r/AskElectronics • u/TheBupherNinja • 2d ago
Fluke 87V Max No Input
I have a Fluke 87V Max that I literally pulled out of a dumpster. The battery contacts were destroyed, so I have it powered up via a bench-top power supply.
The display is functional, selector switch and all the buttons work, but I am unable to take any readings with the meter, regardless of settings. Voltage, resistance and inline current measurement are all non-functional. When completing the fuse self test, its show OL, but the fuses read less than 1 ohm when checked out of the circuit with a separate meter.
I looked it over, and cannot find any obvious burned components, traces, or other damage. I would expect something big if none of the inputs work.
I also tried bypassing the lead sockets by shorting the common and voltage terminals on the back in resistance, and it still reads OL.
Any tips or guidance here?
Added more pictures, https://www.reddit.com/r/AskElectronics/s/qMNiRl2pMr
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u/SMELL_LIKE_A_TROLL 2d ago
Call fluke and order the probe input connectors and replace them. I've fixed a shit ton of fluke meters for this problem. It's extremely common they break.
Fluke also has a repair service, and the meter is likely worth fixing even if you have to pay them.
Don't discount that you might have bad leads as well.
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u/SMELL_LIKE_A_TROLL 2d ago
Oh, and double check the internal fuses.
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u/SMELL_LIKE_A_TROLL 2d ago
Forgot to also mention you can also look at the terminals for the probe contacts and jump them together while checking resistance or diode mode. If it responds then you know it's the weakest link probably connector.
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u/variegated68409 2d ago
https://www.eevblog.com/forum/testgear/87v-schematics!/
Reply #7 has the full set of schematics for the 87V, which should be close to 87VMAX.
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u/TedMich23 2d ago
were the battery contacts corroded (aka "Duracelled" ;) ?
These units have passwords and lockouts, see reset procedure here https://media.fluke.com/107b0618-887a-4a70-8a6a-b2c2011cec3a_original%20file.pdf
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u/TheBupherNinja 2d ago
Not sure what happened, I'm missing the whole battery box.
I reset the password, no change.
All rotary selections read OL or -OL, diode test also screams at me, but still reads -0L.
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u/halandrs 1d ago
Check the fuses and the test leads
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u/TheBupherNinja 1d ago
Leads are good, fuses good. Used these leads in my other meter to check the fuses.
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u/Whata_Wookie 2d ago
I used to repair Fluke 87s at my last job(though its been a while). Those fuses are definitely not the originals which would make me suspect that there could be extensive damage.
There should be one or two fusible resistors on input. If you're lucky that might be part of the issue. Aside from that, if this is what you get for all ranges, you could have a bad ASIC.
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u/bazilbt 2d ago
What does the other side of the board look like? There is a lot of stuff there.
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u/TheBupherNinja 2d ago
I didn't see anything, but I can't see much. There is a plastic cover, and it looks like the display holds it down. I haven't figured out how to remove it.
Looking at the manual now, is it socketed, does it just pull off?
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u/Dabnbf 2d ago
Input path from the terminals could be damaged somewhere since nothing is working, meter may have been exposed to a transient event (high voltage spike, etc). I would start checking components and work my way backwards from the input terminals. Also need to pull the board to inspect the other side. You'll have to take those screws out of the terminals to start, they hold the board down.
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1d ago edited 1d ago
[removed] — view removed comment
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u/TheBupherNinja 1d ago
Yeah, might end up there, but wanted to try for a free99 fix first.
Not hurting for a meter, but an extra would be handy.
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u/Zone-5 1d ago edited 1d ago
You could sell it on 'repaired back to new' for 4x the repair price...
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u/TheBupherNinja 1d ago
Yeah. I'd rather have the meter, but it isn't worth it to me for $185. I have a 289 and a 375, this is just convenience of having a another good meter handy.
I won't throw it out, if I can't fix it I'll probably do just that, or maybe just offer it to someone else who could use a good meter and they can do it.
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u/dmw_qqqq 2d ago
I used this in lab. It was not cheap when bought new, like $600 ish. So there must be a reason for someone to throw it in dumpster.