Mutron Phaser II transformer voltage?

[armdnrdy]

Hi guys,

Does anyone know what the secondary voltage at the power supply transformer in the Mutron Phaser II is? I've searched the net and came up empty. I'd like to build this phaser incorporating a LM78XX voltage regulator and feed it with 18VDC from my DC Brick.

If anyone has this phaser, and could take a reading, I would be very appreciative.

Thanks,
Larry

[Processaurus]

If you aren't cloning the power supply, it isn't necessary to know about the transformer, just what the power supply requirements for the rest of the circuit is.  From my blurry schematic it says the DC power going to the phasor circuit is a split one, +10.8v and -11.3v.  I bet it would run fine on +/-9v if you made a negative 9v out of the +9v with a charge pump IC (like the LT1054).

Here's a schematic someone re did of the power supply, showing the dc voltages being fed to the opamps etc:
http://www.aronnelson.com/gallery/main.php/v/RLBJR65/Mu-Tron+Phasor+II+pg2.GIF.html?g2_imageViewsIndex=1

[Derringer]

Hi guys,

Does anyone know what the secondary voltage at the power supply transformer in the Mutron Phaser II is? I've searched the net and came up empty. I'd like to build this phaser incorporating a LM78XX voltage regulator and feed it with 18VDC from my DC Brick.

If anyone has this phaser, and could take a reading, I would be very appreciative.

Thanks,
Larry

I have one and I just had it opened up a few days ago ... I didn't measure it then but i am pretty sure from being inside of it a while back that you are looking at around + and - 10V for your power supply. If I need to go into it again I'll be sure to measure again and post it.

I am curious what you're going to do for the vactrol? Will you use one LED with six photoresistors or maybe a one to one ratio? The original has a funky self contained vactrol that I don't think is available anymore .... but I'd love to be proven wrong on that assumption.

[armdnrdy]

Derrringer,

A site member Araya, who has been very helpful, has built a working clone utilizing three dual element axial vactrols (VTL5C3/2) which are still available.

Larry

[armdnrdy]

Processaurus,

I was thinking about utilizing a LM7812 and a LM7912 and other components to make an on board split power supply. I will feed the PS with 18VDC from a DC brick and will end up with +12, -12 and the zero point. (virtual ground ) The split power supply circuit is depicted in the LM7912 data sheet. I wanted to feed the effect circuit with 12 volts for more head room.

Does anyone have thoughts on this?

Larry

[gulnare]

Sorry to rehash an old topic, but I'm chasing the same info as the OP.

Copied from an email I sent to some people:

I have recently come into possession of a Mutron Phasor II pedal which the previous owner has accidentally plugged into 240v.
I have replaced the fuse and plugged it into a 110v stepdown transformer and it worked for a short while before the internal transformer got very hot and the pedal ceased to phase.

I measured the 12v traces on the board and am only getting ~+3v and -3v.
Would this indicate to you that the transformer has been damaged? All schematics I can find are quite blurry.
The part number on the transformer is 5707301 EIA606-927.

Given the only schem I can find, I'm assuming given the voltages after rectification that the transformer should be putting out 24vAC. What do you think?
I'm thinking of replacing it with a 240v to 24v tranny to get rid of the external stepdown.

Here's the schem, seems to be the only one people have:
http://www.sonicurbs.com/mutron2/schem.jpg

Cheers!

[armdnrdy]

I found another drawing that lists the transformer at 30v center tapped. 15-0-15

There are other components that make up the power supply that could be bad.

I would disconnect the transformer from the rest of the circuit for testing. You should read somewhere between 12-15 volt each leg to the center tap and 24-30 volts leg to leg.

[gulnare]

Cool, thanks.
Pretty sure it's toast, getting ~3v between centre and each leg and the tranny looks pretty black on the bottom.
Only problem now is the one I bought to replace it doesn't fit the PCB/enclosure.