The Defpom Forum, for RadioMods, S&M Software and Music by The Defpom

I took on the task of trying to fix a buddys, cobra xl 350 powersuply, amp. combo. I was able to fix the power suply part of it. (witch problably caused the amp. part to go out in the first place) What I need now is to find info. on this Headache
woops I meen amplifier. Does any body out there have voltage test point chart,schematics, trouble shooting thuery or any help would be most greatfully appreciated.
Big Mike 8113 Central Coast Calif.

Well almost a full year has gone buy, and I still have my budy's amp. up on the TO-DO shelf in the shop. I still have yet to find any info. on this amp., it's like they were never made.
Big Mike 8113

I still do not have anything at all, sorry.

Big Mike
All the cobra XL350 amplifiers I have seen use the same circuits as the messenger 350hd class Ab. The main difference is how the transistors are biased. The Cobra uses a regulated bias circuit and a variable pot to adjust the idle current. The messenger uses a fixed bias circuit.
CBTricks.com has a messenger ab-350hd drawing you could use for reference.

Also, use your V/O meter to make sure you have 12 volts at the backside of the large output transformer. Most all the Cobra XL amps have a fuse on the board, make sure it is good and passing current.
Next, if you have power, attach a radio. Key radio to verify relay is actuating. If the relay works your keying circuit is ok.

Is there a chance the amp was connected with the + & - reversed? If so, you should find a heavy diode in the amp which is for reverse polarity protection, which saves the transistors. If no protection diode exists and it was connected backwards, you will need transistors.
I hope this can help
rooster

FINALLY SOMEONE ON HERE TOLD HIM TO CHECK CB TRICKS.COM CAUSE WHEN IT COMES TO AMPS ON THIS SITE THEY SEEM TO WHAT TO LOOK AT THE QUESTION BUT DO NOT WHAT TO REPLY TO IT THAT IS WHY I AM MOVING TO THERE SITE THEY TRY AND HELP THIS WAS A GOOD SITE AT ONE TIME