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  • #1

    Amp trouble

    I have a Fender Frontman 15g. I got a blown fuse after using the the aux input and the headphones at the same time. I was experimenting with the aux because whenever I used it, the volume would be maxed out and wasn't adjustable. From what I've now read using the aux can cause problems with this amp.

    After a couple more blown fuses, I tried replacing the output ic (tda 2050 and U4 on the schematics) and the amp worked again for a few minutes. I then shut it off to put the whole thing back together again. When I turned it back on all I got was a buzz, so I took it apart again to see what was going on. When I turned it on the fuse blew so I think the ic was toasted again.

    Any help or advice would be great because I really don't want to have to buy another amp and I'm determined to get this fixed.
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  • #2
    Welcome to the forum!
    I don't see an aux input on the scat I have. There is an ext. speaker jack and a headphone output as well as a guitar input.
    If the unit worked out of the box and then blew after it was re-installed into the box, perhaps something mechanical happened. After you replace the chip again and test it again, eyball how it's goin' back in the cab and see if it's hanging up on anything, or if there is foil or some debris getting onto the circuit board.
    Good luck!

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    • #3
      was there a thin spacer between the IC and the heatsink? Sounds like the IC is shorting to the heatsink.

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      • #4
        Make sure that R40 is not burnt open. Look to the right of U4 across the output line.

        The AUX in on the ones that have it is an unsert after the preamp, so that is why the controls have no effect. yes it is wide open. It is there so you can play a CD through it or something. Assuming the CD player would control the volume. It will not hurt the amp to use this input. Remember, whenever an amp burns up, you are likely to be using SOME input or other. Doesn;t mean that is the reason it failed.


        Make sure none of your main rectifiers has opened or shorted.
        Education is what you're left with after you have forgotten what you have learned.

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        • #5
          Originally posted by chipprogr View Post
          was there a thin spacer between the IC and the heatsink? Sounds like the IC is shorting to the heatsink.
          There is a spacer between the IC and the heatsink, so what do you suggest I do?

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          • #6
            Do a meter check to see if there is any short between the tab of the device and the heatsink.

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