Did I make this old EHX Echo Flanger noisier?

[BrianS]

Try to keep this succinct:
-non-functioning 1978 EHX Echo Flanger comes into shop.  Owned by a long-time user of the pedal.  He's not technical.-Multiple issues found & repaired.  Pedal now works.
-"Upgraded" the AC side of the power supply:  New switch wired so it disconnects both legs of AC.  Earth ground chassis/3 prong cord.  Originally came wired with 2 prong, non-polarized cord.  AC power meets a step-down/isolation transformer and goes on to the rectified/regulated DC supplies.
Current "problem":  pedal is noisy...not white noise/chip noise...mains hum.  Pedal is essentially unusable when amp is set to have overdrive/distortion.  Think of the nastiest 60 cycle hum you can imagine.  "Clean" amp settings are fine for the most part, but the hum is noticeable.

-All input and output jack signal grounds go through the chassis.  I'm wondering if I made the pedal noisier by earth grounding the chassis?  I know these pedals can be noisy regardless, but maybe I made it worse.  These are a real pain to work on, and I'm wondering if it might be worth the effort to either put the old cord back on (or a new, polarized 2 prong cord); or reconfigure the input/output jacks so they are isolated from the chassis & move the grounds to the circuit board.

I know someone will say "try it and find out!", which is a valid response & my next step. Still, hoping someone here has actual experience with something like this.

Link to power supply circuit: https://experimentalistsanonymous.com/diy/Schematics/Flangers/Electro%20Harmonix%20Echo%20Flanger%201.jpg

Link to signal circuit: https://experimentalistsanonymous.com/diy/Schematics/Flangers/Electro%20Harmonix%20Echo%20Flanger%202.jpg

Any insight?  Thanks!
-Brian

[sluckey]

I know someone will say "try it and find out!"

Let me! Let me!   Try it and see.

I would first just disconnect the power cord green wire from chassis.

[Rontone]

A lot of Copicat tape echos are not grounded here in the UK and fitting a 3 wire lead is a typical upgrade, but can introduce noise through the output lead to amplifier, ideally they need a small 1:1 isolation transformer on the output cable to stop any ground loop

Maybe it would help but it is in the signal path, so may change its original sound?

[BrianS]

Tried a few things; nothing helped.  I could fill a page complaining about layout & design of this thing, but I'm not an engineer, just a tech, so what do I know.
There is a part in this pedal that I've never seen before, and is somewhat defective.  I don't know the proper term for it, so I'll just call it a "multi-buss".  It's a long, thin "wafer" that stands vertically with leads coming out the bottom.  It spans the width of the circuit board; basically bisecting it.  This "multi-buss" has 3 "sections:  15V supply; 7.5V supply & ground, all in parallel.  I found that one section of ground was open, so jumped that with a wire.  All the other sections seem to be doing their job, though.  It is kind of de-laminating on one end, though.

I hate to do it, but I'm shotgunning the rest of the electrolytics.  The new parts are here; just have to put them in and pray I guess...
Thanks.

[sluckey]

Picture please.

[BrianS]

Here's a few pics (hopefully this works):



 https://photos.app.goo.gl/pubBzZJb9ZJK5DJL6

Didn't even see the "Bussco" label on the buss until I zoomed in to take the pic!!

[sluckey]

Link doesn't work.

[BrianS]

Edited link...try again?

[sluckey]

 

[goldstache]

I offed the one I had a year or two ago.
Big 60/120hz hum till I realized reservoir cap post power transformer had a lifted pad.
Perhaps?