1982 CHP #0327

[ImEvil1]

Originally Posted by Steve

The Federal MPA2 Siren/Amplifier is very easy to bench test. Today I did that; simply connected B+ and B- to 12 Volts DC, the speaker output to a speaker powerful enough to handle the 100W output, then connected +12V to pin 9 of the input connector. The siren Wail function worked as it should.

So I've got a bad CC1. I opened it up; it has a repair tag inside from 1986. I doubt it's seen any servicing since then.

The plastic output connector, J1, that connects to the MPA2, has seen better days. Both tabs on the sides that hold it in the housing have become brittle and broken off, so the connector floats. Plus all the pins are badly oxidized. I tried to clean them using an emery board, but it is very difficult to do a good job. It is possible the +12V the CC1 siren switch sends to pin 9 for Wail wasn't making it past the oxidized pin.

Fortunately, all of the connectors and pins are still made and are readily available online from DigiKey. So I am going to order a replacement connector, pins, then build a new one. It's tedious work but worth a shot. If after that it doesn't work then the electronics section of the CC1 that controls this signal, and the PA system, are likely bad. I'll then probably just look for a known good CC1 to buy.

Meanwhile, I can always just route +12V through the siren switch directly to pin 9 and make the siren work, which at least gets that part done.

When this is all complete I'll document the whole thing with all the connector and pin p/s, etc.

Nice work. Those CC1s are like tanks...hopefully it's just the bad contact.