Tweet
Hello All,
Joined the forum and looked around a lot. As with all forums, great members and tons of good info. I have an issue I'll probe the masses for. I have an old (board says 1990) GK mb150e 112 that I've used heavily for years, but it's been put away for about 2 years since I sold my bass. However bought a new Fender bass and broke it out (no pun intended). I noted immediately that the speaker surround was toast. Ordered new speaker (8ohm from GK - exact replacement). I replaced the speaker but noted lots of dust on the boards. Bought CRC and cleaned out the (then popping) pots on the front controls and sprayed everything down well to clean it up before putting everything back together. I deliberately let it dry for about an hour before I put it back together and plugged everything in correctly (took pictures to be sure). Plug it in, turn her on and the speaker goes to full excursion and I notice a burning smell. Turn everything off quickly and take her back apart to note the large resistors on the board are toast. I replace them and try again...same issue. I've gleaned from reading here that a shorted transistor is likely to blame. My question is how did I screw up a transistor? Maybe in taking it apart, I exposed a soon-to-fail transistor just because the amp is 24 years old? A long shot, I know...anyway.
#1. I'll research how to identify a blown transistor
#2. Did I not wait long enough and somehow short the transistor (thereby causing subsequent resistor failure (in series it seems)) with the CRC cleaner that hadn't dried?
#3. I'm reading to replace them in pairs, correct?
#4. I'm building a bulb tester/current limiter as depicted on here (thanks for that by the way).
#5. Does it matter if I use quick burning vs. slow burning fuses in the bussman fuses (8amp, 250v)?
Thank you all in advance for your expertise/experiences/suggestions!
-Dave
Joined the forum and looked around a lot. As with all forums, great members and tons of good info. I have an issue I'll probe the masses for. I have an old (board says 1990) GK mb150e 112 that I've used heavily for years, but it's been put away for about 2 years since I sold my bass. However bought a new Fender bass and broke it out (no pun intended). I noted immediately that the speaker surround was toast. Ordered new speaker (8ohm from GK - exact replacement). I replaced the speaker but noted lots of dust on the boards. Bought CRC and cleaned out the (then popping) pots on the front controls and sprayed everything down well to clean it up before putting everything back together. I deliberately let it dry for about an hour before I put it back together and plugged everything in correctly (took pictures to be sure). Plug it in, turn her on and the speaker goes to full excursion and I notice a burning smell. Turn everything off quickly and take her back apart to note the large resistors on the board are toast. I replace them and try again...same issue. I've gleaned from reading here that a shorted transistor is likely to blame. My question is how did I screw up a transistor? Maybe in taking it apart, I exposed a soon-to-fail transistor just because the amp is 24 years old? A long shot, I know...anyway.
#1. I'll research how to identify a blown transistor
#2. Did I not wait long enough and somehow short the transistor (thereby causing subsequent resistor failure (in series it seems)) with the CRC cleaner that hadn't dried?
#3. I'm reading to replace them in pairs, correct?
#4. I'm building a bulb tester/current limiter as depicted on here (thanks for that by the way).
#5. Does it matter if I use quick burning vs. slow burning fuses in the bussman fuses (8amp, 250v)?
Thank you all in advance for your expertise/experiences/suggestions!
-Dave
Mine is from 1990, based on the board I see.
Comment