Heineken
26-02-2022, 04:49 PM
One more Swiss radio arrived with a strange phase-like sound and a wobbly volume knob but otherwise fully working.
Looking at the PCB after removal of the capacitors, the damage wasn't too severe but surprisingly strong around the smaller E818:
14541
With the contaminated areas cleaned by a glass fibre pen it can be seen that a trace underneath E818 was completely eaten away:
14542
The trace has been repaired and covered in solder for protection:
14543
The final, repopulated PCB looks like this:
14544
Not forgetting the Power PCB, the display power supply capacitor and re-tightening the volume knob.
14545
Power PCB
14546
Display Power Supply Capacitor
14547
Thread locker secured Volume Knob
Up to this point it wasn't clear if the PCB repair would solve the strange audio issue observed. Luckily the unit tested perfectly fine.
Since the audio problem was observed on all channels and inputs, it seems the the broken trace affected the output operational amplifier power supply.
14548CD Mode
14549Radio Mode
14550
Tape Mode
An interesting aspect of this repair is that the smaller E818 capacitor leaked before the large ones - in most cases it's the other way around.
The (http://www.nsxcb.co.uk/entry.php?2658-Radio-Head-Unit-Capacitor-Replacement)Head Unit - Capacitor Replacement (http://www.nsxcb.co.uk/entry.php?2658-Radio-Head-Unit-Capacitor-Replacement) section on the blog has been updated and the audio issue added as another possible symptom.
Looking at the PCB after removal of the capacitors, the damage wasn't too severe but surprisingly strong around the smaller E818:
14541
With the contaminated areas cleaned by a glass fibre pen it can be seen that a trace underneath E818 was completely eaten away:
14542
The trace has been repaired and covered in solder for protection:
14543
The final, repopulated PCB looks like this:
14544
Not forgetting the Power PCB, the display power supply capacitor and re-tightening the volume knob.
14545
Power PCB
14546
Display Power Supply Capacitor
14547
Thread locker secured Volume Knob
Up to this point it wasn't clear if the PCB repair would solve the strange audio issue observed. Luckily the unit tested perfectly fine.
Since the audio problem was observed on all channels and inputs, it seems the the broken trace affected the output operational amplifier power supply.
14548CD Mode
14549Radio Mode
14550
Tape Mode
An interesting aspect of this repair is that the smaller E818 capacitor leaked before the large ones - in most cases it's the other way around.
The (http://www.nsxcb.co.uk/entry.php?2658-Radio-Head-Unit-Capacitor-Replacement)Head Unit - Capacitor Replacement (http://www.nsxcb.co.uk/entry.php?2658-Radio-Head-Unit-Capacitor-Replacement) section on the blog has been updated and the audio issue added as another possible symptom.