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SONY TA-1630 PROBLEM, same level sound through ALL INPUTS (AUX, PHONO and TUNER)

Joan Biel said:
Hello,

Thanks to DatunWalnut and the service bulletin now the amplifier has no crosstalk anymore. I follow the istrucctions, fist option B (no change) and then option A, moving the grundig wire (30) to PCB works for me.

Now I'm getting distorted sound from both channels and there is no bias (0mv) on both channles. I replaced the drivers transistors with mje340g and mje350g. Maybe not good subs???

Thanks DatunWalnut.

Joan Biel
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I'd start fitting the original drivers again in place, perhaps you mixed npn and pnp, or some part has different pinout.
 
elnaldo said:
I'd start fitting the original drivers again in place, perhaps you mixed npn and pnp, or some part has different pinout.
Click to expand...
Yes, I will try that first and see if the bias problem is gone. The distortion was there before swapping the drivers though. I think I have some 15032 and 15033. But do you think the 340 and 350 are good subs for the 1124 and 706?
 
No, the distortion was there before I aplied the service bulletin and before i changing the drivers.
DatunWalnut said:
I'm just thinking: did the distortion only occur after you applied the service bulletin? In which case it could be a grounding issue. Is the grounding wire still attached to the chassis?
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I put the origial transistors in place again in one channel. The same, no bias at all (0mv). I check the service manual and i see that the q108/q208 are 2sc1124 and the q109/q209 are 2sa706 on the manual but all the units i see in the web has the 2sc1670 and 2sa840. Maybe a service manual error?

I'm lost at this point. What I'm missing?
 
I changed my 1124s for 2ac2690 they worked well. (Observe lead positions)
Can you tell me off the distortion happens on all inputs including tape in?
Also, what is the DC offset at the speaker terminals? The lack of biasing is a concern.
As I said before, faulty bias pots are a very quick way of of blowing the amp. Change them. Next I'd be concerned about the diodes bolted to the D1061 power transistors.
 
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