farfisa CompactDuo organ

[TimothyH]

Hi all. I just set up my old Farfisa CompactDuo organ after about 20 years. There was considerable "scratchiness" that went away as I played it and turned the knobs, etc.

A couple of problems remained:

1. each G note actually sounds a G# with some distortion. This isn't merely a matter of tuning. I've done some internet searching to learn about this problem and I get the idea that the G oscillator may have a bad germanium transistor. Does anyone have an idea as to whether this might be correct, and if so, how does one find replacements?

2. The 2 2/3' stop seems to give erroneous notes for all the G and C keys.

Any help would be greatly appreciated, since I can't find a shop in my area that works on these organs. I have very fond feelings toward this organ, since playing it payed my way through college and I met my wife while playing it.

Thanks.

Tim

[Regis]

Hi Tim,

Here is a site dedicated to combo organs. They have a Farfisa page and links to other ones. I have a Farfisa given to me that needs major work, I've been putting it off because it will be a big project to restore it.

regis

[Enzo]

Someone suggests it might be a germanium transistor? Gee, I bet every transistor in it is germanium. Now what?

It sounds like that oscillator is off, yes. i would be more inclined to suspect a cap. I don't have my ancient Farfisa files handy, they are out in the warehouse. It was dountful anyone would want to spend what I would charge to restore one of those, so why take up shelf space in the shop?

In some boards there is a master oscillator, top divider and octave dividers, and in other boards, there are 12 oscillators with their own octave dividers. Most run off adjustable RC or LC timers, and as the caps drift, you run out of range on the tuners.

Loss of a transistor would knock out the oscillator or divider stage or whatever, but I woulod not think it would detune things. I could be wrong too.

Check the junction drops with a meter. Germanium has a lower junction voltage than silicon - about half as much. SO instead of .5v it will read like .25 volts or so. FInd the main osc for that note and check all the transistors. COmpare to those in another note for reference.

Get all the notes right, and the problem with the stops might sort itself out. All those are are various routings of the existing notes. SO if the notes are wrong, so then will be the stops.

[TimothyH]

Thanks for the input. I'll try your suggestions.

It turns out that the organ has 12 oscillator boards, each with a divider section.