Bypassing "fancy" switching supply

[Ptron]

I realize this is kind of a lame question, as there's little chance anyone would know the answer for sure, but maybe someone's got some vague ideas on the subject. I've got a Klipsch promedia system surround thingy for computer audio. It's got sort of a unique power supply by BASH Audio which I gather uses not only switching, but a "dynamic output regulator" (my term, not theirs) that keeps the voltage rails just a couple volts above what the power amps need at any given instant.

The power supply was burned out on the one I have. Apparently this is fairly common for this amp as certain parts are underrated. Anyway, after replacing all the burnt out parts, the supply seems to be working up to the "dynamic output regulator" whether the special BASH chip that controls this is dead, or it's not getting the proper feedback from the power amps, or whatever, I don't know. I'm unlikely to find out either as support in the form of service manuals or replacement parts is unavailable.

I'm thinking of seeing what happens if I bypass the “DOR” and just feed the amps with the constant 52V supply. I realize the power amps as well as the power supply could be in danger of overheating due to the extra dissipation but is there any other reason not to try this? I guess at this point I'm down to last resorts anyway so it doesn't matter that much.

[Steve Conner]

Well, if I were a commercial electronic designer (and I am) I'd only bother with the DOR circuit to let me use much smaller/cheaper output devices and heatsinks. It's not like it improves the sound or anything: its only purpose is to reduce dissipation. So I imagine if you bypassed it, the output stages would self-destruct sooner or later.

So if you're going to bypass the DOR stage, it would probably be wise to turn down the main rail voltage from 52V to 35V or whatever. That should be easy with a switching power supply, there will be some feedback resistor somewhere that you just need to fiddle.

*edit* I spotted the BASH amp part of one of these things on fleabay:
link

Maybe the BASH chip will not be burnt out on that one :|

[Ptron]

Originally Posted by Steve Conner

*edit* I spotted the BASH amp part of one of these things on fleabay:
link

Maybe the BASH chip will not be burnt out on that one :|

Cool! Thanks for the heads up. I missed that when I looked before. I'm fixing this thing as a favor, and really, it's not even worth the effort I've already put in but now it's kind of a personal mission to see if I can make it work. I can be a little OCD that way. [Haggard smile emoticon]