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Old 27th Feb 2020, 5:46 pm   #6
1980s_john
Triode
 
Join Date: Apr 2005
Location: Ipswich, Suffolk, UK.
Posts: 23
Default Re: Grundig Concert Boy 1100 (again)

Quote:
Originally Posted by ajgriff View Post
What's actually wrong with the radio?
Nothing unusal, same as examples in other threads. Was sat on shelf for years with a stuck tuning dial, having freed it set was dead. C806 was acting as a 20 ohm resistor so was replaced, set now receives FM OK but very quiet and distorts when volume raised. I found a DIN lead and output there is fine, feeding a sine wave in (switched set to tape) gives a distorted sine out (very asymetric). I've just removed T012 and T013, both had good PN junctions (all about 0.2V on diode test in forward direction, high resistance in reverse direction). Hfe test gave 140 for T012 but only 90 for T013, so I think I need a new AC188K.

Above is on a 9V DC supply, on mains get a loud hum + signal. I haven't checked the zener diode yet.

Regards,
John
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