Question about Zapco Reference 750 Car Audio Amplifier

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Zapco DC Reference 750.2 problem

So I go to turn on the car and I hear pop pop pop pop. All 8 of the high speed switchers on the amp popped. I have replaced them and now the amp fault light turns on, then off, then off, then off. Any idea what else is wrong. Or better yet, schematics?

Posted by Hatters church organ on

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  • Hatters church organ
    Hatters church organ Nov 17, 2009

    Honestly, I don't know how to. I am good with a meter but rely on schematics. Can you give me some guidence?

  • Hatters church organ
    Hatters church organ Nov 18, 2009

    I will be out of town so I haven't had a chance to check.

    Some questions:

    Do I need to pull each one out of the circuit to test accurately?

    Will any old TIP35 and TIP36 do?

    How do they work together?

    I was looking at them in mouser and Digikey and didn't know if there was much difference from manufacturer to the next (BTW I understand the 35 and 36 are two totally different components, my amp had 8 of each).

    I can tell you how much this means to me. Hopefully by next week I'll get it fixed and walk away with a lot of experience.

  • Anonymous May 11, 2010

    The amp likely has shorted output transistors. Did you check them?



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  • 631 Answers

If the amp uses TIP35Cs and TIP36Cs, those will be the output transistors. Measure the resistance between legs 2 and 3 for each of the output transistors. Do any read near 0 ohms?

If you're new to repairing amps. The following page should help.

Posted on Nov 17, 2009


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