Farfisa Mini Compact Schematic

[Leah Soechting]

Littlebrother to the Compact, the Mini offers a good compromise between featuresand size/weight. There are three flavors of the Mini: The basicMini Compact, the Mini Deluxe, and the Mini Deluxe I. The latter two areactually Farfisa designations I've gleaned from literature, but all sport onlythe name "Mini Compact". Those that have a modelnumber on their ID plates list it as "Mod. MC/3 = MINICOMPACT" The word "Deluxe" never appears anywhere on the organ, as far as Iknow.

Volume pedal/Knee Lever: All the Minis feature the famousMulti-Tone Booster and Knee Lever. In the Mini, however, the Knee Leverperforms the dual function of Booster level and Volume control, even with theBooster tabs switched on. With the lever in normal position, the volume isvery low, prompting many Mini (!?) owners to come up with a way to fasten thelever in its fully-pushed position. Thankfully, an optional volume pedal(identical to the one used for the larger Compacts) remedies the situation. When plugged in, the pedal performs normal volume control functions, freeing thelever to concentrate on its more natural function of adding in the Multi-Tonevoices.

"The footage tabs are actuallyassociated with the voice tabs and the multi-tone booster. With MTB off, if allthe footage tabs are off, you won't get any sound, regardless of which voicetabs are engaged. With MTB off, if you engaged 16', 4', dolce, and string, you'dhear 16' dolce, 16' strings, 4' dolce, and 4' strings. You can really get a fairnumber of decent sounds out of the li'l guy"

The Mini-Compact has a volume pedal cablewith a DIN plug on the end, just like a Compact. I'm not certain ofthis, though - some may not have this cable. I don't think any of themhave the DIN jack on the underside of the organ, like the Mini-Deluxe(below)

Underside, with legs stowed. Note the DIN socket near the knee lever - that's for the optional volume pedal Click on the picture for a nice BIG closeup of the tabs. Click on this one for a nice BIG picture of the innards (Pictures courtesy of Sandy Alexander)

Note the gold lettering on the plastic top - "FARFISA ... compact", rather than the MUCH more common "combo ... compact" Henry Badowski tells me that all of the Compacts he's seen in the UK have this wording. From my (far more limited) experience, I'd tend to agree. The one shown here found its way to Australia.

This one's almost a Deluxe. It has the switchable 2nd octave of gray bass keys,and Percussion. The three white bassvolume tabs have been replaced by a Bass Volume knob. There are no other markings, however, to distinguish it from a regular Compact. All the lettering and the ID badge are the same.

Left side controls - here's where the difference is. RIght side - no differences here And here's a nice red one Note the textured plastic top. This is the only version of the Compact that has this type of top - all the others are smooth. Rearcontrol panel: I've only seen a few pictures, but they don't seem to beconsistent. Some appear to be like the Compact (second version), with the4 knobs and output jack, like this....,and some are like the Deluxe, like this:

This Deluxe is highly unusual - the rear plate is identical to the ones on the Compacts. Virtually every other Deluxe I've seen only has the output jack, volume control, and fuse holder (like on the picture at right) This is the typical rear panel on a Deluxe I Compact 7

Fortunately, however, the power supply portion (the really critical part) is relatively easy to duplicate (unlike that wretched Gibson G201 amp/power supply!), being basically just a single-voltage DC power supply and a couple of wires for the audio output (well, it's also got a 9VAC output for the volume pedal bulb). Click here for more information, including a schematicThe F/A-R included a full-size Hammond-style reverb tank, which does not need to be driven by tubes, so it's a fully-transistorized unit Unlike its lesser brethren, The Duo,was only available in a paltry two versions, detailed as follows:

"The tone controls from the F/AR were at maximum all the time. Somedistortion happened in the sound card on some of the demos (especially the firstones). Demos 5-10 have left hand bass. Those sounds that use the 2 2/3 - 2' tabare only available on the Compact Duo "non-effects version". The restof the sounds (demos 1-3, beginning of 8 and 9-10) are available on the basicsingle manual Compact too (except for the better quality spring reverb of theF/AR unit)."

The 2-2/3' tab (single footage, not like the earlier Duo's mixture) on thisversion is pretty much like that found on the Deluxe,with its mellower sound. I'm told that this version of the Duo was used on later (post-Syd Barret) PinkFloyd.

This is an optical pedal - There's a small light bulb and a Light-Dependent Resistor (LDR) in there. As the pedal moves, a mechanical shutter varies the amount of light allowed to fall on the LDR, putting a variable resistance across the output. Why not just use a potentiometer (pot)? Durability and noise. An organ volume pedal gets a LOT of use (way more than the volume knob on a guitar or amp). A mechanical pot would wear out or get dirty and scratchy sounding fairly quickly. With the light bulb/LDR setup, there are no mechanical parts that directly affect the sound, so no matter how much it's used, it'll never get scratchy or wear out. The bulb, however, will sometimes burn out, but it's easy to replace - just remove the little panel on the left..

Note the bracket on the right side of the pedal. That fits into two posts on the bottom of the organ legs. There are thumbscrew adjustments underneath to get the fit just right. The DIN socket on the pedal maybe 3-pin or 5 pin, but only 3 pins are used. The plug from the organ is always a 3-pin, which fits fine into either socket. Pins1 and 2 carry the 12 volts to drive the lamp, pin 3 and the shield connect tothe LDR for varying the volume. Here's a snippet from the schematics:

I am revisiting the Farfisa Transicord because I have been asked to build a power supply unit for one, and after investigation it seems there is a need to clarify the situation and provide some substitute designs.

How hard could it be? Well this apparently simple request resulted in considerable confusion until I found combo-organ.com. While this site only deals with the Transicord in passing, it contains extensive information on servicing the Compact Duo combo organ which is closely related, and provided some valuable missing bits to the puzzle.

The capsule history of Farfisa is that it was a merger of several Italian accordion builders, and the Transicord electronic accordion released in 1962 was their first electronic product, the more conventional keyboard line of combo organs following about two years later. For the full Farfisa story see the link above.

Farfisa's initial decision to split the electronic accordions and organs into two units, the instrument and companion power supply on the floor, was fateful and has resulted in some instruments being separated from their unique power supply and becoming non-functioning junk.

If you have, or a considering buying, either model Transicord (or a Compact) without power supply; these are not available over the counter, however anybody with some electronics skills who can build a robust and safe low-voltage power supply, can build a suitable substitute. We will look at this in detail below.

We also know that the plain Transicord accordion and the early Compact Duo combo used much the same electronics internally and the same F/AR power supply, although the relationship between the Deluxe and later Compact combos is unclear.

Like Farfisa organs generally, there are also a number of Transicord variants, mainly using button rows instead of piano keys for the right hand, with markings in several European languages, and different connectors for American and European models, however internally there seem to be only two major variants, the Transicord with one row of voice tabs, and Transicord Deluxe with two.

We might expect that the Deluxe model would follow the plain Transicord, but if that is the case it represents a leap into the past in styling, and a loss of facility with the dropping of the reverb. Which came first? No idea, and given how Frafisa progressed they could have been trying to cover both modern and traditional bases at the same time.

This design is a simple unregulated single supply of around 11 volts. It may get you going, but at best it is an incomplete subsitute for the F/AR supply required by both the Transicord and Compact Duo, as we will see below, and certainly unsuitable as a replacement for the ATR/3 supply for the Transicord Deluxe.

The supply must be DC, at least 12 volts, and capable of delivering at least 200-250mA. It doesn't need to be a regulated supply but it must have a suitable resistor between the supply and the instrument in the positive lead.

A modern replacement for the ATR/3 could easily be constructed, say in a recovered computer power supply case, using common low voltage transformers and 3-pin regulators. If you already have a dead ATR/3 then repair should be a straightforward matter.

This is my suggested but so far untried (I don't need one) modernised replacement circuit for the above, with PCB layout suitable to be built in an old computer PSU case. Notes: Some tweeking or scaling of the regulator offset resistors may be required to bring the rails to the required voltages before you unleash it on the instrument; and the stability caps on the PCB are not shown on the circuit.

There are two reasons for this change, firstly finding a suitable case for the length of a reverb line, and secondly that modern effects units and pedals are available these days which are much more versatile than just a springline.

The circuit of the F/AR supply alone still left a couple of questions unanswered. The DC output is fed via a resistor network, thus the actual terminal voltage depends on the current drawn, so what should we expect here? The second question is what the 9 volts AC is used for in the instrument.

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