Farfisa Transistors (sft532) substitute?

[urbanopolis]

I have just picked up a nice Farfisa Campact. When I tried it out it
worked nicely, aside from the verb and vibrato.
When I got it home from a 10 mile drive, the C notes are acting up.
Mostly by playing Bflats instead of C's. I suspect the C oscillator
cards dividing transistors which are STE352 (germaniums /i beleive).
What affordable, safe and readily obtainable substitute is there for
that, if any. Or any Farfisa guru's out there willing to help me get
this thing rolling again. It really sounds warm and grindy and oddly I
quite liked it.


best,

joe m

[Scott Dorsey]

urbanopolis > wrote:
>I have just picked up a nice Farfisa Campact. When I tried it out it
>worked nicely, aside from the verb and vibrato.
>When I got it home from a 10 mile drive, the C notes are acting up.
>Mostly by playing Bflats instead of C's. I suspect the C oscillator
>cards dividing transistors which are STE352 (germaniums /i beleive).
>What affordable, safe and readily obtainable substitute is there for
>that, if any. Or any Farfisa guru's out there willing to help me get
>this thing rolling again. It really sounds warm and grindy and oddly I
>quite liked it.

What makes you suspect the transistors and not coupling capacitors in
the dividing chain? Did you heat and freeze them to track the bad one
down?

STE532 is not a valid Pro-Electron number. SFT532 is a valid number but
it's not in the RCA substitition handbook.

Basically, when you sub germaniums, you care about the beta and the breakdown
voltage and not much else, unless the circuit is using leakage to bias the
base. This was a nasty practice but very popular back when germaniums were
new. I don't think that would be an issue in a doubler stage, though.

And I'd make damn sure that you have a bad transistor first.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."