Pro-433 intermittently stuck in Wired mode

[S1MPLET3XT]

After programming this scanner and installing it in my car it suddenly got stuck in wired mode and wouldn't go out of it even after a reset; so I took it out and opened her up and disconnected the wires leading to the PC/IF jack. This seemed to solve the problem at first so I hooked it back up and reprogrammed it and I thought I had it working again...

Nope; now when I turn it on and start scanning I get about maybe 2-3 minutes and then it goes back into wired mode and automatically resets itself after around 30 seconds; after which it scans for a brief second then goes back into the same cycle.

Has anyone else had this problem or know of any solution? Does anyone have the service manual .pdf so that I might trace it to the board? Maybe a bad component?

Thanks in advance!

 

[S1MPLET3XT]

anyone?

this thing is still displaying the same symptoms... seems to last longer when the unit is cooled down and has been unplugged for awhile.

 

[pro92b]

If you again disconnect all the wires to the PC/IF jack, does the problem go away? If so it is probably the jack that is causing the problem. The diagram below is from a PRO-528 which should be similar to the PRO-433. When a plug is inserted into the jack R399 (4.7K) is connected to PC_DET which pulls up the voltage to 3 volts. This alerts the CPU that a cable is plugged into the PC/IF jack. Your radio appears to have an intermittent short in this path and you can check the voltage at TP356 to see if it is around 3 volts (it should be zero) with no cable plugged in to the PC/IF jack.

 

[S1MPLET3XT]

This is what it does with the PC/IF component completely unplugged from the main board... when it is plugged in it does not scan at all and stays shorted in wired mode... I just can't understand why it goes into wired after awhile without the PC/IF plugged in at all, it seems that should make it stay in scan mode... hrmmm... Anyways, thanks for the detailed info(s)! I will have another go at it when I get back to the shop later this week!