XTL5000 magic smoke no control head

[QBFreak]

The list of stupidity from yesterday is long, but this is pretty much at the top. I managed to let some (but not all) of the magic smoke out of my most favorite XTL5000 in such a way that now it now no longer communicates with the control head. I think I totally fried the SB9600 bus but I'm not sure.

The radio is a remote mount with a W7 series head. Flash code 540008-000480-6.

The head gives a Fail 01/90 on power up, and the radio produces an error tone as if it's missing external hardware. I assume it's missing the control head since it's not expecting a siren, but I can't confirm this without a control head I confirmed that the head and the head cable are good on another radio. I tried TIB and flex cable from a good radio with no success. There was definitely an odor of burnt electronics when I pulled the TIB off, and it got a lot stronger when I took the top cover off. A visual inspection of the board didn't give me any obvious signs of what went wrong.

The radio still powers up, minus the head. I can read it with a rear USB cable (thanks for the sticky on that!). It's the only XTL I have with this specific feature set and it's one I'd really like to keep. If at all possible I'd let to get this thing working again but I'm severely lacking in funds so a trip to the depot is out of the question.

I have a pile of dented and rusty XTL2500s that I can use for parts (it's rough being the first ones into the dumpster). If this were an Astro Spectra I'd just shove the S-Records from one radio to the other, move the UCM, run through the tuner and be done with it. I'm not nearly as familiar with the XTLs. Without getting into tools that get us all into trouble, I don't suppose there's any way to save this thing from that direction.

My other option which probably wont end well is to try and figure out what I toasted and replace it. I know how it all went wrong. I just need to do a little investigating to see exactly what I may have shorted to what to figure out where the problem might be. I have a DB-25 cable I built a while back that I used last time I was playing with SB9600. has a male connector on one end and a female on the other mounted in a pass-through shell so it fits really well between a rib and a radio or a radio and a control head. The two connectors are totally isolated from each other. The cable is a 25-pair telco cable, one wire connected to every pin of each connector. It runs out of the shell and after 6 feet or ends with no connectors on the ends. When I use it I generally strip the wires I'm interested in and jumper them together by inserting them into a breadboard. Well I was tired, lazy, in a hurry, and wasn't paying attention to the fact that there were a few extra stripped wires from a previous experiment (apparently unrelated to SB9600 or I would have been using them this time) shoved out of the way and a few of them must have crossed. I just need to look up the color codes, match them to the TIB pinout and see what pins I'm working with. Hopefully I just blew up some protection circuitry or something (doubtful, wouldn't be my luck).

I'm afraid I'm going to hear it's a lost cause, and it probably is. But dangit, it's 700, P25, and Multikey. The only thing that would make it any more useful to me and the systems I touch on a regular basis would be AES and TDMA, but those two I can live without. No P25? might as well just chuck the thing. DES is a serious want.

 

[tuckerm]

You never really told us *how* you fried it. That could help in the investigation.

 

[QBFreak]

I'm sorry, blasted meds make me forget things It's one thing to lose a word when you want to say it, but now whole trains of thought are vanishing. So frustrating.

The short version is random wires plugged into J6 accessory connector accidentally touched. It'll take some time later but I'll figure out exactly which ones were actually exposed and post that. When I made the test cable I never made a cheat sheet to go with it, so I'm not sure what all is in it anymore. I'll post an update later this afternoon once I work out a a list of the possible suspects.

 

[QBFreak]

It turns out I did have a cheat sheet, that was far less painful than I thought it was going to be. It's ugly, but here's what we've got. The following were all exposed and potentially one or more of them shorted together:

PTT*
IGN
RESET B+
FLT AUDIO
ANA GND
MIC LO
RSSI
DIG GND
SWB +

I'm assuming IGN or one of the B+ went somewhere it shouldn't have. Not Good.

I'm doing some more thorough testing of the radio (does it still PTT? still pass mic audio? etc), I'll post the results when I'm done.

 

[QBFreak]

I've done a bit more poking and prodding of the radio and here's what I've found so far:

The Ignition through the control head works. You can power the radio on with the control head power button once it has been connected. Ignition Switch is set to Blank. The radio needs a continuous ignition source to remain powered whether it's the control head or rear accessory.

No PTT through the control head with a Mic (no surprise there). I have an adapter I built a while back to get me use a mic through the rear accessory connector. I get good audio on TX through the rear accessory connector. I tried building a similar adapter for J5 and I can key the radio, but I get no audio even on a good radio, so unknown about TX audio through the front connector.

 

[com501]

If you have a UCM installed, unpower the radio entirely, and remove the UCM and carrier board. Check everything again. If you take the cover off the UCM board and the smell doth increase, your culprit hath been foundeth.

 

[QBFreak]

No joy The UCM is uncharred and as delightful smelling as ever. I removed it and the carrier board, reconnected everything, still FAIL 01/90 and an error tone from the brick. As I feared, I did a number on the main board.