[volt-nuts] HP 3456A -3 Fault

Bill Gold wpgold3637 at att.net
Fri Dec 26 19:36:00 EST 2014


    These things are NOTORIOUS for filter cap failures in the power
supplies.  Check both the voltages and the RIPPLE on the various power
supplies.  It is not sufficent to just check the voltages.  You must check
the ripple with an o'scope.  At least this is the first step before looking
for anything else.

Good luck,


----- Original Message ----- 
From: "David Smith" <w6te at msn.com>
To: <volt-nuts at febo.com>
Sent: Friday, December 26, 2014 3:34 PM
Subject: [volt-nuts] HP 3456A -3 Fault

> 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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