Cobra 139 XLR no transmit at all.

[Staybolt]

A friend of mine gave me his 139 XLR to work on. It does not transmit at all not even the relays inguage. It receives fine and i checked the relays and the mic. Both are ok...

 

[Robb]

Just because the relay is clicking, that is no guarantee that it is working. If considering cleaning it (you should); DO NOT sand the contacts! Use a piece of uncolored matchbook cover and wet it with pot cleaner and place it between/drag it between both sides of the contacts several times. Be very careful not to use too much force that will distort that moving relay. But use some force and repeat the process until you can drag the card thru w/o any residue seen on the card on either side of the relay. Clean out the relay socket with pot cleaner and blow it out. Might also retouch the solder points on the board for the relay too.

The other thing to do is just go ahead and replace C179 (IIRC); a tantulum capacitor - with an equal uf value electrolytic. You can use a 25v electrolytic cap and it will fit nicely. 2.2uf/25v is the value of that part. Every C179 tantalum cap I've ever tested was bad in this radio; so it would just save you time to replace it altogether and get it over with. Some have claimed that you can leave it out; but I have never done that.

The stock final is a 2sc1307; but you can put in a 2sc1969 w/o any problem. Same goes for the driver. It is a 2sc1306 and can be replaced with a 2sc2166. The 1306 and 1307 are no longer made nor can be found any more and can be replaced with the newer part. That is; if either/both have failed after testing. Check/set the bias at 15mA for the driver and 40mA for the final.

That should get you started; but not a guarantee of success . . .

 

[Staybolt]

I don't recall ever mentioning that the relays were clicking... However. I found out someone rewired the mic socket to accept a non stock mic.. I rewired the mic plug and now all is well..