Question about Marshall Amplification Marshall MG250DFX 100W Guitar Combo Amplifier

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Marshall MG 250dfx head gone bad need help thanks

Ok so it started that one speaker went out and i was like hmm then i didnt bother it sits in my room so i keep going then both went out i was like dang then I pulged my other head to the speakers to see if there were blown they work just fine. So i thought it was the input wear the guitar plugs in then i realize if that was it they would both have gone out so its the back speakers out i love this amp if someone could help me i would be forever in there debt thanks.

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Ok guys, read your your posts and i have to say that ive experienced the same symptoms with my dfx250mg. I am a bit of an an adventurer, so i decided to take apart the head and diagnose the issue myself, this is what i came up with. The sections R107 and R96 of the large circuit board have overheated (likely linked to the faulty cooling fan of this particular model). Anyways, i reconnected them temporarily and the problem subsided. Now to resolder and test the results.

Posted on Mar 01, 2010

  • maybeitscal Mar 04, 2010

    My solution was resoldering the two that cam lose, which i named above. Sounds like it did the day i brought it home


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Try checking for internal fuses mounted on the circuit board. Be very careful when taking them out and use a pencil or plastic tool of some sort to pop them out of their holders. Use only your right hand to retrieve the fuses. Absolutely make sure the amp is unplugged. Use the exact replacements for the fuses. If they blow again your problem is most likely a part in the output section named TDA7293. This is not something I would recommend you trying to replace yourself. If you have electronics experience with safety procedures, soldering skills and tools the schematic is here: Hope this helps.

Posted on Feb 04, 2010

  • Joshua Feb 09, 2011

    The marshall MG's and AVT amps all use the same TD7293 IC and the terrible cliff jacks. The inputs/outputs get gummed up or loose and start blowing fuses and sometimes even starts blowing the power ic's. I recently had to rework mine due to the exact same reason! Be very aware of the cliff jacks on these amps ... they even cause weird problems because they are used for the speaker output 1/4" as well.(the two or one 1/4" outputs on the back of amp that are usually red colored.)

    Good Luck!!!



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