Ramsey Electronics R2XL1 User's Manual
Contents
1. 16 Custom Case Assembly 17 Troubleshooting 18 aan yaya asa aha 19 MN RAMSEY ELECTRONICS INC 590 Fishers Station Drive gt b Victor New York 14564 52 Phone 585 924 4560 Fax 585 924 4555 www ramseykits com R2XL1 e INTRODUCTION Welcome to another quality kit brought to you by Ramsey Electronics Inc This kit was designed to allow you to connect consumer audio devices to pro fessional equipment with as little hassle as possible You would think that a product like this was readily available but it isn t Now you can easily go be tween a standard CD player and a studio style mixer or even run a profes sional stereo transmitter directly from your computer It s true that with the correct wiring that you can easily connect consumer au dio devices to professional equipment The problem however is that the result ing levels are way too low The R2XL1 provides plenty of gain so that you can bring consumer levels of 0 7V RMS up to the required 1 228V RMS used by studio style devices This required a gain of 1 228 7 or 1 75 to achieve We expanded that by over 10 times giving you an adjustable gain range of 0 2 to 20 2 This gives you plenty of control to get those levels just right especially when coming from a computer or portable CD player A very simple circuit in principle the R2XL1 uses two quad FET input2. to get the needed gain as well as giving you the required balanced outputs to drive low impedance XLR inputs Another nice feature we added was the Stereo Mono switch It takes the au dio presented on the right input and sends it to both left and right XLR amplifi ers when pressed in This allows you to drive a professional stereo audio de vice from a monaural audio source with a press of a button CIRCUIT DESCRIPTION The R2XL1 is an audio that offers the user a wide range of ad justable output levels To analyze this circuit we will first follow the signal path from input to output and then take a close look at the power supply section The power supply performs a nifty trick in order to get an additional supply rail from a single power source so we ll take the time to discuss it Looking at J1 the dual RCA connector Notice that the signal first goes through a couple of 10 uF capacitors These capacitors are called coupling caps because they filter out any DC on the line while letting the AC signal the music pass through Removing any residual DC component that might be present makes sure there will be no interference with the first amplification stages For now we will only look at the top half of the circuit which handles the right channel audio path Following the first coupling capacitor we see R13 a 10K resistor to ground This serves the purpose of making sure the opamp stage side of the pr
3. All that seems fine with a stereo audio source but how do you handle one that is Mono The mode selection switch S1 allows you to take the right channel audio input and send it simultaneously through both the left and right amplifier stages for dual outputs are the right levels Now on to the power supply Since we are going to run this product from a 12VAC power transformer we will need to convert the AC supply to a DC volt age in order for our opamps to work properly To accomplish this we use a bridge rectifier consisting of D1 4 to take the AC input voltage and convert it to positive DC pulses This directly is too noisy for our application so C12 was added to smooth things out C12 acts like a battery and holds the voltage at a more consistent level to get rid of the pulses also called ripple Since C12 is a very small battery it discharges almost as quickly as it charges so some of the pulses are still present To eliminate these we use a voltage regulator to completely smooth out the remaining pulses The output of VR1 is our positive supply and is completely smooth and ready to use So where do we get the negative supply from Simple we use a voltage doubler scheme This works by using a coupling capacitor C11 in a bit differ ent fashion Here we are isolating the DC component of the positive half of the supply and leaving only the AC component This AC component is then recti fied by D5 and D6 into negative pulses The nega
4. a wrong way to solder it in Diode bands electrolytic capacitor polarity transistor shapes dotted or notched ends of IC s and so forth 4 Solder all connections unless directed otherwise Use enough heat and solder flow for clean shiny completed connections Keeping this in mind lets begin by sorting out our components and cross checking them against the parts list to make sure we have received everything NOTE TO NEWCOMERS If you are a first time kit builder you may find this manual easier to understand than you may have expected Each part in the kit is checked off as you go while a detailed description of each part is given If you follow each step in the manual in order and practice good soldering and kit building skills the kit is next to fail safe If a problem does occur the manual will lead you through step by step in the troubleshooting guide until you find the problem and are able to correct it R2XL1 gt 11 R2XL1 ASSEMBLY We will start with the lowest profile components first and then work our way up to the largest We do this to make assembly much easier since fitting a short component between two big ones can be a real pain D O0 oO oO UO UO UD O 1 Install D1 one of the 1N4002 diodes black body with white stripe marked 1N4002 Note that diodes can only conduct in one direction so part orientation is critical The diode will have a white stripe indicating the cathode end while the parts layout di
5. s move on The signal output from pin 8 U1 C then goes through two more opamp stages U1 A and U1 B for processing before we re done One of these stages has a familiar topology Take a look at U1 B It s another in verting opamp using resistors of R1 and R2 to set its gain Use the formula from before to figure out for yourself what the gain has been set for We ll con firm in a moment if you are correct The other opamp U1 A is configured as a non inverting amplifier A non inverting opamp does just what it sounds like it preserves the original signal polarity while offering the ability to amplify the signal increase or decrease its amplitude The formula for determining the gain of this configuration is given by Av 1 Rf Ri where Ri is the input resistance 0 ohms and Rf is the feedback resistance 0 ohms Since there are no input or feedback resistors the gain works out to be 1 for this stage This type of circuit is commonly called a Voltage Follower for obvious reasons and it acts as a buffer Both stages U1 A and U1 B have their gain set to 1 and 1 respectively did you get 1 for the gain of the inverting amplifier Because one opamp is in verting and the other is not their outputs are always opposite of one another The end results is a combined gain of 2 for these two opamps together How does that work Let s analyze this If the output of our first stage U1 C is 1 volt to make the math easy and it
6. uF electrolytic capacitor 37 Install C13 the last 470 uF electrolytic capacitor 38 Install S2 the power switch Make sure it is flush to the board before soldering 39 Install S1 the Stereo Mono switch Again make sure it is flush before soldering 40 Install R11 one of the 10K ohm potentiometers Solder the mounting pins as well as the electrical contacts for good mechanical stability 41 Install R5 the other 10K ohm potentiometer You may note we left R12 and R6 out of the assembly process This is be cause more often than not they are not needed You can install them at some future time if you find they are necessary to reduce noise and interference in extremely long cable runs We recommend you leave them out for now to en sure better sound quality R2XL1 gt 14 At this point it is time to go back through and check your assembly methods for e Diode orientation Make sure the cathode and the line is in the same ori entation as shown on the assembly diagram e Electrolytic capacitor orientation Make sure the negative side of the ca pacitors are not in the positively marked holes e orientation Let s hope you did this right they are hard to move once soldered e Check for cold solder joints Make sure all connections look nice and clean If in question re heat and apply a bit more solder e Check for solder bridges We have seen some that look just like a trace was supposed to be there so check th
7. Cable Tracer e LABC1 Lead Acid Battery Charger e 67 lon Generator e CT255 Compu Temp Digital Binary Thermometer e LC1 Inductance Capacitance Meter RAMSEY AMATEUR RADIO KITS e DDF1 Doppler Direction Finder e HR Series HF All Mode Receivers e QRP Series HF CW Transmitters e CW7 CW Keyer e CPO3 Code Practice Oscillator e QRP Power Amplifiers RAMSEY MINI KITS Many other kits are available for hobby school Scouts and just plain FUN New kits are always under development Write or call for our free Ramsey catalog R2XL1 KIT INSTRUCTION MANUAL Ramsey Electronics publication No MR2XL1 Rev 1 3 First printing June 2001 COPYRIGHT 2001 by Ramsey Electronics Inc 590 Fishers Station Drive Victor New York 14564 All rights reserved No portion of this publication may be copied or duplicated without the written permission of Ramsey Electronics Inc Printed in the United States of America R2XL1 e 2 Ramsey Publication No MR2XL1 HB Price 5 00 KIT ASSEMBLY AND INSTRUCTION MANUAL FOR R2XL1 RCA TO XLR LEVEL CONVERTER KIT TABLE OF CONTENTS Or Ln uuu uu u ul Suay 4 Circuit Description 4 FAILS ISU tech uu t uuu sus 7 Schematic Diagram 8 Parts Layout 9 Learn as You Build 10 ASS ITIDIV aa R 12 Using the 42 15 Professional Audio Wiring
8. D UD D O0 U O UD 14 Install R1 a 1K ohm resistor brown black red 15 Install R2 a 1K ohm resistor brown black red 16 Install a 100 ohm resistor brown black brown 17 Install R4 a 1K ohm resistor brown black red 18 Install U1 the other LF347 quad opamp Again make sure you orient correctly It is in the same orientation as the last part Dimple indicates the pin 1 end Check to make sure all pins are through then solder all 14 pins 19 Install C7 a 10 uF electrolytic capacitor Note that electrolytic capaci tors are polarity sensitive This means they wont work if put in the wrong way That is why we have indicators on the layouts indicating the positive side of the capacitor Usually the capacitor itself is marked on the negative side We don t do this to confuse you but that has been the standard for years so we aren t about to change it now Just make sure that the side NOT marked negative is in the same side marked positive on the board 20 Install C8 another 10 uF electrolytic capacitor Again check polarity 21 Install R14 a 10K ohm resistor brown black orange 22 Install R13 another 10K ohm resistor brown black orange 23 Install C4 a 10 uF electrolytic capacitor Note orientation 24 Install C1 another 10 uF electrolytic capacitor Make sure the negative pin is not in the positive hole 25 Install C6 a 100 uF electrolytic capacitor Again note orientation for thi
9. ING You would think it would be easy to connect professional audio equipment together but unfortunately it s not There can be all sorts of issues that come up usually it is AC line hum in your equipment you have to deal with This is normally caused by ground loops in the equipment This effect can be caused by only a very little current and can wind up having a tremendous impact on your sound and sanity We will try to clear some issues up for you by showing you how to properly wire XLR connectors and what to do in case of hum Audio Outputs XLR connectors provide a balanced connection that rejects common mode noise for a cleaner audio signal Make sure your XLR connectors are WIRED CORRECTLY Some manufacturers make them incorrectly so you may want to check the connectors and re make them to standards if necessary Current standards dictate that XLR connectors should be wired as follows Ground pin 1 White Pin 2 Black Pin 3 Sometimes you will find red instead of white Both ends of the cable are wired in the same order per the following diagram FEMALE 2 Conductor Shielded Cable SHIELD GND SHIELD GND Across pins 2 amp 3 of the XLR inputs look for 4 dBu 1 228VRMS as equivalent to 0 dBuV The audio output can deliver up to a maximum of 21 2V pk pk but then you have to scale the level back down with your audio gain to get acceptable sound in your destination equipment Solving ground loop h
10. ROAZXLR Converter Ramsey Electronics Model No R2XL1 Have you ever found yourself with two RCA outputs on your audio equipment and you somehow have to connect them to XLR inputs While wiring RCA levels directly to XLR can work the levels will be way too low So what do you do Here is the answer to your conversion dilemma The R2XL1 not only converts your connection types from RCA to XLR it also gives you the added advantage of independent channel gain control for the proper levels e Powered by a 12VAC wall power transformer for ground isolation e Stereo Mono switch so you can drive a stereo device with a mono source e Variable gain settings from 0 2 to 20 2 for full control with independent left and right adjustments Lets you get your levels perfect e Low noise design fully regulated for the best sound possible 6 10 Hz to 50 kHz audio pass band for clear crisp sound e Durable male XLR converters for heavy repeated use RAMSEY TRANSMITTER KITS e FM100B Professional FM Stereo Transmitter e FM25B Synthesized Stereo FM Transmitter e MR6 Model Rocket Tracking Transmitter e TV6 Television Transmitter RAMSEY RECEIVER KITS e FR1 FM Broadcast Receiver e AR1 Aircraft Band Receiver e SR2 Shortwave Receiver e 661 Shortwave Converter RAMSEY HOBBY KITS e SG7 Personal Speed Radar e SS70A Speech Scrambler e BS1 Bullshooter Digital Voice Storage Unit e AVS10 Automatic Sequential Video Switcher e WCT20 Cable Wizard
11. S1 2 1 2 5 AC Power jack J6 1 Dual RCA connector J1 OOOO R2XL1 e 7 R2XL1 e 8 R2XL1 PARTS LAYOUT DIAGRAM H T 3 6 ac OH D5 R12 C6 C5 C3 C2 Ramsey Electronics Inc 1 R2X 1 Rev 3 3 f io R2XL1 e 9 RAMSEY LEARN AS YOU BUILD ASSEMBLY STRATEGY Be sure to read through all of the steps and check the boxes as you go along to be sure you don t miss any Although you may be in a hurry to see results before you switch on the power check all wiring and capacitors for proper orientation Also check the board for any possible solder shorts and or cold solder joints All of these mistakes could have detrimental effects on your kit not to mention your ego Kit building tips Use a good soldering technique Let your soldering iron tip gently heat the traces to which you are soldering making sure to heat both the leads and the pads simultaneously Apply the solder to the the pad when the junction is hot enough to melt the solder The finished joint should look like a drop of water on paper somewhat soaked in Mount all electrical parts on the top side of the board provided The top side is clearly marked with a white silkscreen showing the part numbers you can t miss it This is the side that has little or no traces on it but is covered with mostly copper When parts are installed the part is placed flat to the board and the leads are bent on the backside of the board to prevent the part from
12. U1 for 12 volts and pin 11 for 12 volts It may not be exactly that voltage but 0 5 volts if fine Without power applied the R2XL1 will pass through au dio but not much PROBLEM Sound is very badly distorted SOLUTION You may be using a high level source into the R2XL1 causing it to overload Using this to convert from speaker lever to XLR is not recom mended but it is possible Just turn down your volume a bit Also check that you do not have the gain up all the way Lastly check to make sure your desti nation equipment is set up correctly PROBLEM Audio seems noisy or picking up interference SOLUTION Here is where R6 and R12 come into play The two 560 ohm green blue brown resistors that were left out of the normal construction steps may need to be installed With long cable runs you are more likely to run into this type of problem We left these parts out initially to help increase the over all frequency response of the unit and provide you with a much crisper sound You may need to install them however to combat the effects of long cable runs Note to wired and tested customers By default these are installed on the wired and tested versions of the kit already PROBLEM It just wont work it must be Ramsey s fault SOLUTION Look in the warranty section for information how to contact us and to find out about our free services when it is our fault We would recom mend however that you go through the assembly steps SLO
13. WLY and check for potential mistakes If that fails give us a call and we ll be happy to help R2XL1 gt 18 The Ramsey Kit Warranty Please read carefully BEFORE calling or writing in about your kit Most problems can be solved without contacting the factory Notice that this is not a fine print warranty We want you to understand your rights and ours too All Ramsey kits will work if assembled properly The very fact that your kit includes this new manual is your assurance that a team of knowledgeable people have field tested several copies of this kit straight from the Ramsey Inventory If you need help please read through your manual carefully All information required to properly build and test your kit is contained within the pages 1 DEFECTIVE PARTS It s always easy to blame a part for a problem in your kit Before you conclude that a part may be bad thoroughly check your work Today s semiconductors and passive components have reached incredibly high reliability levels and it s sad to say that our human construction skills have not But on rare occasions a sour component can slip through All our kit parts carry the Ramsey Electronics Warranty that they are free from defects for a full ninety 90 days from the date of purchase Defective parts will be replaced promptly at our expense If you suspect any part to be defective please mail it to our factory for testing and replacement Please send only the defective part s not the
14. agram shows a black stripe indicating the same Make sure and put the part in the same way as shown 2 Install D3 another 1N4002 diode Again pay close attention to orienta tion 3 Install D2 a 1N4002 diode Check orientation 4 Install D4 the last 1N4002 diode to make up the bridge rectifier to give us out positive supply Pay attention to orientation again 5 Install D6 another 1N4002 diode Orientation must be correct or we will get no negative supply Note how this is placed between two large capaci tors Imagine trying to install this after the capacitors were soldered in Good thing you follow directions 6 Install D5 the last 1N4002 diode Again check orientation 7 Install R8 a 1K ohm resistor brown black red 8 Install R9 100 ohm resistor brown black brown 9 Install R10 a 1K ohm resistor brown black red 10 Install C10 a 0 01 uF ceramic capacitor marked 103 11 Install R7 a 1K ohm resistor brown black red 12 Install C9 another 0 01 uF ceramic capacitor marked 103 13 Install U2 one of the LF347 quad opamps Note that the layout dia gram shows a dimple on the end this indicates pin 1 Your actual part may have this same dimple or a dot near pin one When installing ICs it is sometimes easy to have a pin bent underneath the part make sure all pins are through before soldering Always double check your part s orien tation before soldering all the pins R2XL1 gt 12 D U
15. ble causes of damage so that you can receive years worth of enjoyment using talking about and remembering the fun you had building your kit In short TAKE YOUR TIME when assembling the enclosure This is the part that you and your friends will look at and admire for years J 1 Lay the front and rear plastic plates over their corresponding labels to verify which sticker goes with which panel You ll want to work with one panel at a time to avoid possible mix ups 2 Remove the backing material from one of the stickers and line it up properly on its pre punched panel Make sure that they are aligned cor rectly before allowing them to touch the plastic plates They stick the first time line them up right 3 Usea sharp hobby knife to cut out the holes the labels along the pre punched holes A short sawing motion works well around the inner circum ference of the holes 4 Repeat the above steps for the other panel O 5 Insert the board into the case with the knobs and switches extending through the holes in the front panel 6 Raise the rear portion of the PC board and extend the jacks through the rear plastic plate Insert the plate into the grooves on the base tray 7 Secure the PC board to the bottom base tray with 4 short Phillips head screws R2XL1 e 17 TROUBLESHOOTING PROBLEM have no audio gain in fact it only attenuates SOLUTION You will need a voltmeter to check your power Look at pin 4 of
16. curely Insurance is recommended Please do not cause needless delays read all information carefully R2XL1 e 19 R2XL1 RCA TO XLR LEVEL CONVERTER KIT Quick Reference Page Guide uu u u 4 Circuit Description 4 Parne Llum u aou 7 Schematic Diagram 8 Parts Layout 9 ASSOMDIV unu uswa us nites 12 Using the R2XL1 15 Professional Audio Wiring 16 Troubleshooting 18 War anty 19 REQUIRED TOOLS e Soldering Iron Ramsey WLC100 e Thin Rosin Core Solder Ramsey RTS12 e Needle Nose Pliers Ramsey MPP4 or RTSO5 e Small Diagonal Cutters Ramsey RTS04 lt OR gt Technician s Tool Kit TK405 ADDITIONAL SUGGESTED ITEMS e Holder for PC Board Parts Ramsey HH3 e Desoldering Braid Ramsey RTS08 e Digital Multimeter Ramsey M133 Price 5 00 Ramsey Publication No MR2XL1 Assembly and Instruction manual for TOTAL SOLDER POINTS 153 ESTIMATED ASSEMBLY RAMSEY ELECTRONICS INC TIME 590 Fishers Station Drive Beginner AE 2 0 hrs Victor New York 14564 Intermediate 1 5 hr Phone 585 924 4560 Advanced 1 0 hr Fax 585 924 4555 www ramseykits com
17. eamp will always be at the ground potential This is a common practice that helps to reduce the likelihood of power pops and switching transients when you plug and unplug your audio cables R2XL1 e 4 The next component in line is R4 This 1K resistor in combination with R3 and R5 sets the gain of the first inverting opamp stage U1 C An inverting opamp will take the signal presented on its input and flip the polarity of the sig nal on its output giving you the inverse value of the original In our case the resulting output signal from the opamp pin 8 will be opposite in polarity to that of the original input signal on the left hand side of R4 The amplitude of the signal will also change depending on the gain of the circuit The formula for determining the gain in this circuit is given by Av Rf Ri where Ri is the input resistance of R4 and Rf is the feedback resistance of R3 R5 together If we want to find the maximum gain of this stage we can take our 1 000 1K ohm input resistor and divide its value by our 10 000 10K ohm pot and 100 ohm feedback resistors added together 10 100 or 10 1K ohms This works out to a maximum gain of 10 1 the negative value just means it is inverted How does this affect our signal Take for example a 1V input present at R4 Multiply the input signal value by the calculated gain factor 1V x 10 1 to obtain 10 1 volts on the output pin 8 of the amplifier That wasn t so hard was it Let
18. entire kit The part s MUST be returned to us in suitable condition for testing Please be aware that testing can usually determine if the part was truly defective or damaged by assembly or usage Don t be afraid of telling us that you blew it we re all human and in most cases replacement parts are very reasonably priced 2 MISSING PARTS Before assuming a part value is incorrect check the parts listing carefully to see if it is a critical value such as a specific coil or IC or whether a RANGE of values is suitable such as 100 to 500 uF Often times common sense will solve a mysterious missing part problem If you re missing five 10K ohm resistors and received five extra 1K resistors you can pretty much be assured that the 1K resistors are actually the missing 10 K parts guess the red band really does look orange Ramsey Electronics project kits are packed with pride in the USA If you believe we packed an incorrect part or omitted a part clearly indicated in your assembly manual as supplied with the basic kit by Ramsey please write or call us with information on the part you need and proof of kit purchase 3 FACTORY REPAIR OF ASSEMBLED KITS To qualify for Ramsey Electronics factory repair kits MUST 1 NOT be assembled with acid core solder or flux 2 NOT be modified in any manner 3 BE returned in fully assembled form not partially assembled 4 BE accompanied by the proper repair fee No repai
19. falling out before soldering 1 The part is then soldered securely to the board 2 4 and the remaining lead length is then clipped off 5 Notice how the solder joint looks on close up clean and smooth with no holes or sharp points 6 4 5 R2XL1 e 10 We sincerely hope you put this kit together by carefully following the direc tions This project will not work as well as you wished if you just slap it together without following good assembly techniques and all of the instructions No matter how clear we may think our manual is if you have any questions give us a Call at the factory instead of jumping to conclusions We will be happy to help you with any problems Keep in mind that we want to mount all the parts AS LOW AS POSSIBLE to the board A 1 4 lead length on a resistor not mounted close to the board can act as an inductor or an antenna causing all sorts of problems in your circuit The components don t need to be squished to the board just keep them as close as possible to the board CORRECT CORRECT For each part our word Install always means these steps O 1 Pick the correct part value to start with 2 Insert it into the correct PC board location making sure the part is mounted flush to the PC board unless otherwise noted 3 Orient it correctly follow the PC board drawing and the written directions for all parts especially when there s a right way and
20. is amplified by the inverting amplifier U1 B with a gain of 1 its output will be 1 Volt When the same 1V input is ap plied to the non inverting stage U1 A with a gain of 1 its output will be 1 Volt Looking across the outputs of both amps pins 1 and 7 the difference be tween the two works out to be 1 1 2 Volts Hey that s pretty neat Armed with the information that our first stage U1 C has a maximum gain of 10 1 and the second stage U1 A and U1 B has a fixed gain of 2 we can R2XL1 e 5 determine that the total gain of the circuit is 20 2 by multiplying the series gain values together 10 1 x 2 This gives us plenty of control to get our low level RCA signals up to the higher XLR requirements This may be more than you ever wanted to know about a preamplifier de sign but we aren t done yet The output of the two opamps in the last stage are sent through another set of coupling capacitors that removes any DC com ponent we may have accidentally added when we amplified the audio It also helps us to isolate our preamplifier from any DC present from a poorly de signed audio component that you may plug this into We use larger 100 uF capacitors here because XLR specifications say we need to drive down to 560 ohm impedances The larger capacitors help us to preserve our low frequency information The left channel works exactly the same as the right so take a look at the schematic and apply your new found knowledge
21. oroughly for potential shorts Well it looks like it is time to hook up our peripherals and give our newly completed kit a test USING THE R2XL1 The operation is pretty straight forward but want to give you one bit of advise so that you won t get frustrated Don t use your R2XL1 as your primary audio gain control Since we built in a lot of gain it is too difficult to adjust on the fly Even worse there are two controls to tweak making it even harder to keep these at the same setting at the same time Set these once and leave them alone In fact you may want to put a marking on them so you can tell at a glance if someone messes them up on you The last thing we need to mention is the labeling of the panels for the case set This would normally be started by a statement sounding like A funny thing happened on the way to the print house There are regretfully two er rors on the labels that come with the case set one on the front and one on the back The front panel Stereo Mono mode selection switch is backwards and the rear panel RCA Audio Input jacks are labeled backwards We are sorry for the inconvenience but this is usually a set it and forget it type of product Keep in mind from the Circuit Description section Mono mode operation re quires feeding your audio source into the Right RCA input labeled Left on the rear panel sorry Set your levels as needed and your off to the races R2XL1 e 15 PROFESSIONAL AUDIO WIR
22. r will be undertaken until we have received the MINIMUM repair fee 1 2 hour labor of 25 00 or authorization to charge it to your credit card account 5 INCLUDE a description of the problem and legible return address DO NOT send a separate letter include all correspondence with the unit Please do not include your own hardware such as non Ramsey cabinets knobs cables external battery packs and the like Ramsey Electronics Inc reserves the right to refuse repair on ANY item in which we find excessive problems or damage due to construction methods To assist customers in such situations Ramsey Electronics Inc reserves the right to solve their needs on a case by case basis The repair is 50 00 per hour regardless of the cost of the kit Please understand that our technicians are not volunteers and that set up testing diagnosis repair and repacking and paperwork can take nearly an hour of paid employee time on even a simple kit Of course if we find that a part was defective in manufacture there will be no charge to repair your kit But please realize that our technicians know the difference between a defective part and parts burned out or damaged through improper use or assembly 4 REFUNDS You are given ten 10 days to examine our products If you are not satisfied you may return your unassembled kit with all the parts and instructions and proof of purchase to the factory for a full refund The return package should be packed se
23. s and all of the rest of your electrolytic capacitors This will save you from having to read orientation six more times 26 Install C5 another 100 uF electrolytic capacitor 27 Install a 100 uF electrolytic capacitor 28 Install C2 a 100 uF electrolytic capacitor 29 Install VR1 the 78L12 12 regulator Yes this looks like a transistor but it s not In fact has many transistors and a special Zener diode inside Make sure the flat side of the part is installed as shown on the diagram R2XL1 e 13 30 Install VR2 the 79112 negative 12V regulator Again make sure and install it with the orientation shown on the diagram 31 Now it is time to install the larger components We will begin with the jacks Install J2 one of the PC mounted XLR connectors You must be careful when installing these parts that all the leads go in the respective holes For example there is a little pin in the middle of the bottom which is used to ground the cable case This can easily get bent over Make sure all of the pins are through the holes before soldering Also make sure to solder the mounting pins 32 Install J4 the other XLR connector 33 Install J1 the dual RCA connector Make sure the part is flush when soldering for good mechanical soundness 34 Install J6 our 2 5 mm AC power jack 35 Install C11 a 470 uF electrolytic capacitor Check orientation just in case you forgot 36 Install C12 another 470
24. tive pulses are then smoothed by C13 into a negative supply source with a bit of ripple To remove the remaining pulses we use a negative voltage regulator VR2 to completely smooth it out There you go our negative supply At this point we have two regulators VR1 and VR2 with outputs of 12V and 12V respectively This means we have plenty of supply voltage for our opamps to work with Usually opamps have maximum output of 1 4 volts within their supply voltage so our opamps will go from 10 6V to 10 6V giving you a 21 2 Volt total swing More than enough to drive XLR inputs with plenty of dynamic range Ok think it is time to start building our kit R2XL1 e 6 RAMSEY R2XL1 PARTS LIST Semiconductors O 6 1N4002 Rectifier Diodes D1 2 3 4 5 6 1 78L12 12V Voltage Regulator VR1 O 1 79112 12 Voltage Regulator VR2 O 2 LF34 7N Quad FET opamps U1 2 Resistors 2 10K ohm potentiometers R5 11 6 1K ohm resistors brown black red R1 2 4 7 8 10 2 10K ohm resistors brown black orange R13 14 100 ohm resistors brown black brown R3 9 560 ohm resistors green blue brown R6 12 OOOOO 2 2 Capacitors 2 0 01 uF Ceramic capacitors marked 103 C9 10 O 4 10 uF Electrolytic capacitors C1 4 7 8 4 100 uF Electrolytic capacitors C2 3 5 6 O 3 470 uF Electrolytic capacitors C11 12 13 Miscellaneous 2 Male PC Mounted XLR connectors J2 4 2 DPDT push button switches
25. um We don t expect you to come across this but if you do here is what you may do 1 Try running a wire to connect the chassis of your destination equipment to the source equipment AND the R2XL1 If all are grounded well to gether it may prevent the ground loop from traveling down the audio ca bles 2 Try lifting the shield wire on your XLR cable on the FEMALE end the one that plugs into your R2XL1 This will eliminate the path of the ground loop R2XL1 e 16 If neither of these methods works and you have a source of RF nearby like a transmitter it may be RF causing interference This is a more difficult problem to fix but not impossible The first thing to do is move equipment away from the RF source The next is to put the R2XL1 inside of a metal case The last method is to use RF chokes on your audio cables usually snap on ferrite beads of various sizes You should be able to find these at most electronic supply stores ASSEMBLY INSTRUCTIONS FOR CUSTOM CASE The enclosure is a key element to the overall pride you will have upon com pleting your Ramsey kit The enclosure will show how you were able to build from scratch a commercial piece of high tech electronics For some of us the enclosure will also hide a number of not so pretty assembly mistakes Once the kit is enclosed your friends will never know that you were new to soldering Finally the enclosure case will protect your electronics from many possi
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