开云体育

--- On Tue, 8/30/11, David Speck <Dave@...> wrote:

From: David Speck <Dave@...>
Subject: [hp_agilent_equipment] Favorite bad capacitor debugging techniques?
To: hp_agilent_equipment@...
Date: Tuesday, August 30, 2011, 11:55 PM







?









Looking over the list, I have noted that the majority of problems with

old equipment is failure of the electrolytic capacitors in the power

supplies over time.



I wonder if the veterans can offer any suggestions on their favorite

techniques for finding bad caps in circuit, especially those that have

not been so considerate to have blown their end caps off or otherwise

developed obvious physical failures.



I have a critical undocumented circuit board of relatively recent

construction with about 25 vertically mounted axial lead caps. It's

begun eating fuses at an increasing rate, and now, even a 2 amp fuse

blows instantly in a slot intended for a half amp fuse. No way to lift

one lead of the cap without pulling it out of the PCB, with the

attendant risk of ruining the irreplaceable board. (well, I could

replace it for another $6-7,000, but that's not in the budget this week!)



I figured I could put in another 2 amp fuse, and run it on a Variac at

reduced voltage while watching the current consumption, and see what

component heats up, but I really don't want to trash the microcomputer

on the board.



Any one have suggestions for any specific low voltage instruments for

in-circuit cap checking, or home-brew gimmicks that one can work up, to

give better information than the typical DVM and scope?



Thanks in advance,



Dave