Mestro/Oberheim Ring Modulator 9v conversion

[bside2234]

So a friend of mine gave me a Oberheim Ring Modulator to see if I can convert it to use a 9vDC power supply instead of the AC cord attached to it.
I built a bipolar power supply using a couple charge pumps and I can get the required -/+ DC voltages. I even measured the voltages in the pedal. +15 is actually +16.01v and -15 is actually -16.43v so I adjusted my power supply to be as close to it as possible. I'm a few mA off each one.

When I attach my breadboarded charge pump to the circuit, the voltage drops down to a few mA's and the pedal doesn't work. I'm thinking there might be something in the stock power section that is causing this but I don't know what I should try and disconnect. It takes the +/-15 volts and converts it down to +/-12v also so I don't want to mess that up.

Any ideas?

Here's the schematic: http://experimentalistsanonymous.com/diy/Schematics/Ring%20Modulators%20and%20Frequency%20Shifters/Maestro%20RingMod.gif

Edit: Oh, I've been hooking up the +15 to the 1N965/470Ω junction, the -15 to 1N965/390Ω junction, and the ground to ground.

[Paul Marossy]

IIRC, those charge pumps are very limited as far as the amount of current they can do. The circuit may require more current than the charge pumps provide. What happens to the voltages, do they stay where they need to be?

Also, you might want to think about using some voltage regulators to make the power supply exactly what it needs to be.

[bside2234]

When I hook up the charge pump it drops down to ~.3v on both + and - sides. I was thinking the circuit may draw more current than it can supply. I should probably measure the current draw.

[Paul Marossy]

When I hook up the charge pump it drops down to ~.3v on both + and - sides. I was thinking the circuit may draw more current than it can supply. I should probably measure the current draw.

Yeah, probably a good idea.

[bside2234]

Ok. This poses another question. How/where do I measure for current draw on this thing?

[Paul Marossy]

Ok. This poses another question. How/where do I measure for current draw on this thing?

You have to insert your DMM between the circuit and the power supply to measure current. In other words, it has to be in series with the power supply to be able to measure the amperage.

[bside2234]

Yeah, I tried that but wasn't getting a reading. I'll try it again at the bridge rectifier.
I really think something in the power section is affecting my new power supply.  I'll probably end up removing it all and going with my bipolar charge pump and a couple voltage regulators.

[Paul Marossy]

Yeah, I tried that but wasn't getting a reading.

That's probably your problem!  

I'll probably end up removing it all and going with my bipolar charge pump and a couple voltage regulators.

That's probably the way to go, as long as it can provide the current required for the circuit to work properly.

EDIT: BTW, you can parallel charge pumps for more current.