$20 LCR ESR Transistor checker project

[flixHr]

Hi,
I have a problem with my tester and and did not find any hints in this forum so far. I managed to reflash the microcontroller no problem. But the device turns itself off very quickly after each test. So quickly even that it is quite hard to read the result . I tried to edit the POWER_OFF option in the makefile and even tried to change the LONG_WAIT in the config.h file but nothing changed anything. Has anybody any idea what count be the cause for this? Am I overlooking something stupid?

[bianchifan]

I have a problem with my tester ...

1st.. plz tell something more, the are hundreds of variations all around, nobody knows what's your's..
2nd.. IIRC one or two y ago such a prob was discussed in thn german HOME forum, plz have a closer look at mikrocontroller.net (AVR Transistortester or similar), Karl-Heinz has a lot of experience with thousands of faults, feel free to ask

[bianchifan]

AY-AT colour kit is the best ...

I cannot consent at this very moment..
Some weeks ago I ordered such a kit from aliexpress, ok, the cheapest i could find, ~ 9$ 
I recieved a bunch of fuckin' crap!
I ordered for two reasons, I heared from several people about many problems making this kit run so I wanted to try for myself and I liked to get a tester for checking out the "M" firmware.
The PCB is damaged (looks like rejecting stuff), the MCU is programmed with something whatever but a running FW..

There maybe sellers with kits ok of course, but not all.

[flixHr]

1st.. plz tell something more...

I must admit, that was not quite the information needed.
My unit was sold as LCR-T4 and has the ST7565 display controller and an atmega328p micro controller.
I flashed the newest revision of mega328_T3_T4_st7565, mega328_st7565 and mega328_st7565_kit but always got the same problem. The tester shuts itself off immediately after the test is complete.
I made my own firmware by changing the POWER_OFF option in the makefile and changing LONG_WAIT_TIME and MIDDLE_WAIT_TIME in config.h.
I even got the same behavior when flashing 1.30m.

So has anybody seen this strange behavior before or has any hints into what direction to look?
Any help is much apreciated 

[nakcho]

AY-AT colour kit is the best if you want to be able to expand it or upgrade the firmware in the future.
if your just looking to use it then there is a cased unit that also tests zeners with an internal lithium battery - i think called T7?

good morning to all who participate in this forum ... I am entering the subject and trying to understand a little this operation ... I am not an expert .. I am a student ... I like the idea of ??this tester .. I wanted to know if there is any possibility that they tell me how I can install the ST7735R display or how it would be the configuration in proteus of this display ... because I see many connectors I can not make it work .. .. someone to help me please

[madires]

I flashed the newest revision of mega328_T3_T4_st7565, mega328_st7565 and mega328_st7565_kit but always got the same problem. The tester shuts itself off immediately after the test is complete.
I made my own firmware by changing the POWER_OFF option in the makefile and changing LONG_WAIT_TIME and MIDDLE_WAIT_TIME in config.h.
I even got the same behavior when flashing 1.30m.

Does the tester power up and display the battery voltage?

[madires]

good morning to all who participate in this forum ... I am entering the subject and trying to understand a little this operation ... I am not an expert .. I am a student ... I like the idea of ??this tester .. I wanted to know if there is any possibility that they tell me how I can install the ST7735R display or how it would be the configuration in proteus of this display ... because I see many connectors I can not make it work .. .. someone to help me please

Please see the schematic for the AY-AT kit. You can find several copies in this thread.

[flixHr]

Does the tester power up and display the battery voltage?

Yes the tester powers up normally and performs the test. It is quite slow to start the test but i don't know if that is normal.
But after the test the device powers off immediately.

[madires]

Could you please post the fuse settings?

[flixHr]

Hi,
After some poking around and measuring all the MCU pins I finally fount the cause for my wired behavior. The Problem was a bad transistor constantly pulling PD7 to ground. I did not notice this before as the tester did turn on regardless of the broken transistor because the unit would power on through the PNP transistor at the input and would turn off through the second working NPN transistor. So i replaced the burned transistor and everything works again.
Thanks for your reply anyway!!

[nakcho]

good morning to all who participate in this forum ... I am entering the subject and trying to understand a little this operation ... I am not an expert .. I am a student ... I like the idea of ??this tester .. I wanted to know if there is any possibility that they tell me how I can install the ST7735R display or how it would be the configuration in proteus of this display ... because I see many connectors I can not make it work .. .. someone to help me please

Please see the schematic for the AY-AT kit. You can find several copies in this thread.

HELLO ... I APPRECIATE THE INSISTENCE BUT I DO NOT HAVE EXPERIENCE WITH DISPLAY AND I DO NOT FIND THE WAY TO CONNECT IT TO THE ONE I LEFT IN THE CAPTURE ... YOU ONLY GIVE ME A HAND IN THAT PLEASE .. I HAVE DOWNLOADED A PDF WITH THE DISPLAY CONNECTION MODES BUT THAT BUT DISPLAY ST7735R NOT FIGURE ... THIS IS THE VERSION WITHOUT THE FINAL R THAT NOSE IF IT WILL BE THE SAME ... YOU GIVE ME A HAND WITH THE CONNECTION PLEASE

[Willem52]

@nakcho,
Yelling is not what you should do on a forum like this (Using only capitals).
Also it might be a lot more readable if you are using normal lines of text.
Perhaps you have then more chance to be helped by someone.

[madires]

No need to shout! You need to use the SPI mode (4-wire serial mode) and have to add a level shifter, since the controller runs with 3.3V. If you're lucky, your LCD module might already have a 3.3V LDO and a level shifter on board. My ST7735 modules only got the 3.3V LDO. Jake (jakeisprobably) posted a link to his AY-AT schematic (too large for uploading here in the forum) which depicts the level shifter and all you need to know.

[myattorneyusa]

Could anyone post .eep, .hex file for AY-AT, please? Firmware M v1.30m or v1.3k + English + VEXT + Check Rotary Encoder + PWM Plus + Zener 
I have hard time compiling it from source. Thanks

[nakcho]

No need to shout! You need to use the SPI mode (4-wire serial mode) and have to add a level shifter, since the controller runs with 3.3V. If you're lucky, your LCD module might already have a 3.3V LDO and a level shifter on board. My ST7735 modules only got the 3.3V LDO. Jake (jakeisprobably) posted a link to his AY-AT schematic (too large for uploading here in the forum) which depicts the level shifter and all you need to know.

I apologize ... the truth does not tell me about the capital ... I was very focused on this project ... so I focused only on what I needed help ... a thousand apologies ... very good forum

[madires]

I'm working on the 180° rotated output for PCD8544 based LCD modules at the moment. Someone asked for that feature a while ago. Are there any suggestions for other LCD modules to support?

[marklein]

I have a pre-assembled AY-AT unit and it worked great for a month or two... now it won't power on.  Right in the middle fixing a television too!  Now that it's gone I realize how much I used it. I don't want to wait another month for a Chinese replacement and I'm not sure that the ones on Amazon US have the latest firmware installed (anyone know?).

I was testing a capacitor at the time and I wonder if maybe the cap was charged and that caused the failure(?), but it wasn't a very big cap which is why I didn't think to discharge it so I don't know.

Anyway, are there any known issues or obvious things I can check? Thanks folks.

[stj]

check the transistors and 5v regulator.

[upsss]

I was testing a capacitor at the time and I wonder if maybe the cap was charged and that caused the failure(?), but it wasn't a very big cap which is why I didn't think to discharge it so I don't know.

It is NOT the SIZE of a charged capacitor that will damage your tester but the VOLTAGE that the capacitor is charged to.

[progrock]

OK, so I randomly ran into one of these testers today on aliexpress... and then totally randomly landed on this forum and saw this thread (I honestly don't even remember why I came to the forum in the first place, but wasn't for this).

So, it looks like i was lucky I didn't click order yet, I was about to buy a pre-assembled AY-AT clone... but if I'm understanding things correctly, I probably want to buy the DIY assembly kit, and upgrade a few parts.  Either that, or is it recommended to go and print your own PCBs from the official tarball? (When I followed the most recent link I could find to this tarball, it did not allow me to download, there seemed to be some kind of server error.

My current plan is to order one of these kits: https://www.aliexpress.com/item/2016-DIY-kits-ATMEAG328-M328-Transistor-Tester-LCR-Diode-Capacitance-ESR-meter-PWM-Square-wave-Frequency/32815242766.html

Then, instead of using all the parts the kit comes with, replace some of them with the parts listed here: https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg1284997/#msg1286025

Is that pretty much the "correct" route to go?... or did I miss something.

[Per Hansson]

Yes that is good, nice first post
I would make one change: I'd get a 16Mhz crystal too.
That way you can choose either the M firmware or K firmware.
See the following post:
https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg1286135/#msg1286135

Also you should have a 100nF > 1000nF film capacitor when calibrating the unit.

[progrock]

OK, awesome.. thank you for confirming (and seriously confused at how the hell I got to this thread in the first place yesterday... really strange, especially since I had the rebuilt one in my cart, and was gonna pay a few hours before, but got side tracked).  Of course, as usual, now my cart has been expanding.... was also about to build a simple/cheap DIY bench power supply, then saw one of the recent blog videos, and now I have a RD DPH3205 and a DPS5015, lol...

From the skimming I did yesterday, seemed like the M firmware was a solid/popular choice (though I did not look into/compare the K firmware yet)... but thanks for the recommendation... should be easy enough to find one on aliexpress... but does anyone have a specific 16Mhz crystal they would recommend?

**EDIT: Or is aliexpress not the best place for something like that... of course I just got an order from arrow today... guessing they would make more sense... but still open to suggestions if theres a specific on recommended

[upsss]

AliExpress is fine, that is where I got my kit including the 16MHz crystal.

[Willem52]

Look e.g. at:
https://www.aliexpress.com/wholesale?catId=0&initiative_id=AS_20171108094714&SearchText=Eldoer+10PCS+A+LOT+Mini+Passive+crystal
10 pieces for a very small price 😋

[texaspyro]

I bought 100 16 MHz xtals off of Ebay for $5 shipped from China.  Figured they would be crap, but were surprisingly good.