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Parts Fell Out of My PM650 -What are they??

C

cesmith5600

Active Member
Hey everyone. I picked up a Harman Kardon PM650 that needs some love. I bought it as a fixer upper and that’s what I got.

Two issues right off the bat. 1) left channel static, very prominent at low volume, turning the volume up results in protection mode shut down. Right channel is clean and no protection mode issues - that I could force. 2) all front panel lights are out. There is a 400mA 125V fuse that is in the front panel board that is blown. I can’t find this fuse. Hoping a new fuse is a quick fix on this.

Back to the left channel static issue. When working on the unit the parts in the attached pic fell out from the bottom. A diode of some type?? They were inside the red plastic sheaths. Clearly, they overheated over time and eventually fried. Visually I can’t seem to identify where they came from. Any thoughts?
 

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They are diodes and a lot of current passed through them for some reason. Since they fell out on their own, it seems it was enough to destroy the leads. There are other issues downstream in the left channel. I would think that the area they were located on the pcb would show signs of a lot of heat.
Do you have schematics for the unit?
 
RVT1K said:
They are diodes and a lot of current passed through them for some reason. Since they fell out on their own, it seems it was enough to destroy the leads. There are other issues downstream in the left channel. I would think that the area they were located on the pcb would show signs of a lot of heat.
Do you have schematics for the unit?
Click to expand...
Thank you. I have the technical manual with schematics.
 
Almost looks like some corrosion.

What do rest of guts/circuit board look like? Evidence of spills or capacitor leakage?
 
whoaru99 said:
Almost looks like some corrosion.

What do rest of guts/circuit board look like? Evidence of spills or capacitor leakage?
Click to expand...
These parts came from the phono equilibration board. You can see the corrosion. There is also corrosion around in the surrounding area. The rest of the phono board looks clean and all the other boards in the unit look clean. The static issue mentioned previously was through the aux input. Since this circuit is separate from the phono circuit I am thinking deal with this first? The phono board next next assuming you think its fixable and the lights last. See the attached pics. Thoughts please
 

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cesmith5600 said:
These parts came from the phono equilibration board. You can see the corrosion. There is also corrosion around in the surrounding area. The rest of the phono board looks clean and all the other boards in the unit look clean. The static issue mentioned previously was through the aux input. Since this circuit is separate from the phono circuit I am thinking deal with this first? The phono board next next assuming you think its fixable and the lights last. See the attached pics. Thoughts please
Click to expand...
It does look like some leakage around the main filter caps. FYI
 
That corrosion is actually glue that has turned corrosive, at least that’s what it looks like in your picture.
You should remove all of it that you find in the unit.
Good luck on the repairs
 
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