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     Eric Kissinger (eric1152) Username: eric1152 Registered: 10-2013 |
I have a HD-130 bass amp with a separate MM 2-12 cabinet which I bought new in early 1974. At tech's right now but the serial is A000357. It has been my main amp to play bass on all these years with some tube replacements a few times. I did use a Kustom cabinet with 2 early SRO 15s for a good time also. About a year ago while playing the chassis started to really heat up, so hot you couldn't touch it and smelt like wood was burning. I took it out of the case and saw some very large resistors coming off the tube sockets were blown...cooked. I took it to a very good tech friend who restores fender amps. He put all new caps, tubes and checked it all out fixing anything that need be. The amp worked great again...like new! But 3 months down the line It overheated like it did before but I shut it off before any damage was done. Tech then put new tube sockets in, checked the bias, switched out tubes, given it his best shot but the chassis still heats up. Is there any hope for my old friend or is it just the way it goes with an almost 40 year old amps? }} | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
You need t isolate WHERE the heat is coming from. Heat usually means arcing or bad tubes. You have replaced the tubes so let's look at the common causes. Does the amp "light up" the power tubes-meaning do they get red? That amp has conventional bias control and a 12ax7 PI so the bias COULD be letting the tubes run away. If your friend is setting up the amp "like a fender", the bias may be way over the top. Also, those amps had a problem with the driver tubes going bad and cranking things up. I'm not saying that is it but but is something to look at. I would check/replace the driver, bias PROPERLY, and also re-tension the power tube sockets. If you say the resistors on the sockets themselves were burned up, maybe the sockets are arcing. Just some things to look at first. Also, It IS possible that the PT is arcing inside developing heat but taht's where determining WHERE the heat is coming from is the first step. You are probably going to have to play the amp out of the case and see what gets hot first. Mike. |