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Old 14th May 2021, 1:26 pm   #21
Bufo Bill
Heptode
 
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Join Date: Jan 2016
Location: Wolverhampton, West Midlands, UK.
Posts: 535
Default Re: HP 180A Oscilloscope.

Okay, not very well today, but will fill you in on last night . . .
Removed suspected failed cap C412, it is nowhere near 2100uF.
While I was removing it I smelled burning which seemed to be coming from beneath the metal EHT cover. As the unit had been switched off for several hours, I pulled off the cover and found C309 was visibly burned on one corner.

Andy's advice is most welcome as I have never worked on something this complex and even the way to go about this diagnosis and repair is new and daunting to me.

On that point, I was wondering whether or not to continue the project until these two obviously defective Capacitors have been replaced? It seems daft to my untrained mind to continue until the obviously bad bits are replaced, but maybe I am wrong?

Andy, I have a Variac, I may get back to you on the EHT probe.
Cheers from Bill.
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