Batboard

I have a VHF MSF5000 Digital C73CXB7106BT that, for what ever reason is now stuck in transmit. It has a Scom 7K controller interfaced through the MRTI connector. I completely disconnected the controller, plus removed the controller interface cable at the repeater to make sure it was not caused by either of those two items. No change.

It was working fine pior to this for better than a year. With the controller and cable removed, it will do a complete and successful reset, and then goes into transmit. With the digital test set attached, all it is showing is the Tx activated. There are no squelch settings open, besides it is programed as a base station, so an open squelch should not make it transmit.
I even reprogrammed the code plug with my archived file, just in case it
went south, but no joy. I can make it unkey changing the assec/disable switch to disable.

With the controller connected, it passes audio just fine, sounds great as before, but just will not unkey.

I'm not the greatest with the MSF, but I have the manual, digital test set, service monitor, and a little experience with it.

I just need a few ideas as to where to look.

TIA,

Gary

My two bits worth:
I would note on the digital test set the source of the PTT command. eg Line PTT, Local, etc.
I would suspect a short on the local PTT line, perhaps a solder blob, or shorted by pass cap.

Hi Bernie,

Thanks for the reply.

What the digital test set is showing me is the stumper. It is not showing
me any PTT activity while it is stuck in Tx. All it shows is the D002 TX ACT as being active. Of course you get the normal R1 UN SQ, RPT USQ, and RX1 ACT, when activating the receiver via a handheld. It will pass audio when the external controller is in place.

Someone has suggested trying to reprogram the PTT priority one at a time
and see if I can find it by process of illimination. It was also suggested to me to look at the input side of the PTT lines, being as how changing the ACC DIS switch to disable, brings it out of transmit.

I have removed the control tray from the machine and brought it down the hill looking for any visual problems. I cannot do much with it in that state, but I have another VHF machine coming to me next week to use as a test bed.

Thanks again for any, and all your input Bernie.

Gary