[RCM]

I have one of these (#165) I bought several years ago but haven't used it since about 2009. I recently op-checked it to make sure everything works because I wanted to sell it, and it wouldn't power up. I tried a couple sets of new batteries, I checked all the connections, I tried plugging it into AC power using the converter I have used with it many times before, and...nothing. The power light does not light up, and I thought maybe it was burned out or something but when I plugged in headphones...nothing. The unit looks new, I pulled the back cover off and the board looks perfect, so I have no idea where to even start. If anyone has any ideas what might be wrong with it and how to fix it, or can let me know who might be able to fix it since Larocco is out of the business (or at least he was a few years ago), please help a brutha out. If you want it as is, PM me. Thanks, Rod

 

[Pete7]

The only thing I could suggest is to try a different op-amp. Maybe the op-amp is dead, although I'm not sure if that would keep the unit from powering on. Unless it's the PRII MKII, which I believe the op-amp was soldered in (the AD744 in output bypass mode). I had the original model. It's a great amp- hope you can get it working.

 

[Pete7]

Also, Phil Larocco is at Triad Audio now- it was his design. Shoot him a PM. Maybe he'll take a look at it.

 

[RCM]

Thanks Pete...yeah, I shot a message to Triad yesterday evening so they might answer Monday.  The opamp (the one with 8 pins, right?) is removable so if that's the issue and Phil gets back to me it would be pretty simple.  Although right after I got it the batteries would not charge through the amp..I had to take them out and replace with fresh batteries.  The amp always sounded incredible, and looks brand new, so I hope I can fix it as I'd like to sell it.
 
Cheers,
Rod
 

 

[justin w.]

most of the time the LED is wired right after the power switch, so if that's not coming on its a clue that your issue is likely before there.  which could mean:
 
1) bad power switch (also unlikely)
2) a short somewhere, in which case you'd probably notice the batteries getting warm
3) bad connection between the batteries and switch
 
you should post pics

 

[RCM]

I've tried everything I can think of, and the board and all connections look perfect, so pics wouldn't help.  I'm hoping Phil will reply next week.
 

 

[kramer5150]

Quote:

I've tried everything I can think of, and the board and all connections look perfect, so pics wouldn't help.  I'm hoping Phil will reply next week.
 

bad assumption to make.
 
There are guys on this board who can practically draw up a schematic from detailed pictures (EDIT, maybe not here but in the DIY forum), or at the very least can help you trace power through the amp from the batteries.  That would be my next suggestion.  Well first meter the cells, second check for conductivity on the power input side.  Maybe pull the OP amps, clean them up a bit and re-seat.
 
Here are some poor www pics I was able to google.  Good Luck with the repair!!
 

 
 

 

 

[RCM]

OK, here's one of the top, and one of the bottom.
 
Hopefully the glare doesn't interfere, I can take more if necessary.
 
Thanks,
R