Rockford Fosgate T5002

Perry Babin · 2012-10-01 6:31 pm

Q1009's collector is directly connected to Q1016s base. Why are you getting different readings?

S Merlington · 2012-10-01 6:35 pm

Q1009 collector : held the probe on it longer voltage jump around the same as Q1016's base does

Should i try replacing Q1016 and then test voltages?

S Merlington · 2012-10-01 6:59 pm

OK replaced Q1009 and Q1016

Q1009

Collector:14.39
Base:13.70
Emitter:14.41

Q1016

Collector:44.03
Base:14.39
Emitter:13.82

If i turn the Bias pot up the voltage on thoose 2 transistors starts jumping all over the place ...

If i turn the bias pots up the current draw will not increase..

The Pots are fully counter clockwise right now

Perry Babin · 2012-10-01 9:14 pm

What's the resistance between the emitter of Q1016 and the non-bridging speaker terminal?

S Merlington · 2012-10-01 9:27 pm

0.612 K ohms

Perry Babin · 2012-10-01 9:36 pm

What board # is in this amp? The diagram that I have indicates that it should have 28v of rail, not 40+.

S Merlington · 2012-10-01 10:16 pm

PC-4892-A

Perry Babin · 2012-10-01 10:32 pm

I think the voltage on the diagram is wrong.

When you adjust the bias and the voltage fluctuates on those two transistors, is there any significant voltage driven to the speaker terminals?

S Merlington · 2012-10-01 10:42 pm

No voltage remains the same. 0.04

S Merlington · 2012-10-01 11:03 pm

Ok for some reason Now i dont have clean audio on pin7 of U103 and also no clean audio on U203

Perry Babin · 2012-10-01 11:30 pm

Double-check the regulated voltage on the op-amps.

S Merlington · 2012-10-02 2:14 am

Ok i got + - 13 volts on the op-amps..

The gain was turned all the way up thats why i had a square wave on pin 7

Still have very distorted output on both channel outputs..

Perry Babin · 2012-10-02 7:36 am

Are you 100% sure that every component that you replaced was with the correct type/value?

Are you 100% sure that the connections between the bias transistors and the main board are intact?

S Merlington · 2012-10-02 12:43 pm

Yes 100% sure every part that was replaced is the correct one And the correct value..

Yes 100% sure that the bias transistors are making contact with the main board..

Should i replace the Bias transistors to see if they are defective ?

Perry Babin · 2012-10-02 10:21 pm

Check the pots to confirm that they both have the marked resistance across their terminals and the wiper swings (measure resistance at various points in the rotation) from one outer terminal to the other.

S Merlington · 2012-10-03 1:01 am

Both Pots are marked 202 So guessing they are 2K pots ??

Left channel bias pot fully counter clockwise i get :0.647K ohms
With the bias pot fully clockwise i get: 8.3 ohms

Right channel fully counter clockwise i get:0.667K ohms
fully clockwise i get:8.5 ohms

Turning them at various points i get different reading so im guessing they are working like they should

Perry Babin · 2012-10-03 1:24 am

Did the output transistors initially fail in this amp?

S Merlington · 2012-10-03 1:26 am

Power supply Transistors was what failed in the amp along with the gate resistors and drivers for the power supply and the Lm 317T also failed...

Outputs were never touched..

Perry Babin · 2012-10-03 1:42 am

If you place the black probe on the source of Q1024 and the red probe on the gate of Q1024 and turn the bias up, what is the highest voltage that you read?

S Merlington · 2012-10-03 2:46 am

-0.49 volts is all i get no matter where i turn the bias pot the voltage never changes

Rockford Fosgate T5002

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member

Member