Electronics > Repair

Help with Fluke 175 repair

<< < (3/5) > >>

bdunham7:
If you couldn't read the markings on the components prior to desoldering them and the physically fell apart when you took them off, I'd suspect that they got blown up and toasted.  Unfortunately I cannot fnd any 175/177/179 or 77IV teardown photos with enough resolution to read the markings.  However, removing them shouldn't make the meter completely dead either unless one or more of them is actually part of a different circuit and not input clamping.  Hopefully someone somewhere can eventually provide a hi-res photo of that board.

MC2Short:
Again I appreciate the help. If anyone can find it, or happens to have the same board, it's stamped FLUKE 17X-3021 REV 004 at the top of the board. Thanks again.

cardosoluis:
Hi! i don't know it his might be helpfull but i have a fluke 77 iv that i'm repairing myself, here's the pictures of the components.
my board seems a bit different than yours, if you look for Fluke 77 iv erratic behaviour you have thare a full picture of my board to compare

mqsaharan:
Hi MC2Short,
I am not aware of any rules/guidelines that component manufacturers follow for labeling SMDs. You need to be careful while working with these. They are not always easy to figure out.
In the picture posted by cardosoluis, out of six sot-23 devices marked by bdunham7, marking for the first one from top is readable. And a quick search suggests that it is MMBT6429 NPN Transistor.
I am attaching here a picture where the markings for the last 4 as well as the 2nd one from top is readable. I am not sure what device it is. Hopefully, someone knows about it and helps you figure it out.
The last 4 devices have the same markings and look like they are being used as clamping devices. I am not sure exactly what devices these are, but I think they'll be NPN transistors of some sort.
I hope it helps.

EDIT:   Please see the message in the following link for the 2nd device.
https://www.eevblog.com/forum/repair/fluke-77-iv-repair-no-backlight-or-continuity-buzzer/msg3265012/#msg3265012

bdunham7:
If I had been able to see those markings I probably would have suggested only removing the bottom 4 devices marked "JC".  I wasn't able to definitively find what any of them are as those markings and package could be either transistors or dual-diode packages.  There are a few members that seem to be really good at identifying SMD packages so hopefully one of them will spot this thread--or perhaps the OP can post another thread specifically on that subject.

Removing the protection components, whether transistors or diodes, won't cause the meter to stop functioning.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod