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Electronics => Repair => Topic started by: rhb on May 13, 2018, 11:37:06 pm

Title: Fluke 8000A repair [solved]
Post by: rhb on May 13, 2018, 11:37:06 pm
I was given this and am doing something silly and attempting to repair it.  I've got the manual, though the schematic is a challenge as it doesn't tell you what position the switches are in.

It works on all the mA DC ranges.  But the 200K, 2000K and 20M ranges don't work, nor do the 20, 200, and 1200 VDC and VAC ranges.  Shooting up the switches with tuner cleaner helped, but did not solve everything.  I then reworked the range switch solder joints, but still no change.

You an get as good a DMM from Harbor Freight for free, so this is more just a grudge match than anything else.

Is anyone familiar enough with these to offer any hints or insights?

Edit: R1, the 2 W 9.9 M resistor in the input divider is failed open.  Checks of Newark, Digikey and Mouser did not turn up a replacement.  You're actually supposed to replace R1-R3 as a matched set.  So it's just parts.
Title: Re: Fluke 8000A repair [solved]
Post by: Gyro on May 14, 2018, 09:50:37 am
The resistor will have a 1200V (or significantly higher) breakdown rating too. A couple of possible alternatives...

- A close tolerance HV 9.1M resistor in series with a ~800k padding resistor
- An 8M2 in series with 1M8 and a ~30M padding resistor in parallel with the 1M8

This sort of thing only turns up in DMMs, a check on ebay for either a resistor or donor might yield something (you might get a matched set that way).
Title: Re: Fluke 8000A repair [solved]
Post by: rhb on May 14, 2018, 01:25:15 pm
I'm going to offer it for sale in case someone wants parts for a restoration project.
Title: Re: Fluke 8000A repair [solved]
Post by: fixitanonymous354 on May 15, 2018, 12:45:26 am
Something like caddock 1776-8 divider could work if it fits  :-//