MSF5000 Weird Warning Tone

[n5api]

Hi everyone,

I'm getting an intermittent alarm signal from my UHF MSF5000 that has me stumped. Its giving me a four beep tone, which corresponds to an overvoltage alarm, according to another post on the boards. The kicker is, this MSF doesn't have a battery revert system! Additionally, transmit will occasionally drop out for up to five seconds, usually within a few seconds of hearing the alarm over the air.

Of course, I can't get the thing to do it when I'm at the site in front of the machine with the MSF advanced diagnostic panel, and everything else looks fine (RX/TX lock lights, PA Full on when keyed, etc.) Does anyone have any ideas?

Thanks,
John, N5API

[n5api]

Forgot to add that this is an older Analog (CLB) station, with the Tone remote and internal duplexer options, if either of these make a difference.

edit: The TX just dropped for 3 seconds without hearing the alert tone first, so maybe I have two different issues going on.

Thanks,
John

[xmo]

What is the part number of the station's power supply?

e.g. TPN1185A, TPN1186A

[n5api]

I want to say it's an 1186, but I'm not 100% sure. I was planning on going up to the site today with a whole bunch of test equipment and hanging out for a while to see if I can get the thing to act up. I will take a look then.

[n5api]

The power supply is a TPN1186A. The loss of transmit signal is occurring when the MSF reboots, seemingly at random. Voltage on the PA power connector is within what I believe to be acceptable range (15.54v on RX, 14.68v on TX); I haven't been able to measure it yet when the alarm is going off.

Any ideas?

[n5api]

Based on the advice of someone locally, I believe I have found the culprit. Connector J603 on the power supply distribution board somehow got a little crispy and is crystallizing. I cleaned the male end of the connector, and replaced the power supply, since I had brought a spare to the site. This should hold me until I can replace J603.

Can someone look on MOL, and see if part number 28-82984N10 (the J603 connector; male, 9 contact plug) is still available, and the estimated price?

Thanks,
John

[escomm]

Currency: US
Your search for item numbers beginning with 2882984N10 returned 0 record(s).

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[n5api]

Escomm, thanks for looking for me. Does MOL supply a current parts list for the TPN6138B Power Supply Distribution Board? I'm looking for the J603 connector part.

Thanks,
John

[escomm]

Not unless it's down deep in a service manual somewhere. I would suggest contacting Parts ID, they should have a breakdown of the components. You should be able to reach them by calling 800.422.4210, selecting options 2 - 1 - 1

[n5api]

Yeah, that's where I got the first part number, the depths of a 25 year old service manual. I'll call Parts ID on Monday.

Thanks!

[bernie]

My two bits worth:
This is a garden variety el chepo connector, available at the parts store. Be sure to replace the male pins also, or the problem will re occur. I usually just solder the lead on the pin, replace the connector if it ever becomes necessary to replace the board.

Bad filter caps in the power supply can cause a similar problem, the A+ sags on key up, causing the control board to reset when the 5V regulator drops out of spec. I have seen several control boards replaced because of bad filter caps.

A power supply with the battery charger option can do the same thing if the battery is dis connected, or dry, the regulator board has such a slow response that the voltage can sag on key up, especially if the power is set high. The solution is to set the regulator for 14.9 or so WITHOUT BATTERY.

[luisa.kmet]

If you have the Battery backup option sometimes the DC dropout relay get a light oxidization of the contacts and due to the high resistance the MSF 5000 will resets on a power glitch. Not that easy to reach, but you can clean the relay contacts sometimes by just opening a closing the relay manually a couple of times. I usually run a piece of clean paper through the closed contacts and you can see the oxydization rub off on the paper.