Members Dr. Tweedbucket Posted September 29, 2017 Members Share Posted September 29, 2017 It seems to be a common thing with these cheap but good sounding practice maps. Does anyone have info on what fries on these and how to fix them? Basically, no output, tubes are all good. Slight output from the line jack. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted October 2, 2017 Members Share Posted October 2, 2017 The first few things I'd have you try is see if you get a signal from the line out by plugging that into another amp. That will tell you if the preamp is working or not. Don't think it has an effects loop so you cant test the power amp in a similar manor. The only thing you can do is try replacing the power tubes and inverter to see if that brings it back. The amp is rated for 8 ohms. Hopefully your weren't running higher impedance which tend to make tubes go bad prematurely. The rest of the amp is solid state. This amp is a hybrid so the biggest danger to the low voltage, low temp solid state components when you stick them in a small cab with tubes cooking away. If you don't have good ventilation to allow the power tubes to vent the silicone chips mounted on the PCB are going to heat up and fail. I have a music man head which is a Hybrid. I always worry abut such failures but the heads are actually designed quite well. The head doesn't use IC's, it uses ceramic coated transistors which are designed for high temps. They are also plugged into sockets and stand a half inch above the board which reduces direct heat transfer so they run cooler. The tube sockets on the Fender are mounted to the PCB's which are another thing I dislike. You heat a fiberglass board long enough and it turns black around the sockets as it carbonizes, then it becomes conductive and shorts out the high voltage. I've seen boards so badly cooked, I had to make new ones in order to get the amp working again. You cant be chassis mount tubes when it comes to tube amps. Once you start sticking tubes on a PCB the amp has no chance of lasting long term. Link to comment Share on other sites More sharing options...
Members Cornholio Farquarth III Posted October 14, 2017 Members Share Posted October 14, 2017 Heat buildup in the enclosure could be a likely culprit causing a short life for the solid state components. That and some of the SS components may not have adequate heat sinks. Link to comment Share on other sites More sharing options...
Moderators daddymack Posted October 14, 2017 Moderators Share Posted October 14, 2017 I had a 1W 100ohm resistor burn out on mine. Fixed it...and it was working great for a while, then some thing else failed...been too busy to open it up and look...not like I don't have enough amps here Link to comment Share on other sites More sharing options...
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