TC1 lcr-meter transistor-tester fix

[njsw88]

thankyou so much

[dlkeng]

I recently received a LCR-TC1 tester from AliExpress and it is the same blue board one with the LGT8F328 MCU shown on page 11 and replies #320 and #321.

If anyone is interested, I have reverse-engineered its schematic and have attached it here.

[MarkMLl]

I recently received a LCR-TC1 tester from AliExpress and it is the same blue board one with the LGT8F328 MCU shown on page 11 and replies #320 and #321.

If anyone is interested, I have reverse-engineered its schematic and have attached it here.

Could we have a robust link to that on AliExpress, since there are many sellers represented with different products?

MarkMLl

[dlkeng]

I don't know that there is such a thing as a robust link to an AliExpress product as each time I have returned to the page of the item I ordered, it seems to have a different price! (it was about $14 when added it to my shopping cart, but I was charged $11.73 for it and it is now advertised as $9.57)

Anyway, the link to the page I ordered from seems to be:
 https://www.aliexpress.us/item/32611989538.html

[MarkMLl]

I don't know that there is such a thing as a robust link to an AliExpress product as each time I have returned to the page of the item I ordered, it seems to have a different price! (it was about $14 when added it to my shopping cart, but I was charged $11.73 for it and it is now advertised as $9.57)

Anyway, the link to the page I ordered from seems to be:
 https://www.aliexpress.us/item/32611989538.html

That certainly works at the moment.

Bear in mind that price will depend on exchange rates, which will depend on multiple countries' whim.

I'd add that it's interesting that the photos on that page show that the cased variant has a USB connector for charging, while the uncased variant has a clip for a PP3 battery. It's almost as though they're intentionally preventing anybody swapping in the cheaper board when they blow the cased meter...

MarkMLl

[SA]

i have solved "tools-> make all -> pile of errors."problem with uploading msys-1.0.dll new version to winavr installation folder.
Now i have fully working, with correct lcd offsets and other corrections TC1 dip atmega368p model with 1.47 M firmware since i have not been able to adopt it to 1.49 or 1.48.

Can you please share the hex and epp files? I also have got TC1 with atmega328p DIP. Fried the MCU.
Thanks in Advance

[galaga1982]

Thyristor measurement error?

Hello?
I got a lot of information from here and helped me to repair TC1 lcr-meter well. However, I have a new question.

When measuring Thyristor with TC1 lcr-meter, has anyone experienced it being marked as PNP or NPN transistor instead of accurately? The Thyristor I measured was common TYN610 (ST), 5P4M (NEC).

Another strange thing is that after setting DMM in diode measurement mode and connecting + probe(red) to Cathode and - Probe to Anode to check for failure, the resistance value is infinite, and when I short Gate and Anode, the current is not maintained, and it is immediately released. If it is normal, it is said that this should hold current. Is my Thyristor failure measurement method wrong?

Thank you.

[Kim Christensen]

Your Thyristor needs a minimum hold current to stay on. It also has a minimum trigger current. For the TYN610, the trigger current could be up to 15mA and the hold current up to 30mA. The DMM and TC1 probably doesn't provide enough current for that. Build a simple test circuit  instead. (Adjust lamp size and R1 for your Thyristor) :

[galaga1982]

Thank you. I briefly thought about the gate-triggering current, and I think that's right. I'll try it and let you know the result.

[algorithm]

Having had a tc1 since before this thread was started, I find the device useful often in many ways, double checking. Though everytime I reach to use it lately its dead even though it was fully charged. Sometimes in as little as 1 week. Using a usb power meter it saysitsdrawing between 18-24mA , even when dark/off.

According to others posts this is in line with shorted c6/c7.
Im keen to replace these, though hesitant as I dont know the correct capacitances.
Anybody know what value those 2 mlccs are?

Hoping I can properly fix this rather than hacking a dipswitch into the battery. Though with no battery it draws 0mA 

[madires]

They shouldn't be critical, maybe 100nF?

[indman]

According to others posts this is in line with shorted c6/c7.

Why don’t you admit that there may also be a leak in capacitors C2-C5?
You need to check all the capasitors that are in the battery circuit. Their capacitance, as madires correctly noted, is not particularly important, but usually in such circuits, to eliminate possible interference and noise, several capacitors of different capacitances are placed next to each other, for example 1nF, 100nF, 1mkF, 5-10mkF

[algorithm]

They shouldn't be critical, maybe 100nF?

I halfway expected that but also didnt want to assume and find out I was wrong.
Thats perfect if so because I have a tape of 100nf suitable. Thanks for chiming in.

According to others posts this is in line with shorted c6/c7.

Why don’t you admit that there may also be a leak in capacitors C2-C5?
You need to check all the containers that are in the battery circuit. Their capacitance, as madires correctly noted, is not particularly important, but usually in such circuits, to eliminate possible interference and noise, several capacitors of different capacitances are placed next to each other, for example 1nF, 100nF, 1mkF, 5-10mkF

Well I can dig that, just going off the past 14 pages. I saw multiple posters stating that draw was fixed by replacing 1 of those 2. Though you are right, im not sure what the cause is.
I also read that could be a fried mcu or shoddily programmed mcu. But id hope I could get lucky and only need to replace a few caps.

Found a parts list for the gm328r, not sure if that is applicable but that had 100uF and 100nf.
Wish the tc1 schematic had values. But yeah testing c6 and c7 shows like 6uF but c7 shows 0uF randomly (with good contact on probes )

[BILLPOD]

Having had a tc1 since before this thread was started, I find the device useful often in many ways, double checking. Though everytime I reach to use it lately its dead even though it was fully charged. Sometimes in as little as 1 week. Using a usb power meter it saysitsdrawing between 18-24mA , even when dark/off.

I too have one of the earliest models, and mine was killing the batt. when off, so I installed a tiny toggle switch in the battery positive line.

[algorithm]

 

To answer my own question c7 is 10uF, c6 is 100nF.
Confirming the wise topological words from indman pertaining to interference/noise suppression.

Seems c6 was shorting. Though after replacing it its still drawing 18mA.

EDIT: im an idiot. I was trusting that cheap usb power meter.
After thinking about it I realized that I was only seeing the current consumption on charging...
And after I still saw 18mA draw after replacing c6, I left it on charge until full.
Upon full charge the power meter declared 0.00mA consumption though.
So I tried to test the draw with a multimeter in series with the battery +.
I got 2.xx mA when powered. After timeout it dropped to 0.10mA (100 microamps) screen dark. After 10-15 seconds it drew 0.00mA. 

So another satisfied customer after replacing c6/c7. (Though I didnt change c7 as it tested good out of circuit). I just wish I would have tested the consumption correctly with a dmm before replacing the cap.
Rather than lazily trusting the usb power meter. I definitely know something was wrong because it would lose a full charge in a week.

For fun and irony I used the tc1 to test c6 and it would show 95nf 0.17k esr. If I hit test again it would read "no unknown or damaged part", repeating the test repeated the result. So yeah if your capacitor randomly drops to 0.00uF while testing worth suspicion.

I might have avoided the toggle switch mod.

Having had a tc1 since before this thread was started, I find the device useful often in many ways, double checking. Though everytime I reach to use it lately its dead even though it was fully charged. Sometimes in as little as 1 week. Using a usb power meter it saysitsdrawing between 18-24mA , even when dark/off.

I too have one of the earliest models, and mine was killing the batt. when off, so I installed a tiny toggle switch in the battery positive line.

I guess I will have to do the same BILLPOD, better than it being dead everytime its needed right.
I also would like to mod some banana jacks to the inputs. Would be neat to use tweezer probes with it + anything else. I always found myself struggling with holding my diy probes and hitting the stiff button with my pinky. But with tweezers it would be easy.

[galaga1982]

Hi,

As you said, a simple circuit for thyristor test was constructed. The LED turns on when you close the gate and anode as shown in the picture. And even when opened, my 5P4M thyristor seems to be normal as it remains on.

By the way, why is thyristor not accurately marked on the LCR meter as shown in the picture? I'm using LCR-TC1 2.12K FIRMWARE, and this wrong information was the same for other types of monochrome LCR meters. It would be very appreciated if madires, indman or anyone else could answer this symptom. 

Regards,

[indman]

galaga1982, The tester can test parts with a voltage of maximum 5V and a maximum current of only 5-7mA. This is stated in the author's instructions. For your 5P4M Gate-trigger Current(Igt) is 10mA, so the tester cannot create it and reliably open the thyristor. Therefore, thyristors and other parts that require higher voltage and current cannot be detected correctly. We must always remember this!

[madires]

The 5P4M has a maximum trigger current of 10 mA and a typical holding current of 10 mA. That's is bit more than the tester can provide.

[gmc]

Purchased a TC1 from Alix and also received a blue version with U1. The numbers on the chip have been erased but guessing its a LGT8F328

Attaching a photo for reference.

Is there any firmware dump for this version?

[madires]

Yes, the MCU's pinout matches a QFP48L LGT8F328. So far I haven't seen any firmware dump for that one.

BTW, jm_araujo replaced the LGT8F328 of his T7 with an ATmega328: https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg5518618/#msg5518618

[SA]

I have fried my TC1 with charged capacitor. The MCU also fried. My TC1 comes with ATMega328p DIP IC. I am not an expert in but if I could get complied code, I would be able to fix it. Please help me

[madires]

Have you already tried with U2 and D1 (weak input protection) removed?

[Kim Christensen]

I have fried my TC1 with charged capacitor. The MCU also fried. My TC1 comes with ATMega328p DIP IC. I am not an expert in but if I could get complied code, I would be able to fix it. Please help me

There are compiled versions out there. But on another note, while a pin or two might be fried, you may still be able to read the Flash and eeprom. (You need both) Then simply write it to a new chip.
Depends on whether the chip has copy protect enabled or not.

[slash14]

Hello Everyone,

Sorry for being a little off topic here, but this picture caught my attention.

I was intending to play a bit with one of these component testers (first by attempting to flash an original, latest firmware, just to try).
So got my self a T7, which has exactly this blue PCB.
And I was wondering: the ISP connection (at the very top of the picture if not mistaken) seems to have only 5 pins, instead of the usual 6.
Am I missing something?
Like on the picture above, none of the pins are labelled on mine, apart from the +5VDC and G(nd) pins.
Any ideas about what are the 3 other pins, and why only 3 and not 4?

The MCU marking on my unit has been erased, I doubt it is a genuine Atmel thing. Could be a LGT8F328 of some sort but who knows. Therefore I can't really find out the pins from a MCU datasheet.

Thank you.

[madires]

Yes. that's an LGT8F328. Pin 21 is SWD which is also part of the SWD programming interface (Gnd, Vcc, SWD, SWC, Reset). Pin 21 of a genuine 32-TQFP ATmega328 would be Gnd.