Author Topic: $20 LCR ESR Transistor checker project  (Read 4237216 times)

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Offline Cosmic_Starlight

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Re: $20 LCR ESR Transistor checker project
« Reply #9800 on: December 08, 2024, 04:08:15 am »
well today it certainly has been a rollercoaster

so today i replaced all transistors and ICs so i replaced T1, T2, IC2,and T3, also replaced both caps of the crystal and the crystal, tried replacing both 10uf caps but the one under the screen the one i got was too tall so i had to put the original back in, the other one i did replace

so before attempting to turn it on again i made doubly and triple sure that there were no solder bridges on any transistor or IC

i also havent put back the TL431 (IC3) back in for the time being

so i put the battery in, press the encoder, screen is white, then it disappears, and wow, it appears to be alive, , however its function seemed to be a bit erratic, like it would keep cycling asking me to calibrate and such, there was one time it booted me to the main menu and i could scroll up and down it no problem, so i put one of the S9012 i bought and it measured it alright (as much as an uncalibrated unit could)

but the unit wouldnt turn off on its own for whatever reason, even when left alone for a few seconds, also the battery voltage when it first turns on seems to be erratic too not to mention there seems to be a character missing on screen (when it first turns on?

so i searched for a YT video on how to calibrate this thing, and i knew before hand that booting it up with zif socked 1-2-3 shorted it would start on self test mode and calibrate itself, well so did they guy on the yt video, so i did just that, one small cat5e wire going from pin 1 to pin 2 and from pin 2 to pin 3 and tried turning it on buuuuuuut....

now am back at a solid white screen again, on he atmega vcc pin i read 5.0 something volts so i dont think is that ?!

i dunno, if trying to calibrated it without the TL431 IC3 in place was an error or not

so what could have happened ? i cant hear the faint fizzing noise i could hear before so idk what is wrong with it

i will attach some photos of when it worked (it wasnt very long)

 

Offline Cosmic_Starlight

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Re: $20 LCR ESR Transistor checker project
« Reply #9801 on: December 08, 2024, 05:29:19 pm »
OK this is making me want to pull my hair out so first thing I did today was try and turn it on again and it did but for whatever reason it thought that there was a transistor connected and it was measuring some capacitance, so I tried putting a transistor in the zif socket and when I turned it on, white screen again

So that s where I am currently, no idea what's wrong with it or what to check

I also found a wall adapter for it from an old router, does this device expect center positive or center negative ?
 

Offline Feliciano

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Re: $20 LCR ESR Transistor checker project
« Reply #9802 on: December 08, 2024, 05:48:35 pm »
So it was sort of working until the moment you shorted T1,T2,T3?
Did you measure whether one or more of those terminals had 0V or 5V static? (like having a damaged protection circuit). Because maybe you could damage the MCU if that was the case :(
You could measure now whether those have a short to ground or to 5V.

PS. Normally we work with 9.0Vdc center positive, unless you're talking about music pedals.
« Last Edit: December 08, 2024, 05:53:34 pm by Feliciano »
 

Offline Cosmic_Starlight

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Re: $20 LCR ESR Transistor checker project
« Reply #9803 on: December 08, 2024, 05:54:49 pm »
So it was sort of working until the moment you shorted T1,T2,T3?
Did you measure whether one or more of those terminals had 0V or 5V static? (like having a damaged protection circuit). Because maybe you could damage the MCU if that was the case :(

PS. Normally we work with 9.0Vdc center positive, unless you're talking about music pedals.

I didn't measure any voltage anywhere, it still sort of works, like I said I turned it on today and even if I kept removing battery power it kept thinking there was a transistor connected and it kept measuring it

That was until I put a transistor in and its now back to a solid white screen

So I can't try powering it from a 12v wall adapter ?
 
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Offline Feliciano

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Re: $20 LCR ESR Transistor checker project
« Reply #9804 on: December 08, 2024, 06:05:42 pm »
If you disconnected the programming cable, and the MCU detects there is a phantom component there, probably is damaged now.
Some units have a protection section of SRV05-4 plus a TVS or a Zener between Vcc and GND, that is located very close to T1,T2,T3. Sometimes those parts get damaged (let's say somebody forgot to discharge an electrolitic capacitor), and if still being used can damage your new microcontroller. Shall that parts get damaged (shorted to Vcc or GND), you could remove it, replace the ATmega, and try again.

Regarding 12V or more, your series voltage regulator could accept that voltage and still deliver 5V, depending on whether it's a good quality component or a lousy fake. You know the reputation of the store you bought those from, so it's up to you to decide and proceed.
 

Offline Cosmic_Starlight

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Re: $20 LCR ESR Transistor checker project
« Reply #9805 on: December 08, 2024, 06:12:31 pm »
If you disconnected the programming cable, and the MCU detects there is a phantom component there, probably is damaged now.
Some units have a protection section of SRV05-4 plus a TVS or a Zener between Vcc and GND, that is located very close to T1,T2,T3. Sometimes those parts get damaged (let's say somebody forgot to discharge an electrolitic capacitor), and if still being used can damage your new microcontroller. Shall that parts get damaged (shorted to Vcc or GND), you could remove it, replace the ATmega, and try again.

Regarding 12V or more, your series voltage regulator could accept that voltage and still deliver 5V, depending on whether it's a good quality component or a lousy fake. You know the reputation of the store you bought those from, so it's up to you to decide and proceed.

You mean those tiny smd components below the zif socket ? I don't have any tools to work on them, done even know how to about testing them of they're good

I also haven't connected any programming cable since I don't even have one yet

I still don't understand how it could've gotten damaged if what I did was what you do when it asks you to calibrate it

Also I don't understand how it didn't turn on last night but today did until I put a transistor in the zif socket
 

Offline Feliciano

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Re: $20 LCR ESR Transistor checker project
« Reply #9806 on: December 08, 2024, 06:15:10 pm »
Something like the attached, and the related "b" schematic. Once you know how it is internally made, you can deduce how to test it, and if damaged, elucubrate on how could damage the MCU when it tries to pull the terminals high and low to measure a component.
« Last Edit: December 08, 2024, 06:20:13 pm by Feliciano »
 

Offline Cosmic_Starlight

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Re: $20 LCR ESR Transistor checker project
« Reply #9807 on: December 08, 2024, 06:23:26 pm »
Something like the attached, and the related "b" schematic. Once you know how it is internally made, you can deduce how to test it, and if damaged, elucubrate on how could damage the MCU when it tries to pull the terminals high and low to measure a component.

So I just put my dmm on continuity mode so it beeps I put negative lead on the battery negative pad on PCB and it only beeps on the smd components on the bottom side of the two on the left and the 6 legs one only on the right side middle one
And the atmega only beeps on its ground pins nowhere else
 

Offline Cosmic_Starlight

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Re: $20 LCR ESR Transistor checker project
« Reply #9808 on: December 08, 2024, 11:25:22 pm »
am about to give up on this unit, tried replacing S9012 (T3) like a comment on a yt video said and put in place the N3906,

so i just put a blob of solder between the 3 legs so it would desolder easier, and it did it slid right out so easily it almost fell out on its own (transistor didnt even get enough time to even get luke warm), so then i used a desolder pump to clean the holes for the new transistor, and it did clean the holes alright, so good in fact it lifted the middle pad of T3,

anyway since the trace right next to it was a little exposed or had solder already i managed to solder it to that and  that made sure there were no solder bridges and tried turning it on but same result solid white screen (also the S9012 was still good)

idk how i managed to lift that pad, havent done it working on 40+ years pcbs but i managed to do it here without even trying

anyway sometime next week i will buy the little usb programmer thing and try re-flashing the current atmega and the spare one, maybe change the other electrolitic cap too

if that still doesnt work i will just buy another AY/AT but this time a pre-built one, am not going to solder all that stuff again for it to not work because some random component was defective

 
« Last Edit: December 08, 2024, 11:30:57 pm by Cosmic_Starlight »
 

Offline Yuriy_K

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Re: $20 LCR ESR Transistor checker project
« Reply #9809 on: December 09, 2024, 08:11:39 am »

anyway sometime next week i will buy the little usb programmer thing and try re-flashing the current atmega and the spare one, maybe change the other electrolitic cap too

if that still doesnt work i will just buy another AY/AT but this time a pre-built one, am not going to solder all that stuff again for it to not work because some random component was defective

Everything shown at the beginning of this page indicates that your tester is not working properly. You cannot check parts without TL431, and even more so calibrate, i.e. make changes to the firmware of the program for incorrect operation of the tester.
You need to measure the resistance between inputs 1-2, 2-3, 1-3 with the power off, in all measurements the resistance value should be greater than 200 MOhm. This indicates that there are no parasitic traces of soldering flux.
In my opinion, you do not have enough knowledge to assemble and independently configure such devices, buy and try to gain experience in communicating with this seemingly simple, but in fact complex measuring device.
 

Offline hapless

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Re: $20 LCR ESR Transistor checker project
« Reply #9810 on: December 09, 2024, 06:36:52 pm »
[...] You cannot check parts without TL431 [...]

Why not? It's been said numerous times before that you don't need to have a shunt voltage reference if your VCC supply is within a certain tolerance. I would get something more precise than TL431 if I had to replace it, but not putting it in is, or at least used to be, a very valid option. If looking for something to blame, instead, it looks to me like the MCU is fried, and probably was long before it was sold...
 

Offline valcher

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Re: $20 LCR ESR Transistor checker project
« Reply #9811 on: December 09, 2024, 06:54:34 pm »
To completely de-energize the ESR02 Pro, I connected the negative battery wire to the disconnect contact of the external power connector. To disconnect the battery, I insert an empty plug into the external power socket.
 

Offline Cosmic_Starlight

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Re: $20 LCR ESR Transistor checker project
« Reply #9812 on: December 09, 2024, 09:10:41 pm »
i do admit my knowledge in electronics is very basic and barely enough to somewhat understand how this thing works (and not even then is enough) but thanks to the help ive gotten in this forum ive was able to at least get it to turn on and show stuff on screen (which is more than i wouldve been able to have gotten on my own)

thanks to that i at least know the screen is good

even if i do end up fixing this particular unit or not at least i think it was a valuable learning experience managed to refine my soldering technique a bit further, tho my de-soldering technique still needs some work)

i will buy the programmer for the other atmega i got, but since i dont know for sure if the original one its fried or not, much less if it was because of some problem on this device or not i will leave it alone for now until i buy another AY/AT unit

i honestly dont understand how doing the procedure to calibrate it couldve damaged it (maybe it really was defective from before shipping or maybe its fw was corrupt and caused it to get damaged ?

the thing is i dont know if i should buy another DIY kit again (which are a bit cheaper) or buy a pre assembled unit (both have the risk of being defective, and i dont want to get my AE account banned due to excessive disputes) so am not sure how to proceed

after i get another unit (hopefully fully working this time) i will use it to check the other unit as reference and manually test all the parts of the old one, hell i will even repair all the traces that are damaged too with some very thin wiring if i must (dont care if it looks ugly)

but even if i buy it today it will probably take 20+ days to get to me so it will most likely arrive early next year
 

Offline Feliciano

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Re: $20 LCR ESR Transistor checker project
« Reply #9813 on: December 09, 2024, 09:38:00 pm »
If your skills are not so good, and you want less trouble, buy an already assembled unit.

You repeat you want to learn/udnerstand, but did you at least read the FAQ I wrote? Anyways, here's a summary:

To program your another ATmega is not fool-proof. First thing: If you prefer the k-firmware, you will have to look for an already compiled version for the unit you buy. Or if you prefer the m-firmware, you will have to edit several configuration files and compile the firmware, then flash it.

The CTester test a component sending pulses over high and low value resistors, and measure responses on the terminals.

On the other hand, if you look carefully at the circuit diagram of the protection I shared before, you will see several diodes (including the pin numbers), plus a Zener or TVS. That is supposed to help protect the unit if somebody insert a charged capacitor. But sumetimes that protection gets damaged, and the MCU gets damaged as well. You tested it with your buzzer, but you should have tested it with the Diode function. That's why I shared the diagram for you to analyze and proceed. If you still want our support please understand we can't fix this unit for you, you have to do your homework.
 

Offline Cosmic_Starlight

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Re: $20 LCR ESR Transistor checker project
« Reply #9814 on: December 09, 2024, 10:15:42 pm »
If your skills are not so good, and you want less trouble, buy an already assembled unit.

You repeat you want to learn/udnerstand, but did you at least read the FAQ I wrote? Anyways, here's a summary:

To program your another ATmega is not fool-proof. First thing: If you prefer the k-firmware, you will have to look for an already compiled version for the unit you buy. Or if you prefer the m-firmware, you will have to edit several configuration files and compile the firmware, then flash it.

The CTester test a component sending pulses over high and low value resistors, and measure responses on the terminals.

On the other hand, if you look carefully at the circuit diagram of the protection I shared before, you will see several diodes (including the pin numbers), plus a Zener or TVS. That is supposed to help protect the unit if somebody insert a charged capacitor. But sumetimes that protection gets damaged, and the MCU gets damaged as well. You tested it with your buzzer, but you should have tested it with the Diode function. That's why I shared the diagram for you to analyze and proceed. If you still want our support please understand we can't fix this unit for you, you have to do your homework.

am sorry, it appears i have bitten more than i could chew because it appears i have missinterpreted/missunderstood or not understood at all some troubleshooting guidance that was given to me

i will take a break from this and maybe some time down the line with a fresh mind and hopefully some new found knowledge and understanding i can hopefully fix it, in the mean time i will just buy another one (that hopefully works) and use that one as is

am very sorry of i caused you any frustration i fully understand none of you cant do much besides saying do this or check that and that will be useless if i cant understand it or be able to read the schematics or even know how to read them or how to test specific components

nevertheless all your help and the others help has been greatly appreciated i honestly never expected to get this much help
« Last Edit: December 09, 2024, 10:17:36 pm by Cosmic_Starlight »
 

Offline SA

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Re: $20 LCR ESR Transistor checker project
« Reply #9815 on: December 14, 2024, 05:42:09 pm »
Hello, Madires
Don't you think it is time for an upgrade?
Atmega328p is limited by its flash memory, eeprom and sram. What is your opinion to Atmega 2560 as a suitable candidate?
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #9816 on: December 14, 2024, 05:49:44 pm »
ATmega644/1284 and ATmega640/1280/2560 are supported by the m-firmware.
 

Offline Yuriy_K

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Re: $20 LCR ESR Transistor checker project
« Reply #9817 on: December 15, 2024, 01:22:43 pm »
Atmega328p is limited by its flash memory, eeprom and sram. What is your opinion to Atmega 2560 as a suitable candidate?
You need to familiarize yourself with the existing publications.
https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg4504399/#msg4504399
On the following pages there are more examples of measurements on this TTester with K-firmware.
« Last Edit: December 15, 2024, 01:26:52 pm by Yuriy_K »
 
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Offline bobrov1989

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Re: $20 LCR ESR Transistor checker project
« Reply #9818 on: December 15, 2024, 09:03:18 pm »
After reading about available options (kits/Chinese devices) I decided to make own PCB 😅. I mainly used to old k-software based LCR T4 for components/transistors testing and wanted an upgrade for it. So I used ATMega644, 2.4" color LCD, rotary encoder and USB-C Chartable Li-Po battery. The PCB is not ideal, but working fine with the latest m-software (1.53). I've shared the project on GitHub https://github.com/vitaliy-bobrov/avr-transistor-tester
 
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Offline ART_ME

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Re: $20 LCR ESR Transistor checker project
« Reply #9819 on: December 16, 2024, 06:35:26 am »
Hi.
I compiled my version for ATMEGA328BP under ubuntu, there was no any problems.
The device works, turns on and off, measures resistors and capacitors successfully, it seems.
But there was a problem with measuring the stabilization voltage of the zener diode - the ADC gives much higher readings, for example, a zener diode at 7.5 V shows as 11.12 V. I noticed that the battery voltage is also indicated by strange numbers - 3.9 V is indicated as 4.94 V.
Connecting the zener diode to PC3 through a 100 k \ 12 k divider, connecting the battery to PC4 directly.
I changed the versions - the result is always the same. I also changed a lot of things in the settings, but I still did not achieve the desired result.
Now I work on the hardware assembly with Arduino Nano 3.0, I reduced the capacitor on the AREF to 1000 pF.
I changed the Arduino Nano - the result is the same. I checked the ADC operation with my software - it works fine.
Which way should I look to solve my problem?
I will be grateful for any ideas.
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #9820 on: December 16, 2024, 11:02:03 am »
Could you please measure the voltages at the pins VCC and AVCC? Are they both 5V?
 
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Offline ART_ME

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Re: $20 LCR ESR Transistor checker project
« Reply #9821 on: December 16, 2024, 11:48:06 am »
Thanks, that's a good idea.
I haven't tested it yet.
 

Offline ART_ME

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Re: $20 LCR ESR Transistor checker project
« Reply #9822 on: December 16, 2024, 03:13:10 pm »
Dear madires,
You were 100% right - I found a power supply problem inside my both Arduino Nano.
Thank you very much for your help.
 :-+
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #9823 on: December 21, 2024, 10:59:23 am »
This time just a few improvements and bug fixes:

v1.54m
- Improved filter for Ge BJTs in CheckDepletionModeFET() (thanks to KenBC1).
- Changed threshold for output of leakage/reverse current to 10 nA (suggested by fafa80@EEVblog and indman@EEVblog). Also adapted GetLeakageCurrent() to support low currents at nA scale.
- Fixed capacitance measurement issue for diodes with high leakage current (was Regression in LargeCap(), reported by fafa80@EEVblog).
- Updated Brazilian Portuguese texts (thanks to wandows@EEVblog).
- Fixed compiler error for a counter variable in 5V-Meter (reported by Alkapton@GitHub).
- Added option for display of base-emitter capacitance C_be for BJTs (SW_C_BE, suggested by edgard22@EEVblog).
- Added remote control command C_BE for base-emitter capacitance of BJTs.
- Different position of question mark symbol in function Show_Fail() when UI_CENTER_ALIGN is enabled (reported by carrascoso@EEVblog).
- Updated Spanish texts (thanks to pepe10000@EEVblog).

Please download at:
- https://github.com/madires/Transistortester-Warehouse
- https://github.com/kubi48/TransistorTester-source

PS: Bohu's updated PDFs for 1.54m are also available.
« Last Edit: December 21, 2024, 02:22:41 pm by madires »
 
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Offline bobrov1989

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Re: $20 LCR ESR Transistor checker project
« Reply #9824 on: December 21, 2024, 03:48:22 pm »
It looks like SW_C_BE is missing in the config file, tried to define it anyway as I can see checks for it in the code ;)
 


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