Basic electronics guy looking at a few poorly functioning DBX single-rack-space units...

[Roboburger]

Are these generally repairable by the intermediate DIY'er? Is there a good source for Service Manuals- I'm scared to death to click on any website littered with "CLICK HERE! NOW! TO DOWNLOAD!" adverts.

I have two (166A, 266XL) that work in stereo, but CH2 won't do squat in Dual Mono. My instinct would be that that is fixable. Is this common? Any Advice for or against?

Thanks!

 

[dmp]

You can check if the schematic is in the tech docs section here at the forum, if not find it on the web somewhere.

Stereo/dual mono works by linking the sidechains together. A mechanical part will often be the first place to look when something is not working.
However, a switch usually fails open, not closed, so stereo link is probably working fine. When the stereo link is disabled, both channels need to receive RMS_IN signals. The problem is that one of the channels (CH2) is not receiving a RMS_IN when stereo link is defeated. These RMS signals look like they pass through insert jacks on the back and the jack may be failing to short when no plug is connected. Check if the jacks are passing the signal when nothing is plugged in.

 

[Script]

Those units are SMD, right? Not thru-hole, I think.

If other than mechanical failure (jack or switch), while probably fixable, in principle, maybe two reasons against it:

(1) SMD is somewhat tedious to work with and not all component values are easily identifiable
(2) those two units are rather cheap in comparison, even so when still fully functional ( used or unused)

Two reasons for it:
- you want to learn how to fix SMD stuff at a component level (and I think these units are)
- with these cheap units there is not much to lose if you mess up...

...but then again, being cheap units, there is also not much to gain really.

Personally I'd pass and save me the time and money. Or maybe pick up a broken 166 black face (cos thru hole).

 

[Roboburger]

great places to start! Thanks all.