[orpheus]

The left channel on my system started distorting today.  I swapped cables around and checked offset,  and found my Chime (self built from kit) was the source.  I changed the tubes (luckily I have a few sets thanks to a friend loaning me some tubes to try) and it didn't fix the problem. 

I popped it open (hadn't done that since I got it working 3 or so years ago) and thought that resoldering might help.  On opening, I noticed there was some yellowing (perhaps flux I didn't clean well before) around some of the resistor joints and on the tube sockets.   I went through the board (only the analog board) and reflowed the solder points, paying particular attention to the tube sockets.  I cleaned the board with 99% rubbing alcohol, and reassembled. 

When I powered it back on, only the back LED lit, and did go from red to green.  There was also a little bit of smoke.  I quickly turned it off and waited for a few hours.  I thought that the smoke might have been the alcohol, perhaps it hadn't completely dried when I powered up.  I also smelled around the board, and couldn't get a real burnt part smell, and didn't see any burnt resistors or caps.  When I powered it again, the same thing, power LED lights, the others don't, but this time there is no smoke.  I pulled the bottom off and tried applying power again and measured.  The 295 volts and 305 volts check points were OK, but the 8 volt + and - were measuring around .2 volts.  This means that I need to replace the 8 volt regulators. 

Are there any other parts I should replace while I am ordering?  None of the resistors or caps have any sign of damage.  Should I replace the Q components while I am at it, or would that be overkill? 

Could the initial problem of distortion be caused by the 8 volt regulators going bad?  If not, what might have caused that problem?  I would be happy to order a slew of parts as long as they might be the culprits.  I think I'm going to get a new set of all of the regulators and the Q parts, just in case they are the problem.  Anything else I should order just in case?

Thank you so much for your time and help.

Aaron.

[orpheus]

I decided not to wait for responses and ordered new parts from Mouser and Digikey.  I'm going to try replacing the regulators (starting with the 8 volt + and -) and go from there if it doesn't work.  Luckily the parts are not expensive.  It feels good to be able to repair something that I built instead of having to try to track down a service manual and the part numbers.  It will also be nice to desolder from such a sturdy well built board.  I've had to work with weak one sided circuit boards recently, and they can be a real pain to desolder from.

If anyone has any suggestions as to what could have made the left channel distort (mostly in the higher frequencies), I would love to hear them.  In the meantime, I'll replace the regulators and hope that fixes everything.

Aaron.

[hagtech]

Sounds like a short circuit somewhere.  Maybe blown electrolytic cap?  It is probably not the regulators.  Maybe the low voltage power transformer?

jh

[orpheus]

Sorry that it took me so long to reply, I forgot to thank you for responding to my post.  I had ordered replacement regulators before you responded.  When they arrived I popped the hood on my Chime and decided to reheat some of the joints again, particularly in the circuit of the 8 volt regulators.  When I tested it after reheating joints, the voltage was back, and the audible problem is no more.

Thank you again for your suggestions about the fix for my problem.  I have learned over different builds and repairs to step back and look for the simplest solution, because I often jump to blame the active parts instead of capacitors (which in consumer goods fail often, but in builds we use much better caps) and soldering.

I'm happy to have my Chime up and running again.  Thank you for sharing your design with the DIY community. 

Best,
Aaron.