Author Topic: HP6632B repair - cap on ADC  (Read 911 times)

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Offline artag

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HP6632B repair - cap on ADC
« on: January 26, 2017, 12:28:24 pm »
I had a problem on a 6632 psu : the volts/amps meters always read close to zero. Tracked it down to a faulty AD677 ADC and have fixed it - but there was a small capacitor soldered across the input pins, and I damaged it.

I think it's a standard production mod, but the digital board isn't in the service manual so the mod probably isn't in a service update either.

Anybody know what the value should be ?

 

Offline artag

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Re: HP6632B repair - cap on ADC
« Reply #1 on: January 27, 2017, 03:16:05 pm »
I made an approximate measurement on another supply. If anyone else needs this info, the answer is 'about 100pF'.
 
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Offline SeanB

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Re: HP6632B repair - cap on ADC
« Reply #2 on: January 28, 2017, 09:24:03 pm »
Sounds around the right value to solve a RF pickup issue that probably was causing voltage instability with a cellphone near the unit in operation.
 


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