Soundstream Rubicon 1002

[caraudioguy2100]

Amp powers up and produces rail and regulated voltages .

All outputs test fine .

Both clip leds are lit

Any ideas what might cause this ?

 

[Perry Babin]

Does it produce any audio?

Q172 voltage on all terminals?

 

[caraudioguy2100]

Amp doesn’t produce any audio

Q172

Emitter :-16.66
Base: -16.70
Collector :-6.19

 

[Perry Babin]

If Q172 is not shorted, same for Q174, 168, 167, and 187.

 

[caraudioguy2100]

Q172 tests ok

Q174

Emitter:-16.67
Base:-16.08
Collector:-16.74

Q187

Emitter:-0.06
Base:-1.42
Collector:13.28

Q167
Drain: -1.58
Gate :13.28
Source :-0.06

Q168

Emitter:0.46
Base:-0.04
Collector :-16.82

 

[Perry Babin]

Is R250 within tolerance?

If so, install a 10k in its place. Does that allow the amp to produce audio?

 

[caraudioguy2100]

R250 measures 100k out of the board

Replaced it with a 10k still no audio

 

[Perry Babin]

DCV on the collector of Q172?

 

[caraudioguy2100]

-6.17 on the collector of Q172 (leg3)

 

[Perry Babin]

Pull Q174. Be careful powering up. Does the amp produce audio?

 

[caraudioguy2100]

Pulled Q174 clip leds are off and amp produces clean audio

 

[Perry Babin]

Re-post the numbers for all of the transistors with the 10k resistor. Post the numbers on the pads for Q174.

 

[caraudioguy2100]

Q172
Emitter :-16.53
Base:-15.83
Collector:-16.61

Q174 pads
Emitter:-16.65
Base:-12.48
Collector:-15.92

Q187
Emitter:0.04
Base:-1.30
Collector:13.27

Q167
Gate:-052
Drain:13.26
Source:0.04

Q168
Emitter:0.65
Base:0.04
Collector :-15.98

 

[Perry Babin]

DCV across R268 (110 ohm 2w)?

Voltage on Q192 terminals?

 

[caraudioguy2100]

R268:-0.03

Q192

Emitter :0.03
Base:0.03
Collector:13.05

 

[Perry Babin]

Why is the voltage different between Q167 gate and Q192 collector?

 

[caraudioguy2100]

Not sure I will have to trace the circuit back

 

[caraudioguy2100]

Ok my mistake I had the pin configuration wrong on Q167

Gate of Q167 :13.26

Collector of Q192:13.26

Q192

Emitter:0.03
Base:0.00
Collector :13.26

 

[Perry Babin]

Reinstall Q174 and remove Q167. Does the amp produce audio?

 

[caraudioguy2100]

Installed Q174 and removed Q167 and amps clip lights are back on and no audio