I am trying to debug the SMD board as I can not find a schematic I have a schematic for an RD60 which seems to have similar audio design. My issue is that there is a constant static sound on all sources, line in, DAB, BT, FM. The static is heard at all volume levels particularly very low. It’s a constant crackling sound and is only heard on the speaker output:
The static is not present on line out and not present on the headphone out as they seem to have their own IC-based amps.
does anyone have a diagram of the audio stage? Or any suggestions as to what to look at next? There seem to be two op-amps feeding the output stages but it’s hard tracing an SMD board. Also hard identifying these chips. the op-amps are labeled 2100 H057F. Any ideas would be most appreciated.

 

Hi,
https://www.bing.com/videos/riverview/relatedvideo?q=Roberts+Radio+RD70+problems
Good luck...........

 

If the speaker is disconnected when the hedphone plug is inserted the problem may be the contacts on the headphone socket that disconnect the speaker. Another possibility is if the radio has been dropped the voice coil may be rubbing on the magnet on the speaker. Try connecting the speaker to another audio source.

Les.

 

I do appreciate the tips. I’ve tracked it down to a dry soldering joint on one of the op amps that feeds the audio output stage. Re-soldered it and so far no further issues.