[volt-nuts] HP 3456A -3 Fault

David Smith w6te at msn.com
Sat Dec 27 19:56:06 EST 2014


Wow Christopher, Thank You! I'm blown away by your kindness!
I will get two sets of these caps ordered on Monday and see if I can get these two 3456's back in operation.
Thanks again!

Dave - W6TE

> Date: Sat, 27 Dec 2014 15:08:04 -0900
> From: cbrown at woods.net
> To: volt-nuts at febo.com
> Subject: Re: [volt-nuts] HP 3456A -3 Fault
> 
> 
> 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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