| Author | Message | ||
     Robert Templeton (rtempleton) Username: rtempleton Registered: 10-2013 |
I have a 112 RD 65 GD-2,6CA7 board. I've only got sound out of the distortion side. The footswitch seems to be working but no sound from the clean channel. I tried replacing the MC14053B switch and the MC14016B but neither worked. Can't see any broken contacts anywhere. Any suggestions? Thanks, Robert. | ||
| Lars Verholt (lmv) Username: lmv Registered: 11-2009 |
Hi Robert, if you have a 'scope it's of course relatively simple to trace the signal and see where it disappears. Since you have sound in distortion mode, we can assume that IC-2 works. This leaves us C-18 as a likely culprit - or possibly a bad connection to/from the gain control for the clean channel. Another place to look is around the volume controls. You can try swapping the middle wire (wiper) between the two pots and see if you get sound. If so, you should look closer at the clean channel volume control. Good luck! -Lars Verholt | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
In addition to what Lars said, if you DON'T have a scope and DO have a spare amp, you can build yourself an audio proble from a .1mF 6oov cap, a 1 meg pot and and old probe and go in and LISTEN to where it goes poof. I think I posted a pic of it here somewhere. Mike. | ||
| Lars Verholt (lmv) Username: lmv Registered: 11-2009 |
Good point, Mike. Even a DVM on the AC setting can help you greatly if you are able to feed a constant signal to the amp (e.g. a tone generator). If you don't have that, you can use a computer and generate a suitable test tone here http://www.audiocheck.net/audiofrequency signalgenerator_sinetone.php Cheers, Lars Verholt | ||
| Ian Azrikan (inertian) Username: inertian Registered: 10-2013 |
I built the probe that Bill M. describes in detail here: http://billmaudio.com/wp/?page_id=1254. It's come in very handy a number of times. In fact, it took me longer to build the probe than it took to troubleshoot my first amp problem with it! I use a tone generator app (TestTone) on my Droid phone and plug into a battery powered small amp to monitor the signal. |