EE Minimax DAC repair

Thanks Mofi,

I pulled out the chips to inspect, then made sure they were seated correctly, but no dice - I still can't get the unit to power up.

Bill had no other suggestions, either. I was hoping someone here might have more info (I think Bolder had some options for this unit at one point) or know someone who could fix....

NJS and Morganc - thanks for the input...

Both original OpAmps and proposed, regardless of position / orientation, do not change the outcome - unit no longer powers up.

I'm assuming this is a power thing, but can't rule out the board - anyone have wiring diagrams, specs, or similar for these?

Thanks

Hello Douglas, Al, and Mofi,

Thanks for your time and energy.

Although I recall seeing the "squares" on the NE corners of the OpAmps after initial inspection, I can no longer rule out the unlikely. I have no illumination from within the unit - board, diodes, or otherwise - so if we assume one or more of the OpAmps were installed incorrectly, what is the likelihood that the entire unit, as opposed to simply the OpAmps, is salvagable (vs replaced)?

I realize more trial and error might be necessary to answer this, but my time to do so grows short (honey-dos, kids, etc.). Is there a qualified technician / repair shop that might be able to further diagnose / fix this - I have been unable to locate one?

Cheers.

Hello again Al, Douglas,

Al -

No LED light. I tinkered a bit more and found that there is power coming to the board, but nothing after that (unable to trace circuits beyond taps to see where problem is). It's beginning to look like a paperweight....

Douglas -

I contacted Bill a few weeks ago about this and asked if he knew of any repair technicians that might be able to help / fix. His first response was to check power line and fuse, which I told him were fine. He then asked which OpAmps, I responded, and on his third email he stated

"...It is really hard to tell what was messed up when folks tinker with the innards of the DAC. It seems unusual that it won't even fire up. maybe a short in the power supply somewhere. Sorry I can't be of more help."

So regardless of the problem, it seems there is no one available to fix this unit, which is unfortunate. It looks like I won't be able to try those discrete Opamps you speak of.

Thank you.

Hello Al and Bill,

Al -

Thanks for your optimism. At this point I think I'm going to shelve the project, perhaps attack with new vigor at some point in the future. I've already spend quite a bit of time trying to figure this out and it's probably best to take a break and put some energy into other things.

Bill -

Thanks for your offer. Since it sounds like buying new is more practical than trying to fix (if possible) we then venture into "which one do I want" territory. I think there can be a case for this unit, the DAC Plus, or a number of other units (Metrum seems to be getting some A'Gon press). The problem for me is that my "discretionary spending" is not what is was a few years ago, and my original hope with the Opamp upgrade was to tie me over until things change (financially), then see what's on the market.

Perhaps we can speak again in a few months?

Thanks to all.