$20 LCR ESR Transistor checker project

[avr]

I have put short wires between terminals but the device don't detect the short circuit in the calbration procedure.

I have measured these wires with the transistor tester in the testing mode and it shows 0.00 ohms between 1-2 and 2-3. But in the calibration...

[indman]

I have a transistor tester with a 328p and a 16x02 display. I have compiled the 1.55m firmware and I have uploaded it to the device.
It works well testing components, but I can't do the calibration and the autotest. When I access the calibration in the menu, the device asks for shorting the test points, when I do this the tester doesn't do any change. It remains without changes. If I rotate the encoder the tester shows an "error" message.

First of all, you need to show us photos of your tester with a good resolution. And make a short video where you show the problem. This will make it easier for other participants to help you find a solution.

[avr]

Hello

I post some images and a video of my device.


I used the pcb form this page:  https://www.pcbway.com/project/shareproject/Transistor_tester_7ef1c32f.html It's similar to base schematic presented here: https://github.com/madires/Transistortester-Warehouse/blob/master/Documentation/English/ttester-1.13k.pdf

Video: 

As I said, the tester works well when testing components, but it cannot perform the calibration and the autotest.

Thanks

[indman]

I post some images and a video of my device.

My tips, try them:
1. Remove the capacitors from the 21 pin ATmega328. They are not needed for this firmware.
2. From the photo of the board, it is clear that your soldering is not very high quality and there is a lot of flux residue and dirt. Thoroughly wash the board and renew the soldering in the problematic areas.
3. Remove the long conductors that connect the test pins 1-2-3 for a while. Use short copper conductors that need to be soldered to the board for calibration.

[avr]

I post some images and a video of my device.

My tips, try them:
1. Remove the capacitors from the 21 pin ATmega328. They are not needed for this firmware.
2. From the photo of the board, it is clear that your soldering is not very high quality and there is a lot of flux residue and dirt. Thoroughly wash the board and renew the soldering in the problematic areas.
3. Remove the long conductors that connect the test pins 1-2-3 for a while. Use short copper conductors that need to be soldered to the board for calibration.

Ok, I will try your indications.

Thanks for the answer.

[Dumidan]

Hello!

Try starting the calibration procedure WITH TERMINALS 1-2-3 FREE. From the video I see that you start the calibration with 1-2-3 SHORT, but the multitester has to do some measurements before asking you to short 1-2-3.

[indman]

but the multitester has to do some measurements before asking you to short 1-2-3.

This is incorrect and unnecessary, as the adjustment or self-test procedure performed from the menu should be initiated immediately without prior measurements.
Contacts 1-2-3 may be closed before this, but this will not prevent you from adjusting the tester.

[avr]

Hello!

Try starting the calibration procedure WITH TERMINALS 1-2-3 FREE. From the video I see that you start the calibration with 1-2-3 SHORT, but the multitester has to do some measurements before asking you to short 1-2-3.

I have done this and the result was the same. It is not shown in the vídeo because i couldn't hold the phone, press the the button, put the wires, etc.

[Yuriy_K]

but the multitester has to do some measurements before asking you to short 1-2-3.

This is incorrect and unnecessary, as the adjustment or self-test procedure performed from the menu should be initiated immediately without prior measurements.

You need to do it as described in the instructions...

[indman]

You need to do it as described in the instructions...

This action is not required for the self-test procedure. You can also perform the adjustment procedure directly from the menu.
The reason for the avr error is not this, but as I mentioned above, there are several serious reasons.

[avr]

Hi
I have tester the three tips. But it doesn't work.
In fact, when I remove the capacitor from 21 pin, the tester start to measure bad.
I am going to test with 8MHz quartz and other firmware.

[avr]

Solved!!!!   

As I said, I have changed the quartz, using one of 8MHz, and I have programmed with 1.55m for 8MHz and now it performs the autotest and the calibration without problems. It is my second tester that doesn't work well with 16MHz. I don't know why.


Thanks for your answers

[indman]

This is good! But you should have told us right away that you were using a 16MHz crystal instead of the original 8MHz crystal shown on the PCB.

[Yuriy_K]

Solved!!!!   

As I said, I have changed the quartz, using one of 8MHz, and I have programmed with 1.55m for 8MHz and now it performs the autotest and the calibration without problems. It is my second tester that doesn't work well with 16MHz. I don't know why.

You need to accurately measure the capacitor on pin 21, it should be in the 1000-1100 pF range. Cut the jumper between pins 7 and 20. Solder a 10 µH inductor to the back. Connect pin 20 to pin 22 with a 1 µF ceramic capacitor. Select a 5-10 µF ceramic capacitor between pins 7 and 8. After these modifications, it will work stably with a 16 MHz crystal.

[avr]

Bad news.  After a first calibration test the  device does not repeat the calibration or autotest.

I have reload the same firmware but it does not do nothing with calibration.

[avr]

I have loaded the 1.13k firmware and, with this, the selftest is performed flawlesslly. I don't know what was happenning with the 1.55m.

[Yuriy_K]

I have loaded the 1.13k firmware and, with this, the selftest is performed flawlesslly. I don't know what was happenning with the 1.55m.

It's all explained by changes in the parameters of the microchips being manufactured. The manufacturer (China) recently started producing DIP chips with low values, highlighted in red. Now, testers have to be adjusted to these parameters. I encountered this two years ago.

[indman]

I have loaded the 1.13k firmware and, with this, the selftest is performed flawlesslly. I don't know what was happenning with the 1.55m.

In the author's versions, there are now a lot of configuration settings that can significantly affect the stability of the firmware.
Therefore, it is important to carefully read the manual to make the correct settings for your hardware configuration.
This should never be forgotten!
Additionally, I recommend that you perform a self-diagnosis procedure on firmware 1.13k and provide us with the results of the T1-T7 hardware tests in text format.

[avr]

Hi

These are the values I get with 1.13k:
R0=.11 .14 .14

Ri_Hi=14.8
Ri_Lo=12.5

C0 39 40 41 pF
     41 41 41 pF

REF_C=-6
REF_R=11

C0samp 1:2
45.5 45.8 pF

C=samp1:3
45.3  45.4 pF

C0samp 2:1
46.0 46.1 pF

C0samp 2:3
45.6 45.8 pF

C0samp 3:1
44.3 44.4 pF

C0samp 3:2
45.2 45.2 pF

[avr]

I have loaded the 1.13k firmware and, with this, the selftest is performed flawlesslly. I don't know what was happenning with the 1.55m.

It's all explained by changes in the parameters of the microchips being manufactured. The manufacturer (China) recently started producing DIP chips with low values, highlighted in red. Now, testers have to be adjusted to these parameters. I encountered this two years ago.

Ok, this could be the problem with my device as I am using a 328p from a chinese dealer.

[indman]

These are the values I get with 1.13k:

Is this all the information available in the self-test procedure?
I am more interested in the T1-T7 tests, for example, in the following form:
Т2 -3 -3 -3
Т3 -7 -7 -7
Т4 -7 -7 -7
Т6 -6 -5 -2
T5 RH-
0 -1 0
T6 RH+
0 -1 -1
T7 RH/RL
0 0 0

[Yuriy_K]

These are the values I get with 1.13k:

All test results are normal. Try measuring different types of electrolytic capacitors and show photos of the measurements. I'll advise you on the necessary adjustments if there are deviations in the ESR.

Here are my tests for comparison...

[avr]

These are the values I get with 1.13k:

Is this all the information available in the self-test procedure?
I am more interested in the T1-T7 tests, for example, in the following form:
Т2 -3 -3 -3
Т3 -7 -7 -7
Т4 -7 -7 -7
Т6 -6 -5 -2
T5 RH-
0 -1 0
T6 RH+
0 -1 -1
T7 RH/RL
0 0 0

I only posted the results obtained from the menu options.

I wil perform the calibration and record the results.

Thanks

[madires]

I have put short wires between terminals but the device don't detect the short circuit in the calbration procedure.

I have measured these wires with the transistor tester in the testing mode and it shows 0.00 ohms between 1-2 and 2-3. But in the calibration...

Since you've got one of the newer ATmegas with a lower internal resistance it could be possibly a fringe case for function ShortedPair(). If the values from the selftest don't reveal anything obvious, please edit function ShortedPair() in probes.c. Look for following lines:

Code: [Select]

  Min = (Cfg.Vcc / 2) - 30;        /* lower voltage */
  Max = (Cfg.Vcc / 2) + 30;        /* upper voltage */
And change 30 to 50 (then recompile and flash new firmware).

[avr]

Hi

These are my results for the tests T0-T7:

R0=.08 .09 .12

T1 Ref=1093mV
RHf=866

T2 +RL- 12 13 23
-18 -18 -3

T3 +RH-  12 13 23
-11 -43 -34

T4
-11 -43 -34

T5 RH-
14 9 8

T6 RH+
-15 -13 -13

T7 RH/RL
 1 1 1

Ri_Hi=14.8
Ri_Lo=12.7