| Electronics > Repair |
| Fluke 87-I repair |
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| staze:
True, but those parts can often be bad... burned out by overvolting the meter. Really, this meter is probably a parts unit itself... =/ I did just email Fluke asking for pricing for R1 and R2... guess we'll see. |
| staze:
Ouch, got back to me. Lead time for the parts is nearly 6 weeks, and about $20. =/ Might have to see if Digikey can get them. |
| lowimpedance:
For the 909K , if space permits you could try the 1M ohm gs-3 in parallel with this 10M (High voltage and pulse withstanding 1/2W) http://www.digikey.com/product-detail/en/HVR3700001005FR500/PPCHF10MCT-ND/720093. Both are in stock at Digikey. Should get you close enough to the 1%. Have you checked R12 (most likely fine, but..). Bodging in close enough values to test the overall function and fault find further is the way to go until your confident the meter is fully operational then get the Fluke parts to finish off. But if something major has gone (IC!) then well nothing much lost, and you have a parts unit and motivation to get another one :) |
| staze:
--- Quote from: lowimpedance on February 20, 2014, 11:59:45 pm --- For the 909K , if space permits you could try the 1M ohm gs-3 in parallel with this 10M (High voltage and pulse withstanding 1/2W) http://www.digikey.com/product-detail/en/HVR3700001005FR500/PPCHF10MCT-ND/720093. Both are in stock at Digikey. Should get you close enough to the 1%. Have you checked R12 (most likely fine, but..). Bodging in close enough values to test the overall function and fault find further is the way to go until your confident the meter is fully operational then get the Fluke parts to finish off. But if something major has gone (IC!) then well nothing much lost, and you have a parts unit and motivation to get another one :) --- End quote --- Yeah, think I'm just going to wack in some 1/4W resistors for now to get 900K or so (since that'll be within 1%). Then a 1K 1/4W for R1... and a 100K 1/4W for R29... I haven't done the math (since, I'm not sure how to start), but it would be curious to see if the combination of R29 reading 170K, plus R2 reading 850K, and R1 being open, combined would lead to how far out the DC volts is. I'm kind of guessing it would explain it. R12 I haven't checked. It's on the back, so I hadn't even tried. =P |
| staze:
bodged some 1/4w 1% resistors in to replace R1, R2, and R29. No change at all. Voltage on the input jacks in the DCV setting seems to be coming from the R1 side of things (lower voltage on the input jack side of R1). I need sleep, but I think I'll hook the scope up tomorrow and see if it's just a constant voltage, or if there's something obvious about where it might be from. One of the transistors seem like an obvious, or something still wrong with the rotary switch, but I've cleaned that thing so many times at this point... Thanks! |
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