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TDA7294 blown

Terry Ackland
Prodigy 20 points
Other Parts Discussed in Thread: TAS5630

Hi,

I have just purchased a 2 chip tda7294 stereo amplifier board that only required a heatsink and a transformer.

After making the additions, I tested the amp out on a pair of unused speakers in my basement and all was good. I  then brought the amp upstairs and connected it to my usual equipment and it sounded great.

After a while I decided to to check the temperature of the heatsink and when I touched it there was a flash and a pop and a cloud of smoke from one of the 7294 chips. On looking at the burnt chip I noticed that the mica plate was not parallel to the chip which meant there was a gap under one corner of the chip.

It is very cold here in the winter and there is much static in the house and  shocks are common when touching a metal radiator or water tap and even the cat!

 Is it possible possible that a static charge caused a spark to jump across the small gap left between the chip and the heatsink when I touched it and caused the chip to blow?

Thanks. Terry

PS,  I have been using a little tda7297 board for several months and I cannot believe how good it sounds.

  • 0
    TI__Guru**** 189401 points

    Hi, Terry,

    Some of those old ST parts are nice. I havent seen many new parts from them, have you?

    ESD is certainly a possibility. I assume the heat sink is connected to probbably pin 7 or 8 of the IC so you very well could have experienced an ESD event, although they are less likely on an assembled board. 

    Take a look at the TAS5630. It blows that old part away!!!

    D2

  • 0 in reply to Don Dapkus
    Prodigy 20 points

    Don Dapkus said:

    Hi, Terry,

    Some of those old ST parts are nice. I havent seen many new parts from them, have you?

    ESD is certainly a possibility. I assume the heat sink is connected to probbably pin 7 or 8 of the IC so you very well could have experienced an ESD event, although they are less likely on an assembled board. 

    Take a look at the TAS5630. It blows that old part away!!!

    D2

    Thanks for the prompt reply Don.

    Pin 7 on the board was badly burnt, so I'm guessing it was ESD?

    I checked out the TAS5360 and they offer more power than I would ever need, my big old vintage speakers  draw less than 1 watt rms for serious listening. Could you suggest a less powerful amp?

    Regards, Terry