Author Topic: HELP Fluke 8010a AC overrange  (Read 672 times)

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Offline HendoNZTopic starter

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HELP Fluke 8010a AC overrange
« on: April 14, 2021, 07:58:58 am »
Hi all,

I recently got a Fluke 8010a multimeter but it seems that the AC function seems to be reading Over range all the time. I've tried different voltages, but still the same reading.

Anyone got any ideas to look at when I pop the lid on this one?

Cheers
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Offline HendoNZTopic starter

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Re: HELP Fluke 8010a AC overrange
« Reply #1 on: April 14, 2021, 09:08:33 pm »
Ok, after some digging around I've got some questions. I was checking the op amp AR1 (LF351n) and here are the voltages on the pins. 1. -13v 2. 0v 3. 0v 4. -13v 5. -13v 6. 0v 7. 0v 8. +13v. The Va should be +15v  +-1v (I know it's.on the low side. Also, U8 pin one is supposed to be 4.3v (if I'm reading it right) it's 13v.

Any help would be appreciated.
 

Offline BobRyan

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Re: HELP Fluke 8010a AC overrange
« Reply #2 on: April 14, 2021, 11:29:32 pm »
You report pin 7 of AR1 is 0v. Is this with S4 in AC mode? If so it looks like S4E isn't properly switching +VA which powers U8 and (partially) AR1. I would check TP10 for the +15v+-1v as specified. If that's not 0 it's likely you just need to clean/cycle your switches.

I've had four 8050A and an 8010M in use for several years and all of them have needed some switch cleaning. Deoxit D5 has worked well for me.
 

Offline HendoNZTopic starter

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Re: HELP Fluke 8010a AC overrange
« Reply #3 on: April 15, 2021, 07:07:36 am »
Thanks for the reply.

Yeah the AC switch was engaged. Looks like that was only a small problem. I've now got voltage to pin 7. Still no joy on a reading though.

I've tracked an AC single into U8 using a scope, and followed it around the board. Unfortunately there are no schematics for that board so I don't know what I'm looking for.

I think I might be stuffed for AC unless I can find a replacement U8 board. If anyone out there might be able to donate one - that would be amazing.

If anyone is interested the chips on the board are (from right to left) are LF351n, 7849, CA3049 and a LF351n.

Cheers
 

Offline BobRyan

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Re: HELP Fluke 8010a AC overrange
« Reply #4 on: April 15, 2021, 03:11:28 pm »
Have you checked DC coming out of U8? I'd poke around R18/R19/R21.
 


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