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Looking at the circuit I see it uses quite a number of 2SA 70 transistors in the IF stages, they do suffer from tin whisker
disease.. They're the larger diameter transistors in your pictures.
They have a fourth screen leadout which
also goes to the can.Physically
identical to the British Mullard
AF114,AF117 etc series which
had bad tin whisker disease
also.Symptoms can be intermittent
and tapping the transistor can make it
work sometimes.
I Had a 5"Sony which used those in the
IF's also,think a later version IF board used
different transistors.
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