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

hello guys,,i have a cobra 29 ltd,,i am having alittle trouble with..it had no receive audio,and no am modulation..did the p.a. jack test..it had no audio at first..so i changed the audio chip and the shunt capacitors..now on the pa test i have low audio,but still not right..now i also have low level receive..if you turn the volume wide open,you can hear low level receive.some one also put an echo board in it..so i thought maybe this is the trouble..so i bypassed it and hooked up audio wire straight..but still no help.i am thinking maybe the mic amps..but i dont think receive audio will be affected by these.i also changed out tr-23,they had wrong transistor here..they has a 2sc1226 there..so i checked another of my 29s and it has the 2sd 880 here..so i changed it out to the proper transistor.still no help.they have also put a channel kit in this radio..but i dont think it is the problem..just thought id put in here just for safety sake..anyone have any ideas..something maybe ive missed..i would appreciate your input......ramblingman

since it has a channel kit in it have you checked to make sure either L20 or L21 has not dropped out.I do a lot of channel kits on this radio for truck drivers and if the pots are out just a little this will happen also.some of the older 29s are just not broad band enough to handle a channel kit if the pot is off just a little.see if this helps.

Un-solder the collector of TR13 and see if the PA is OK. If not check try checking the caps around the AF amp and check for dry-joints around AF amp. Once you get the PA working OK the RX will probably OK.

You may find this diagram easer to follow.
http://www.cbtricks.com/radios/cobra/29 ... ic_sch.pdf

Rick.