DHD NTX-3105

S Merlington · 2012-07-06 2:08 am

Amp powers up but no output..

Amp is producing both + _ rail voltages and both + - regulated voltages but still no output..

Any suggestions ?

Perry Babin · 2012-07-06 2:35 am

Post a photo of the inside of the amp.

S Merlington · 2012-07-06 2:51 am

Heres a couple of pics let me know if you need more

Perry Babin · 2012-07-06 4:10 am

Have you operated all switches and potentiometers through their entire range to see if the audio ever played through normally?

If it did not, remove QM1 to see if that allows that channel to produce audio.

S Merlington · 2012-07-06 4:20 am

I cleaned all switches with contact cleaner and amp never produced audio

If i remove QM1 I get clean audio from left channel

Perry Babin · 2012-07-06 5:31 am

You'll need to follow the circuit back from pin 3 of that transistor to see what's driving it.

S Merlington · 2012-07-06 8:55 pm

Its being driven by QP6 an C2316 transistor.. Is there a good sub for that ?

Perry Babin · 2012-07-06 9:02 pm

The problem may be farther back in the circuit. Did you check the transistor to determine if it was defective?

If it's not defective, you'll have to follow the circuit back from the base of QP6 to see what drives it.

While you have it out of the circuit, reinstall QM1 to see if both channels will produce clean audio.

S Merlington · 2012-07-06 10:01 pm

If i remove QP6 and reinstall QM1 the amp doesnt produce audio..

QP6 tested fine out of circuit..

So I need to follow it back further ?

Perry Babin · 2012-07-06 10:06 pm

Post the highest resolution photo that you can of the area shown in the photo below.

S Merlington · 2012-07-07 2:48 am

Here are a couple of pics showing that area of the board

Perry Babin · 2012-07-07 6:51 am

Reinstall QP6 and remove QP7. Does the amp produce audio?

What's the part number on QP7?

S Merlington · 2012-07-07 2:41 pm

QP7 is a C3200

If i reinstall QP6 and take QP7 out te amp still doesnt produce audio

Perry Babin · 2012-07-07 8:48 pm

Post a photo of the bottom of the board in that same area. When you take the photo, angle the board a bit so that you don't get the flare from the flash. The bottom of the basic repair page has suggestions for getting good photos.

S Merlington · 2012-07-07 9:39 pm

1st pic is around the area of the board you requested..

2nd pic is where QM1 and QM2 sit i marked them in the pic

Perry Babin · 2012-07-07 9:52 pm

What is the part number on QM1?

What is the DC voltage on QM1 with the black probe on leg 1 and the red probe on leg 3?

S Merlington · 2012-07-07 9:58 pm

QM1 is a C343

Voltage is 1.79

Perry Babin · 2012-07-09 1:31 am

If you desolder one leg of RP34 does the amp produce audio?

DHD NTX-3105

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