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

[J. Forster]

Look at the Ohms readings. It's not open, if the readings are right.

-John

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


> Try putting a light load on the transformer when you measure the output
> voltage (maybe 1K).  You may find that terminals 2-3 are open circuit
> rather than short.  Maybe that's why CR10 survived - the transformer
> blew first.
>
> Ed
>
> Brooke Clarke wrote:
>> 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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