Capacitance Meter Manual
Contents
1. 0 when zeroing button is pressed gt Check R11 R13 R15 R16 and related connections gt Test poles short pin 1 2 and 3 short to GND can cause this problem too 3 Broken Display gt Check all connections related to the LED display Look for opens as well as shorts 4 Bad serial data output gt Make sure level converter is in place if connected to standard RS232 devices gt Make sure correct data format is selected Revision History Version Date Descriptions 01 2008 09 17 First created 02 2008 11 28 Modified for 109 06000 00B PCB Removed reworking instructions since errors in previous PCB had been corrected 03 2009 12 01 Added more detailed explanation for serial date format 04 2010 02 25 Re wrote the section How To Assembly Revised the section How to Use Added the section Troubleshooting JYE Tech 2 www jyetech com2. DN060 02v04 Capacitance Meter Manual Features How to i About 1 accuracy No calibration needed Measuring range 1pF 500uF Automatic range select Zeroing available Real time serial output of measurement read outs with time stamp Low cost and easy to build assemble Install components listed in the BOM onto PCB by following schematic and labels Please ignore components that are not listed in the BOM even they appear in schematic and PCB These parts are designed in for possible change in future or serve as options Without them the meter works fine 2 Please note the polarity of C5 and C6 Their positive poles should go into the square pads How to Use Measurement Insert the capacitor to be tested into J5 Capacitance will be displayed Alternatively caps not fitting into J5 can be connected through J3 with a pair of clips Usually large caps take longer to show results but should not longer than 2 seconds Zeroing Remove cap if any from J5 and J3 Press the ZERO button CO will display Wait for it to disappear Now the stray capacitance is compensated The compensation value is stored in EEPROM and will remain in effect until another zeroing is performed To obtain good measurement results for small capacitance shielding is required To do this put the board into a metal box and connect the ground of the meter to enclosure Serial Data Format The ASCII output from TXD pin of J4 contains three fields
3. sequence number measurement time in seconds and measured capacitance The line format is as below SSSSS TTTTT tt CCCCU where SSSSS is 5 digit sequence number TTTTT tt is 8 digit time stamp in second and CCCCU is 5 digit measured capacitance with U being unit digit Different fields are separated by 1 space Each line is ended with LF 0x0A and CR 0x0D Output baud rate is 38400bps fixed Data format is 8 data bits 1 stop bit and no parity Output level is 5V So a level converter is needed to connect to RS232 compatible device PC serial port for example Specifications Error lt 2 Range 1pF 500uF Power Supply voltage 8 16 DC Power Supply current lt 30mA Troubleshooting 1 No Display or garbage display without activity gt First power supply should be checked Make sure 5V is available at MCU power pins pin 7 amp 20 of U1 gt If power supply is good check if MCU gets clocked This can be done by measuring the DC voltage at pin 10 of U1 MCU This pin is oscillator s output It should read about 2 5V if oscillator is working If not Y1 C1 C2 and MCU should be checked Usually this problem is caused by defective Y1 C1 or C2 MCU not programmed or programmed wrong can cause this problem too JYE Tech 1 www jyetech com Capacitance Meter Manual DN060 02v04 Note When we say voltages we mean voltage with refer to GND if not stated otherwise 2 The display is stuck at C
Download Pdf Manuals
Related Search