q10 12.62-13.48-13.44
ic2 tl494c
1.) .858
2.) 3.402
3.) .054
4.) .027
5.) 1.303
6.) 3.565
7.) 0.000
8.) 4.930
9.) 2.010
10.) 2.011
11.) 4.930
12.) 12.46
13.) 4.930
14.) 4.930
15 ) 1.973
16.) 1.637
the protection light is now on, i removed the r68 and amplifier still has no drive.
ic2 tl494c
1.) .858
2.) 3.402
3.) .054
4.) .027
5.) 1.303
6.) 3.565
7.) 0.000
8.) 4.930
9.) 2.010
10.) 2.011
11.) 4.930
12.) 12.46
13.) 4.930
14.) 4.930
15 ) 1.973
16.) 1.637
the protection light is now on, i removed the r68 and amplifier still has no drive.
The 2Vdc on Pins 9 and 10 indicate drive. You should see pulses with a scope. Replace IC3-18021 and be sure R105-4.7 ohm is in value and this should restore drive to the gates. Once you have established drive to the gates(R68 still removed) You can replace Q14 & Q15 and the power supply should be restored. Be sure to check filter caps-C76,77,78,79 and D24 & D25.
ok drive was fixed. the output section has rail +-36.42vdc regulated +-15 at op amps, ok. yet no audio and has .532v on the speaker terminal?
Check Vdc around IC4-IRS20957 and and post, also screenshots of Pin 3 and Pin 13.
Also check the Vdc around Q17. Black probe should be held at ZD8-13v zener diode(-Vcc).
You should see ~13Vdc on the emitter and base, and -28Vdc on the collector, middle lead.
Also check the Vdc around Q17. Black probe should be held at ZD8-13v zener diode(-Vcc).
You should see ~13Vdc on the emitter and base, and -28Vdc on the collector, middle lead.
ic4
1.) 10.21
2.) 10.21
3.) 2.506
4.) 0.00
5.) .001
6.) -47.91
7.) -52.10
8.) -49.61
9.) -52.91
10.) -47.67
11.) -40.74
12.) -0.001
13.) -0.024 fluctuation
14.) 4.093
15.) 11.98
16.) 2.117
q117
1.) 13.65
2.) 26.34
3.) 12.75
1.) 10.21
2.) 10.21
3.) 2.506
4.) 0.00
5.) .001
6.) -47.91
7.) -52.10
8.) -49.61
9.) -52.91
10.) -47.67
11.) -40.74
12.) -0.001
13.) -0.024 fluctuation
14.) 4.093
15.) 11.98
16.) 2.117
q117
1.) 13.65
2.) 26.34
3.) 12.75
Check Q19 and Q20-200N15 if you haven't already. check C92,93,94,95 with an ohmmeter.
Check the voltage at R10-(+15VB) & R14(-15VB) both sides.
With a scope check on either side of C124, and IC7-LM311 Pins 2,3 and 7, IC4-Pins 3 and 13 and post screenshots.
Check the voltage at R10-(+15VB) & R14(-15VB) both sides.
With a scope check on either side of C124, and IC7-LM311 Pins 2,3 and 7, IC4-Pins 3 and 13 and post screenshots.
So the class D and output drive appear to be good. Focus on the input side. Signal trace through the opamps. Look for bad solder around the through hole box capacitors and the remote gain control port.
So the drive is good. The amplifier is stuck into protection still. Ps drive and regulated all look good. Yet the protection remains. Currently the outputs are removed from the curcuit. Could use some advise.