TC1 lcr-meter transistor-tester fix

[bob91343]

My unit works okay but the display is bad.  It displays data as expected but the screen has become hard to read.  I can change viewing angle for some improvement but still it's bad.  It's an early monochrome.

I bought another but want to fix this one, as it seems more accurate.

[shved]

If you have a mono lcd panel - that's a different model.
Most designs using those kind of displays have a contrast POT or a set of resistors witch are responsible for contrast. Check for all of those, + check for panel damage + check for corrosive flux damage.
If you indeed have a different model - give this thread a quick read and try to find threads and schematics for your specific or a similar unit.

[vk3ohm]

Does anybody have a document that explains the principle of operation of these, or similar, devices? I would love to give a presentation to my radio club about how they work, but I've been unable to find any information anywhere.

[ledtester]

Does anybody have a document that explains the principle of operation of these, or similar, devices? I would love to give a presentation to my radio club about how they work, but I've been unable to find any information anywhere.

The site for the project:

https://www.mikrocontroller.net/articles/AVR_Transistortester

Go to the Downloads section and get the manual in the language of your choice, e.g.:

https://github.com/svn2github/transistortester/tree/master/Doku/tags/english/ttester_eng112k.pdf

[ledtester]

Should add that this is the main eevblog forum thread for these devices:

https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/

[madires]

https://github.com/svn2github/transistortester/tree/master/Doku/tags/english/ttester_eng112k.pdf

That mirror is obsolete. Please use https://github.com/madires/Transistortester-Warehouse.

[billy_gr]

Hi,

Measured a cap without discharging it and now i got a T7 that measures a cell voltage between pins 1 and 2

Removed both the DZ1 DZ2 but the issue remains. Should i assume that the ATmega is toasted ?

Thanks in advance

[madires]

Yep, it's toast. You can replace the ATmega or buy a new tester, whatever is simpler or cheaper for you.

[billy_gr]

Yep, it's toast. You can replace the ATmega or buy a new tester, whatever is simpler or cheaper for you.

Thank you !!!

[speedsterharry]

Hi all, I'm new to the forum.

I found this thread thanks to the amazing power of search engines, and was glad to make my TC1 work again (it was only detecting a 5V cell whatever what was connected to the leads). The SRV05 was dead, after removal the TC1 worked like before.
What kind of problem will the lack of ZD2 mean to my TC1 tester ? I don't want to fry it for good !!!

Thanks, the amount of good info available here is FANTASTIC !

EDIT: I'd like to upgrade my TC1 firmware. Does anyone in France, preferably near Lyon who does that kind of service ? I'm about to get 2 new TC1 just for spares and would like to have them upgraded as well when I get them. I don't want to do it myself, I don't have the tools nor expertise to do that (and don't want)

Or maybe one of the developers sends the TC1 with latest firmware ?

[madires]

ZD2 (SRV05) is a weak over-voltage protection. The tester works also fine without it, but make sure that you always discharge capacitors before connecting to the tester.

[belzrebuth]

Is there a programming header on the TC-1 or should I directly attach wires to the MCU?

I destroyed mine with a charged capacitor and I replaced the atmega but I now need to re-upload the firmware.
With an older tester I needed to solder wires directly to the 328p in order to update it.

[madires]

You just need to solder an ISP header (unpopulated footprint at the top).

[belzrebuth]

Thanks madires.
Do you maybe have an avrdude command for the atmega 644?
I'm thinking of using the m-firmware.
I don't know what fuse settings I need to set on the ATmega 644.

[belzrebuth]

Here are the commands I've gone with; fuses set as follows:
avrdude -c usbtiny -p m644 -U lfuse:w:0xff:m -U hfuse:w:0xd9:m -U efuse:w:0xfc:m
avrdude -c usbtiny -p m644 -U flash:w:ComponentTester-TC1.HEX
avrdude -c usbtiny -p m644 -U eeprom:w:ComponentTester-TC1_eeprom.HEX

I think I've managed to upload the firmware fine since I got a "Bye!" on the LCD.

I then powered the unit with 3.7V on the battery pins but the tester still doesn't work.
The LCD just flashes in white.
I think there's something wrong with my "U4" maybe.
I tried reprogramming that as well but my chip is scratched down and I can't see the markings on top.
I've set various ICs as DUT but no configuaration recognises it..
I've gone with STC15W104, STC15L104, STC15L104W, STC15W104 so far..
My FTDI adapter outputs a VCC of 3.56V instead of 3.3V would this be the fault maybe??

[madires]

You can run "make upload" after setting the programmer in the Makefile. And for the fuses it's "make fuses". Regarding U4 you can alternatively replace U4 with a simple two-transistor circuit (https://github.com/madires/Transistortester-Warehouse/blob/master/Hardware/TC1-Mod.kicad.tgz) which also has a lower quiescent current.

[belzrebuth]

The STC-ISP managed to recognise the IC as STC15L104W but I still can't get it to upload the firmware.
I have my 6V8 diode removed from circuit while the DZ2 is installed.
Can this prevent the tester from working.
I only have a 6v8 zener in a thru hole package.
Can I install this one?
Does it need a high wattage (1W or so) or any 6V8 diode will work?
Sorry for all these questions madires, I really appreciate your help.

edit: I can't even re-recognise the IC when I try to "check MCU" from the STC software.
It did it once and I can't make it to repeat it.
So no wonder it can't upload the .hex file.
I need to power the DUT under a certain timing frame or something?


edit2:
To define what my problem is:
If I power the tester with 3.7V from my bench supply it starts up and measures components fine.
Power consumption is around 240mA when this is happening which I think is a bit excessive.
So I let cycle thru "Probing.." around 3 times and then it displays "Bye" and shuts off.

If I press the button I get about 200mA current consumption again but all I get is a white screen and then the tester shuts off.
What could be causing this behavior?

I need to mention that I put diode D0 backwards once I removed it to check it.
I powered up the unit one or two times with that diode placed backwards, I hope I haven't managed to destroy my 2nd atmega.

[belzrebuth]

@madires
Do you have a picture or something of your TC-1 U4 replacement mod?
I did download it but it's kicad files which can't be opened with Eagle and I can't open it with Kicad either cause there are some libraries or footprints missing as it says.
I think I'm going to remove U4 as I can't seem to be able to program it or even check its status.

[madires]

The Zener/TVS plus DZ2 are a weak overvoltage protection and can be removed without any problem. DZ2 is often damaged in case of a charged cap. 240 mA are much too high. So there's some bad component. The TC-1 mod archive includes three images.

[belzrebuth]

I quickly bodged your replacement circuit in a small piece of proto and it worked
Current consumption is now 200mA or so when it's on, I find it a bit high as well.
But it also works with a semi-discharged battery so I guess it's okay now?!

What a typical current draw should be if external power is applied at the battery terminals?

[madires]

I'm not sure about the exact current draw of the TC-1 since the boost converter also creates the 40+ V for the Zener check. OP zappenduster measured 300-400 mA which are quite high. The standard circuit needs about 20mA @ 5V on average. Add the backlight, the Zener test voltage and a possibly low efficiency boost converter.

[belzrebuth]

I could try applying 5V at the output of the 5V regulator and measure the current draw at that rail to check if it's within this figure (20mA) or so.


Another thing I wanted to ask if it's normal for the tester to repeat a component test for 5 retries instead of just freezing at the component measurements.


With a component at the input terminal it just shows the result and then repeats the measurement for 5 times.
Without a component it does 5 retries displaying "no component" and then switches off.

[madires]

Either press the start button for > 300 ms when powering on or enable UI_AUTOHOLD in config.h. There are many configuration switches to optimize the firmware for your needs.

[indman]

OP zappenduster measured 300-400 mA which are quite high.

Yes, this is the amount of current I measured on my TC-1 with a 3.7 V power supply at the time of launch. Later the current value can be kept at the level of 150mA.This is quite high,so the circuit requires a fairly capacious battery. From the +5V power supply, the circuit together with the display backlight consumes up to 30-50mA.

[peteb2]

So to take the thread into another (massive apologies) direction.... i have owned a TC1 for the last 4+ yrs & today just when i need it the battery is discharged... So as usual i've set it onto charge but this time.... NoGo! So here's my quandary:

Replace the internal rechargable LiOn looking thing...& if i do that i might as well replace the ZiF socket that is hammered on '1,2,3' on a thing with a now yellowed coloured case with soldering iron burns *OR*...  do i stump up for a new (probably badly made knockup rendition) *OR* is there a better alternative?

I'm thinking a USB interface breakout module that interfaces with workbench PC that runs what the TC1 did and does in a GUI on screen, the same kind of thing but more accuracy ...please i'm a tech who fixes a lot of gear & yes i should at least fix my own old TC1, but is there a better alternative by any chance & not waste time o this used to death thing?  I already own a Peak DCApro semiconductor USB curve tracer tester but it appears to have a lower range of ability than my old TC1...  tia