Behringer DX3216 help needed

[3rddawn]

Just bought this secondhand, was assured that "it has only crashed once, a long time ago".

Left it on for a couple of hours to test that it was going to be ok to use live, it froze. When I turned it off and on again it was the same.
I left it off for a couple of hours, turned it on again and it was fine, fully functional.

Left it on for a few hours again, had frozen again. This time, no amount of waiting makes a difference.
On switch on, I get alternate lights on all the sections, LCD can be black, stripey or clear (different when switched off and then on again, at random).



I've taken out the power supply and tested all the voltages at each of the pins with a voltmeter, they all seem ok.

Close inspection shows that the PSU looks ok - there's only one suspicious looking capacitor (slightly domed on top, little mark in the middle - see photograph).



Any ideas what to try next?

Thanks
3rddawn

[Jazz P Bass]

That capacitor does look a little bit "domed".
Can you push down on it? (the cap)
If it moves back down, then that is possibly a bad cap. (hydrogen gas venting)
Not having the power supply schematic, I do not know the function of that particular cap.
Did you try testing the power rails with the unit hooked up?
If not, that is a good place to start.

[Steve Conner]

This is a DDX3216, right? Not a DX3216.

We had a big repair thread on these things a while back. There are several known faults. Use the search function to look for DDX3216.

[3rddawn]

Steve: Sorry that was my typo - it is DDX3216. I've read and reread all the threads before posting above. They don't seem to relate to my problem.

Jazz: Having found all the power rails seemed in order with no load, having hooked the PSU back up and tested it again, now I'm showing no lights or display or anything. The 8, 17, 48V all seem ok, but the 5V pretty consistently show 72mV across the connectors and the 3.3V ones are showing nothing.

I can do soldering etc, but just don't know enough about electronic circuits to know what to change.

The schematics of the PSU are available on the repair thread Steve mentioned. I'd repost but I've tried 4 times and my PC (in 2 different browsers) has decided to crash every time ... sorry!

Thanks for any help anyone can give.

Cheers
Lawrence

[diydidi]

Lawrence,
Almost certainly that capacitor!!!

[Steve Conner]

I agree, the capacitor looks like a sick puppy! I just saw it now, wasn't able to load the pictures before (my own fault, not the forum)

You might as well replace all of the big electrolytics.

[jrfrond]

That's a bad cap, and for the record, you should just recap the entire supply, using good caps e.g. Panasonic or Nichicon in 105°C temperature rating. You will need to physically measure the existing caps and compare them to the catalog measurements because they are a somewhat tight fit.