Service Manual/Full Schematic for Biddle BM10 Megger

[The Boz]

Hey all,

I'm looking for something to help me repair a Biddle BM10 megger.
Capacitor C-16 has mechanical damage and requires replacement, I think
several of the 1N5400 diodes are bad I need a better capacitance meter
to troubleshoot further - I'm working on that. I have other questions a
schematic would help with.

TIA,

Boz

 

[The Boz]

I removed the 1N5400s, they tested fine when isolated. Probably a
Huntron would have helped in that regard.

Perhaps someone has suggestions on testing TO-92-cased transistors in
circuit? I've Googled it but find ambiguous, sometimes confusing
instructions. One method even said it of itself, it was potentially
destructive...yikes.

The Boz

 

[Asimov]

"The Boz" bravely wrote to "All" (26 Nov 05 22:12:07)
--- on the heady topic of "Re: Service Manual/Full Schematic for Biddle BM10 Megger"

TB> From: The Boz <[email protected]>
TB> Xref: core-easynews sci.electronics.repair:349653

TB> I removed the 1N5400s, they tested fine when isolated. Probably a
TB> Huntron would have helped in that regard.

TB> Perhaps someone has suggestions on testing TO-92-cased transistors in
TB> circuit? I've Googled it but find ambiguous, sometimes confusing
TB> instructions. One method even said it of itself, it was potentially
TB> destructive...yikes.


To test the TO-92 transistors in-circuit just use a dmm on diode
function to test the junctions. If you want to be thorough, then
isolate 2 of the 3 transistor terminals to run a hfe gain test. I
haven't met a TO-92 transistor I couldn't desolder using a solder pump
or a solder wick.

A*s*i*m*o*v

.... Letterman of Borg - "Ok, Top 10 reasons why resistance is futile:"

 

[Andrew Tweddle]

I removed the 1N5400s, they tested fine when isolated. Probably a
Huntron would have helped in that regard.

Perhaps someone has suggestions on testing TO-92-cased transistors in
circuit? I've Googled it but find ambiguous, sometimes confusing
instructions. One method even said it of itself, it was potentially
destructive...yikes.

The Boz

One instrument that I use on occasion is a "Supercricket".
It will test transistor gain incircuit.The other method is the back to
back diode check with a multimeter.Not quite as reliable and not always
useful on FET's.

Andrew