Rockford Fosgate T500-1bd

[cajones65]

Hi guys, I am needing a little help with the T500-1bd. Amp powers up and I have a good signal on the PS Fets. and I am getting rail voltage (40.2) between the rectifiers. However; I do have some weird looking signals on the output of Q2014 and Q2015. The voltages on the third leg of 44h11's are 11.1, 11.1 and 6.3 and the 45H11 no voltage on any leg. Thanks in advance

 

[Perry Babin]

Check R1091 and R1022.

 

[cajones65]

Thank you Perry, are the 44H11's and the 45H11 drivers for the outputs or are they a regulator

 

[Perry Babin]

Regulators.

 

[cajones65]

Perry R1019 and 1022 check good, they are in parallel correct? Reading 10ohms on two 20ohm resistors.

 

[Perry Babin]

OK.

Post the DC voltage on all terminals of the LM337.

 

[cajones65]

Not 1019 but R1091

 

[cajones65]

I will do that this afternoon, when I get home. Thanks

 

[cajones65]

LM337
1.-13.32
2. -17.63
3. -14.15
Ref to amp power grd

 

[Perry Babin]

Do you have -17v on both ends of the two 20 ohm resistors?

 

[cajones65]

Perry I don't understand what happened, after i checked the resistors, and they did have the -17vdc on them. I checked the 45h11 and it has voltage now. Pin 3 has -5.2. Plus I have -2.4vdc across my speaker terminals.

 

[Perry Babin]

Do you have rail-rail oscillation on the output transistors?

If so, is the amp producing audio at the speaker terminals?

 

[cajones65]

No sir I don't

 

[Perry Babin]

Read section 25 of the following page of the tutorial:
repair_tutorial\miscellaneousstuff\rockford\repairnotesrockford.htm

Do you have the same driver board as shown in that section?

 

[cajones65]

Yes sir I do have the same driver board, I was looking at it from the wrong side.

 

[Perry Babin]

Pull the rectifiers and install a jumper wire as shown in that section. Don't use too much heat.

To take the rectifiers out of the circuit, desoldering and lifting the center terminal will be good enough.

 

[cajones65]

Perry that test has been done. They all tested good, good looking signals

 

[Perry Babin]

Is the duty cycle very near 50%?

 

[cajones65]

yes sir,47-53%

 

[Perry Babin]

Reconnect the rectifiers and remove the jumper. MEasure the DC across the speaker terminals.

With the black probe measure the DC on the two points where the jumper was connected.