Maestro PS-1 Phase Shifter Questions

[JeffersonRhodes]

Hi,
I'm not too knowledgeable about electronics in general, but can do some minor repairs etc.

That being said...

I recently came across a Maestro PS-1 Phase Shifter. This thing is from the 70s and I use it through a Rhodes electric piano. My question is probably pretty simple to answer or at least I hope it is.

Common with vintage equipment, there is a low 60 cycle hum coming from this pedal. What can I do to help reduce the hum? Can I add copper shielding inside the pedal?

Also, this pedal seems to cut the volume quite a bit. Is there some tweaking that can be done so I can keep my volume at a decent level??

Thanks!
Matt

[Mark Hammer]

Hmmm. Could be that your hum and level problems are linked.

Do you have a schematic for it?

[JeffersonRhodes]

Hmmm. Could be that your hum and level problems are linked.

Do you have a schematic for it?

I do have a schematic for it.

http://img441.imageshack.us/img441/5877/oberheimps1fg9.jpg (http://imageshack.us)

Does this help at all? I would love to get in there and tweak with the tone and phasing, do you think that's possible?

Thanks for the help!
Matt

[Enzo]

First thing I'd do would be to make sure the +15 and -15 volt supplies are close to their proper levels. COnsidering the minimal expense, and the age of the parts, I would replace the two 470uf filter caps in the power supply as well.

I would loosen and then remount all jacks to make sure they have a fresh contact with ground - the chassis.

Is this lower level signal only in effect mode, or is it diminished in bypass as well?

[JeffersonRhodes]

It does not diminish the bypass, but I can hear quiet "clicks" in the background of the phaser still in action waiting to be kicked on.