DB Drive WDX3k

[Deadly Sones]

DB Drive WDX3K has a nasty turn on pop. And a slight turn off pop. When amp came in, it had shorted outputs, damaged drivers. The gain was full blast and the lpf was all the way down, lol. Not sure if the cranked gain might have damaged something else.. it's running fine aside from the turn on/off pop. is there something I can do to make it fix the problem or make it better? Owner said it did it before the repair... but ya... it's a nasty startup pop.

 

[Perry Babin]

Does the mute pin stay high for a few seconds on startup then drop to 0v?

 

[Deadly Sones]

Good afternoon Perry. I assume it must be one of these transistors on the output card... or maybe over here? I haven't worked on one of these before. I'm not certain which one is the mute transistor. Is there an easy way to trace to it?

 

[Perry Babin]

A close diagram is in the repair_tutorial\miscellaneousstuff\sinuslive folder

Q21 in that diagram has failed in some amps.

Generic Class D - Type 4 of the tutorial covers these amps.

 

[Deadly Sones]

Awesome, I shall check it out. Thanks!!

 

[Deadly Sones]

Ok... I replaced Q21... and it still makes pop noise. I have the following readings on Q21. "2T" transistor. base = 12.86v, collector = 0.017v and emitter = 13.08v referenced to the main ground, while amp is playing. Unless it's not the mute transistor. He's on his way to pick it up, says he doesn't care about the thump... I'm just trying to get it better before he gets here,

I'll have to look over the schematic.

 

[Perry Babin]

Is the mute voltage at the driver board going from 12v to 0v on startup?

 

[Deadly Sones]

The output driver board?

 

[Deadly Sones]

OK, so pin 3 of the output card has nothing at first... when I add remote, it climbs to about 0.03v for a couple seconds, then goes to ground.

 

[Perry Babin]

That's the problem. If you see this again, determine why the voltage isn't going from 12v to ground. The circuit is fairly simple. The equivalent of Q21 (if the circuit isn't identical) pulls high and then turns off which allows a resistor to pull the mute pin low and enable audio.

 

[Deadly Sones]

OK, ya, I seen that in the demos. I'm going to try and trace that pin 3 back to somewhere and see if I can figure this out before he gets here. Good thing about SMD stuff, can easily work without needing to remove it from the case.

 

[Deadly Sones]

Unfortunately this amp is now gone... but he tells me it has been doing this since new. I told him if it ever needs to come back or he gets tired of it, I'll figure it out next time. Thanks again Perry.

 

[Uven]

Guys, anyone have the schematics for this amp? Mine is also WDX 3k but I installed in reversed polarity and now amp turns on but stuck in protect mode. Please help!

 

[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.

 

[Uven]

Oops my bad.. 😅