[volt-nuts] HP 3456A -3 Fault

[Christopher Brown]

First suspect is always the small electrolytics on A10, followed by the
large one on A10, and large one on A3, but those last 2 are large/high
qual and seem to last much better.


All 6 of my 3456As had or developed issues with one or more of the small
caps.

All 6 have been re-capped with

<part id>
<original P/N and spec>
<replacement P/N>

A10C7
0180-3009	47uf ±20 50vdc Al
Nichicon		UPM1J680MPD6

A10C8
0180-2803	100uf +50/-10 50vdc Al
Nichicon 	UPM1J331MHD6

A10C13/A10C15
0180-2635	1000uf +50/-10 35vdc Al
Nichicon		UPM1V152MHD6

A10C16
0180-3014	330uf ±20 50vdc Al
Nichicon		UPM1J391MHD6

A10C19
0180-3008	470uf +50/-10 35vdc Al
Nichicon		UPM1V681MHD6


These are all direct match for lead spacing/etc except C8, where the
replacement is wider leads _but_ has a thick slotted base so you can
dog-leg the leads to match the original spacing.

All are long-life ± 20% parts, all are larger but fall within the
original range spec except C8, where going from 150uf (originally
selected part) to 330uf reduced p-p ripple from .45v to < .2v


DO check voltage and ripple, but if it comes down to it, the re-cap
takes about 20 minutes, including removing A10, pre and post recap
cleaning and re-install.


On 12/26/14, 14:34, David Smith wrote:
> Hello Friends,
> I have two HP 3456A's that have the same "-3" fault in the "test" mode. Both DVM's started exhibiting this same fault about the same time. I've troubleshot one of the DVM's to a failure in the Isolation Logic "Transmitter." I have no waveform at the output of A3T1.
> Before I continue with troubleshooting I thought I'd ask a question of the group.  Is there a common mode failure of these DVM? Is there something in particular or area that I should be looking at/for?
> It's probably coincidental that they would both fail at about the same time with the same -3 fault.
> Your input is greatly appreciated.
> Best regards,
> 
> Dave - W6TE 		 	   		  
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