$20 LCR ESR Transistor checker project

[perieanuo]

If possible, I am thinking to put in an encoder later but the interations on taobao are much faster than mine.

And please don't forget to take some pictures of the PCB

Yes, shall do so when it arrives.  For the time being, more screenshots:

How much do you payed?
Regards Pierre

Envoyé de mon HUAWEI NXT-L29 en utilisant Tapatalk

[all_repair]

About 21 euro, plus another or two euro to ship to Singapore.
But the order is stuck for at least 10 days because of China National Day(according to seller).  Mastech canceled my other order of a new LCR tweezer.  Got a feeling they are using Taobao to test demand, and also selling well ahead of their production.  The LCR tweezer has been 2 months , nd still on pre-order status.  But at least they did not reject my order this time.

[perieanuo]

About 21 euro, plus another or two euro to ship to Singapore.
But the order is stuck for at least 10 days because of China National Day(according to seller).  Mastech canceled my other order of a new LCR tweezer.  Got a feeling they are using Taobao to test demand, and also selling well ahead of their production.  The LCR tweezer has been 2 months , nd still on pre-order status.  But at least they did not reject my order this time.

Thanks. It's really possible that they test before.
Anyway the case look good. For me it's one of the best variants.
Regards Pierre

Envoyé de mon HUAWEI NXT-L29 en utilisant Tapatalk

[jakeisprobably]

I just finished the LCD master project schematic. Let me know if you find any errors or other stuff I should note before sending it off to KH.

...and here is a link to my latest AY-AT schematic (J1.3) in PDF form linked through one of my google drive accounts because it's 1.5mb due to the pictures of the PCB that are included in the PDF. It's over the 1mb limit so I can't upload it directly here. ...Still gots to figure out that whole github nonesense.
-Jake

[indman]

I just finished the LCD master project schematic. Let me know if you find any errors or other stuff I should note before sending it off to KH.

Thanks,jakeisprobably!
I would like to specify some nominals of elements on the diagram:
R8-33k (in the original 27k)
C2-100nF (in the original 10nF)

[mauroh]

But for some reason the rotary encoder doesn't work anymore. It works as a pushbutton now. To navigate the menu you click once to move next, press and hold to select, and press and hold to exit the selection.
Also I think I buggered one of the transistors now because with the battery plugged in, the LED and screen lits up without pressing the encoder.

I'm like the opposite of having the Midas touch.

I bought a latching button and just turn it off when the battery is plugged in. It turns on whenever its plugged in now.

Hi penmarker, I think you are really close to solve all the issues!!
Most probably the culprit is one of the transistors in the power section.
Since the tester is responding to the push button of the encoder, T2 should be fine.
Try to remove T1 and T3 verifying that T1 is really a PNP and T3 is NPN.
Verify also that base, emitter and collector are correctly oriented (refer to the schematic and ignor silkscreen) since similar transistor can have different pinout (base not in the middle).

Mauro

[penmarker]

But for some reason the rotary encoder doesn't work anymore. It works as a pushbutton now. To navigate the menu you click once to move next, press and hold to select, and press and hold to exit the selection.
Also I think I buggered one of the transistors now because with the battery plugged in, the LED and screen lits up without pressing the encoder.

I'm like the opposite of having the Midas touch.

I bought a latching button and just turn it off when the battery is plugged in. It turns on whenever its plugged in now.

Hi penmarker, I think you are really close to solve all the issues!!
Most probably the culprit is one of the transistors in the power section.
Since the tester is responding to the push button of the encoder, T2 should be fine.
Try to remove T1 and T3 verifying that T1 is really a PNP and T3 is NPN.
Verify also that base, emitter and collector are correctly oriented (refer to the schematic and ignor silkscreen) since similar transistor can have different pinout (base not in the middle).

Mauro

Thank you very much for everything, you've been a very big help.
I'm still at work now so I can't test anything yet but I'll be leaving in a bit so I'll edit this post again later.

I can confirm T3 = T2 because I replaced both with new transistors.
I don't think I can remove to test either transistors because I've soldered them flush to the board and it makes desoldering hard. When I replaced them out I had to destroy the originally installed ones.

There's also the possibility of the transistors I replaced recently are shoddy quality because the shops there gets their supplies from China. I've attempted to buy some Sanken 2SA2922 from the same shop before but when I asked if they were genuine the clerk said no. I bought them from Digikey instead.

One question, could faulty transistors (T1/2/3) cause the rotary encoder to behave like pushbutton? My gut feeling says the atmega chip got reformatted or the firmware is now working as a push button model mode.

[mauroh]

If you had trouble replacing the transistors it could be possible that you have damaged the PCB near the transistors legs...
Try to make a single blob of solder on the 3 pins of the transistors and pull them out gently.
Verify the continuity of the traces near the pads on bouth sides.
If you remove T1 and replace it with a short between emitter and collector the tester shold power on immediately after applying power and you should be able to test T1 with the tester (now I'm not kidding...)

I don't have the tester with me so I don't know if I short emitter and collector of T1, also my encoder will be disabled... I'll try it later, or someone that knows the firmware better than me can cofirm if this make sense.

Mauro

[madires]

Just the rotary encoder's push button is part of the power circuitry. A & B got pull-up resistors and are connected via additional resistors to the MCU in parallel with the display.

[mauroh]

Yes, but I was wondering if for some reason the firmware were disabling the encoder functionality because it was starting with PD7 (Pin13) low instead of high or something like that.
If T2 is fine I don't know how Pin13 can be low without pressing the push button, perhaps something wrong with T2 orientation...

Edit: or that was before replacing T2

Mauro

[madires]

No, the rotary encoder won't be disabled. But the read function checks for valid Gray code steps. If there's something wrong with the encoder the bad input will be ignored and nothing happens.

[jakeisprobably]

...for some reason the rotary encoder doesn't work anymore....

Let's have some fun Mr Penmarker...
Those AY-AT diagnostic tools are from the creation of this:https://youtu.be/mRMRtrzh6rI
   I'm no expert but it sounds like you have a bad connection somewhere.

[jakeisprobably]

the last few days homework.... I think I got the 2 buttons option figured out. I wasn't able to find an example related to this project but I used another schematic I found. It looks like it's just the rotary encoder replaced with 2 buttons, if I set it up correctly. I also tried to adapt the MC34063 circuit from Nick's schematic. His is set up for a lithium battery and it doesn't have the same regulator isolation so there may be some errors there as well.

  I've also been looking into either building an adaptor for an ATmega1284 to 328 pinout or trying to design a board like this. It's an arduino clone/mod, but that's exactly what I had in mind for this project. I am surprised no one has built a design like this that can fit either an ATmega328 or ATmega1284 on the same footprint and breakout the extra pins. It seems like a no brainer for cheap clone manufacturers.

[madires]

Just wanted to share a picture of the extended frequency counter option from Karl-Heinz' documentation (ATmega 644 circuit). The SMD transistors are hidden at the bottom side and there's a 32.768kHz watch crystal in the socket for the LF oscillator. The other one is a 20MHz crystal (measures 20.000960MHz). The channel can be changed by pressing the test button or turning the rotary encoder.

[turbochris]

Hi All,
I bought an new style AY-AT tester kit off ebay that was advertised as the latest version. When I got it, there were 2 pcb-



I think when they made up these kits they just threw a new PCB in the old kits as the power jack, the 3 screw terminals and some resistors were missing.
I built it and the LED and display backlight come on when I press the encoder down and stay on for about 30 seconds but there is nothing displayed. I'm willing to bet that the ATMEGA328P-PU is programmed for the display used in the older kit. I'm not sure but I think my display is the ST7735. I found newer firmware here and I wanted to try it so I added an ISP header to the tester-



and hooked it up to an arduino to use the arduino as an ISP programmer-





I loaded the arduinoISP sketch into the arduino and this is as far as I got. I can't figure out the command line string for avrdude to use the arduino and I'm not sure where I need to put the .hex and .eep files I downloaded. Please help!

[mauroh]

Generally speaking do not use the firmware found on the thread. Usually they are customized for a specific reason like 16MHz crystal or with specific functions enabled.

To start, use the official one.
This is the repository for your variant:
https://www.mikrocontroller.net/svnbrowser/transistortester/Software/trunk/mega328_color_kit/

This is the avrdude string I use with ArduinoISP sketch

avrdude -c arduino -p m328p -B 0.5 -e -P COM5 -b 19200 -U flash:w:"TransistorTester.hex":a -U eeprom:w:"TransistorTester.eep":a -U lfuse:w:0xF7:m -U hfuse:w:0xD9:m -U efuse:w:0x04:m

You will need to change the COM port number and (if this works...), to speed up the process you will change the BAUDRATE to 115200 on the sketch and on the string.

Let us know if you have any issue
Mauro

[jakeisprobably]

If anyone wants to know more about the GPSDO Ublox modules/problems with the circuit design from Scullcom Hobby Electronics read this. Use the forward and next links to read more and find additional references and information.  I believe this is the "Time Nuts" reference that was made a few pages back. I had no idea what "Time Nuts" was referring to at the time.
   Also, I do not understand the full implications beyond "this isn't optimal." I have attempted to read several IEEE papers on the subject as referenced in that mailing list conversation. However, going into this info any further should probably be done elsewhere in another thread.
  This post is simply a reference for those that are interested and because Karl-Heinz included a GPSDO reference in his PDF on Page 124. I have attached an image version of both the Time Nuts message that I felt best explains the issue, and page 124 from KH's PDF for quick and easy reference.

[jakeisprobably]

...I'm not sure but I think my display is the ST7735.

Yes that is a ST7735 color TFT screen

I loaded the arduinoISP sketch into the arduino and this is as far as I got. I can't figure out the command line string for avrdude to use the arduino and I'm not sure where I need to put the .hex and .eep files I downloaded. Please help!

Follow this post on page 103 (it also continues on page 104)

[turbochris]

Thanks for your replies! I'll let you know how it goes. My brain still hurts a little from messing with it I have to let it rest. Mauroh I subscribed to your YouTube, my YouTube name is Krugtech.

[turbochris]

SUCCESS! another place where I was screwing up was I was using a leonardo, not an uno and the pinout was different. I'm going to mod this thing now, I have a 16 mhz crystal, what would I need to do to be able to use it? I'm also going to get precision resistors and a regulator. Thanks for your help!

[stj]

the regulator is fine, swap the reference - lm341 for a lm4040a

to use 16MHz crystal you just need 16MHz firmware - no other changes.

[turbochris]

Got the 16mhz crystal in on the new style AY-AT tester and found some firmware and it's all good! So the firmware part of that upgrade is done now. next project, this fish8840 based model with a color display- it seems like it has the ISP header and an 8mhz crystal. is there some 16mhz firmware available for it?

[mauroh]

Hi turbochris, glad you was able to fix your unit that easily 

Now that upgrading the firmware is a piece of cake, you can consider also the m-firmware to play with.
As you might know there are 2 main developments/developers of the firmware:
k-firmware manteined by karl-heinz kubblerer (this is the firmware you loaded on your unit)
m-firmware manteined by Markus Reschke (madires here in the forum)

Both great firmwares and great guys!!!

For the k-firmware, there are available the precompiled files for most of the hardware out there and the official folder is here:
https://www.mikrocontroller.net/svnbrowser/transistortester/Software/trunk/
The fish8840 is present, but for the 16MHz you need to compile it changing the parameter in the Makefile (or someone will provide it to you...)

The m-firmware need to be compiled from source, but for the most common hardwares you can find the compiled files in the forum.
The m-firmware official folder is here:
https://www.mikrocontroller.net/svnbrowser/transistortester/Software/Markus/
The current version is the 1.29m

Thank you for your interest in my YouTube channel!!! I'm doing my best to be more active 
I've watched some of your videos, are you a drag racer??
Mauro

[all_repair]

Not Mastech.  Probably the most useable and practical one out there now.  The tilt display make the meter easier to read.  Left and right button for left and right handed people.  LCD ribbon is not soldered, so burning of new firmware shall be easier.
The other side of PCB shall need to wait.  Desoldering of some thick pins needed and do not look easy

[turbochris]

Hi Mauroh,
I don't race, I have 2 exhibition vehicles, the little bike and minivan. it's better than racing because I get paid to run them without worrying about winning a race  I was on a pit crew for the pro mod you may have seen on my yoube channel but my business has been too busy to find time for that. I work on laser cutting systems up to 6kw for a living.

Compiling the firmware sounds like another good challenge. I'm 57 years old, I need the brain exercise. Thanks for your reply!