I have a model 87 fluke multimeter with Q8 showing bad and I am looking to replace it. Fluke no longer stock it and don't have a substitute for it I can't see any markings on it so can't find a data sheet. Was wondering if someone could recommend a substitute from the schematic attached
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Fluke 87 Meter repair
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Re: Fluke 87 Meter repair
What happened to the meter that caused Q8 to go bad?--- begin sig file ---
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Re: Fluke 87 Meter repair
Originally posted by retiredcaps View PostWhat happened to the meter that caused Q8 to go bad?Last edited by davg; 08-05-2020, 06:26 PM.
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Re: Fluke 87 Meter repair
Q8, Q10 are at the power system for the DMM IC, which is never supposed to see any overloads. It could happen if you were running the DMM from a bench power supply instead of the 9V battery and caused a ground fault. But this is uncommon.
I would say good chance the DMM IC is fried if those parts failed There's a bunch of parts to protect the DMM IC and why didn't they work?
You could leave out Q8, Q10, Q3 and jumper battery(-) to VSS at C21 just to see if the meter can boot up. If there is a short or overcurrent on the VDD/VSS I think the DMM IC has shorted.
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