SONY TA 636 v. 1979 defekte Z-Diode

Frank, please start your telepatie-generator. Ordinary mind-reading doesn't work over long distances

What I'm saying is, that I have the service-manual but I need to know the position-no. of the Zener to tell you the correct value. Most likely it's a 22V Zener but to be sure please provide the information.

mfg,

/tri-comp

Hi, the z-diode is located in the REGULATOR CIRCUIT. It is D 505 . This item is rather fat - bigger than the usual z-diodes.
Regards
Frank

Hi,

The Zener is indeed a 22V-Zenerdiode.
When it's a 'fat' one I would suggest using at least a 1W type. The original is 'only' 0,5Watt but they tend to become hot. Better use a 1-Watt type in my opinion.

This could be something like 1N4748A:
http://www.microsemi.com/datasheets/SA5-33.PDF
or the European types BZX85C22:
http://www.eworld.ru/store/smc/ds/bzx85.pdf

It is NOT uncommon for a Zener to become defective BUT there MAY be a reason for this.
The Transistor Q501/2SD809 should be examined for shorts or leak. If it's dead a new Zener will become defective immediately.
When you are at it, check or even better REPLACE the electrolytic cap's in the positive and negative supply-circuits.
These are: C504 to C511 inclusive.
You may even want to do the same around the Output IC to prevent it from blowing-up because of self-oscillation caused by failing electrolytic cap's.
Here the cap's are: C301, C304~C307, C351, C354~C357

Good luck,

mfg,

/tri-comp

Opps, forgot to say that according to the manual the typeno. of the original Zener is: EQA01-22R

@ TRI-COMP,
thanks for your very, very precise information ! I will do my very best...

Frank