• You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.

Cobra 2000 No rx audio or TX audio on am

fernan_01

Member
Mar 10, 2011
22
6
13
Need a little Help here... My cobra 2000 all of a sudden stoped receiving or tx on AM.. I can TX on SSB but no RX... i have good carrier just no TX audio on am or rx on am and ssb but i do have ssb audio... Also i can see the Signal meter moving like it is receiving good signal just no audio..
thanks
 

If you have no RX audio, and no TX audio, but you have a deadkey on AM, your audio IC has gone fault. Another way to check is to plug the external speaker into the PA and try the PA. If no PA audio, that audio IC is bad. Replace the audio IC and that should remedy your problem. It's (usually) a Toshiba branded TA7222AP. It's an IC that bolts up on the right side of the wall towards the back of the radio. It's a 10 pin Single Inline Pin configuration (SIP) IC chip.


~Cheers~
 
  • Like
Reactions: Klondike Mike
so i changed the audio IC and now i do get some receive and transmit audio but it is very low.. at one time it started to work fine but little by little the audio started to go lower and lower it did it twice .. and now i just get low audio.
 
im going to check on those ... But now i do have another issue on which it was my fault... by accident i touched a diode that its close to mb3756 and my freq counter got stuck on 27.531.2 and doesnt matter what i do it doesnt change freq. i replaced the mb3756 but it's still the same... any clues where to start?? thanks
 
the audio problem is fixed c179 fixed it.....now the freq. problem still there... im going o take a pic. and post it.. because that diode is under the board and has no letter or num. and on of the legs of the diode goes to the MB IC... its is locked to that freq. and when i transmit it transmits on another freq.
 
diodev.jpg


i marked it red where i touched the diode to with the flat tip. lke i daid before the radio is stuck on a freq. and even if i try to change it it wont. Also i notice its not transmitting now on ssb... Audio problem is fixed now i can TX, and RX on AM ... i already changed the mb3756 that is close to that diode just ncase but it didnt fix the problem.. thanks..
 
i pulled tr47 and tr53 to make sure they are good and they tested ok... any other tips where i can start to look??? thanks
 

dxChat
Help Users
  • No one is chatting at the moment.
  • dxBot:
    Tucker442 has left the room.
  • @ BJ radionut:
    LIVE 10:00 AM EST :cool:
  • @ Charles Edwards:
    I'm looking for factory settings 1 through 59 for a AT 5555 n2 or AT500 M2 I only wrote down half the values feel like a idiot I need help will be appreciated