[time-nuts] HP 3458A ISOLATOR DTACK err @ pwr up

J. Forster jfor at quik.com
Thu Jul 30 17:32:44 UTC 2009


Seems low for shorted turns. How physically big is the transformer? It
still might be shorted turns, if the transformer is small (say under a 1"
cube) and has a high primary resstance..

Shorted turns or an open winding are single point failures. Other failures
(two point)are much less probable.

FWIW,
-John

=============


> Hi John:
>
> It's hard to say.  With the A4 Inguard p.s. board removed when powered up
> the
> fan comes on and the display lights up with the error message.
>
> So, measured on the primary side, there's 25 ma AC current going to the
> transformer then to the Outguard p.s. and fan.
>
> Have Fun,
>
> Brooke Clarke
> http://www.prc68.com
>
> J. Forster wrote:
>> Looks like it. Does the transformer draw much current with the PCB
>> removed? If it has shorted turns, as it appears, it likely will. Does it
>> get hot?
>>
>> -John
>>
>> =================
>>
>>
>>> Hi:
>>>
>>> I think the power transformer got cooked.  Have a look at the Vac and
>>> Ohms
>>> data:  http://www.prc68.com/I/HP3458DVM.shtml#T1
>>>
>>> Force a browser refresh to see the latest schematic.
>>>
>>> Have Fun,
>>>
>>> Brooke Clarke
>>> http://www.prc68.com
>>>
>>>
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>>
>>
>
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