Powerbass XTA2250D

[caraudioguy2100]

I have the outputs they came in today .

I haven’t installed them yet .

I tested for rail voltages and get -83 volts but only get +71 volts .

Is this normal or do I have a problem somewhere ?

 

[Perry Babin]

Do you have the black probe on the secondary ground?

 

[caraudioguy2100]

Ok now I do and tail voltage is the same +- 83 volts

Do I have to discharge the rail caps like in some amps before installing the outputs ?

 

[Perry Babin]

I think there are bleeder resistors near the rail caps. Confirm that the voltage drops quickly after you remove power. If not, drain them manually.

 

[caraudioguy2100]

With the outputs installed the amp draws excessive current .

Here is a pic of the driverboard .

Is there something on the driverboard that usually goes bad ?

 

[Perry Babin]

There are a lot of things that can fail.

As with power supplies, it's important, when possible to check the drive signals before installing the FETs.

With every amp of this type, Q7, 11, 19 and 22 along the top of the board are suspect.

 

[caraudioguy2100]

I found the problem had a broken solder connection .

I will clamp everything down and test

 

[Perry Babin]

If you don't replace the transistors listed previously, you can expect the amp to come back.

 

[caraudioguy2100]

Amp powers up and ideals fine .

Relay engages but no output at all .

All regulators are working correctly I have +- 83 volts of rail .

Any ideas on where to check or is the driverboard still a likely suspect ?

 

[caraudioguy2100]

Anyone have a high resolution picture of this driverboard ?

Or know the values of
R45
R6
R22
R29

As you can see in the pics they are burnt .

 

[Perry Babin]

All 4 in that group are the same. If the remaining 2 are 470, all 4 are 470. On some boards, they use 270 for all 4.

 

[caraudioguy2100]

Ok thanks for the pic .

I should also replace all the smd transistors among the top of the board correct ?

 

[Perry Babin]

They have a very high failure rate. I don't remove the driver board to do work on it. I stand the amp on end and replace the parts.

 

[caraudioguy2100]

Do you have a picture of the entire driver board ?

It appears someone has worked on this before and wanna confirm the values are correct . Also I found another burnt resistor R24 near the bottom right of the board


It appears work has been done on this before and wanna confirm the values are correct .

 

[Perry Babin]

http://www.bcae1.com/temp/dwm1216classDdriverboard02img287x.jpg

 

[caraudioguy2100]

Thanks for the link .

I can’t quite make it but do you know the value of this resistor ?

 

[Perry Babin]

Did you click the image to go to full size? You can then ctrl-roll mouse wheel to zoom in further.

180 ohms.