[sdiy] 1970's organ repair and multi-capacitor PS caps

Gordonjcp gordonjcp at gjcp.net
Wed Jun 10 11:55:39 CEST 2020

On Sun, Jun 07, 2020 at 09:25:51AM -0700, John Speth via Synth-diy wrote:
> Hi experts,
> I'd like to attempt hum elimination on a 1972 Wurlitzer 4027 organ. I'm
> pretty sure the bridge rectifier filter electrolytic caps are aged to the
> point at which they don't filter so well anymore. The power supply uses 4
> inch tall multi-capacitor cans mounted on the PS chassis with pins in the
> chassis and the cans external to the chassis. All caps are employed for a
> total of 10 caps in three metal can packages. Are these antique parts even
> available in new, recently manufactured form anymore? If so, where?
> There are three cans comprised of:
> 1. 500uF/25V x 2, 500uF/35V, and 1000uF/25V (4 caps)
> 2. 1000uF/25V x 2 and 5000uF/25V (3 caps)
> 3. 3500uF/25V and 1000 uF/25V x 2 (3 caps)

Now those *are* going to be pretty dead by now, and NOS ones will be no better.

As others have said, you can cram a lot of capacitor into a small space these days so if you don't mind getting messy corrosive goo everywhere you can open them up, fit modern caps inside, and glue it all back together.

Some folk just stuff the caps in but I'd be inclined to make a plastic spacer to keep them from rattling about.


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