Then connected the SS-amp modules.
One of them works!, and i could adjust difference in output Voltage to 0V with P2
The other one dont
Anyone has some good input?
I tried measured the voltage (with reference to ground) around the circuit:
voltage on good amp in ()
out- +285V (11)
out- -295V (11)
P2/R36 -18,9V (-1,52 on good amp)
P2/R35 -19,3V (-1,53 on good amp)
R36/Q2 -18,8V (-1,57 on good amp)
R35/Q1 -19,4V (-1,56 on good amp)
R26/R27 297 (201)
R27/R28 291 (106)
R23/R24 100 (202)
R24/R25 -91 (106)
R33/R34 130 (5,4)
R32/R31 -156 (5,0)
Q4/R6 -300 (-243)
Q3/R5 -300 (-243)
R11/R12 -160 (-160)
R6/Q7 -300 (-300)
R5/Q6 -300 (-300)
Then my child woke up from sleep ...
I might try to check the transistors tonight ...
All KSC5027 (replaced 5042) measured ok on both amps (HFE around 25 in circuit)
both 1156 is hard to measure in circuit (HFE around 2 in circuit ... ) But the same on both amps.
Q1 and Q2 (sj74 bought on ebay, matched quad with Idss around 15,9)
- both has a drain-to-source resistance about 75ohm on good amp
- on bad amp Q2 has 75 ohm as well, but Q1 is 88 ohm.
Is that enough to change the pair? i'd suspect a bigger deviance, if the fet was blown....
the BC550's is hard (impossible) to measure in circuit ...
Anyone got some tips??
Edited by pedefede - 2/13/11 at 4:00pm