Does anyone know where I can get transistors for a 30 yr old Spectral amp DMA200?

Never heard of the output mosfet devices listed. www.exicon.info, Exicon makes lateral mosfets for your class a amplifier. Each n and p device respectively should be matched else current sharing per device will be compromised. This means n's are matched and p's are matched. Also, voltage biasing for these new Exicon devices tends to be lower so the voltage biasing circuit may need modification to accommodate the new devices otherwise biasing current will not be able to be adjusted low enough.  

you can the VN0120N5  here at the below company, they may have a min..25 pieces in stock. 

Standard radio

631-234-3330

They refused to work on it because it is so old. But the 200w of pure class A sounded very good. Spectral doesn’t make pure class A anymore.

You would think that at Spectral prices they would have kept a supply for future repairs.

@czarivey Thanks.

One of the datasheets to match parameters:

https://www.datasheets360.com/part/detail/vn0116n5/-2706982422070585151/

All other datasheets you can find same place for your further research.

Search transistors by datasheet is possible below:

https://www.digikey.com/en/products/filter/transistors-fets-mosfets-single/278

After finding possible choices, you can use best available even if it's far not the best.

Stephen thinks those VN transistors are not authentic.

It sounds like VN are gone but PN are not gone yet. I guess the VN's could be replaced and pray that it will play. Larger heatsinks are being put in.

@chungjh if you only replace the bad ones (VN), then do you need the PN ?
 

@holmz thanks. It looks like they have the VN but not PN

I've had luck finding obsolete semis on eBay. Just do NOT buy from China as they are most likely fakes. 

You or your friend might first investigate the possibilities offered here, and then come back if the parts cannot be found.  Someone like Nelson Pass or Bill Thalmann may also be able to advise about a modern part that is interchangeable with the needed part.  Such newer parts are often better than the originals.  What makes you or your friend think that the latter two transistors are "near failure"?  Anyway, you guys have to do the searching and asking.

Might try Electronic Goldmine.  I found a Capacitor there for my wife's old sewing machine. It was the only place that had one.

Chuck 

@holmz thanks. It looks like they have the VN but not PN.

@lewm  or the OP could just get them from the first link that showed up?
(A testimony to the power of my 2 cups of coffee.)

First, google those part numbers. You might find the parts right away. Then check Jameson Electronics on the West coast. Then ask the Spectral designer if he’s still alive or anyone associated with the company. Then ask Nelson Pass. I hope you’ve consulted Bill Thalmann in Springfield, VA, to do the work.

… that are probably near failure …

I doubt it. Fighter planes and spaceships run this gear, and they either work or fail.
(Sometimes it is possible to have them go bad in a non binary way.)

Did you try “GTS” (Aussie slang for “Google that $hit”)?

https://www.standardradioelec.com/vn0116n5