Batboard

MCS2000 w/dual control heads was installed in a fire engine. During some maintenance, wires were shorted together in the headset wiring. Radio immediately died.

I put it on my bench and was able to power it up about 2 times out of 30 tries... rest of the time it just sits there powered off. Both times I got it to turn on, no audio. Figured it might be a blown audio IC (I'd actually been thinking that before it even got to the bench), so I pulled the IC, but the radio still won't power up.

Looking for some hints as to what to try next... do I need a good audio IC back in there in order for the power button on the control head to work? Is there another common component that dies and produces a similar symptom?

well for one the audio on the MCS2000 is a floating ground so any short can and will blow the audio IC. There is a 5v regulator that has known to have a cold solder joint on it, if this is the case the radio will not power up. Try reflowing solder on the 5v regulator and replace the IC for the audio and that hopefully will fix the problem, I have a ton of junk MCS boards so I can help repair the board for ya if need be... Also check to see if you have power on the ign sense lead, if you goofed up the processor by anymeans it might be looking for ign sense only on the radio. PM me if you need some more help...

Rod Farva wrote:well for one the audio on the MCS2000 is a floating ground so any short can and will blow the audio IC. There is a 5v regulator that has known to have a cold solder joint on it, if this is the case the radio will not power up. Try reflowing solder on the 5v regulator and replace the IC for the audio and that hopefully will fix the problem, I have a ton of junk MCS boards so I can help repair the board for ya if need be... Also check to see if you have power on the ign sense lead, if you goofed up the processor by anymeans it might be looking for ign sense only on the radio. PM me if you need some more help...

I second this. I can't say how many MCS 2000 problems I've cured by reflowing solder around various surface-mount joints. As Rod Farva pointed out, the 5v Regulator is a known issue with these radios, I've seen it myself, and based on your intermittent power up issue, I'd wager you've got something that's busted off the board in there. 8 out of 10 times you can see it with the naked eye. If the component flexes, it's loose.

Motorola still supports these, too, as I just received one back from the depot with an entirely new board in it for the flat rate fee.

I would Depot the radio ONLY if I could not fix it, the problem sounds like a simple repair to me....

Not wanting to point the finger at anyone, but by any chance have you checked to make sure the jumper is in
place for the emergency keying. If it is missing and the software is set up for it, you will get into all sorts of
problems.

There is a fixed audio out on the accessory connector. It has a DC bias voltage on it, so you should cap
couple it. But you can use that source to see if the radio is working. It does not use the audio out amp
for the fixed audio. Want to say it is pin 11, but would have to go find the manual to be exact. If you can
get the radio to stay on, you can test the receiver using the fixed audio output.

Jim

ka6sqg wrote:MCS2000 w/dual control heads was installed in a fire engine. During some maintenance, wires were shorted together in the headset wiring. Radio immediately died.

I put it on my bench and was able to power it up about 2 times out of 30 tries... rest of the time it just sits there powered off. Both times I got it to turn on, no audio. Figured it might be a blown audio IC (I'd actually been thinking that before it even got to the bench), so I pulled the IC, but the radio still won't power up.

Looking for some hints as to what to try next... do I need a good audio IC back in there in order for the power button on the control head to work? Is there another common component that dies and produces a similar symptom?

I have an mcs2000 vhf high power. Keys on the control head light up but nothing else. I believe I have located the problem it's one of the board componants. Is there anywhere I can find junk boards I can pull parts off of? I can provide a picture is needed.