Onkyo M-504/M-508 main filter cap mod

itsikhefez

Member
Paid Member
2015-08-24 2:28 pm
Hi,

The original filter caps used on the Onkyo M-504/M508 used 4 pins with irregular spacing and this part is unobtainable AFAIK.

To my understanding 2 pin caps are fine functionally but they simply cannot be fitted into the original holes. Some folks have found various "hacks" but I'd like to do something more elegant, especially since there are 8 caps and something can go wrong.

I was thinking about making a circular PCB in the diameter of the original cap, where a standard 2-pin can be soldered onto, and it would have 4 pins in the original spacing. In this case 8 PCB's would be used.

Another option is to have a single rectangular PCB, where all 8 caps will be soldered on to. The PCB will can then have pins soldered on the bottom, or attached with standoffs and connected via wires to original locations.

I've never designed a PCB and have no idea where to start.
Is this a good idea? bad idea? Anything else to consider?

Thanks!
 

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itsikhefez

Member
Paid Member
2015-08-24 2:28 pm
Yea, I am a bit reluctant to drill holes... afraid to screw up
Just bending 2 pins won't be sufficient though, as all 4 pins were used in the original PCB. I would then have to jumper to the other pin.

Not incredibly difficult but was thinking a conversion PCB would be more elegant and less error-prone
 

itsikhefez

Member
Paid Member
2015-08-24 2:28 pm
I have no idea... and all the folks that attempted to fix this have asked the same question.

The unit I have is stuck in protection, so I need to fix that regardless and I doubt the issue is with the main filter caps.
I was planning on replacing all electrolytics as the amp is ~25 years old but perhaps I'll replace all except those main filter caps
 
I have no idea... and all the folks that attempted to fix this have asked the same question.

The unit I have is stuck in protection, so I need to fix that regardless and I doubt the issue is with the main filter caps.
I was planning on replacing all electrolytics as the amp is ~25 years old but perhaps I'll replace all except those main filter caps




I drilled and it's going well I think it's the best solution! Here is a photo with the capacitors installed
 

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