Phono Pre-Amp stopped working out of no where

I had a Pro-Ject Tubebox DS phono pre-amp I bought new. Worked fine, I probably used it less than 20 hours. I upgraded my amp and so I sold this pre-amp on eBay (mistake). It was in mint condition.

The seller received it, said he was a musician and claimed it didn't work at all. He sent it back and in deed it doesn't work at all now.

  • It powers up, the light is on and everything but neither channel is putting out any sound what so ever. I even tried a different power cable and no luck.
  • I checked the jumpers on the back, they seem fine and set according to spec.
  • I plugged my turntable directly into my amp, it works. I plugged another device into the unbalance line in the amp and it works. So it's not my turntable or that input channel on my integrated amp.
  • I removed the top shields on the tubes of the pre-amp, and the tubes look like they're in solid. I tried taking them out but they're rather difficult so I was nervous about pull them out.
  • The shipping box and inside box are all pristine. No dents or anything. No water damage. The unit itself seems perfect too cosmetically.
Any ideas or thoughts on what could have gone wrong? Did the buyer plug this in to a live channel and blow something? Could the tube be loose? Do you think this could be easily fixed?

I'm a bit frustrated as this was a like-new amp and this seller now is claiming I tried cheating him and I'm stuck with a broken $400 phono-preamp. I'd love to pass it along to someone else to enjoy.

These things can take quite a beating in shipping. I think you should at least try replacing the tubes.

Ultimately, unless you are handy with these things, the $75 fee to have it professionally checked out is probably worth it if you find it is not simply bad tubes.
Your in an audio world of hurt as the buyer is usually right.You should give him his money back.Good luck!!
Post removed 
Thanks everyone.

  • The tubes do light up. Soft orange glow.
  • Yeah, even though the box doesn't have any dents, I wonder if there was just crazy shaking that may have broke something? But the original packaging had foam all around it and I had an outer box around that.
  • The buyer filed a case with eBay and I refunded him. I'm not sure what happened, he may have received it not working.
  • elizabeth, I was suspect that too, I checked the serial number and it's the same as the one I shipped. And I'm not sure I can imagine someone sitting on a broken Tubebox DS in mint cosmetic condition waiting to make this swap scam. But I did think about this as well.
  • Appreciate the link. Yeah, I wonder if the buyer plugged this into a live powered line and it zapped the pre amp. Even still, I can't believe a pre-amp would break that easily.
The Tubebox DS feel pretty solidly built so I'm just surprised shaking from shipping or a "zap" or power surge would break it. (The latter I realize to do more with circuitry and surge protector.)

This is why we can't have nice things! :)


Could have loosened a solder joint? Just a guess. Can you open it up and check? Is there a fuse in power supply?
I think the front end got fried by his connecting the inputs to a line level source. Preamps can be permanently damaged this way. You need to have it repaired if you care about capturing any of the value of it in the future. See if you can get the buyer to describe exactly how he hooked it up. If he is honest, he will reveal the error. In any case, swap out those tubes for fresh ones!
“I think the front end got fried by his connecting the inputs to a line level source”

You mean like plugging a CD player into a phone preamp? Interesting. Must take a real knucklehead to even try something like that.
Or, one of those tables that has a built in preamp which wasn't bypassed or switched out, let the stylus fall on the record...I can envision that easily.
Post removed