This is more of a feeler thread right now. In my infinite wisdom, I attempted to read my 560VDC B+ voltage with my Fluke 87 III set to resistance. After the sparks flew (literally at the probe to B+ contact point), the meter still reads, but voltage readings are low by about two orders of magnitude; I haven't diagnosed the other settings. I've found a schematic on Fluke's site, but I'm not making much sense of it. Is there a Fluke repair group out there (Yahoo group or forum), or would one of you be willing to hold my hand while I attempt to repair this (if possible)?
Announcement
Collapse
No announcement yet.
Killed my Fluke 87 III
Collapse
X
-
Originally posted by defaced View PostThis is more of a feeler thread right now. In my infinite wisdom, I attempted to read my 560VDC B+ voltage with my Fluke 87 II set to resistance. After the sparks flew (literally at the probe to B+ contact point), the meter still reads, but voltage readings are low by about two orders of magnitude; I haven't diagnosed the other settings. I've found a schematic on Fluke's site, but I'm not making much sense of it. Is there a Fluke repair group out there (Yahoo group or forum), or would one of you be willing to hold my hand while I attempt to repair this (if possible)?
-
This has happened to me before. It fried the main chip inside the meter, and I had to throw it away.
That was with a cheap no-brand DMM though, and Flukes are supposed to be tough.
So, check internal fuses as suggested. Also check the schematic for any protection devices such as MOVs, TVS diodes, clamping diodes or the like. A good meter should have these, and one of them might have blown out, giving its life to save the chip."Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"
Comment
-
Hi all,
Steve's right, Flukes are really tough, and I think Fluke included something in the circuitry to protect the meter from misusing it ( I think we all burned a DMM at one point in our lives, I did it too, and I'm not ashamed to tell, as they say, you live, you learn ).
Since the reading you're getting are low by two orders of magnitude, I would expect something in the selectable voltage divider has gone south ( the meter's processor should normally select the appropriate divider ratio ). Usually there are several 10x scaling resistors, namely, 909 K, 90.9 K, 9.09 K, 909 Ohms....etc. possibly enclosed in a plastic envelope ( array ).
Hope this helps
Best regards
BobHoc unum scio: me nihil scire.
Comment
-
Originally posted by defaced View PostThis is more of a feeler thread right now. In my infinite wisdom, I attempted to read my 560VDC B+ voltage with my Fluke 87 III set to resistance. After the sparks flew (literally at the probe to B+ contact point), the meter still reads, but voltage readings are low by about two orders of magnitude; I haven't diagnosed the other settings. I've found a schematic on Fluke's site, but I'm not making much sense of it. Is there a Fluke repair group out there (Yahoo group or forum), or would one of you be willing to hold my hand while I attempt to repair this (if possible)?
Comment
-
Looks like 90% positive means you're 100% wrong. I have a Fluke 87 (no roman numerals), the board is dated 1986, so I'd say it's of the right vintage. Service manual is 12MB, so here's the link to Fluke's site that has it:
http://assets.fluke.com/manuals/83_85_87smeng0500.pdf
Layout and schem starts on PDF page 83.
Both fuses test good, 0.2 ohms and 0.8 ohms.-Mike
Comment
Comment