Fluke 87 repair - "care package of parts" needed. - Page 1
Forum section: electronics / testgear

author: Piie
author_rank: Newbie
timestamp: December 28, 2021, 02:01:29 pm
content: HiHoping someone could either point me to e source where I can find some replacement parts for a Fluke 87 meter, or perhaps have some lying around?Fluke 87 "base" model.Suspect both replaceable fuses are toast, as well as the 3 spark gap caps and the large brown resistor with green and blue stripes.

author: AVGresponding
author_rank: Super Contributor
timestamp: December 28, 2021, 02:17:27 pm
content: Quote from: Piie on December 28, 2021, 02:01:29 pmNot sure what you mean by "spark gap caps", are you referring to the MOVs or PTCs maybe? A pic might be helpful here.The resistor is a standard enough thing, but if all the input protection circuitry is toast, I'd be quite surprised if it's repairable, sounds like it's had a major calamity...It might be worth trying to raise an RMA with Fluke, the worst they can do is say no.

author: Piie
author_rank: Newbie
timestamp: December 28, 2021, 03:04:25 pm
content: I'm afraid an RMA is out of the question - I didn't know about the life long warranty so I already started to molest it - I don't live in the US...The "spark gap" thingy is indeed an MOV. Pic of "original component" attached (mustard coloured), as well as the varistor I replaced them with (Blue).The large fuses are toast (no continuity through them)

author: AVGresponding
author_rank: Super Contributor
timestamp: December 28, 2021, 04:09:04 pm
content: I'm assuming you didn't fit those fuses, or that 1kΩ 1/4W resistor that goes past the anti-tracking slot...Those fuses look like 15A and 1A, when they should be 11A and 440mA respectively.That resistor appears to have been bodged on to "repair" the 1kΩ fusible resistor (the big one with the blue and green bands on it). It doesn't meet either the voltage or power specifications for that fusible resistor, and the way it is fittedseriouslycompromises the input protection of the meter.

author: bdunham7
author_rank: Super Contributor
timestamp: December 28, 2021, 04:21:27 pm
content: This is an original 87, not an 87V. So the fuses are correct and the 'spark gap cap' is indeed a spark gap. What was supposedly wrong with it? A MOV is not an appropriate replacement for it in any case.It would help to know what the history and current issues are with the meter. Did it get fried but now after some bodging it more or less works and you just want the right parts for it? Or is it still not working? The fusible resistors are almost impossible to find if you want exact replacements, but good-enough substitutes can be had. I have a batch of Fluke 1K fusible resistors that fit different models, but they look different than yours.You might want to start by looking up all of the parts in the manual and making a list by Fluke part number. If you don't have a service manual, here it is:https://xdevs.com/doc/Fluke/87.pdf

author: Piie
author_rank: Newbie
timestamp: December 28, 2021, 04:45:00 pm
content: Thanks all - really appreciate the help and input.OK, so an idiot that has the same ID photo as me used the 87 to see if the electric fence was still on...It is still "working" as in, it switches on, but it doesn't make any readings that makes sense.Yes, it was indeed me that put that 1K resistor on the back - just for testing to see if things got better - had not effect - but I assumed it was because other parts were also damaged.Thanks for the service manual, I'll try to see which parts I need but from the ones I either already ID's as faulty, and the ones I mistakenly replaced, it would be:2x Fuses1x fusable resistor3x spark gaps

author: bdunham7
author_rank: Super Contributor
timestamp: December 28, 2021, 04:58:53 pm
content: Quote from: Piie on December 28, 2021, 04:45:00 pmI don't think there are 3 spark gaps, only one, and unless you destroyed it removing it I don't know if you need a new one. In any case, if you've bypassed the fusible resistor, none of those parts will help make your meter work. I'd suggest seeing if you can make it functional--you likely have blown a protection diode or something even worse.An electric fence is unlikely to damage the fusible resistor or the fuses. If it did, I'd stay away from that fence.Do you have another meter you can test things with?

author: Piie
author_rank: Newbie
timestamp: December 28, 2021, 05:04:54 pm
content: Yes, I bought a 87V - which is now properly handledYou are correct, there are only 2 spark gaps - on the schematic, they are listed as RV1 and RV2 - "Varistor 910" with part no: V910L8X1399The other part, which I also replaced with a varistor is a 1500V surge protector (E1 on schematic), part number 100TII do have a SMD "tester" that can also test capacitors...

author: BeBuLamar
author_rank: Super Contributor
timestamp: December 28, 2021, 05:16:52 pm
content: Quote from: Piie on December 28, 2021, 03:04:25 pmThe warranty is expired 7 years after Fluke discontinue making it. I had an 87 bought in the late 80's. I sent it in for repair around 1994 and they fixed it for free. Next time around 2004 and they said they can't fixed it no longer and offer me a $100 toward the purchase of the 189.

author: bdunham7
author_rank: Super Contributor
timestamp: December 28, 2021, 05:19:14 pm
content: Quote from: Piie on December 28, 2021, 05:04:54 pmRV1 and RV2 are MOVs, not spark gaps. E1 is a spark gap and should remain so. Unless the original is physically damaged I doubt it is bad in any way that would cause the meter not to work. For testing purposes on blown-up meters, I will typically remove all of these protection devices as the meter will work fine (on the bench, with care) without any of them installed. Perhaps you should start there. Then maybe have a look at the three transistors and four diodes near the positive input terminal. These can also be simply removed for testing.

author: Piie
author_rank: Newbie
timestamp: December 29, 2021, 06:44:41 am
content: Thanks, so by "removing" you mean bridge them out, or desolder and leave the circuit broken where they were?

author: bdunham7
author_rank: Super Contributor
timestamp: December 29, 2021, 03:19:14 pm
content: Quote from: Piie on December 29, 2021, 06:44:41 amJust desolder them and leave the circuit 'open'. They are all shunt protective devices and are normally open circuits. I'm not referring to fusible resistors or PTCs, of course.