Polymoog 203A joins the fleet and queue for repair

Few synthesizers have such a bi-polar reputation.  Amazing sounding and tedious to maintain, much less restore are the two poles of this equation.  Moog churned out a few of these – I am guessing a little over 3000 since they started with 1001 and this fellow is serial number 4021.  The reference to the latest one I’ve found is 4141.  Gary Numan famously used the Polymoog (280a I think – Vox Humana most recognizably) and so did a list of other luminaries if VSE is correct, but there isn’t anyone recent on that list.  I’m excited to fix this to see what it can do in a modern setting.IMG_6922

It just happens sometimes.  You mention you have an X you are looking to get rid of, and a friend says they have a Y they’d like to get rid of.  A little cash one way or the other sweetens the deal.  In such a way this complete, clean, low mileage, semi-functional Polymoog joined the menagerie.


Always job 1: see what’s inside.  Dubsounds, a site dedicated to the Polymoog has some discussions around getting one of these playable, and it looks like the place to start is replacing the capacitors in the power supply then calibrating the voltages to the rails. IMG_6927

The serial number is hand written in several places.  Note how yellowed the sticker on the panel is.  I wonder if it can be made white with retrobright, or if there is an appetite in the Polymoog community for a reproduction sticker. IMG_6928

One of my first jobs on all keyboards I get is to clean the keys.  Soap and water goes very far and you get instant gratification, because it will look so much better when they are all clean.  Not many keyboards start with the E key!


Here’s the power supply ready for a new capacitors.  This is one of the first I’ve seen with a 4700uF/16V capacitor.  Do I replace the 3 LM723CN’s?  Foil is to protect (and protect me from) the white grease they put on the power supply chassis – probably to keep it from buzzing.


2 thoughts on “Polymoog 203A joins the fleet and queue for repair

  1. Only replace the voltage regulators if they’re broken. The white grease is thermal transfer compound, to dissipate the heat from the pass transistors down to the chassis of the keyboard.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s