[sdiy] SSM2164 last time buys

[Oscar Salas]

Hello Tim!

No, It is not  a mosquito. It is a real problem.
V2164 and SSM2164, If they have not protection, accordingly my tests die if negative rail is not present.

This means that if negative rail falls will kill all the 2164s that are in that power supply. 

In a modular synthesizer where exist the possibility of reverse and short the negative rail, the 2164s *must* be protected. Also if the module is not for yourself you don't know where it will be connected(quality of the power and distribution supply)

It happened to me once that three of my quad VCAs (six chips) died, and now after my recent tests there is not any other possibility that I accidentally shorted the negative rail. I should house my modular better. I had include a resettable fuse in the PCB but I bought a wrong one that trips over a few amperes.

So, Tim, could you do a test? Could you cut the negative rail of -for example- one of your Mankatos -it is one 2164- and see if the chip dies. And which is the resettable fuse?

> I would also like to know if a simple resistor would work
> okay. I
> believe it will. On my first parts list for the Mankato
> VCF, I
> specified a resettable fuse and protection diode for each
> rail on the
> power input (totally stole the idea from John Blacet), and
> the part I
> listed had a fairly high resistance. This affected the rail
> slightly
> and made the peak to peak outputs a little lower, but
> caused no
> problems otherwise. I've since specified a part with a much
> lower
> resistance, but like I say, I'd be interested to see if a
> simple
> protection scheme would work properly. BTW, how often does
> this
> problem really happen? I've never really had it crop up and
> it doesn't
> seem to be a common occurence, so I'm wondering if we
> aren't hunting a
> mosquito with a bazooka here.
> 
> 
> Tim (proudly displaying the stuffed and mounted mosquito
> head on the
> wall of my den) Servo
> -- 
> "Sire, the church of God is an anvil that has worn out many
> hammers."
> - H.L. Hastings
>