help repairing a RF T5001bd

[Perry Babin]

What is the DC voltage on the following transistors?

Place the black meter probe on the amplifier's ground terminal. Place the red meter probe on the point where you need to measure the voltage.The amp will need to be powered up. Insert a 10 amp fuse in the B+ line and have all transistors tightly clamped to the heatsink.

Q207
Leg 1:
Leg 2:
Leg 3:

Q212
Leg 1:
Leg 2:
Leg 3:

Q208
Leg 1:
Leg 2:
Leg 3:

Q214
Leg 1:
Leg 2:
Leg 3:

 

[Flashpoint GSX]

I'll get started on that now. Should I measure these voltages in the few seconds before the protect LED turns on, or does it even matter?

 

[Flashpoint GSX]

Here's what I got:

Q207
Leg 1: 4.8
Leg 2: 24.7
Leg 3: 0

Q212
Leg 1: 4.7
Leg 2: 24.6
Leg 3: 0

Q208
Leg 1: -25.7
Leg 2: 0
Leg 3: -30.7

Q214
Leg 1: -27.2
Leg 2: 0
Leg 3: -30.5

I held the lead on each leg until the voltage was pretty steady, which took a few seconds. But the protect LED didn't come on.

 

[Perry Babin]

Those voltages are about what I'd expect. It appears that the drivers survived.

Do you have an oscilloscope or any way to trace an audio signal?

Do you have a test tone DC or a sine wave generator?

Do you have approximately ±15 on the power supply pins of U103?

Do you have approximately ±6 on the power supply pins of U203?

 

[Flashpoint GSX]

I do not have an O-scope unfortunately, although I can probably use one at school if I have to.

By test tone DC, did you mean CD? Because I do have a test tone CD.

I'll check those voltages tonight.

Thanks for sticking with me on this 🙂

 

[Perry Babin]

Test tone DC? One day I'll learn to type.

Yes. Test tone CD.

You may be able to trace the signal with a multimeter but it's not as good as a scope and can be misleading.

 

[Flashpoint GSX]

The power supply pin is the top left, correct? pin #8?

Assuming so, I got 12.9V on U103 and 5.7V on U203. My power supply voltage is about 12.5.

 

[Perry Babin]

Pins 4 and 8 are power supply pins. Measure the voltage on both of them.

 

[trininadimpro]

problem encountered

i have T30001db amp an the startup IC has failedis there any parts available for this model amp i am from trinidad.
thanks for the help

 

[Perry Babin]

The ICs (UC3526ADW?) are readily available but you'll have to find a distributor that will ship to Trinidad.

 

[trininadimpro]

thanks

thanks very much for the help.. have u experienced any other trouble with this model of amps?? the 1 that the startup ic blow pulls the speaker inwards......strange i knw let me knw if u have any thing to add about this stuff

 

[Perry Babin]

If the speaker terminals have DC on them (causing the speaker cone to be forced from its point of rest), the amp probably has shorted output transistors (and the SG3526 is likely in good working order). Have you tested the output transistors to see if any are shorted?