[time-nuts] HP5370A self test fault characteristics and diagnosis

[Bruce Griffiths]

Bruce

Rex wrote:
> Bruce,
>
> I've never seen you post a new thread as a response to an existing,
> unrelated thread, as you've done here. You are not the first to do
> this, but I thought you might be aware of these subtleties.
>

I was being lazy.
How can you tell, looking at the message source I wasn't able to see any
indication of this?

> In the spirit of quasi-related posts...
>
> On the 5370A part, I recently bought one cheap and it sort of works
> but seems very noisey in its lower order digit readings; clean
> external ref doesn't help. I haven't looked at obvious things like the
> power supply yet, but I'm curious if the group has any thoughts of
> common problems to look for.
>
One cause of this can be misalignment of the 10MHz to 200MHz frequency
multiplier chain filters.
Another thing to look at (if you are using the rear panel 10MHz output)
is the signal may not be clean enough in which case checking that the
output filter is working properly and/or using an external bandpass
filter may be necessary to cleanup the signal sufficiently.
What is the indicated std deviation of the delay between the STAR and
STOP inputs when connecting the rear panel 10MHz signal to both START
and STOP inputs using the STAR COM position of the channel mode switch?
>
> Bruce Griffiths wrote:
>
>> For the benefit of HP5370A and/or HP5370B users I have added a webpage
>> detailing the characteristics and diagnosis of a fault that my HP5370A
>> recently developed.
>> With the 10MHz rear panel output connected to both inputs it developed
>> an overange error when set to measure the time delay between the START
>> and STOP inputs.
>> Details are on the  web page:
>>
>> http://www.ko4bb.com/~bruce/HP5370_Faults.html
>> <http://www.ko4bb.com/%7Ebruce/HP5370_Faults.html>
>>
>> At Didier's suggestion I've also included a link detailing the imaging
>> setup and camera settings etc used to acquire the chip image on the
>> above page.
>> Whilst it is possible to obtain good quality images with less precise
>> multiaxis positioner than those used, at least it is very easy using
>> such equipment
>> The chip image confirms the diagnosis inferred from measurements of
>> various signals within the 5370A.
>>
>> Replacing A22U21 cured the problem,
>>
>> Bruce
>>
>>
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>>  
>>
>
>
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Bruce