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TC1 lcr-meter transistor-tester fix
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madires:
They shouldn't be critical, maybe 100nF?
indman:

--- Quote from: algorithm on April 05, 2024, 04:35:30 pm ---According to others posts this is in line with shorted c6/c7.

--- End quote ---
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:

--- Quote from: madires on April 05, 2024, 04:47:00 pm ---They shouldn't be critical, maybe 100nF?

--- End quote ---

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.


--- Quote from: indman on April 05, 2024, 04:53:45 pm ---
--- Quote from: algorithm on April 05, 2024, 04:35:30 pm ---According to others posts this is in line with shorted c6/c7.

--- End quote ---
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

--- End quote ---

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:

--- Quote from: algorithm on April 05, 2024, 04:35:30 pm ---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. :phew:





--- End quote ---
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.


--- Quote from: BILLPOD on April 05, 2024, 06:40:12 pm ---
--- Quote from: algorithm on April 05, 2024, 04:35:30 pm ---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. :phew:






--- End quote ---

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. ;)


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