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Strange noise after replacing caps ?

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kajbcp
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Strange noise after replacing caps ?

Post by kajbcp » Thursday, 22 March 2018, 5:38 AM

Hi ,

One month ago, I bought President Jackson MK1 near to mint condition. From 1991 it was in a box. When I connected it, it was working for a few days with muffy modulation. And then it stopped working. when I would press PTT , you could hear sound like claxon horn. I have changed all electrolitic caps and now it works, only when I press PTT, person on the other side can hear silent noise withing 2 seconds like a bad filtering power supply, after that sound disappears. Seems to me like some electrolytic capacitor discharged through faulty ceramic condenser or something. All solder points, shorts on board after soldering ,cap polarity and values , are triple checked .Any advice is welcome! 73 sasa




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MDYoungblood
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Re: Strange noise after replacing caps ?

Post by MDYoungblood » Thursday, 22 March 2018, 12:07 PM

It sounds like a cap in backwards, I see you checked everything several times but you may have missed it, only other thing is one was labeled wrong, it does happen. Try another mic too, possible a contact in the PTT is making before breaking.

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sasabcp
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Re: Strange noise after replacing caps ?

Post by sasabcp » Friday, 23 March 2018, 3:13 AM

Hi Greg TNX for reply . I have tough the same as you . I hope that some electrolytic cap will deform/expand , that is my last hope to make proper diagnose .




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