Sansui 9900Z Repair

[Szalbierz]

Welcome guys,

i am reparing my Sansui 9900Z. I bought this Reciever some years ago on Ebay.
On Power Amp. Board all drivers (Q7-Q11) and power transistors (Q1-Q4) were burned.
Q12 and Q13 were fine, just like "kQFT1" (JFET x2).
I decided to change all of them here is the list:

Q1 2SC3858
Q2 2SA1494
Q3 2SC3858
Q4 2SA1494

Q5 2SC2238
Q6 2SA968

Q7 2SC3503
Q8 2SA1381

Q9 2SA1220
Q10 2SA1381
Q11 2SC2690

Q12 2SC1845
Q13 2SC1845

Q14 2SA2690

After I did this one of the Transistors Q1 of left channel failed.
Reciever was already repaired and yeasterday I saw that OP AMP 4558D was replaced with MB3607.
I changed it for 5532D. Now i dissconected all of Power Transistors, both Potentiometer counter clockwise and measured the voltages.
Q5 E=7,7V C=72,5V B=7,7V
Q6 E=7,7V C=-72,5V B=7,7V

OP AMP should get sth about +15,5V and -16,3V
I am getting +8,7V and -6,7V
Can somebody please explaine me how is it possible?

 

[Hyperion]

Kr33 (x2) damaged? - or counterfeit/damaged OP amps? - could be many things - check power supply voltages.

I didn't realise that the 9900Z is a 'Super Feed Forward' design, you'll have fun setting the DC offset.

 

[Szalbierz]

I just made a schematic of one channel.
I still have to check all connections, not sure I did it well.

 

[Szalbierz]

Would be nice to make new PCB.
Could someone look on it?
I think about making 2 separate channels and put them on passive radiator.

 

[Szalbierz]

Update:

 

[DB-7]

Why aren't you using the service manual and schematics that are readily available For Free online? Instead of dreaming up your own schematics.

I don't know what your goal is here, but butchering up a very collectible Sansui doesn't seem like the logical thing to do.

The xx00z series is gaining steam fast in the collectors market.