I have tested sound out of the Pre Out port and it is clean, and plugged the speakers into another amp to find that they are not blown. The sound out of the amp in total whether on the clean or distorted channel sounds like it's cutting out nearly to a distortion tone. I also swept all of the pots to see if any of them broke up more or cleared up the sound, but none did. Adding some detail: I am an electrical diagnostic specialist in automotive applications, have experience in circuit board soldering, and have a schematic of the board I'm looking at. I may not be fully read in on circuit board component testing, but I am good at troubleshooting and following direction. I'm asking for help with ideas of common failures to this model, or some guidance in the next diagnostic steps to figure it out.
It does indeed sound like the power amp section. Contact the manufacturers customer service department for the schematic. Then trace it back to the problem. If you do not know how to do this, you're best taking it to a repair shop. If you poke around inside with out knowing what you're doing you can fry something or get a nasty shock.
SOURCE: fender M-80 electric Guitar Amp.
You might have a ground problem. Does it do it in different outlets or when you take it to someone else's house? One easy solution to ground problems can be running a three prong to two prong adapter on the power cable. Give that a try and see if it helps.
SOURCE: no clean tone
Look for bad electrolytic caps in the bypass caps for the power to the preamp stages.
Testimonial: "Thanks, we dont have the means to check them but after swopping them out it sounds a lot cleaner Brian"
SOURCE: Fender Concert II preamp is faint and distorted on 2 channel
It sounds like a job for a technician. There are high voltages in the chasis and the potential for a serious shock to the unwary.
That said, I can suggest several possibilities.
First, make sure the controls aren't causing the problem. Contacts can build up dirt and oxides and block the signal. Try twiddling the controls and see if the problem comes and goes, or if you hear scratchy noises. If symptoms are found, buy a contact cleaner spray, take out the chasis after unplugging and letting it set for an hour, being very careful not to touch any exposed conductors inside. You'll see some holes in the control bodies; squirt cleaner for 2-5 seconds and work the controls.
Also see if the problem happens without the footswitch, and try the channel switches several times - same problem, dirt and oxidation.
Other possibilities - cathode bypass capacitors drying up, and it looks like the amp uses some opto-couplers at various stages.
SOURCE: My hot rod deluxe has internal distortion problems.
There are many components in the system. Electrolytic capacitors are most suspect. C49, C50, C45, C51
There are many others but these are top suspects. You MAY be able to detect a change by cooling these components with circuit cooler spray.
ALSO check the +/- 16 volt power sources in the unit.
Testimonial: "I haven't fixed the problem yet, there is more to it now that I have pinpointed the general problem, but he was right on the mark."
SOURCE: The pre amp out and
No, when you plug into the power amp in that disconnects the feed-through of the preamp.
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