Ut61e repair of the IC Cryustek ES51922 attempt - Solved

[Bitflops]

After I bought a UT61e, rebranded (it is blue!) for very low money, I traced the defect back to a shot IC (Cryustek ES51922). Some functions do still work, others do not. Some long research and emailing to the asian world,  it seem that the ic can be bought app. 20$ without shipping. I would be something that makes me proud if I could repair it. But what are your personal thoughts and experiences about replacing the multimeter IC. Just drop in and go or dead end with eventual recalibrations  issues after the IC replacement...perhaps would like to know if someone has already tried replacing a dedicated Multimeter IC?

Take care!

[don.r]

The chip alone is a 1/3rd the price of a new meter and you run the risk of further damage in the repair process. I would say forget about it and use it for the functions that still work. Put the money towards a new meter, preferably something with a more robust front-end so things like that don't happen again.

[kripton2035]

I recall someone here asking kindly the manufacturer cyrustek for some sample, as he had like you a blown es51922 chip, and they kindly send him a working chip. resoldered and ok. I dont remember that a calibration was necessary after that. search the forum for cyrustek you will find the thread.

[ProBang2]

Are you sure: The chip is toasted? I`m just curious.
If the misfunction shows wrong ranges (e.g. set to V, it displays Hz), then it´s not the ES51922.

[Bitflops]

Are you sure: The chip is toasted? I`m just curious.
If the misfunction shows wrong ranges (e.g. set to V, it displays Hz), then it´s not the ES51922.

Hi,
I'm curious now, because that is exactly the case! On several positions the range is wrong and I found a workaround with a manual switch to pull-low or high FC1 of the Cryustek to 3V in order to put it into the desired range when it was not. But then in the other ranges the multimeter switches off. Also this worked but is results in a high battery drain.

Originally I found the two protection diodes D1 and D3 had to be replaced and did so. This could speak for a current overload as origin of the error.

Next thing was the wrong ranges. So I found that FC1 was not was it's supposed to be according to the switch position (Ref Table in the chematics):

Volt    => Ohms
mV     => Farad
Ohms => Ohms
Hz      => Hz
yA      => Ohms
mA     => Ohms
A        => A (OK)

So I do not get the FC1 to be High

But in the positions where the range is faulty the FC1 is not closed to another contact.

FC1 is connected through the double diode D4 that tested 0.3V forward and OL in reverse on both diodes. I Guess the diodes are working.

After that I'm losing the overview..

Ps: The contacts in the range switch look ok and are all there.

What is your experience with the wrong ranges problem?

[ProBang2]

I have no personal experiences with the range problem, sorry.
But it seemed immediatly possible to me, that your problem was similar to the case of this guy:

http://youtu.be/GJuvhqfO4Rk

http://youtu.be/dKdTcXE-Kc4

http://youtu.be/M_p1SKtAbuc

http://youtu.be/ILgTIap4FUM

This guy suspected a defective pullup resistor as the culprit. He made a work around.
And again: Sorry. That resistor is part of the ES51922.

But maybe the videos above are at least a little bit helpful...

[Bitflops]

Well thank you for thoughts on this  . It was in fact the exact problem I had as well. The Pull-up resistor of the chip was blown and by installing an external resistor on the FC1 pin to the 3V rail the meter works fine on all the settings of the switch again.

In my case a 256 Ohm resistor was enough though, which means less current.

Happy I did not go into buying another IC...pfiuu.
Made my day!
Grüße aus Berlin

[ProBang2]

Glad I could help.