MTX Thunder 1501D

[Jason Smith 616]

Amp piowers up and idles fine

I get + - 78 volts of rail and + - 15 volts on all op amps

Amp will not produce output..

Anyone have any ideas?

 

[Perry Babin]

Does it have rail-rail oscillation on the output transistors?

 

[Jason Smith 616]

No ..

All outputs test good but I noticed I have 2.88 volts measured directly arcoss the output terminals .. the voltage pulses from 2.88 down to 2.70 then back up to 2.88 and cycles like this

 

[Perry Babin]

Just to confirm, this is the old model and not the newer thunder elite. Correct?

 

[Jason Smith 616]

Yes

 

[Perry Babin]

Measure the voltage across pins 5 and 8 of the 3120 opto-couplers. Post the voltages. Don't let the probes slip.

 

[Jason Smith 616]

16.95

20.12

 

[Perry Babin]

Is LED238 lighting up?

 

[Jason Smith 616]

Yes

 

[Perry Babin]

Does it remain on after initially lighting up?

Is there DC across the speaker terminals before the LED is lit?

 

[BumpinYota]

I have the same problem as Jason Smith with the exact same type amp, however led 238 is NOT illuminating and my voltages on the octo-couplers are way off. One has no significant voltage on any pins and the one closest to the physical edge of the amp has negative rail on both pins 5 and 8

 

[Perry Babin]

Please don't post in a repair thread that was started by someone else unless you are trying to help them.

Start a new thread if you need help with a repair of your own.