This is a common fault in this amp model and others from Aiwa, same age. VFD display doesn't work. Everything else OK, if you can operate it blindly.
The culprit is C15 and C16. C15 is 47uF/50V and C16 is 33uF/50V, both electrolytic. They put two 50V caps in series to get a 100V cap, but this is as crappy as putting rectifier diodes in parallel to add current. It works for a time, but ends up unbalancing and one component is exposed to more voltage (case of capacitors in series) or to more current (case of diodes in parallel) than the other, exceding its maximum and failing prematurely.
I've repaired this receiver two times. 2008, 2012 and now. It lasts 4 years. Now I want to do something different. This means an equivalent 20uF/100V, not easy to get. Perhaps this is why original enginer splitted it in two.
I attach schematic fragment. Any smart idea?
The culprit is C15 and C16. C15 is 47uF/50V and C16 is 33uF/50V, both electrolytic. They put two 50V caps in series to get a 100V cap, but this is as crappy as putting rectifier diodes in parallel to add current. It works for a time, but ends up unbalancing and one component is exposed to more voltage (case of capacitors in series) or to more current (case of diodes in parallel) than the other, exceding its maximum and failing prematurely.
I've repaired this receiver two times. 2008, 2012 and now. It lasts 4 years. Now I want to do something different. This means an equivalent 20uF/100V, not easy to get. Perhaps this is why original enginer splitted it in two.
I attach schematic fragment. Any smart idea?
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