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Guitar amp problem

  • 25-08-2010 11:53pm
    #1
    Darkglasses
    Registered Users, Registered Users 2 Posts: 14,526 ✭✭✭✭


    Hi all, guitar amp trouble! I'd appreciate any suggestions! :)

    Last week I was playing through it, all going fine, then kinda slowly the sound dropped in volume and the distortion started disappearing. Then there was a kinda farting noise for about 10 seconds, and then the sound died all together. It still switches on and the lights come on and everything, but there's no way of getting any sound out of it. Have tried it with different leads and pedals and guitars and everything, but still nothing.

    There was usually a kinda healthy popping noise when I switch it on, but I don't hear that when I switch it on now. Have been meaning to try play an MP3 player thru it to see if it's just a problem with the guitar input, but I strongly suspect it's more serious than that..

    It's a Line 6 30W Spider II, a fair few years old now, so it's presumably choc-full of transistors and solonoids and soldering joints and whatever else, so I guess any one of them may have failed? It's not my best amp anyway so I'm not majorly bummed about it, and I don't play guitar as much as bass any more anyway...

    Will probably buy a Micro-cube next month to replace it anyway, but can you guys think of anything simple that could be the problem? Dry joint springs to mind...Should I open up the back and take a look?


Comments

  • #2
    Darkglasses
    Registered Users, Registered Users 2 Posts: 14,526 ✭✭✭✭Darkglasses


    Actually thinking of buying a Vox DA5 now, any other suggestions?


  • #3
    darrenw5094
    Closed Accounts Posts: 2,126 ✭✭✭darrenw5094


    Roland Cube 15w or a 30w with effects if you are not going to play that much.


  • #4
    FarmerGreen
    Registered Users, Registered Users 2 Posts: 1,134 ✭✭✭FarmerGreen


    Just had a look at the circuit diagram and the power amp chip is a TDA7293. (Farnell have them at €7.)
    ..............Older versions may have a TDA2050

    Same as in the old Marshall AVT and well known for going 'pharrrp'.
    You can usually see its gone by the smoke blackened hole in the plastic.
    Mark the connector J1 and the board with a dot so you know which way round they go. Unplug the connector
    Check for a short circuit between the metal tab on the chip and the heatsink, a small burr can cut through the mica washer after a period of time causing it to pop.
    They just go faulty anyway, but its worth checking.


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