EEVblog Electronics Community Forum

Electronics => Repair => Topic started by: Paceguy on December 04, 2022, 06:58:08 pm

Title: GW INSTEK GOM 802 repair question, seeking help.
Post by: Paceguy on December 04, 2022, 06:58:08 pm

Hi everyone
I picked up this GW Instek GOM 802 milliohm meter some years back. A reject tag attached to it says unstable on low range. I plugged it in and there is fluctuation on low ohm readings. Does anyone know where I can find the service manual ? I found the operation manual on line, but there is no service info in it . Even a schematic diagram would be of help. I suspect that it's a filter cap problem but want to know what the supply rail voltages are suppose to be and where the  test points are.
Thanks in advance !

Title: Re: GW INSTEK GOM 802 repair question, seeking help.
Post by: Paceguy on December 29, 2022, 03:27:53 pm

I checked the ESR of all the electro caps and all tested good. I observed that on some scales it displays OL, on others scales, I can make measurements, this all done with 4 wire / K.clips. I'm starting to think that it's something with the input section. Any ideas or service info would be much appreciated.

Title: Re: GW INSTEK GOM 802 repair question, seeking help.
Post by: Ugur on December 30, 2022, 06:37:00 am

Take your multimeter to the amper stage and connect it to the source + and -  section,
  do you read a constant current in all stages?
At the lowest measuring range, you will need to measure 1A.
You will need to read values such as 100mA, 10mA, 1mA in other stages.
LTC1052 may be faulty!

Title: Re: GW INSTEK GOM 802 repair question, seeking help.
Post by: Paceguy on January 03, 2023, 07:56:10 pm

Thanks, I will try that