rockford fosgate T5002 problem

[boot35]

problem with this amplifier T5002, the amplifier is intact, no signs of a previous repair are seen; the problem is that it turns on the ignition source, but there is no sound, probe all the source and output transistors and they are fine, but measuring voltage on the diodes I have -10 +8 volts only, measuring with the voltmeter in the central leg of the diodes and black wire on the shield of the rca, what would be the next test? Thanks in advance.

 

[Perry Babin]

What if you place the black probe on the ground terminal?

The shield floats a bit.

 

[boot35]

practically same voltage +9.2 and -10.8

 

[Perry Babin]

Do you have a good drive signal at the gates of the power supply FETs?

 

[boot35]

Low voltage, measures 0.360 and 0.390 volts

 

[Perry Babin]

You would need to post the DC voltage on all pins of the driver IC to troubleshoot drive issues.

 

[boot35]

CI: UC3526ad

pin 1 7.6 volts
pin 2 1.01
pin 3 6.62
pin 4 6.93
pin 5 7.6
pin 6 0.0
pin 7 0.0
pin 8 3.4
pin 9 6.10
pin 10 3.3
pin 11 0.0
pin 12 7.6
pin 13 0.026
pin 14 12.48
pin 15 0.0
pin 16 0.28
pin 17 12.48
pin 18 7.6

 

[Perry Babin]

It looks defective, unless something is pulling pin 16 up. It's supposed to be 5.1v ±1%.

 

[boot35]

If pin13 and pin16 have low voltage, do you recommend replacing it?

 

[Perry Babin]

I would. The low output is likely due to the reference voltage being wrong.

 

[boot35]

replace UC3526ad and practically the same results, where else can I search?

 

[Perry Babin]

Voltage on pin 16?

 

[boot35]

pin #16 0.028 volts

 

[Perry Babin]

Sorry, pin 18.

 

[boot35]

pin #18 7.62 volts

 

[Perry Babin]

Something must be pulling it up externally, unless you accidentally reinstalled the same IC.

 

[boot35]

nope, the ic used has the legs with tin solder, I was careful not to get confused.

 

[Perry Babin]

Find what's pulling it up.

 

[boot35]

sorry, I do not know what exactly I have to look for

 

[Perry Babin]

First, lift lead 18 and compare the voltage on the pad and on the lifted lead.