Members Deadbeat Son Posted January 24, 2012 Members Share Posted January 24, 2012 I picked up a "Level 4" customer return Hot Rod Deluxe III from Musician's Friend hoping the issue would simply be a bad tube or blown fuse. Unfortunately, neither of those seem to be the issue with this amp. The power light doesn't turn on, and the tube heaters don't light up either. I think I have the problem tracked down to the power transformer. I show good voltage going into the trans, but I measure 0v coming out of it. What can cause a faulty transformer? If I buy a new one and install it, what are the chances the new one also blows due to downstream issues? Are bad power transformers even common? It seems like they should be rather robust. Thanks for the help! Link to comment Share on other sites More sharing options...
Members gspointer Posted January 24, 2012 Members Share Posted January 24, 2012 Is the pilot on the secondary? Link to comment Share on other sites More sharing options...
Members Deadbeat Son Posted January 24, 2012 Author Members Share Posted January 24, 2012 Is the pilot on the secondary? Please excuse my ignorance, as I'm not much of a tech, but I'll try to answer to the best of my ability. Also, I couldn't find a schematic for the series III, so I'm going solely off of the power of observation. I assume what I am referring to as the "power light" is what you are calling the "pilot." I believe it is powered off of one of the two sets of secondaries. I measured zero voltage coming from the secondaries as well. Also of note, my cheap-o DMM is acting a bit wonky, so I'm going to borrow a friend's Fluke today and verify all of my previous measurements. Link to comment Share on other sites More sharing options...
Members fly135 Posted January 24, 2012 Members Share Posted January 24, 2012 I had the PT go out on my Laney LC15 and replaced without fixing anything else. The whole story is a bit longer. First it had a blown fuse. In my normal bull in a china shop manner of fixing things I put tin foil on the fuse. Then the PS smoked... literally. However a new fuse and PT and nothing else suggested to me that the PS was already bad and blowing the fuse. The tin foil just allowed me to melt it further. Link to comment Share on other sites More sharing options...
Members Deadbeat Son Posted January 24, 2012 Author Members Share Posted January 24, 2012 Interesting; thanks for the info! Link to comment Share on other sites More sharing options...
Members Deadbeat Son Posted January 24, 2012 Author Members Share Posted January 24, 2012 Okay, so I'm officially a moron. I was measuring the output of the PT in VDC, hence the reason I was showing no output. When measuring VAC, I do get a positive reading. Back to square one; it looks like the PT is not likely the issue. Link to comment Share on other sites More sharing options...
Members gspointer Posted January 24, 2012 Members Share Posted January 24, 2012 You measured secondary voltages also? Link to comment Share on other sites More sharing options...
Members Deadbeat Son Posted January 24, 2012 Author Members Share Posted January 24, 2012 Yes. Turned out to be the fuse on the pcb subassembly the 6L6s are attached to. I thought I verified the fuse with a DMM, but I must have touched my lead to an incorrect solder joint on the back of the board. I installed a new fuse, and the amp fired right up with no issues. The HRD isnt my favorite amp, but at $282 plus a $1 fuse, it's worth it! Link to comment Share on other sites More sharing options...
Members Deadbeat Son Posted January 24, 2012 Author Members Share Posted January 24, 2012 Hmmm...I switched the amp back to standby after playing it for an hour or so, and the fuse blew again. I'm going to have to investigate more later tonight. I'll try all new tubes and see what happens. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.