BC760XLT - Audio weak and distorted

[racal]

BC760 was not used for several years. Now, back in service, audio is weak and distorted. Speaker is OK. Suspect electrolytic capacitor(s). No schematic. Any ideas?

 

[DaveH]

Is this problem on all bands/frequencies, or just some?

Dave

 

[racal]

Same low/distorted audio on all freqs/bands. Audio is OK at extremely low volume levels. When volume is turned up to a usable level, the audio gets extremely distorted. Appears to be in the audio amp/output section. I'm suspecting an electrolytic cap. Possibly a coupling cap. Had to replace an electrolytic in the power supply section to kill PS hum.

 

[pro92b]

The audio chip is a TDA1905. Along the side of the chip are four electrolytic capacitors as listed below. Replace all of them.

C61 10uF 16V
C62 1uF 50V
C63 220uF 10V
C64 47uf 25V (old version); 100uF 25V (new version)

Use 100uF 25V for C64 even if the original is 47uF.

 

[racal]

pro92b...Have all those spotted on the PCB. Mine has the newer C64. Will hit the parts house ASAP. Will report results as soon as installation is accomplished. Thanks for the quick come back...RC

 

[johnnymitch74]

sorry for bringing up an old thread, but i have this EXACT problem with the same radio. I replaced all the parts as told here, but it didn't work. can anyone help me out?

Thanks a ton!

edit: it should be noted that this happens no matter what is plugged into the radio, be it an ext. speaker or headphones. as well as with the internal speaker. (and the discrim. tap, for what it's worth).