| Author | Message | ||
     William Nexson (nexsen) Username: nexsen Registered: 08-2006 |
The amp was workling well until it made a kind of "chirp". After that, everything is massively distorted and very low volume. Insides look-no obvious burned or overheated components, solder joints look good. The big 100ufd caps are oozing but not blown out. I plan to replace the electrolytics, the 2 150K 2watt resistors on the caps, and maybe the 2 driver transistors. Any thoughts? | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
That would be as good a start as anywhere. I assume you looked and both power tubes are still lit. Almost sounds like it's got one dead one or should I say one in runnaway. Don't have that schem handy but that's a good start. | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
Also, forgot to mention that you should replace the electrolytic cap on the bias supply side, I think it's c25. I can't read it very well but it looks like a 20mf cap, if that's the version that you have. I think the other one says like a 10mF and is c32. I can't read the schematics very well without my glasses(or even with them sometimes!) I assume that you have isolated whether or not it's in the final or preamp-tried both the high gain inputs and the normal-oh damn, the early ones look like single preamp-input stages. Ok, I'd also check and make sure that your 16v drivers are supplied with the proper voltage. Check for the 16 output at the junction of c26 and d15. Also make sure you have -16 voltae at the junction of d16 and c27. This is your SS voltage source. You also need to identify which amp thet you have, gd-1 or gd-2. They are drastically different. ! uses 6l6's , the other el34/6ca7's. THen we'll try to go further. | ||
| William Nexson (nexsen) Username: nexsen Registered: 08-2006 |
Thanks Mike. I have the 6L6 version. I ordered parts last week and included the bias supply caps. Parts should be here Monday or Tuesday; I'll check voltages when I have the new parts in and report back. |