Rockford Fosgate T-10001

[seankane]

Hello everyone.

I have a Rockford T-10001, with an issue. The amp powers up fine and does not go into protect. The amp has no sound. Just hear kinda of like a clicking pulsing out of the speaker then it stops. There was a missing diode by the power supply fets. It was D6 on the board. The marking was 81H. I took one out of another amp and replaced it with same result.

Some of the power supply caps are buldging at the ends but nothing looks split or leaking. The amp also has no rail voltage to speak of on the IRF3415 output fets. The amp does not draw excess current. I dont believe the output are shorted, but not 100%

Just wondering if someone good give me a heads up on where to start, and what to check...

Thanks again in advance for any advice and help.

[Perry Babin]

What is the DC voltage when you place the red probe on the center leg of CR5 and the black probe on the center leg of CR6?

[seankane]

Originally Posted by Perry Babin

What is the DC voltage when you place the red probe on the center leg of CR5 and the black probe on the center leg of CR6?

It reads 78 vdc

[Perry Babin]

That's the rail voltage.

Do you have any significant DC on the speaker terminals?

Do you see a triangle waveform on pin 5 of U203? Start with 5v/div and 10us.

[seankane]

No DC on speaker terminals.

I cant even get the scope to trigger on pin 5

[seankane]

The amp is drawing hardly any current, as in barely registers on the power supply. The power light is on but its like the amp is not powering on fully. The protect light on the board is a very faint yellow. Not sure if its suppose to be bright or what cause the blue led power light on the board is very bright.

[Perry Babin]

It's common for the amber LED to be lit slightly.

At 5v/div do you see a haze that swings ±1 div?

If so, did you try switching to 2v/div?

Did you try changing the coupling (hfrej, lfrej...)?

Do you have positive and negative 15v on the power supply pins of the op-amp?

[seankane]

Originally Posted by Perry Babin

It's common for the amber LED to be lit slightly.

At 5v/div do you see a haze that swings ±1 div?

If so, did you try switching to 2v/div?

Did you try changing the coupling (hfrej, lfrej...)?

Do you have positive and negative 15v on the power supply pins of the op-amp?

There is no haze the line remains solid and drops 1 division below the baseline. The lower I set my vol/div the lower the line drops until it goes off the screen.

I tried a bunch of different settings and cant get a trigger.

I dont know which op-amp your refering to but if your refering to U203

Pin 4: -6.19 vdc

Pin 8: -8.50 vdc

These are from the LM6172 (U203) So I have negative on both pins.

[seankane]

I have barely a fraction of a volt on any of the output fet legs when the amp is powered up. Its like they are not turned on. The amp powers up but its like its not turning the whole amp on.

[Perry Babin]

From this point on, you should (without having to be told to do so), you should...

check all op-amps to confirm that they have power supply voltage (positive and negative for all audio op-amps)

operate all switches and pots through their entire range.

confirm that the amp has rail voltage.

if no voltages are present, confirm that you have good supply and remote voltages inside the amp.

If those are OK and the amp has no DC voltage on the gate terminals of the power supply FETs, post the DC voltage on all pins of the power supply IC.

This is the basic repair sequence and applies to most all repairs. If you (or anyone asking for help) can't remember these items, print this out.

Is R50 out of tolerance?

If not, post the voltage on all 3 terminals of Q201?