts Outside Load Cell cccccccccsececcceeeceeeceeeeeeseeeeceesseeeeeesaeeeeeesaaaeeess 5 3 Discovery Balance Load Cell Parts cccccssseeeceeeeeeeeeeeeeeseeeeeeeseaeaseeeeeessanseeeees 5 4 Calibration Menu flow Press No until the desired option appears then Yes A 1 Service Calibration Menu Sequence cccccseecceeceeeeeeeeeeeeeeeseeeeeeesseeeeessaeeeeeeeas B 1 Com Porn GOMIGUIANOMINGMUisieites cticewsicnrertea nina cher ian a C 1 Software Service Tool s Restore EEProm tab ccccsseeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeas C 2 software Service Tool s Replace Load Cell tab eeeeeeeeeeeeeeeeeeeeeeeeeeeeees C 3 software Service Tool s Replace PCB tab 0 ceeeceeeeceeeeeeeeeeeeeeeeeeeeeaeeeeeeeeeeaes C 4 Software Service Tool s Download Software tab cccccccecssseeeeeeseeeeeeeeeeeeeees C 5 Software Service Tool s Diagnostics tab cccccsseseececeseeseeeeeseenseeeeeeeseseeeeseaes C 6 TABLE OF CONTENTS CHAPTER 1 INTRODUCTION 1 1 INTRODUCTION This service manual contains the information needed to perform routine maint
19. DIX C SOFTWARE SERVICE TOOL INSTRUCTIONS Gl Restle EEPROM Data iera A A a C 2 Ge Replace kodadele mee a tr mee arte eee nennet ane erm erene Goren ements Sn ene rt Onna C 3 C 3 Install new Main Printed Circuit BOard cceecccccccccceeeceeseseeeceeeeeteeeceeseeeeseeeeetsaaees C 4 C 4 Update Software in the Balance cccccccseeecceceeeeeeeeseeeeeeeaeeceeeseeeeeeseeeeeeeseeeeeeeeeas C 5 Co DIAGN OSUCS sesan i Cd dacneclc naetel seein ea E wershoas searte saat C 6 C 5 1 Incal Weight Mechanism TeSting cccccescccsssseceesseesceeeseeceeseeeeeeeseeaeeeessaaeeess C 6 LIST OF TABLES TABLE NO TITLE 1 1 Masses Used to Test Discovery Balance ccccccccceeceeeeeeeeeeeeeeseeeeeeseeeeeeseeeeess 1 3 1 2 Discovery Balance Model SpecifiCations ccssccccccssseeeeeceeeeeeeeeneeeeeeeeeeeeesaaeeees 1 4 2 1 Balance WILNO TUG Of en sueuesatuvientuas tenetan eea Eea ENE RENARE SENE 2 2 2 2 Balance Does Not Respond to Front Panel Controls ccccecceesseeeseeeeeseaeeees 2 3 2 3 NO DISpIay OF Partial DISDIAY cnciauiattaiccase iadabamnmebvantaiuitinndenniee ea aacueabicierina 2 3 2 4 Balance Cannot Calibrate Using External Weights ccccsseseeeeeeeeeeeeeeeeeeeees 2 4 2 5 Balance Cannot Calibrate Internally ccccccceccceceeseeeeeeeeeeesseeeeeeseeeeeesseeeeeeeeas 2 5 2 6 TOM GOODE S anar vata oaunieeuaneeiinssaybaasnaseeieus tun nedeisosusicavnvereieneineuoaeia nena 2 6 3 1 Display Assembly P
20. EPROM Replace Loadcell Replace PCB Mot File To Download To Scale None Selected Change Download Mot File To Scale Mot File Not Found Select New Start Download Figure C 5 The Software Service Tool s Download Software tab 4 Enter the path to the file to download or click the Change bution to locate the file 5 Click on the Start Download button 6 When prompted disconnect the power from the back of the balance then re connect 7 The software will indicate the download process When complete disconnect the power from the back of the balance then re connect 8 Perform Service Calibrations see Appendix B Test the balance APPENDIX C SOFTWARE SERVICE TOOL INSTRUCTIONS C 5 Diagnostics 1 Connect the balance to your computer 2 Start the Discovery Software Service Tool 3 Click on the tab labeled Diagnostics Discovery Service Tool 1 00 E aloj x File _ Settings f RestoreEEPROM ReplaceLoadcell ReplacePCB Download Software Command String Send Print InCal Weight Control Arae Fartial Load 1 Partial Load 2 Total Load Figure C 6 The Software Service Tool s Diagnostics tab 4 To test communications enter a Command String as found in Table 4 3 RS232 Command Table Click the Send button 5 The scale s response will be shown in the box on the right C 5 1 Incal Weight Mechanism Testing Note This procedure is used
21. OCEDURES 3 2 5 Installing the Load Cell 8 Place the Printed Circuit Board PCB Mounting Plate on the Load Cell aligning the screw holes on the left and right Ensure that the cable from the Load Cell to the Main PCB lies flat passing though the small slot on the left of the Load Cell Cover Cable from Load Cell to PCB lies flat in slot beneath PCB Mounting Plate 9 Insert copper colored stand off screws through holes in PCB Mounting Plate Tighten with a wrench 2 7 Se Figure 3 96 Stand off screws secure PCB Mounting Plate 10 Connect the cables to the PCB Pass the small cable through the rectangular slot on the right of the PCB Mounting Plate CHAPTER 3 REPAIR PROCEDURES 3 2 5 Installing the Load Cell 11 Install the InCal Weight Assembly 11 1 Carefully remove any dust or debris from the Weights Weight Holders and their environment using alcohol on a clean cloth 11 2 Install the Weights and Weight Holders Note A clean glove should be worn when handling Weights 11 3 Place the InCal Weight Cover over the Weights aligning the screw holes left and right The screws will be installed in the Display Cable Shield Plate which rests on top of the InCal Weight Cover Sie Weight Cover P j i Figure 3 98 Proper position of InCal CHAPTER 3 REPAIR PROCEDURES 3 2 5 Installing the Load Cell 12 After putting the Weight Cover on connect the Display Cable to the main PCB C
22. OFF or SET ON Press No to toggle the display from AUTOCAL SET ON to AUTOCAL SET OFF then press Yes Press Exit to exit the Calibrate Menu Repeat this process to re activate AutoCal Automatic internal calibration is included in all Discovery models APPENDIX A STANDARD CALIBRATION A 2 Span Calibration Before initiating Span Calibration determine the balance s model number It appears when the balance is powered up Also be sure to have masses available Press and hold Cal Menu until Menu Calibrate is displayed with CALIBRATE blinking then release the button Press Yes to enter calibration CAL AUTOCAL is displayed Press No Press Yes to initiate span calibration For a split second SPAN_ CLEAR SPAN will come up on the display and then 100 ACCEPT Press No to toggle to 50 ACCEPT and back to 100 ACCEPT for the acceptable weight used if the acceptable weight is 100 grams Then press Yes Next the display shows the Add Weight message with the weight selected Place the indicated weight in the Pan Calibration will begin The SPAN BUSY message flashes while the balance reads the maximum weight setting When the maximum weight reading is taken the Clear Pan message appears Remove weights to allow the zero reading to be taken While the balance takes the zero reading 0 BUSY is displayed If calibration is successful the SPAN DONE message appears and an appears on the left of the screen signifying that t
23. Print To clear tare enter O for x CHAPTER 4 TESTING 4 5 Print Test Printing data to an external computer or printer requires that the communication parameters in the RS232 submenus be set to match external device communication parameters 1 Remove all weight from the Pan 2 Tare the balance 0 0g should be displayed 3 Place a mass on the Pan 4 Press Print button the computer or a printer should indicate the mass value as shown on the display 4 6 Testing the AC Adapter The AC Adapters are available with different input voltages Before testing the Adapter make sure the Adapter rating agrees with the power source being used All Adapters are rated with an output of 12 V AC at 1 0 Amp Adapters can fail by having shorted internal windings producing low voltage output or no output at all Measure the Voltage between Pin A and Pin B of the Adapter see Figure 4 6 to assure the proper voltage Note Measure the Voltage between Pin A and Pin B Pin A Pin B Figure 4 6 AC Adapter Cord CHAPTER 5 PARTS LISTS amp DIAGRAMS 5 1 DISCOVERY HOUSING TABLE 5 1 PARTS LIST FOR DISCOVERY HOUSING Pan Sealing Tape Figure 5 1 Discovery Balance Housing CHAPTER 5 PARTS LIST amp DIAGRAMS 5 2 DISCOVERY DISPLAY ASSEMBLY TABLE 5 2 PARTS LIST FOR DISCOVERY DISPLAY ASSEMBLY Discovery Display Assembly
24. Seevinnawandacuiss lt aesd aeeneadead sient 3 14 Calibration Motor close up Showing cam in rest POSITION ccceeeeeseeeeeeeeeeees 3 14 Removing Display Cable Shield Plate cccccccccccesseseeseeeeeesseeeeeeseeeeeeesnaees 3 15 The InCal Weight Cover sits beneath the Display Cable Shield Plate 3 16 Removing Weights and Weight Holders while wearing a clean glove 3 16 Lifting off the PCB and its Mounting Plate from the Load Cell cccceseeeees 3 17 Lining On Load Gell COVER issiria uses atest tana teens saa e E 3 17 Load Cell with Cover removed acesi a 3 18 Removing Cantilever Arm from Load Cell cccccccceseeceeeeeeeeeseeeeeeeesaeeeseesaaees 3 18 Bottom Housing Ol Load Celkroreniie a ia 3 18 Load Cell chassis with keyway position highlighted ccccsecceesseseeeeeeeeees 3 19 Load Gelli PeMOV SG siscascasccien teenie lances cnvekornobsehedsiciaasaetesutnepavsiwadaiasiorannnsyacaorenen 3 19 Removing screws from Load Cell top COVE cccccseeeceeeeeeeeeeeseeeeeeeeeeeeeeesnanes 3 20 Load Cell with top cover removed ccccsseececceeeececeseeeceeceeeeeeeeeeaeeeeseeaeeeesaaaeeess 3 20 Removing screws from Load Cell bottom COVE ccccccceeeeeeeeeeeseeeeesaeeeeeeees 3 20 Load Cell with bottom cover removed cccccseeeceeeseeseeeeceeeeeeesaeeeeeeseeeeeeseaeeees 3 20 Screws on bottom Flexure Arm assembly ccccseeeececeeee
25. Service Tool s Replace Load Cell tab Enter the IDNR number xxx xx xx xxxx from the label on the back of the balance Click the Start button 10 The software will indicate the download progress When complete disconnect the power from the back of the balance then re connect 11 Perform Service Calibrations see Appendix B Test the balance APPENDIX C SOFTWARE SERVICE TOOL INSTRUCTIONS C 3 Install New Main Printed Circuit Board PCB 1 Follow steps in Sections 3 1 3 to replace the PCB Then connect the balance to your computer 2 Start the Discovery Service Tool Software 3 Click on the tab labeled Replace PCB Discovery Service Tool 1 00 File Settings Restore EEPROM Replace Loadcell Figure C 4 The Software Service Tool s Replace PCB tab 4 Enter the S N value from the label on the back of the balance 5 Enter the IDNR number xxx xx xx xxxx from the label on the back of the balance 6 Click the Start button 7 The software will indicate the download progress When complete disconnect the power from the back of the balance then re connect 8 Perform Service Calibrations see Appendix B Test the balance APPENDIX C SOFTWARE SERVICE TOOL INSTRUCTIONS C 4 Update the Software in the Balance 1 Connect the Balance to your computer 2 Start the Discovery Service Tool Software 3 Click on the tab labeled Download Software Discovery Service Tool Y1 00 File Settings Restore E
26. Test Equipment 99 Washington Street Depot Melrose MA 02176 Phone 781 665 1400 1 800 517 8431 Toll Free 1 800 517 8431 fF OHAUS SERVICE MANUAL DISCOVERY BALANCE 2 OHAU SERVICE MANUAL DISCOVERY BALANCE The information contained in this manual is believed to be accurate at the time of publication but Ohaus Corporation assumes no liability arising from the use or misuse of this material Reproduction of this material is strictly prohibited Material in this manual is subject to change Copyright 2007 Ohaus Corporation all rights reserved TM Registered trademark of Ohaus Corporation TABLE OF CONTENTS Page No CHAPTER 1 INTRODUCTION kE WAUOGUCTON espn E E reac ebedewetiew 1 1 EZ sO CRVICC Tr ACIES eerie a EE E ate Lat 1 1 1 3 Special Tools and Test Equipment Required cccccsseeeeeceeeeeeeceeeeeeeeeeeeseeaeees 1 2 t4 TestMasses I ACOUINCO ranis r chemo niacacers neice E 1 3 Te SSDCCHICANONS eao a a a 1 4 CHAPTER 2 DIAGNOSIS Ze M OUDIESNOOUN eaaa int en eaters h tect ak coatacttes oestrone aun ceesgciatate 2 1 Ze Diagnosis OUE eie EE E ease 2 1 22i Dagos renep E E 2 1 23 TabEOLENOrGOdES ye N e E E E 2 6 CHAPTER 3 REPAIR PROCEDURES Gel REDArPrOCCOUrES enuia E ee a a eal 3 1 3 1 1 Housing Disassembly Opening the Balance ccccceececseeeeeeeeeeeeseeeesseeeeeeaees 3 2 3 1 2 Display Removal amp Replacement cccccccccssccceececeeeeeeeeeseeeeseeseeseeeseeessaees 3 5 3
27. aanes 3 39 Top Flexure Arm Assembly with Flexure screw heads facing outward 3 39 Installing the Upper Flexure Arm cccccescsecesesecenesecenseeeessasereneeeessaeeessaereneaes 3 39 Load Flexure aluminum washers steel washers and SCIeWS 0 0cceeeeeeeeees 3 40 Load Flexure on top of Hanger with elongated screw hole at bottom 3 40 Hanger with Thumb screws removed cccceeeceeeeeeeeaeeeeeseeeeeseueeeeseeeeeseaeessaaeees 3 41 Pushing Brass Fixture from grooved side cccseecceceeeeeeeeeeeseeeeeeaeeeeeeaeeeesaaes 3 41 Pulling Brass Fixture out from square SICE cccccessececceeeeeeeceeseeeesseseeeeesaneees 3 41 Note stops on sides of bottom Load Cell Cover ccecccccecccceeeeeeeeeeeeseeseetseeees 3 42 Tightening screws on bottom Load Cell Cover ccccceccccessseeeeeeseeeeeesaaeeeesaaees 3 42 Top Load Cell Cover rests flush against bottom COVET cccccsseeeeeeeeeeeeeeeeees 3 43 Tightening screws on top Load Cell COver ccccccccssssseeeeeeceeseeeeeesaeeseeeeeeseaaeaes 3 43 lf Hanger moves smoothly assembly is successful cccccceeeecseeeeeeeeeeeeeeeees 3 44 Load Cell Chassis with keyway at point of triangle c cceeeeeeeseeeeeeeeeeeeeeeeees 3 45 Three screws on bottom that secure the Load Cell to the Chassis 3 45 Cantilever Arm in correct POSITION ccccseeseeeeeceeeeseeeececeeeeeeeeeesaesseeeees
28. amp x Figure 3 90 Load Cell Chassis with Figure 91 Three screws on bottom that secure keyway at point of triangle the Load Cell to the Chassis 2 Mount the Cantilever Arm sliding it under the Hanger so that its stop shelf rests on Cantilever Arm Right side of Hole under Cantilever Arm Left side of Hole under Cantilever Arm Figure 3 92 Cantilever Arm in correct position 3 Make sure the Load Cell is properly aligned The spaces of the hole underneath the left and the right of the Cantilever Arm should be equal See Figure 3 92 Note J The Cantilever Arm is delicate and should be handled carefully Do not use the Cantilever Arm to adjust the Load Cell position CHAPTER 3 REPAIR PROCEDURES 3 2 5 Installing the Load Cell 4 Tighten the 3 mounting screws after aligning Load Cell Tighten screw at point of triangle first then re check alignment and adjust as necessary Then tighten 2 screws at base of triangle Re check alignment and adjust as necessary 5 Connect the flexible cable on Load Cell using the back of a pair of tweezers to press cable into place Also connect cable on Calibration Motor Assembly 6 Place the Load Cell Cover over the Load Cell 7 Note the notches for cables top left for Load Cell cable and bottom right for Calibration Motor Assembly cable Figure 3 94 Load Cell with Cover in proper position cables resting in notches top left and bottom right CHAPTER 3 REPAIR PR
29. ants LIST ccoctanvctantestatubarhvenniodunboenesinigectvanntenetibventavainclemedtaanligons 3 5 4 1 DISCOVERY TESUIMASSES usien a E 4 5 4 2 COMIHntenace PINMCONMECUONS wisi cater ceiecs a a et Guee 4 7 4 3 Ro232 GOMM MNG TADE nerion coven cuieahas Saedenaadeaectetai 4 8 5 1 Parts List for Discovery Housing ccccscccsseecceeeeceseeceeeseeeeeceeeseusesseeesseeeeseeess 5 1 9 2 Parts List for Discovery Display Assembly cccccceeseeeceeeeeseeeeseeeesseeeeseeeeseeeens 5 2 5 3 List of Internal Parts Outside Load Cell nnnnn0nnnnnannnnnannnnnenennnnnennnnnrnennnnnnnnnnnnne 5 3 5 4 Listor Discovery Load Gell Parts e 2snteenniinc nuked E 5 4 LIST OF ILLUSTRATIONS FIGURE NO TITLE 1 1 Service Toolset Part No 80030340 oo cc eececceccecceeeeceecesaeseeceeceeaeeaeeesaneaes 1 2 3 1 Breeze Ring Breeze Ring Base Grommet and Pan removed from Discovery Balance c cccccssececceeeeeceeeeceeeecseeeesseeeeseeseesegeeseas 3 1 3 2 Removing Discovery Balance back COVED ccccccescceseseeesseseeeneneseseeeeeeneueeensaaees 3 2 3 3 Balance with back cover rOMOVEG cccsscccccseeeecseeeeeeeeeeeceseeseaeeessaeeeeseaeessaaeeeess 3 2 3 4 Scale bottom showing Draft Shield Assembly cccccecceeesseeeeeeseeeeeeeseeeeeeseaees 3 3 3 5 Discovery Balance with cover removed ccceececseeeeceeeeeeeeesseeesseeeeseeeeseeeesseeeess 3 4 3 6 Keyway hole on cover guided over cone shaped brass screw head
30. are Service Tool See Appendix C 1 Replace Main PCB Error 9 5 Production calibration not Perform Service Calibration present See Appendix B Error 9 8 User calibration data not Calibrate balance present Required for LFT ON only Error 53 EEPROM checksum error Cycle power on off If balance fails to operate restore EEPROM data LOW REF WT Average piece weight too See Instruction Manual for small Warning only more detail count will continue REF WT Err Reference weight too small Increase sample size The weight on the pan is too small to define a valid reference weight Busy during tare zero printing Wait until completion calibration etc Unstable weight reading If balance is level in appropriate environment repair Load Cell CHAPTER 3 REPAIR PROCEDURES 3 1 REPAIR PROCEDURES This section of the manual contains detailed disassembly procedures of the Discovery Balance Section 5 of this manual contains exploded views and associated parts lists for all models Refer to Section 5 drawings before disassembling the balance Components inside of the balance are delicate Handle with care 3 1 1 Housing Disassembly Opening the Balance To disassemble the balance refer to Figure 3 2 Components shown below must be removed before gaining access to the inside of the balance Proceed as follows y ae rn Always use an anti static kit 1 Turn the balance off 2 Disconnect the power cable
31. arefully position the cable so it fits under the Display Cable Shield Plate 13 Place the Display Cable Shield Plate over the InCal Weight Cover carefully checking that the flat Display Cable fits in the raised groove 14 Before tightening the screws in the Display Cable Shield Plate check that the Pan Socket is centered in the hole Then tighten the screws See Figure 3 99 EE iF TE a i _ ee aa ee eS a Figure 3 99 Inserting screws in Display Cable Shield Plate after checking that Pan Socket is centered in hole in middle of Plate Display Cable running under Display Cable Shield Plate Figure 3 100 Correct position of Display Cable under Display Cable Shield Plate CHAPTER 3 REPAIR PROCEDURES 3 2 5 Installing the Load Cell 15 Replace the PCB Cover taking care not to bend the alternating teeth that secure it to the Load Cell Cover Insert and tighten the screws on left and right Alternating teeth in PCB Cover a Figure 3 101 Securing PCB Cover 16 Replace the Housing Pan Grommet Breeze Ring and Breeze Ring Base following the steps in Section 3 1 1 in reverse order 17 If anew Load Cell has been installed connect the balance to a personal computer with the Discovery Software Service Tool installed Refer to Appendix C 2 and follow instructions to Replace Load Cell 18 Perform a Span Calibration in accordance with the instructions in Appendix A 2 19 Check the performa
32. by moving the sample to different areas of the Pan 1 Place half of the balance capacity in the center of the Pan 2 Note the reading 3 Move the mass halfway between the center and the edge to the front of the Pan Note any differences in the displayed weight reading 4 Repeat the test for the back left and right position of the Pan CHAPTER 4 TESTING 5 Maximum allowable change in displayed weight readings is shown in Table 1 2 page 1 3 for each of the four positions If this reading is exceeded follow procedures in Section 4 2 4 Adjusting Off Center Load 4 2 2 Adjusting Off Center Load If the Off Center Load OCL is excessive perform adjustment as follows 1 Pop out the hole plugs and insert both Allen Keys from the Service Toolset as shown in Figure 4 2 EN Key Allen Key inserted in a ae pop out hole in back cover in back cover Figure 4 2 Holes in back cover must be popped out to insert Allen Keys The recommended position for the OCL adjustment is shown in Figure 4 3 Figure 4 3 Proper position for adjusting Off Center Load CHAPTER 4 TESTING 4 2 2 Adjusting Off Center Load 1 Place a weight close to full capacity at the pan center Press TARE 2 Move the weight to the back edge and note the display 3 Move the weight to the front edge and note the display 4 Move the weight to the right edge and note the display 5 Move the weight to the left edge and note the display Figure 4
33. cord the weight and remove 6 Place Load 3 on the balance and press TARE 7 Place the test mass on the balance and record the weight 8 Place Load 4 on the balance and press TARE 9 Place the test mass on the balance record the weight and remove 10 The difference in the weights of the test mass should be within the tolerance in Table 1 2 If not perform an internal calibration see Appendix A 1 and repeat the test 11 If the balance remains out of tolerance the Load Cell may need to be repaired CHAPTER 4 TESTING 4 3 RS232 Interface Test The Discovery Balance Interface can be tested using an external printer or computer connected to the Balance The RS232 menu provides communication parameters which can be set to accommodate external printers or computers It contains three submenus Baud rate Parity and Handshake 1 Set the RS232 Baud rate Parity and Handshake as required on the balance 2 Set the communication parameters on the computer to the same settings as the balance 3 Connect an RS232 cable Part Number 80500525 between the balance and the computer Baud Rate Use the submenu to change the Baud settings Baud rates can be set from the range of 600 to 19 200 The default setting is 9600 Parity Use the submenu to change the Parity settings Parity can be set to 7 Odd 7 Even 7 No Parity or 8 No Parity The default setting is 8 No Parity Handshake Use the submenu to change the Handshake setting
34. ding to the required weight Add the amount of weight indicated A Busy message will appear together with a number corresponding to the indicated weight When the span calibration is completed the Span Clear Pan message appears When the balance determines the Pan is empty the 0 busy message appears If calibration was successful the Span Done message appears If calibration was unsuccessful the Span Abort message appears and the menu returns to Service Ramp If Span calibration fails refer to Chapter 3 and check the InCal Weight Mechanism and the Load Cell assembly Clean and or repair as necessary APPENDIX B SERVICE CALIBRATION B 5 Service Internal Calibration InCal Use internal calibration from the service menu after any service procedure NOTE The balance should be perfectly level before attempting a service calibration Use the balance s leveling feet at the rear of the balance together with the leveling bubble which is just inside the left Door Side Draft Shield After pressing No to Ramp and Span press Yes to start the internal calibration The INCAL Busy message appears If the calibration is successful the INCAL Done message appears lf the calibration is not successful the INCAL Abort message appears First try to re stabilize the balance and try again If calibration still fails refer to Chapter 3 check the InCal Weight Mechanism and the Load Cell assembly Clean and or repair as
35. e dirty mis aligned or defective Calibration Motor Assembly may be defective Main PC Board may be defective Load Cell PCB is defective PROBABLE CAUSE REMEDY Level the balance using leveling feet on rear of chassis together with leveling bubble just inside the left Door Side Draft Shield Disassemble the InCal Weight Hardware and test It gt InCal Weight Hardware Disassembly amp Testing 3 1 4 If there are problems with the Weight Arm movements check the Calibration Motor and replace if necessary gt Removing amp Replacing Calibration Motor Assembly 3 1 5 Verify that all other functions are operational If not the Main PC board may be defective gt Main PCB Removal amp Replacement 3 1 3 Replace Load Cell PCB See p 3 27 CHAPTER 2 DIAGNOSIS 2 3 ERROR CODES The following table lists error codes possible causes and remedies If the problem persists contact Ohaus Corporation TABLE 2 6 ERROR CODES ERROR CODE PROBABLE CAUSE REMEDY Error 7 0 Unstable weight reading Eliminate vibration and when defining the reference drafts weight Error 8 0 Weight reading below Put pan on balance Power On Zero limit Error 8 1 Weight reading exceeds Clear pan Power On Zero limit Error 8 3 Weight reading exceeds Clear pan overload limit Error 8 4 Weight reading below Put pan on balance underload limit Error 9 0 Internal fault Restore EEPROM data using Softw
36. eaeaeeeensnas 3 45 Replacing Load Cell COVER ariris nine arria E E ination E 3 46 Load Cell with Cover in proper position cables resting in notches 006 3 46 Placing PCB Mounting Plate on Load Cell nnnnannnannnnannnnennnnnnnnnennnnnnnnenennnnnnne 3 47 Stand off screws secure PCB Mounting Plate cccceccccsseeeeeseeeeeeeeesseeeeees 3 47 Installing Weights and Weight HOIderS ccccssecececeeeeeeeceeeeeeseeeseeeesaneeeesaaees 3 48 FIGURE NO 3 98 3 99 3 100 3 101 4 4 4 2 4 3 4 4 4 5 4 6 5 1 5 2 5 3 5 4 QNNN0NWF OORUN J gt TABLE OF CONTENTS LIST OF ILLUSTRATIONS Cont TITLE Page No Proper position of InCal Weight Cover cccccccecssseeeeeeeseeneeeeesesaeeeeeeesaaneeeess 3 48 Inserting screws in Display Cable Shield Plate after checking that Pan Socket is centered in hole in middle of Plate 3 49 Correct position of Display Cable under Display Cable Shield Plate 3 49 SCUO FOB COVEN nannan 3 50 LCD Full Display for Discovery Balance ccccccccccseeeeeseeeeeeeeeeesaeeeeeseeeeeeneeeeeas 4 1 Holes in back cover must be popped out to insert Allen Keys cccseeeeeneeees 4 3 Ohaus engineer demonstrates adjusting Off Center Load cceccceseseeeeeeeeees 4 3 Allen key rotation directions needed for back edge heavy back edge light right edge heavy and right edge light conditions 00
37. eeeeeeeeas 4 6 442 TASZ32 GOMIMANGS serso iger nr AEEA AEN 4 8 Aao OS na E EE E T E EAE AEO 4 9 46 WOStINGINE AG AGADICN aer aie oieedcntteaaeneie casita temerity 4 9 CHAPTER 5 PARTS LISTS amp DIAGRAMS Dill WISGCOVETY IOUS IN Ciara stor assnsie e E sunt sssutenshid estat saestsuactantendsaavouse 5 1 5 2 Discovery Display ASSEMDIY cccccccccsscccsseeccesecceeeecececscesseeeeceeenseeenseeessasessaess 5 2 5 3 Discovery Internal Parts Outside Load Cell cccccecceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeaas 5 3 De Discovery Load CEPAS asn N 5 4 TABLE OF CONTENTS Page No Appendix A STANDARD CALIBRATION A 1 Automatic Internal Calibration Advanced Auto Call cccccccecseeeeeeeeeeeeseeeeseeeeeees A 2 A2 Span Calibration saxe sicatteste teicieee eh eeetiat ox qn gaea cetera aA A 3 AS Galibration VesttGal TES sj ti rin Soccer ett a eennae era eens A 4 A 4 Calibration Adjustment Gal AG dascssvosiessstel ee tet oocaienosnindedaesen se di alalaiea A 5 Appendix B SERVICE CALIBRATION BA INAVIG ATOM aussaristdennuesannuese teaemandaansgeade patna EE AEE E EEA B 1 Biz Emering Sevice Meni sarran a eMail a ened war aeo tates B 1 Bo IRIN eceterate eiGlaesatepeenutees cia anderen ihi nea iamaancne ta caniaeeeiashumancthnerarniasnanninurcusmecemmeendiis B 2 BA SENICE Span CollbratOn ese E B 3 B 5 Service Internal Calibration InCal n00nnnaannonnnnnannnnennnnnnnnsnrnnnnnnsnnnnsnnrnsrrrrnnrnnene B 4 APPEN
38. eeeeeeeeeeesaeeeeeeesaeeeeees 3 21 Screws on top Flexure Arm assembly ccccceccccceseeceeeseeeeeeeeeeeeeeseaeeeeeseaeeeeeeas 3 21 Service Toolset Part No 80030340 o oo eee eeceeceeceeceeeeceeceseesaeseceeaeeaeeaeanes 3 22 Brass Fixture inserted part way under the Load Cell s Hanger c 0008 3 22 Brass Fixture fully inserted under the Load Cell s Hanger 0 ccceseeeeeeeeeees 3 22 Thumb screws and Hanger on top of Load Cell cc ccccccseececeeeeeeseeeeeeseeeeeees 3 23 Screws securing Load Flexure to Hanger on top of Load Cell ceeeeee 3 23 Load Cell with Load Flexure 2 screws and 4 washers removed cccseeeeees 3 24 Flexures can be removed from Flexure Arm after removing Flexure Arm from Load Cell frame 0 0 0 cccceeeeeceeeeeeeeeeeeeeeeeeeeeaes 3 24 Removing the top Flexure Ari cccccccseecccesceceeseceeeeccseeeceusecseecsueeensneessasessaees 3 24 Solder points connecting fine wire to Load Cell PCB cccccccceeeeeeseeeeeeeeeeees 3 25 Lifting Ratio Beam to insert Brass Rod cccceececseeeeceeeeceeeeeeeeeeaeeeeeseeseeeeeaaees 3 26 Brass ROG IMNStAN OG sesyen sener e E 3 26 Screwing in Threaded Rod on front of Load Cell cccccccscsseeeeeeeeeeeeeeeeeeeeees 3 26 Removing screws from PCB Note stepped washer under rear screw 3 27 Magnet Cover WiIhOUt PCB assarrar tee eear ee edace 3 27 Solder points on top of Load Cell
39. een 50 and 100 of the balance s capacity Using a weight at the balance s capacity will give the most accurate results To determine specified capacity see Table 1 1 Masses Used To Test Discovery Balances A 3 Calibration Test Cal Test Calibration test allows the stored calibration data to be tested against the current mass being used for the test A 4 Calibration Adjustment Cal Adj Calibration Adjustment allows adjustment of the internal calibration to match an external calibration weight Note A N Calibration will be locked out if the balance is in Legal For Trade mode To regain access to locked balance settings break the seal on the back and power up the balance while depressing the Lock Switch that was covered by the seal Calibration can also be locked out from the Lockout Menu To allow calibration from the Lockout Menu press and hold Menu then press No until Lockout appears Press Yes When Calibrate appears press No Then press Exit The Calibration Menu To navigate the Calibration Menu proceed as follows Press and hold CAL until Menu Calibrate appears Press Yes to see sub menus Press Yes to choose the sub menu selection Press No to advance to the next sub menu selection Press Back to go to previous sub menu selection Press Exif to return to weighing mode CALIBRATE Figure A 1 Calibration Menu flow Press No until the desired option appears then Yes Before beginning calibration have
40. ell s weight Fall Beam Rod should NOT support Figure 3 76 Load Cell should rest on Threaded Rod left and base of frame right CHAPTER 3 REPAIR PROCEDURES 3 2 4 Load Cell Assembly 18 Install the bottom Flexure Arm with Flexure screw heads facing inward by inserting the 3 screws as shown in Figure 3 73 Screws connecting bottom Flexure Arm to frame Flexure screw heads face inward Screw connecting bottom Flexure Arm to frame Figure 3 77 Installing the bottom Flexure Arm 19 After the bottom Flexure Arm Assembly is installed remove the Threaded Rod 20 Install the top Flexure Arm with Flexure screw heads facing outward by inserting the 3 screws as shown in Figure 3 78 Figure 3 78 Top Flexure Arm Assembly with Flexure screw heads facing outward Figure 3 79 Installing the upper Flexure Arm CHAPTER 3 REPAIR PROCEDURES 3 2 4 Load Cell Assembly 21 Set the Load Cell on its back frame and position the Load flexure with elongated hole on the bottom Load Flexure with elongated screw hole at Screws Steel Aluminum bottom washers washers Elongated screw hole goes on the bottom Figure 3 80 Load Flexure aluminum washers steel washers and screws Figure 3 81 Load Flexure on top of Hanger with elongated screw hole at bottom 22 Genily tighten the upper screw then the lower screw NOTE J lf Load Flexure begins to rotate when tightening screws STOP
41. enance and service on the Discovery Balances The contents of this manual are contained in five chapters three appendixes and are listed as follows Chapter 1 Introduction A guide service facilities tools test equipment calibration masses and specifications Chapter 2 Diagnosis A diagnostic guide for troubleshooting and an error code table Chapter 3 Repair Procedures Disassembly assembly repair and replacement procedures Chapter 4 Testing An operational test segment display tests and performance tests Chapter 5 Parts Lists and Diagrams Exploded view drawings and parts lists for Discovery Balances Appendix A Standard Calibration Procedures for Automatic Internal Calibration Span Calibration Calibration Testing and Calibration Adjustment Appendix B Service Calibration Procedures for Service Calibration Appendix C Discovery Service Tool Instructions Used to update software restore EEPROM data install a new Main Printed Circuit Board and install a new Load Cell Before servicing the balance you should be familiar with the Instruction Manual Part Number 80104130 which is packed with every balance The procedures in this manual assume the technician performing them has a working knowledge of standard hand tools and the repair of precision instruments 1 2 SERVICE FACILITIES To service a balance the service area should meet the following requirements e Should be temperature controlled and
42. for mechanical obstructions Any foreign object touching any part of the moving Pan can cause a balance to fail the Repeatability Test specification Inspect and correct if necessary An error in the Off Center Load Test can affect the results of the Repeatability Test Inspect and correct if necessary See Section 4 2 3 Off Center Load Test Foreign material or debris located in the balance between the Pan and the Draft Shield Bottom can cause the balance to fail the test Environmental influences such as vibrations drafts or a non level surface can also cause failures CHAPTER 4 TESTING 4 2 5 Linearity Test This test is used to determine the linearity of the unit throughout its operating range The masses used to perform this test can be utility masses NOTE A N The balance must pass the Off Center Load Test and Repeatability Test before the Linearity Test may be performed Loads do not have to be test masses They can be anything that totals the mass value The test mass can be anything that weighs near the test mass value TABLE 4 1 DISCOVERY TEST MASSES Capacity g Test Mass g Load 1 g Load 2 g Load 3 g Load 4 g Model g 1 Place the test mass on the balance record the weight and remove 2 Place Load 1 on the balance and press TARE 3 Place the test mass on the balance record the weight and remove 4 Place Load 2 on the balance and press TARE 5 Place the test mass on the balance re
43. ftware Service Tool P N 80104129 CHAPTER 1 INTRODUCTION 1 4 TEST MASSES REQUIRED The masses required to test the Discovery Balances must meet or exceed the requirements of the Class specified The calibration points for the Discovery Models are listed in Table 1 1 Use the minimum number of masses to total the calibration point value Table 1 1 MASSES USED TO TEST DISCOVERY BALANCES pT SPAN CALIBRATION POINTS asm om CALPOINTS g CAL POINTS 9 Class 1 DV314C 300 100 200 Class 1 DV215CD 81 210 200 CHAPTER 1 INTRODUCTION 1 5 SPECIFICATIONS Specifications for the Discovery Balances are listed in Table 1 2 After a balance has been serviced it must meet the specifications listed in the table Table 1 2 DISCOVERY BALANCE MODEL SPECIFICATIONS Model Number DV 114C DV 214C DV 314C DV215CD ny Std dev a Off Center Load 72 eap 2 distance Weighing Units mg g oz ct dwt ozt GN taels 3 momme Custom unit Weighing Parts Counting Percent Weighing Application Modes Checkweighing Animal Dynamic Weighing G N T Totalization High Point Density Statistics Pipette To Capacity by Subtraction External Adapter 100 120VAC 1A 220 240VAC 1A 50 60Hz equirements Calibration Automatic internal and manual external Display Type 2 line e an backlit LCD Display with Text Prompts Display Size in cm 4x A AOK2AB 10 x 2 5 Pan Size Diameter 3 5 9 on Free Height above 9 5 04 Pan in cm Dimensi
44. fully move the Display Cable to the side It does not need to be disconnected for this procedure CHAPTER 3 REPAIR PROCEDURES 3 1 4 InCal Weight Hardware Disassembly amp Testing 4 Lift off the InCal Weight Cover It does not have screws a D ol Figure 3 14 The InCal Weight Cover sits beneath the Display Cable Shield Plate Note A A clean glove should be worn when handling Weights Figure 3 15 Weights and Weight Holders can be removed but should only be handled while wearing a clean glove 5 Remove both Weights and Weight Holders and set them aside 6 Carefully remove any dust or debris from the Weights Weight Holders and their environment using alcohol on a clean cloth CHAPTER 3 REPAIR PROCEDURES InCal Weight Hardware Disassembly amp Testing T Weight Cradles 8 10 11 Test the InCal Weight Mechanism with Weights and Weight Holders removed using the Software Service Tool as explained in Appendix C Sections C 5 amp C 6 While running the test observe the movement of the Weight Arms with the black tips shown in Figure 3 16 Each Weight Arm should move inward when its Partial Load button is clicked Partial Load 1 or Partial Load 2 and both should move inward when the Total Load button is clicked Weight Arms sae C iy KEN Pay Figure 3 16 InCal Weight hardware with Weights and Weight Holders removed Weight Arms with black tips are on either side of
45. he balance is stable A small O appears on the top left of the screen meaning the zero reading is set lf calibration is unsuccessful SPAN ABORT appears This may mean the balance is unstable level the balance and try again If still unsuccessful check for problems as explained in Chapter 3 of this manual When calibration is finished the balance returns to the weighing mode APPENDIX A STANDARD CALIBRATION A 3 Calibration Test Cal Test Calibration test allows a check of a known calibration mass against the last stored calibration information in the balance With the balance on press and hold Cal Menu until Menu Calibrate is displayed with CALIBRATE blinking then release the button Press Yes to enter calibration CAL AUTOCAL is displayed Press No CAL SPAN is displayed Press No CAL CAL TEST is displayed Press Yes and follow the screen instructions CAL TST CLEAR PAN appears for a split second Be sure the Pan is clear 100_ADD WEIGHT appears ww Place the specified weight on the Pan RIR 7 TT Aa ILAIA 4 After a short period the display indicates the difference in weight from the last calibration and then will display the calibration weight on the Pan After the test remove the calibration weight from the Pan To leave the menu press Exit APPENDIX A STANDARD CALIBRATION A 4 Calibration Adjustment Cal Adj Calibration Adjust may be used to adjust the result of the internal calibration by
46. he top Flexure Arm by removing the 3 screws Screws connecting Flexure ee tn Arm to Load Cell frame Washers Flexures Screws Figure 3 43 Flexures can be removed from Flexure Arm after removing Flexure Arm from Load Cell frame Figure 3 44 Removing the top Flexure Arm 10 Before removing the bottom Flexure Arm secure the Ratio Beam by installing the threaded rod as illustrated in Figure 3 48 Then turn the Load Cell over as shown in Figure 3 76 and remove the bottom Flexure Arm as in Step 9 NOTE When handling the Flexure Arms use care to prevent bending the Flexures 11 Carefully examine each Flexure to see if it is bent If uncertain place the Flexure on a Clean flat surface and check that both sides rest evenly on the surface If a Flexure is bent even slightly it must be replaced CHAPTER 3 REPAIR PROCEDURES 3 2 2 Load Cell Disassembly There are two fine connecting wires called Wire Conductor Strips soldered to the Load Cell s PCB and to a smaller PCB on the top front of the Ratio Beam These wires must be carefully disconnected from the Load Cell s PCB in order to further disassemble and repair the Load Cell 12 Unsolder the wires at the solder points on either side of the set screw atop the Load Cell s PCB 13 Remove the solder with a solder sucker to clear holes in PCB so the wires can pass through when you need to solder them back in place 14 Use tweezers to remove wires from holes
47. he yoke align with the frame AN of the Load Cell If they do not Ratio Beam Flexures may need to be replaced as explained next page in Section 3 2 5 1 Ratio Beam Flexure Replacement Align each front side of Ratio Beam yoke with Load Cell frame Screw on side Screw on side of yoke of yoke Ratio Beam Ratio Beam Flexure Flexure Figure 3 63 Yoke of Ratio Beam must align with frame of Load Cell 2 Insert Brass Rod on back side under the Ratio Beam Be sure Threaded Rod is on front See Figures 3 45 3 46 and 3 47 page 3 26 pee r 4 X i 1 i Magnet Temperature Sensor Tube Brass Rod pea Gap between Coil Coil inside and Magnet Magnet Figure 3 64 Installing Ratio Beam with hole centered over the Temperature Sensor Tube 3 Ensure that the hole in the Ratio Beam is centered over the Temperature Sensor Tube and that the gap between the Coil and the Magnet is even Move the Ratio Beam assembly only by the yoke until it is perfectly centered CHAPTER 3 REPAIR PROCEDURES 3 2 4 Load Cell Assembly 4 Once the Ratio Beam is centered remove the Brass Rod in the front and the Threaded Rod in the back and gently move the Ratio Beam up and down from the rear checking for any friction If there is friction replace the Brass Rod and repeat the centering process 5 Tighten the screws on each side of the yoke shown in Figure 3 65 when the Ratio Beam is centered Re check movement NOTE If Ratio Beam Coil does
48. hen the Main PCB should be replaced gt Main PCB Removal amp Replacement 3 1 3 TABLE 2 3 NO DISPLAY OR PARTIAL DISPLAY SYMPTOM PROBABLE CAUSE REMEDY Display is not on or Display PC Board is The Display PC Board is replaced partial characters are defective as a whole assembly Check displayed procedures in Table 2 1 first and verify that other problems do not exist gt Display PCB Removal amp Replacement 3 1 2 CHAPTER 2 DIAGNOSIS TABLE 2 4 BALANCE CANNOT CALIBRATE USING EXTERNAL WEIGHTS SYMPTOM PROBABLE CAUSE REMEDY Balance can be turned on Incorrect weights but will not calibrate manually Balance is set for Legal For Trade operation Balance not level Balance is unstable Verify that proper weights are used Set the Setup Menu Legal For Trade setting to Off See Instruction Manual Sections 3 7 12 amp 3 8 Level balance Perform Automatic Internal Calibration gt Appendix A 1 If the balance fails to calibrate properly enter the service mode Appendix B and perform a Span Calibration If this fails check the InCal Weight Assembly and the Load Cell Assembly Section 3 1 5 3 2 7 Ensure that all parts are clean and properly aligned CHAPTER 2 DIAGNOSIS TABLE 2 5 BALANCE CANNOT CALIBRATE INTERNALLY SYMPTOM Balance can be turned on but will not calibrate using internal calibration Balance may be unstable The InCal Weight Hardware may b
49. hown until the reading is two to three times the the specifications in Table 1 2 Then re test as shown in Section 4 2 1 6 1 Use small adjustments no more than a quarter turn at a time 6 2 As you get close to the tolerance you have to reduce the amount of the turn Work front to back first then side to side This process is complete when all four edges of the Pan are within tolerance specifications 4 2 3 Repeatability Test Repeatability is a word used in balance specifications meaning the Standard Deviation of a set of similar weight readings To determine whether a balance meets the calculated Standard Deviation value in the Specification Table 1 2 perform the following test 1 2 Tare the balance The reading on the display should be 0g Select a mass weighing near the maximum capacity of the balance and place the mass on the center of the Pan Observe and record the reading Remove the mass Reading should return to Og 1 count Repeat the test for ten readings If the standard deviation of the readings is within the specifications in Table 1 2 Discovery Balance Model Specifications page 1 3 the balance passes the Repeatability Test 4 2 2 Remediation If the deviation for any set of readings using the same mass placed on the center of the Pan is greater than the specifications in Table 1 2 the balance does not meet the Repeatability Test specification Inspect and correct the following areas if Check
50. it is removed from its protective housing Prior to opening the Load Cell be sure to have the Service Toolset Part No 80030340 which includes a fixture that must be installed to protect the Flexures during both disassembly and assembly A tas NOTE Always use an anti static kit when opening the balance and handling its electronic parts 3 2 1 Load Cell Removal 1 Disassemble the Housing and open the balance Refer to Section 3 1 1 2 Remove the 2 screws from the Display Cable Shield Plate and lift it aside a h Figure 3 21 Removing Display Cable Shield Plate 3 Carefully move the Display Cable to the side It does not need to be disconnected at this time CHAPTER 3 REPAIR PROCEDURES 3 2 1 Load Cell Removal 4 Lift off the InCal Weight Cover It does not have screws Figure 3 22 The InCal Weight Cover sits beneath the Display Cable Shield Plate Ah Note A A clean glove should be worn when handling weights Figure 3 23 Weights and weight holders can be removed but should only be handled while wearing a clean glove This will leave only the Platform Holder on the chassis 5 Remove both weights and weight holders and set them aside 6 Remove the Main PCB cover as indicated in Section 3 1 3 7 Disconnect the cables from the PCB 8 Remove the copper colored stand off screws that secure the PCB Mounting Plate CHAPTER 3 REPAIR PROCEDURES 3 2 1 Load Cell Removal 9 Lift off
51. ll Removal in Section 3 2 1 2 Remove the two screws shown on each side to remove the top and bottom covers Be careful of the Flexure Arm assemblies Figure 3 31 Removing screws from Load Cell top cover Figure 3 33 Removing screws from Load Cell bottom cover Figure 3 34 Load Cell with bottom cover removed AN NOTE N When covers are removed touch only the frame of the Load Cell CHAPTER 3 REPAIR PROCEDURES 3 2 2 Load Cell Disassembly 3 Tip the Load Cell onto the back frame and loosen the 2 screws that connect the bottom Flexure Arm to the frame NO MORE than half a turn This is preparation for installing the fixture to protect the Flexure Arms Screw connecting bottom Flexure Arm assembly to frame Screw connecting bottom Flexure Arm assembly to frame Screw connecting top Flexure Arm assembly to frame Screw connecting top Flexure Arm assembly to frame Figure 3 36 Screws on top Flexure Arm assembly 4 Loosen the 2 screws that connect the top Flexure Arm assembly to the frame NO MORE than half a turn This is preparation for mounting the fixture to protect the Flexure Arms CHAPTER 3 REPAIR PROCEDURES 3 2 2 Load Cell Disassembly 5 Be sure to have the correct Service Toolset as shown below Brass Fixture Thumb screws Allen keys Brass Brackets Centering Pin Threaded Rod Brass Rod Figure 3 37 Service Toolset Part No 80030340 containing two Allen keys one Brass Fix
52. llowing steps Connect the balance to the PC and start the Discovery Software Service Tool Click the tab labeled Restore EEPROM Discovery Service Tool 1 006 File Settings Restore EEPROM Replace Loadcell Replace PCB Download Software S N IDNR Image File _chenge Write Image File Figure C 2 The Software Service Tool s Restore EEProm tab Enter the balance s Serial Number and IDNR number Enter the path to the image file or click the Change button to locate the file Click the Write Image File button The software will indicate the download progress When complete disconnect the power from the back of the balance then re connect 10 Perform Service Calibrations see Appendix B Test the balance APPENDIX C SOFTWARE SERVICE TOOL INSTRUCTIONS C 2 To Replace a Load Cell 1 2 8 9 Follow the steps in Section 3 2 to replace the defective load cell Open the packet containing labels that was supplied with the replacement Load Cell These labels each contain a model number followed by the IDNR number Carefully select the label that matches exactly the model number of the balance Put the new label on the balance Power the balance from an AC adapter Connect the balance to your computer Start the Discovery Service Tool Software Click on the tab labeled Replace Loadcell gt Discovery Service Tool 1 00 File Settings Restore EEPRUM Figure C 3 The Software
53. masses available Masses required for calibration are listed in Table A 1 at the end of this section APPENDIX A STANDARD CALIBRATION A 1 Automatic Internal Calibration Advanced Auto Cal Internal calibration can be done without using an external weight Note Be careful not to touch the scale or the table while calibration is in progress as it will cause the process to fail With the balance on press the Cal button and then release it Automatic calibration begins It will take a minute or so When it is complete AutoCal Done appears lf calibration fails AutoCal Abort appears If this happens level the balance and try again If it continues to fail perform a Service Calibration If this also fails refer to Chapter 3 of this Manual When calibration is finished the balance returns to the weighing mode AutoCal will automatically calibrate the balance each time there is a change in temperature significant enough to affect accuracy or after every 11 hours In certain circumstances a user may need to prevent automatic calibration for example while taking a series of weights AutoCal can be turned off from the Calibration Menu as follows With the balance on press and hold the Cal Menu button until MENU CALIBRATE is displayed and CALIBRATE is blinking Press Yes CAL AUTOCAL is displayed Press Yes to select it The current AUTOCAL setting will then be displayed The AutoCal setting will be displayed as either SET
54. mperature Sensors as shown in Figure 3 51 Then remove the Temperature Sensors and set them aside Remove the Temperature Sensors from the new PCB Insert and solder the Temperature Sensors from the original PCB into the new PCB The new PCB is now ready to re install Top Temperature Sensor Solder points for top Temperature Sensor Solder points for bottom Temperature Sensor Bottom Temperature Sensor Figure 3 51 Solder points on top of Load Cell PCB Figure 3 52 Solder points on bottom of Load Cell PCB CHAPTER 3 REPAIR PROCEDURES 3 2 2 Load Cell Disassembly 18 Remove the Up down Stop Plate that controls the Ratio Beam s movement Figure 3 54 Removing Temperature Conducior Figure 3 53 Up Down Stop Plate 19 Remove the Temperature Conductor as shown in Figure 3 53 20 Remove the two screws that secure the Magnet Cover and carefully remove the Magnet Cover by lifting it straight up 3 a y ae F a ait iB gu Figure 3 55 Removing screws that secure the Magnet Cover CHAPTER 3 REPAIR PROCEDURES 3 2 2 Load Cell Disassembly 21 Remove the Hanger by removing Thumb screws which will release the Brass Fixture inserted earlier Figure 3 57 Removing Thumb screws Figure 3 58 Load Cell without that hold Hanger in place Hanger and Brass Fixture Note Brass Fixture will be released uncovered Magnet in background 22 Release Ratio Beam yoke by removing screws on each side
55. nce of the balance using the tests in Section 4 2 CHAPTER 4 TESTING 4 1 TESTING After servicing the balance an operational test and various performance tests should be made to confirm that the balance meets specifications Turn the balance on and allow it to warm up for at least one hour before performing these tests NOTE A N Make sure the test area is free from drafts and that the balance rests on a level and vibration free surface The masses used for final calibration must be adjusted to ASTM Class 1 or OIML Class E1 tolerance or better 4 1 1 Operational Test 1 Connect a functioning AC Adapter to the balance Power Jack located at the rear of the balance 2 Plug the AC Adapter into a suitable power source If the AC Adapter supplied with the balance is rated for a different voltage use an appropriate adapter to match the supply voltage 4 1 2 Models Segment Display Test 1 Turn the balance on by pressing ON ZERO Off all segments are enabled and displayed briefly then followed by a software revision number See Figure 4 1 for full display OV A VF eee FO 015 GN ow NET WN IATA IATA TA AXA PC MEM PTBG JAM AM IAM IAN ANT AN ANE ANE AME ANT Figure 4 1 LCD Full Display for Discovery Balance 2 Tare the balance The display should indicate a zero weight 4 2 Load Cell Performance Tests 4 2 1 Off Center Load Test The Off Center Load Test is used to determine whether displayed weight values are affected
56. necessary APPENDIX C SOFTWARE SERVICE TOOL INSTRUCTIONS APPENDIX C SOFTWARE SERVICE TOOL INSTRUCTIONS The Discovery Software Service Tool is used for 5 purposes 1 To restore EEPROM data 2 To install anew Load Cell 3 To install a new Main Printed Circuit Board PCB 4 To update the software in the balance 5 For diagnostics Install the software on a Personal Computer running Microsoft Windows NT 4 0 or later or Microsoft Windows 98 or later Insert the CD and run Setup exe After installation run the program Service Tool The program has 5 tabs across the top of the screen Click on the tab for the function you wish to perform If the default settings for communication have been changed click on settings and change the settings in the software to match Fort Baudrate Data Parity otop bits Flow contral Detaults Cancel Lik Figure C 1 Com Port Configuration menu APPENDIX C SOFTWARE SERVICE TOOL INSTRUCTIONS C 1 To Restore the EEPROM data 1 Record the following information from the balance to be repaired 1 1 Serial Number from the label on the back of the balance 1 2 Model Number from the label on the back of the balance 1 3 IDNR Number just above the label on the back of the balance Contact Ohaus Corporation in Pine Brook NJ and request the data file to download Provide the information recorded above After receiving the data file from Ohaus continue with the fo
57. o balance tip balance up and insert 2 screws on the bottom 10 Replace balance cover performing Housing Disassembly in reverse order 11 Check balance performance and perform Span Calibration See Appendix A 2 CHAPTER 3 REPAIR PROCEDURES 3 1 3 Main Printed Circuit Board PCB Removal amp Replacement If the main Printed Circuit Board PCB is suspected of being faulty it should be replaced To replace the main Printed Circuit Board proceed as follows 1 Open the Housing by referring to Section 3 1 1 RS232 Screws Figure 3 9 Display Balance Load Cell Cover 2 Remove 2 screws from the Main PCB cover and remove the cover 3 Remove the 2 screws that secure the RS232 connector CHAPTER 3 REPAIR PROCEDURES 3 1 3 Main Printed Circuit Board PCB Removal amp Replacement Battery PCB Screw A EEProm Chip Cable Connections PCB Screws Figure 3 10 Discovery Balance Printed Circuit Board PCB CAUTION Jn WHEN HANDLING THE PRINTED CIRCUIT BOARD HANDLE BY EDGES ONLY DO NOT TOUCH FOIL SIDE OF BOARD STATIC DISCHARGE MAY DAMAGE SOME COMPONENTS ALWAYS USE AN ANTI STATIC KIT Disconnect the cables from the PCB 4 5 Remove the 3 screws securing the PCB 6 Remove the PCB 7 Before installing the new PCB remove its EEProm chip and replace it with the original PCB s EEProm chip The original EEProm chip has data specific to the Discovery Balance EEProm Chip Figure 3 11 EEProm
58. on for further information CHAPTER 2 DIAGNOSIS SYMPTOM Balance will not turn on TABLE 2 1 BALANCE WILL NOT TURN ON PROBABLE CAUSE REMEDY Main power source is off On Zero Off switch defective or actuating fingers on top housing defective Main PC Board is defective Check the main power source outlet for proper voltage See Table 2 2 If the balance fails to turn on and On Zero Off switch is OK the Main PC Board is defective and should be replaced gt Main Printed Circuit Board Removal amp Replacement 3 1 3 CHAPTER 2 DIAGNOSIS TABLE 2 2 BALANCE DOES NOT RESPOND TO FRONT PANEL CONTROLS SYMPTOM PROBABLE CAUSE REMEDY Balance does not PC board switch or Open the balance Refer to respond to front panel actuating fingers on top Section 3 1 1 Using an controls housing are defective Ohmmeter measure the resistance between the pins of the ON Zero Off switch It should be open Press the switch through the top housing and check that the resistance is zero Check each switch in a similar manner If continuity is not present on a particular switch replace the affected switch or actuator Display PC Board is If the balance fails to turn on and defective On Zero Off switch is OK the Display PC Board may be defective and should be replaced gt Display PCB Repair amp Replacement 3 1 2 Main PC Board is If Balance fails to turn on and Defective Display PCB has been replaced t
59. ons W x Hx D in cm 7 9 x 11 8 x 18 20 x 30 x 45 7 Net Weight lb kg 22 9 10 2 CHAPTER 2 DIAGNOSIS 2 1 TROUBLESHOOTING This section of the manual contains troubleshooting information Information is contained to isolate specific problems using Table 2 1 2 5 Diagnostic Guide and Table 2 6 Error Codes Follow all directions step by step Make certain that the work area is clean Handle balance components with care Use appropriate Electro Static Device 2 2 DIAGNOSTIC GUIDE Tables 2 1 2 5 are a Diagnostic Guide designed to help locate the problem area quickly and easily The probable causes are listed with the most common cause first If the first remedy does not fix the problem proceed to the next remedy Before attempting to repair the balance read all chapters of this manual to be familiar with the balance components and operation 2 2 1 Diagnosis 1 Isolate and identify the symptom 2 Refer to Tables 2 1 2 5 Diagnostic Guide and locate the symptom Also consult the Error Code Table for solutions to specific codes 3 Follow the suggested remedies in the order they appear 4 Perform the indicated checks or see the appropriate section of the manual 5 Repair or replace the defective section of the balance NOTE lf more than one symptom is observed approach one area at a time and remember that the symptoms may be interrelated lf a problem arises that is not covered in this manual contact Ohaus Corporati
60. play should remain constant without fluctuations It is OK for the last digit to fluctuate as long as it stabilizes with the addition of a small mass To view the Ramp value press Yes A number will appear on the lower portion of the display and should be constant Place masses on the balance from minimum to maximum capacity The reading will increase but should not fluctuate The example at right is with no weight on the Pan The reading will vary with other balances To exit the ramp function press Exit then No The balance advances to the Span calibration menu Press Yes to perform Span Calibration Press No to advance to Int Cal Calibration and No again to End Srv If you press Yes at this point the balance goes off APPENDIX B SERVICE CALIBRATION B 4 Service Span Calibration Span calibration from the service menu allows you to set a new zero and maximum setting This is distinct from user level span calibration which allows a user to adjust the zero and maximum setting within the range established by the service menu span setting NOTE A N The balance should be perfectly level before attempting a span calibration Use the balance s leveling feet at the rear of the balance together with the leveling bubble which is just inside the left Door Side Draft Shield When the balance determines that the Pan is empty the Span Busy message appears In a few seconds the Add Weight message appears with the number correspon
61. r Ratio Beam tab and PCB screw receptacle on Magnet Cover 15 Install the Up Down Stop Plate as shown in Figure 3 72 16 Place Load Cell PCB over screw receptacles on Magnet cover and secure with 2 screws shown in Figure 3 73 Insert Step Bushing before screw on back end Place Step Bushing before inserting screw on back of PCB Figure 3 74 Load Cell PCB is secured with 2 screws A Step Bushing goes in before the screw in the back CHAPTER 3 REPAIR PROCEDURES 3 2 4 Load Cell Assembly 17 Re solder the two fine wires that connect the Load Cell PCB to a smaller PCB on the top front of the Load Cell Follow these steps 17 1 Carefully clean the solder out of the solder holes 17 2 Use tweezers to thread the fine wires through the solder holes 17 3 Carefully replicate the original smooth arc of the wires as shown in Figure 3 71 to ensure proper functioning of the balance 17 4 Solder the wires into place Solder points y a Figure 3 75 Fine wires must have smooth arc shown here for the balance to function properly CHAPTER 3 REPAIR PROCEDURES 3 2 4 Load Cell Assembly Note A N Do not rest the Load Cell on the Ratio Beam Rod The Load Cell should be supported on the Threaded Rod to protect the Ratio Beam Rod The Threaded Rod should support the weight of the Load Cell and not the Ratio Beam Rod Screw See Figure 3 72 Note Make sure Threaded Rod is used to protect Ratio Beam Rod from the Load C
62. s Handshake can be set to Off XONXOFF or Hardware The default setting is XONXOFF 4 4 RS232 Connection 4 4 1 Connecting the RS232 Interface On the rear of the balance the 9 pin female subminiature D connector COM 1 is provided for interfacing with other devices Figure 4 1 is a diagram of the RS232 connector with pin holes numbered Table 4 2 indicates the respective pin functions 4 4 1 Connecting the RS232 Interface CHAPTER 4 TESTING 00000 0000 Figure 4 5 Com 1 Connector as it appears on balance s back cover TABLE 4 2 COM1 INTERFACE PIN CONNECTIONS 1 2 3 4 5 6 T7 8 9 Not used TxD RxD DSR Ground DTR CTS RTS Not used CHAPTER 4 TESTING 4 4 2 RS232 Commands All communications are accomplished using standard ASCII format Only the characters shown in the Table 4 3 RS232 Commands are acknowledged by the Balance Invalid command response ES error indicates the Balance has not recognized the command Commands sent to the Balance must be terminated with a carriage return CR or carriage return line line feed CRLF Data output by the Balance is always terminated with a carriage return line feed CRLF TABLE 4 3 RS232 COMMAND TABLE Command Function S Immediate Print of near weight se or unstable P prm aspayea wog sabi runs C sabe weght sP Auto Print stable non zero displayed weight xP Interval Print x Print Interval 1 3600 seconds OP ends Interval
63. tered If not loosen Threaded Rod and adjust Ratio Beam to center it Then tighten Threaded Rod Place new Flexure with oblong hole resting on Ratio Beam and round hole resting on yoke Re insert Flexure screws and tighten them Remove Thumb screws and detach Brass Fixture and Brass Brackets Remove Centering Pin Loosen Threaded Rod Check centering If necessary loosen screws that attach yoke to frame and adjust slightly to center CHAPTER 3 REPAIR PROCEDURES 3 2 4 Load Cell Assembly 10 5 20 Remove Brass Rod and check vertical centering over Temperature Sensor Tube and around Magnet 5 21 Tighten screws on yoke checking again to ensure Ratio Beam remains centered 5 22 Re tighten Threaded Rod 5 23 Re install Hanger and Thumb screws and Brass Rod and re check centering NOTE Repeat the process as necessary to ensure that the Ratio Beam is centered Re check that everything is assembled properly Remove the Brass Rod and Threaded Rod and ensure that the Ratio Beam moves up and down without binding When satisfied that the Ratio Beam moves correctly reinstall the Brass Rod and Threaded Rod Install the Hanger with the Brass Fixture and the Thumb Screws from the Service Toolset The Brass Fixture is inserted between the Hanger and the frame of the Load Cell Use the Brass Brackets from the Service Toolset to position it properly Then tighten the Thumb Screws Double check that the Ratio Beam is centered
64. the Cantilever Arm Test the mechanism again with Weights and Weight Holders in place to ensure they are properly positioned Place the Weight Holders to the left and right of the Cantilever Arm and re insert the 2 screws with their bushings that secure the Weight Holders Then carefully place the Weights in their Holders As each Weight Arm moves inward when its Partial Load button is clicked check that the Weight above it is lowered into place resting fully on the Weight Cradles Both Weight Arms should move inward when the Total Load button is clicked and both Weights should rest fully in their Cradles If Weight Arm responses are acceptable both empty and with Weights and Weight Holders in place the Incal Weight Mechanism Test is satisfactorily complete lf there are problems with the Weight Arm movements open the Load Cell Cover and check the Calibration Motor for defects If the Calibration Motor needs to be replaced see the procedures in the next Section 3 1 6 Removing and Replacing Calibration Motor Assembly Upon satisfactory completion of the InCal Weight Mechanism Test be sure all hardware is perfectly clean then reinstall the Weight Holders and Weights and re assemble the InCal Weight Assembly following this section in reverse order CHAPTER 3 REPAIR PROCEDURES 3 1 5 Removing and Replacing Calibration Motor Assembly 1 First perform Load Cell Cover removal following Section 3 2 1 Baur 3 17 Calibration
65. tion Points 1 Weight Class DV114C 100g ASTM Class 1 OIML E1 DV314C 300g ASTM Class 1 OIML E1 DV214C 200g ASTM Class 1 OIML E1 DV215CD 200g ASTM Class 1 OIML E1 APPENDIX B SERVICE CALIBRATION APPENDIX B SERVICE CALIBRATION This section describes the Service Menu and sub menus which allow authorized service personnel to perform factory calibrations Please refer to the Menu Sequence diagram NOTE The Service Menu cannot be entered if LFT is ON See page A 1 SERU ILE AAP Figure B 1 Service Calibration Menu Sequence B 1 Navigation In general a blinking item in the primary or secondary display indicates a choice Pressing Yes selects the displayed sub menu Pressing No causes the next sub menu to appear B 2 Entering the Service Menu Turn the balance off Enter the Service Menu by pressing and holding the On Zero Off and the left Tare buttons until the balance turns on This takes a few seconds As the balance powers up the display advances through several screens SERVICE is displayed with RAMP flashing Press Yes to select Ramp See next page Press No to advance to Span Calibration See page B 3 APPENDIX B SERVICE CALIBRATION B 3 Ramp The first sub menu in the Service Menu is Ramp The ramp display shows the percentage of use of the Ato D circuit The normal range is 6 10 The value is not as important as how it changes It should increase as the weight on the balance is increased The ramp dis
66. to perform an InCal Weight Mechanism test This test is done with the Discovery Balance Software Service Tool see Appendix C especially C 5 and C 6 installed on a personal computer which is connected to the balance s RS232 port using a standard serial extension cable Observe the weight displayed on the balance for each of the four conditions No Load Partial Load 1 Partial Load 2 and Total Load If the display does not stabilize after a few seconds in each condition this could be caused by a defect in the Weight Mechanism hardware one or both of the weights might not be fully lowered in their cradles a part of the mechanism might have come out of position or dust or debris might have entered the mechanism Depending on the balance capacity Error 8 3 Weight reading above underload limit may be displayed when Total Load is applied This is normal NOTE AN The following procedure should only be performed in a clean dust free environment which is also free of vibrations that could affect the ultra sensitive calibration of the balance To identify and correct any of these problems use the following procedure to disassemble inspect and clean the InCal Weight hardware 1 Remove the housing and open the balance Follow the steps in Section 3 1 1 2 Remove the 2 screws from the Display Cable Shield Plate and lift it aside i we p por Figure 3 13 Removing Display Cable Shield Plate 3 Care
67. to test that the Incal Weights move smoothly When each of the weights are in the lowered position the display reading should be STABLE 1 Click on one of the InCal Weight Control buttons No Load Partial Load 1 Partial Load 2 or Total Load 2 Observe weight displayed on balance A fluctuating display value indicates the weight is not stable This could be because the weight is not fully lowered and or because it is touching something To correct this symptom follow the procedures in Section 3 1 5 InCal Weight Hardware Disassembly amp Testing 2 DHAUS Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com x 8 0 10 4 1 3 5 P N 80104135 SERVICE MANUAL DISCOVERY BALANCE
68. ture two Thumb screws two Brass Brackets a Centering Pin a Threaded Rod and a Brass Rod A N Note The Load Cell is delicate Handle with care The following steps are performed to protect the Flexures during the disassembly process Figure 3 39 Brass Fixture fully inserted under the Load Cell s Hanger Figure 3 38 Brass Fixture inserted part way under the Load Cell s Hanger 6 With the Load Cell resting on its back frame slide the Brass Fixture from the Service Toolset under the hanger After inserting the Brass Fixture part way gently lift the Brass Fixture allowing the Brass Fixture to be positioned in place CHAPTER 3 REPAIR PROCEDURES 3 2 2 Load Cell Disassembly 7 Install the 2 thumb screws from Service Toolset as shown Hanger oo Thumb screws Figure 3 40 Thumb screws and Hanger on top of Load Cell It is now safe to remove the Load Flexure Load Flexure Screws Flexure to Hanger on top of Load Cell 8 Carefully remove the two screws shown together with 2 washers each one steel closest to screw head and one aluminum CHAPTER 3 REPAIR PROCEDURES 3 2 4 Load Cell Disassembly Load Flexure Aluminum washer Screws ees Figure 3 42 Load Cell with Load Flexure 2 screws and 4 washers removed NOTE All Flexures must be perfectly straight lf they are even slightly bent they need to be replaced for the balance to function properly 9 Set Load Cell on its feet and remove t
69. y should be carefully examined and cleaned cccsseeeeeseeeeees 3 30 Yoke of Ratio Beam must align with frame of Load Cell cccccseeeeeeeeeeeeeees 3 31 Installing Ratio Beam with hole centered over the Temperature Sensor Tube 3 31 Yoke aligned with frame side to side and flush with frame on front 3 32 Centering Pin goes into Temperature Sensor Tube in middle of Magnet 3 33 Hanger installed with Brass Fixture and Brass Brackets 3 34 Magnet Cover has oblong hole that clears Ratio Beam s stop tab 006 3 35 Inserting screws to secure the Magnet Cover ccceeeeeeneeeeeeeeeeeeeeeeeeeeeaaeees 3 35 Inserting the Temperature Conductor in the middle of the Magnet Cover 3 35 The Temperature Conductor groove should line up with the two Screws 3 35 Up Down Stop Plate which rests on Magnet Cover ccecceecceseeeeeeeeeeeeeaeees 3 36 Up Down Stop Plate inserted over Ratio Beam tab and PCB screw receptacle on Magnet Cover cccceceeeeeeee cece ee eeeeeeeeeeeeeeaaaeeees 3 36 Load Cell PCB is secured with 2 screws with Step Bushing on the back 3 36 Fine wires must have smooth arc for the balance to function properly 3 37 Load Cell should rest on Threaded Rod and base of frame ccceeeeeeeeees 3 38 Installing the bottom Flexure Ari cccccccseeeeeeceeeeeeeeeeseeeeeaeeseeeeseeeeeesaaneeees

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