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Radio Head Unit (EU 1992) Repair and Capacitor Replacement

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Aug 5, 2014
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Germany
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:

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With the contaminated areas cleaned by a glass fiber pen it can be seen that a trace underneath E818 was completely eaten away:

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The trace has been repaired and covered in solder for protection:

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The final, repopulated PCB looks like this:

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Not forgetting the Power PCB ..

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.. the display power supply capacitor ..

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.. and re-tightening the volume knob:

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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.

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Since the audio problem was observed on all channels and inputs, it seems the the broken trace affected the output operational amplifier power supply.

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 Head Unit - Capacitor Replacement section on the blog (NSXCB) has been updated and the audio issue added as another possible symptom.
 
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