Vintage Synth Repair

> Its amazing that Roland and Yamaha took the opposite paths with polarity, while using identical plugs!

Just as a sidenote, if repairing DC-operated gear adding a overvoltage / 
reverse polarity protection diode is usually not a bad idea. These are 
cheap parts that will definitely save from the more expensive external 
power supply operation related repairs. Heck, I'm constantly wondering 
why is it that gear manufacturers even consider these diodes something 
worth omitting. Definitely a wrong place to save up on mfg costs!

Anyway, with polarity protection you do lose a bit of the DC over the 
diode, but most equipment usually work even despite the drop. AC fed to 
this protected input gets clipped to whichever half cycle is allowed to 
pass, so it's a safeguard against AC as well.

Personally, I'm also quite a big fan of self-resetting thermal fuses 
these days. There's hardly ever the need to solder in a new one once you 
put one in, so it does save up time spent on glass tube fuse shopping 
sprees ;)

.Arto.
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