Batboard

I've searched and got close with these two threads, but Nand edited most of his posts, which have the detail that I need to fix my radio.

http://batboard.batlabs.com/viewtopic.p ... monitor+PL

&

http://batboard.batlabs.com/viewtopic.php?t=13566

I've tried everything that I know to make the monitor light turn off. The radio transmits with PL, but always receives in CSQ, no matter what. This is a problem in my base setup as I'm constantly hearing repeaters from Virginia and South Carolina (I'm in North Carolina). As a temp fix, I've turned on the "Busy Channel Lockout." This forces the radio to always use PL even if the mic is off the hook (which my radio thinks the mic is always off the hook). I'd just like to actually fix this radio instead of using a work-around.

Thanks,
Scott

Have you tried a different mic?

Have you taken the front off to look at the mic jack / vol control board and cable to logic board?

I have tried several different mics and all of the mics I have tried work fine on all of the Maxtracs that I have. I have not taken the radio apart yet.

RESCUE161 wrote:I've searched and got close with these two threads, but Nand edited most of his posts, which have the detail that I need to fix my radio.

http://batboard.batlabs.com/viewtopic.p ... monitor+PL

&

http://batboard.batlabs.com/viewtopic.php?t=13566

I've tried everything that I know to make the monitor light turn off. The radio transmits with PL, but always receives in CSQ, no matter what. This is a problem in my base setup as I'm constantly hearing repeaters from Virginia and South Carolina (I'm in North Carolina). As a temp fix, I've turned on the "Busy Channel Lockout." This forces the radio to always use PL even if the mic is off the hook (which my radio thinks the mic is always off the hook). I'd just like to actually fix this radio instead of using a work-around.

Thanks,
Scott

It has been a while since I have worked on those, but I think the back of the mic hang up button needs to be grounded to make the radio go into tone squelch. If that isn't it, have you checked the programming to make sure the radio has tone squelch in receive on the channel your using?

Jim

Also make sure the lead in the RJ45 mic plug that takes care of the on-hook (pin 3) hasn't been removed. I've come across radios in the past where the wire was physically disconnected. This particular radio was used in data service so I'm not sure why you'd want to but just something to check.

I have tried a jumper between Pin 3 and Pin 4 and I've tried grounding the mic clip, but nothing will make that LED turn off.

Nand was giving suggestions to replace a certain transistor, but he erased all of the posts pertaining to that. You can see the response from ku4zs that whatever Nand suggested worked. I can't remember why Nand erased mosts of his posts... Take a look at the last post of the second link that I provided.

Okay - good - you tried a jumper plug - that answers the question whether the mic was properly grounded. The radio apart and look at the vol control board to see if someone modified it.

Is one of the rear accessory pins programmed for monitor? If it is, maybe that's keeping it off hook.

Rescue,

Check Q811 on the logic board. This is the interface between the Hook line and the Micro/CGA.
It is located on the bottom side of the logic board near the control head header for 16ch (4 layer) or on the top side near the 5V regulator for 8ch (2LAYER).

Part Number: 4880947V01 NPN TRANSISTOR W/BIAS RESISTOR $.68

Cool. I'll have to wait until this weekend to take it apart.

A simple check/test: The monitor pin should have almost 5 volts on it.

If it has 5 volts, then it is a programming problem..not set for PL receive.

Just getting back around to this. I was mistaken in that it was a GM300. It is actually an M216 Radius. The monitor LED does turn off, but it takes about 2 1/2 minutes after the mic is hung up. I've looked all through the programming and can't find anything to shorten that time. During the 2 1/2 minute wait time, scan does not work no matter what I do. Once the 2 1/2 minutes have lapsed, the monitor LED goes out and the radio resumes scanning.

Has anyone seen this before?

Check the voltage on the Hangup line, is it going to ground right away? Then trace that to the uP.

Yes, the voltage is going to ground right away. I followed the flow charts in the service manual and they all point to a bad logic board. It's not that big of a deal as I'm just giving the radio to my uncle for ham use and scan isn't really needed.

Finally fixed. Checking Q811 as 35echo suggested showed that it was good. The problem was a cold solder joint on R880 (on the collector of Q811. So when Q811 was on [mic off hook], ground was felt on the collector (good), but when Q811 was off [mic on hook], I wasn't getting the 5V on the collector (bad). Reflowing solder on R880 allowed the 5V to be sent to Pin 50 of U803 solving this horrible problem.

The 2 1/2 minute 'wait time' had increased to around 5 or 6 minutes this morning. I guess constantly moving the radio and probing on the board made that joint worse. Once I touched the left side of R880, the monitor LED instantly turned off. Glad I can finally put this to bed.