Prodigy: PSU Replacement

[hydorah]

Hi All I have an old Prodigy that just doesn't work properly any more, just makes weak whistling noises!

I think it's the power supply - according to the schematic / specs it is delivering too little voltage (I get 18v where I should see 23v)

So I want to replace it and see if my Prodigy starts singing again

I'm in the UK so I need input voltage of 220 - 240v anyone know where I might source a replacement?

Cheers!

[megavoice]

My tech is building VERY High Class PSUs for nearly all vintage synths. I`m gonna tell him that you need one, but he has a lot of work to do presently.
It`s good for you as for the shipping costs that you`re in the UK.

[torinkrell]

It's likely that if it's really only your power supply that is malfunctioning, it may only need some of its capacitors replaced. This is much easier and cheaper than replacing the whole power supply. Complete power supply replacement, with quality vintage synths, makes the most sense with some of the early poly synths which drive the power supply hard making it run rather hot (like the Prophet 5).

[megavoice]

It's likely that if it's really only your power supply that is malfunctioning it may only need some of its capacitors replaced. This is much easier and cheaper than replacing the whole power supply. Complete power supply replacement, with quality vintage synths, makes the most sense with some of the early poly synths which drive the power supply hard making it run rather hot (like the Prophet 5).

Yes, you`re right in some way, in the first place caps can be the culprit but they`re not the only ones. Those units are VERY old now and worn down, "antique" conceptions, and in worst case they`ll blow the whole instrument.
Note also, a PSU for a Prodigy is not that big and expensive like fore vintage polys

[thealien666]

"antique conceptions" ??? That's a new one on me. Unless it's made up of valves and cardboard casings capacitors ?

It's simply a very simple and standard linear PSU, like those found in millions of devices even today, although the switching type PSU is gaining in popularity I'll give you that.

It's made up of very few components: a transformer (that's still working obviously), an AC/DC rectifying bridge composed of 4 diodes (one of the diodes might be defective resulting in a "dirty" DC supply and could explain the slightly lower input voltage measured at the inputs of the regulators), a couple of filtering electrolytic capacitors (those might not be as effective anymore at filtering ripples, but that should not result in a "dirty" DC at the outputs of the regulators), and two voltage regulators (one +12V and one -12V). That's it. Nothing complicated or antiquated here.

With the power off, check each diode in the bridge for proper functioning with your multimeter. Replacing a possibly faulty component and recapping is much less costly than replacing a whole PSU.

Although I doubt very much that anything is wrong with your Prodigy's PSU to begin with, as 18 Volts is more than enough to drive those regulators properly to output 12 Volts.

From my experience in dealing with such "antiques" ( ) as the Moog Prodigy, the problem of weak whistling noises has most probably more something to do with scratchy pots, switches, and poor connectors contacts, or even cracked solder joints somewhere.

Oh, and welcome to the Moog forum, hydorah !

[megavoice]

Yes, indeed, that thing is very simple.
I also had been told recapping and replacing the stabilizers should be at first eneough. It doesn`t need promptly to replace the whole unit, but having a new and healthy heart in you body is life essential at any rate...........
For that faulties described above of course there may be other reasons as well to be possible...............

[atkbg]

As alien noted, the PS are simple and the parts are inexpensive. In a simple synth with minimal power requirements shouldn't need a mega psu.

A former member here said that he always checked power, then gave everything a bath. Many issues would disappear after that.

[megavoice]

I didn`t ever tell that a MEGA PSU is needed.....................

[megavoice]

Might be interesting for anybody here, but my tech told me yesterday he had two Prodigys for repair with a broken tranny, each.
SO simple as they are........................