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CDM1550 VHF overheating

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CDM1550 VHF overheating

Postby wcu02mpa » Fri Apr 21, 2017 6:01 am

I have a CDM1550 VHF (non-LS) AAM25KKF9AA5AN. It is recently acquired. It reads and writes fine, transmits and receives fine. The problem is when I plug it in the heat sink gets hot, even when not transmitting. Any ideas?

I have never seen this before.
I may not fire the first shot, but I will fire the last one.

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Re: CDM1550 VHF overheating

Postby d119 » Fri Apr 21, 2017 7:43 am

Probably a failed or failing PA transistor.

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Re: CDM1550 VHF overheating

Postby tdats » Fri Apr 21, 2017 11:34 am

If there is anything connected to the accessory connector, make sure that none of the speaker output pins are grounded. I had a bus radio do that do me on a swap out one time, the speaker they already had was grounded.

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Re: CDM1550 VHF overheating

Postby jackhackett » Tue Apr 25, 2017 8:35 am

Is it a remote mount? If it is, open the head, and put some insulation between the circuit board and speaker terminals. A couple layers of electrical tape should do. In the remote mount kit they put an exposed ground pad on the board right under where the speaker terminals are and there is not much clearance so it shorts and causes the radio to get very hot, eventually killing the radio.

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