Thanks to all who replied. I finally found the trouble, C48, the 1000uF
15V cap on the 12V supply. I was confused by the fact that the buzz
would randomly fade and go away, somewhat like if a tube filament was
cooling off, which was obviously not happening. Finally my imperfect
eyes saw the physical damage on that cap. Fixed, but I figure I should
replace all the electrolytics after 42 years.
On 4/14/2010 17:22, Charles Ring wrote:
My 2-C, which I bought new in 1968, suddenly developed a very loud
buzz which is there, unchanging, no matter what position any controls
are in. Suspecting the main filter cap, I took the bottom cover off
and turned the receiver upside down, turned it on and the buzz was
gone. I could not provoke it to come back. So I reassembled it and it
worked fine for a few days, but now the loud buzz is back. I'd expect
a bad electrolytic to stay bad. Is there a known cause for this
behaviour? I have the manual with schematic.
73 de W3NU
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