$20 LCR ESR Transistor checker project

[Andbro]

Hi,

It's my mistake, i have looked the bad schematic. On AY-AT, the encoder is not in parallel with the ZIF.
When i check with a precision multimeter between the ZIP and MCU pin, the resistor is 0.1 ohms.
May be a bad MCU ? The precision is very good. For two resistors 1K @ 0.1%. i.m reading:
1-2 1000 ohms
2-3 1001 ohms   

It's a mystery this 0.6 ohm

Thank

[indman]

Hi,
I have bought a new AY-AT. When i'm calibrate, the values R0= 0.62, 0.64, 0.63
I found these values very high or it's normal ?

Show the photo what you 're using as calibration jumpers?

[madires]

It's a mystery this 0.6 ohm

Since it's consistent across all three probe pairs it shouldn't be any issue.

[Andbro]

Hi,

See picture of the jumper.

[indman]

Andbro,what kind of material is this jumper made of?
What would be the result if you made the same detail out of copper?

[Andbro]

It's a lead of power resistor 2W

[Monkeyboi]

I ordered the GM328A (SMD version) with the black solder mask from a seller on fleabay.  Firmware version is 1.13K.  Biggest piece of snot I've ever bought.  The seller claims it tests SCRs, TRIACs, BJTs, FETs, MOSFETS et al, but it only seems to be able to identify and check BJTs, FETs, MOSFETs and diodes.  It identifies a SCR as an "unknown or damaged part" and it identifies a TRIAC as an NPN BJT.  Darlington BJTs can't be tested or correctly identified either.

When it comes to testing inductors it's a joke. Tested a known good 5H inductor.  It reported the inductance as 46.2H which is not only way off but the meter specs only measures up to 20H.  WTF?  Checking on my DER-5000 LCR meter the inductor reads correctly.  I was wondering what the measuring frequency was of the GM328A so I hooked up my DSO across the part and determined the burst frequency was 1kHz.  So I decided to do a comparison of the inductance reading by setting my DER-5000 LCR meter to measure using the same 1kHz frequency.  Yes the DER-5000 did report the 5H inductor as a higher inductance but nowhere the way off reading obtained by the GM328A.  Curious to see how inaccurate the GM328A module was I measured several other inductors from 100uH upwards and compared them with the DER-5000 using the same measuring frequency.  No surprises, the GM328A was all over the place with its readings.

The capacitance tests didn't fair much better.  Used precision 0.5% micas and various other capacitors from ceramics through to electrolytics to evaluate the accuracy of the GM328A.  Not good at all and ESR measurements were way off.  The resistance tests weren't too inaccurate but give me a Fluke DMM any day.
 
The GM328A has an inbuilt frequency meter.  Found it not too bad for a quick and dirty reading.  Seemed to work well enough to 2.3MHz which is slightly above the claimed spec of 2MHz after which it just reported the same frequency no matter what the actual frequency input was.

The in-built oscillator is a PITA to set the frequency.  Apparently the rotary encoder switch needs a series of timed presses to step up through the ranges.  Fiddly and frustrating to use.

The voltmeter function is polarity conscious.  If you reverse the connections you read 0mV. 

General consensus is this gadget has potential if only it worked as described.  The one I got is a piece of snot.  Yes, I did run it through the calibration process several times but alas it still has inaccurate readings.

Does anyone know of a model, version number and a supplier of one that actually works as its supposed to?  Recommendations would be much appreciated.  Cheers.

[silvestrogatto]

Thank you madires

Tonight I will try to flash the firmware you suggested and will post the results.

[madires]

General consensus is this gadget has potential if only it worked as described.  The one I got is a piece of snot.  Yes, I did run it through the calibration process several times but alas it still has inaccurate readings.

For limitations of all Transistortester clones please see Karl-Heinz' excellent documentation at https://github.com/madires/Transistortester-Warehouse/tree/master/Documentation.

[Monkeyboi]

Thanks madires for the link to the document.  Most appreciated 
It is most informative.

Cheers,
Monkeyboi

[SirAlucard]

The test function runs several checks (T1...), each check is done 5 times. Note the results (second line) once for each check. It's explained in the README.

Alright I have T1, T2, T3, T5 and T6, is there no T7? I realize T4 is just remove the short.

But these are my results.


T1: 1093 on all of the tests

T2: 12 13 23 14 19 19

T3: 12 13 23 2494 2495 864

T5: 0 0 4985 4995

T6: 4990 4990 4995

So on measuring a 1uF capacitor across 2-3 the system shuts down. It also shuts down accross 1-3, but it measures just fine on 1-2. Measuring a .14nF cap across 1-2 works and measures in the ballpark of 140p however measuring 2-3 gives me 49.61uF 130.4 Ohms I_1 20.44uA. If I put that same 140p cap across 1-3 it shows up as 1-2 5pF. I've no idea what's going on.

[madires]

Please remove SRV05-4 (IC4) and check again.

[indman]

T3: 12 13 23 2494 2495 864

In T3 test at you very low indicators - 864 between points 2-3. It means that there are a leak and fault. Here than hardware tests are useful. One of the possible reasons as correctly noticed madires, in fault of protective diode pack of SRV05. T5 test is also not pleasant to me! If you measured not discharged capacitor, then first of all this protective assembly suffers.

[madires]

May I bother you with a new version of the m-firmware?

v1.37m:
- Fixed error in DS18B20_Tool() when ONEWIRE_IO_PIN is enabled (reported by  Bohu).
- Fixed issue with display of error message on color displays when the watchdog is triggered.
- Added new tool: event counter (HW_EVENT_COUNTER, suggested by Bohu).
- Changed the basic frequency counter to use TestKey() for user feedback.
  Exit counter by two short key presses (was single press).
- Added option to show reverse hFE for BJTs (SW_REVERSE_HFE, suggested by
  towe96@EEVblog). Also added "h_FE_r" command to remote command option.
- Added bitclock setting (BITCLOCK) for avrdude in Makefile (suggested by Bohu).
- Resolved issues with TRIAC detection in case of too high I_GT in Q3 or too high I_H (I_GT issue reported by petroid).
- Moved texts Tester_str, PWM_str, Hertz_str and CTR_str to language specific header files (suggested by indman@EEVblog).
- Changed output of frequency values to use common unit string instead of of split "H" and "z".
- Added option to display key hints (UI_KEY_HINTS), currently just "Menu/Test" (suggegsted by carrascoso@EEVblog).
- Updated Polish texts (thanks to szpila@EEVblog).
- Updated Russian texts (thanks to indman@EEVblog).
- Updated Spanish texts (thanks to pepe10000@EEVblog).

Download the latest version at https://github.com/madires/Transistortester-Warehouse/tree/master/Firmware/m-firmware.

[Andbro]

Hi,


Do you know this TFT model, i don't remember ?

Thank

[madires]

I'd guess it's a ST7735.

[Andbro]

Hi,

I have upgraded to Markus 1.37. How add a digit to Zener (Voltage) measure ?

Thank

[madires]

Do you mean an additional digit for 10mV resolution? If yes, you can modify Zener_Tool() in tool.c. Remove following line:

Code: [Select]

      Value /= 10;                 /* scale to 0.1V */

And change

Code: [Select]

        Display_Value(Min, -1, 'V');    /* display minimum */

to

Code: [Select]

        Display_Value(Min, -2, 'V');    /* display minimum */


[Andbro]

Hi madires,

I have follow your instructions, For a 8.67 Volts, When i push and hold the encoder, the value display is 86.7V and
when i release, i can read 8.67v Min

Thank

[madires]

There's another line to change. From

Code: [Select]

        Display_Value(Value, -1, 'V');

to

Code: [Select]

        Display_Value(Value, -2, 'V');


[Andbro]

Thanks madires,

the voltage display is perfect at two digits.

[indman]

Andbro, аnd for what to you such accuracy and permission when testing zener?

[Andbro]

Hi indman,

My model is a AY-AT and i don't have the zener tester circuit.
I'm using this input for reading a low voltage under 10 volts and not for testing zener.

Thank

[towe96]

Thank you for the reverse hFE addition, works great!

Attached are the .hex and .eep.hex files for 1.37m on my AY-AT clone.

[Andbro]

Hi,


Where we can change the CPU Frequency in 1.37M ?

Thank