Studio Reference Amplifier

Dear Mr. Mile S...
I have a problem now on my second built SR200 amp, I can not set bias for one channel, the other one is just fine. Both of them sound good also, but they have difference heat sink temperature (because of bias setting I guess), and the one that I can set bias is sound better that the other one.
I already changed DB139, 2sc4793/2sa1837. I have check all small transistor (bc's) I think they are OK...
I need you advice.
Thank you so much..
Best Regards..
 
Dear Mr. Mile S...
I have a problem now on my second built SR200 amp, I can not set bias for one channel, the other one is just fine. Both of them sound good also, but they have difference heat sink temperature (because of bias setting I guess), and the one that I can set bias is sound better that the other one.
I already changed DB139, 2sc4793/2sa1837. I have check all small transistor (bc's) I think they are OK...
I need you advice.
Thank you so much..
Best Regards..

What is voltage measurements on R28, R29 and R30 resistors?
 
:hohoho:
Circuit can work with IRFP240/IRFP9240 (R30-10k, without C10,C11-100pF). Zobel network with 10R, 22nF and 4R7,10uH is on PSU pcb. MJE340/MJE350 must have heatsink (10mA), amp can work with +/-90V DC rail voltage with more outputs (R20,R21,R22,R23-100k instead 47k, R24-12k/1W instead 6k8).



What is ZOBEL NETWORK means sir? Sorry, i,m just a beginner in diy.
 
Voltage on R11 must be 15V, replace R9 and R10 with 1k instead 2k2.

Last night I used jumper instead of R10 (to make R9 and R10 = 2K2 both), measured zener diode 15v (D2) = 7,4 volt .
Measurement also conducted on zener diode 15v (D1) = 7,5 volt with R7 and R8 are still 2K2 each...Do D1 and D2 need to be replaced?
I measured the other SR200 channel, both of D1 and D2 are 15 volt..and I can set bias without problem...
I need your advice...
Thank you so much
Best Regards..
 
Last night I used jumper instead of R10 (to make R9 and R10 = 2K2 both), measured zener diode 15v (D2) = 7,4 volt .
Measurement also conducted on zener diode 15v (D1) = 7,5 volt with R7 and R8 are still 2K2 each...Do D1 and D2 need to be replaced?
I measured the other SR200 channel, both of D1 and D2 are 15 volt..and I can set bias without problem...
I need your advice...
Thank you so much
Best Regards..

Yes, you must have 15V on zeners.
Regards
 
Yes, you must have 15V on zeners.
Regards

Mr. Mile S...
Absolutely right...
Last night I replaced those two zener diodes, install back 2k2 resistor and check the diodes...Finally I got 15Volt on those ones...Thank you so much..
For the first run I set 1V on R10 (instead of fuse)...
Dc offset measured at 24mv...it is a little bit high, isn't it?...But I have not test the sound yet, it was too late of night....
I will try to take pictures and post them in this forum...
Thank you so much Mr. Mile S. for sharing this SR200 design...
Best Regards...
Arif