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?

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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.

  • Perry Babin 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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