Spares and Repairs

1. Baldwin Organ Parts
2. Baldwin Organ Schematic

Where can I find a user manual for a Baldwin MCX 1500 spinet organ? I would like to find the technical manual for the Baldwin Studio II (213DR)organ.

Common Problems	Sources for Parts and Manuals	Where to go for repairs
General DIY Information

Free Schematics and Manuals!

Combo Restoration Projects!
Follow along as fellow Combonauts repair and restore their bargain finds

Restoration Project #1
An Italian Continental complete with all parts, but in pretty poor shape
Restoration Project #2
Another Italian, this one started as a collection of parts in bags, with some major structural parts missing!
Restoration Project #3
A sad UK Continental is brought back to life - and he didn't need a PhD in Electronics!
Restoration Project #4
Not a complete restoration, but a well-documented repair effort on an Ace Tone TOP-9

Common Problems (or modifications) and how to deal with them

NEW!Vox key removal, replacement, adjustment
Testing for bad oscillators, dividers and key contacts
How to tune your combo organ
How to clean key contacts
Farfisa Compact Duo and Gibson G-201 power supply
Gibson G101/ G201 and Lowrey T2 Percussion/Repeat circuit problems
No output at all
Yamaha YC-series Touch Vibrato
Vibrato doesn't work or is too fast/slow
Checking Electrolytic Caps
Organ makes a constant whiny racket, or growling noise when any key is pressed
Vox Continental Vibrato Speed/Depth Control mod (this is a link to a different web site - thanks, Daniel)

Vox key removal, replacement, adjustment

Vintage Vibe has done a great YouTube video on replacing the bushings on a Vox keyboard. He shows how to tell if you need bushing replacement, how to remove the keys, replace the bushing, adjust the keystop, and adjust the key actuator. His method should work for any Italian vox keyboard (Continental, Super Continental and Jaguar). Click here to view the video

Testing for bad oscillators, dividers and key contacts

Most combo organs will have at least one or two bad divider circuits, often several. Dirty key contacts are pretty common, too (see the cleaning procedure, below), and a bad oscillator pops up now and then. Bad dividers are easily overlooked when testing, because if you have more than a few footages selected, they can be masked, or it will seem as though some notes just sound a little 'off'.

Test procedure

First turn off ALL tabs, drawbars, etc. You'll want to work with only one voice at a time, and ONLY even-numbered footages, and ONLY Flute (or flutelike) voices - ignore any fractional voices or mixtures. Fractional voices, mixtures, and non-flute voices may add additional notes to confuse the procedure.

To test the oscillators, turn on the highest even-numbered footage voice, usually 4' or 2'. Play the twelve highest notes on the keyboard. If any of the notes fails to play, then you probably have a bad oscillator. To confirm this, play that same bad note in lower octaves. If it fails in all octaves, then the oscillator is bad. If it plays correctly in the lower octaves, then you probably have a bad key contact in that top octave. The Oscillator circuit is usually a small collection of components near the tuning coil on the generator board for that note. Oscillator problems can be a bad transistor or capacitor, a loose connection, or, in rare cases, a bad tuning coil. It would be extremely unlikely for a tuning coil to have a broken connection inside - it's most always the connection from the coil to the circuit board that's gone bad.

From here, we'll test each divider circuit. There may be as many as 5 or 6 dividers for each note. With the same tab on as previously, play each successive lower octave. The first octave below the top octave (with the highest even footage on) is the first divider, the next lowest octave is the 2nd, and so on. When you reach the bottom of the keyboard (NOT descending into the Bass octaves), then turn off the voice tab you have on, and turn on the next lowest even footage, and play the same note (the lowest one short of the bass octave). Continue to do that until you hit the 16' foot tab, which will be the lowest divider in the chain. If a note stops functioning that worked in the previous octave, then there's your bad divider. Divider problems cascade - once you have a bad one, none of the notes below will play correctly. The good news is, once you fix that divider, there's a good chance the lower notes will suddenly come to life. The bad news is, if you have more than one bad divider for a given note, you can't test the lower ones until you get the ones above it working.

Each divider circuit is a small collection of components on the generator board. You'll see a repetitive formation of components starting near the oscillator circuit. Each formation surrounds a pair of transistors. In my experience, most divider problems are caused by a bad transistor, but bad capacitors or just bad solder joints can be the culprit. It could even be a bad resistor, but that would be rare.

Is it a bad divider or key contact?

As noted above, a bad key contact in the top octave displays the same symptoms as a bad oscillator circuit. With dividers, the same can happen, but it's tricker to diagnose. Here are a few tips:

Check lower notes: When a divider goes bad, it almost always affects all the successive lower octaves. If you think you've found a bad divider, play the lower octaves of the same note - if they fail, then it's likely a bad divider. If they play properly, then you've got a bad key contact for that particular note. If the failing note is the lowest on the keybard, with the 16' voice on, then it could be either - there's no way to tell without checking the contact out and/or testing with a signal tracer (see below)

What about the bass octave(s)?

We've been ignoring the bass octave(s) til now, because they can muddy the waters of diagnosis. On some organs, the bass notes are just additional divider outputs, but filtered differently. On others, a separate, single divider circuit serves the entire octave(or maybe two). On some organs (the Rheem Mark VII comes to mind), there's a combination of these two. Generally, if a bass octave is polyphonic (you can play more than one note at a time and they all sound), then it's driven off the lowest divider(s) in the chain, and can be treated like the rest of the keyboard for diagnosis and repair. If the octave is monophonic (only one note plays, no matter how many keys you press), then there's probably a single Bass Divider circuit that serves the whole octave. In this case, if the divider circuit is bad, the whole octave will be affected. Bass Divider circuits are usually on a separate card by themselves. On the Vox Jaguar/Howard/Doric organs it shares a circuit card with the Vibrato circuit.

Repair

DISCLAIMER: The advice given here is intended for use by people who have a fundamental knowledge of electronics, soldering, test and repair procedures. It is NOT meant to be 'Organ Repair for Dummies'! If what I've written here doesn't make sense to you, then please seek out a qualified repair technician or a friend who IS able to understand what I have here. If you generally understand the procedures, but just have specific questions that I may not have addressed or clarified, feel free to contact me. If, however, your question is more along the lines of 'what's a power supply?' or 'which ones are the transistors and which are the capacitors?', then you probably fall into the category of people who should not attempt this sort of repair. Please do not contact me expecting extensive hand-holding through the entire procedure, or some magical 'connect the red wire to the blue wire' quickie answer to your problem.

First, if you're working on a Vox UK or Italian Continental, your fix may be as simple as adjusting the bias pot. Turning this pot slowly while checking the notes will often bring the missing ones back to life. If doing that seems to fix the problem, but only intermittently, then you may need to replace the bias pot. These are available at Northcoast Music

Next, if the organ in question has plug-in oscillator boards, the first (and easiest) thing to try is to remove the board and clean the contacts (both on the board and on the socket it plugs into). Use alcohol or a good contact cleaner, and a soft applicator like a toothbrush or Q-tip. A pencil eraser does an excellent job of cleaning the contact traces on the circuit board itself. Re-seat the board, and pay particular attention to make sure none of the contact is bent or otherwise prevented from making good contact.

At this point, you've identified the problem area(s), and all you have to do is replace the failed components, right? Unfortunately, I know of no way to determine which component is bad. For dividers, I usually just replace one transistor, test, then replace the other. If the board is difficult to remove or access, it might be best to just replace all transistors and capacitors and be done with it. I've found that in divider circuits, the problem is almost always a bad transistor, but capacitors can be the problem, too. With Oscillator circuit transistors, try to get a close match to the original. NTE Electronics has a pretty good cross-reference here. Divider transistors are a lot less critical. As long as you get the type correct (NPN or PNP, Germanium or Silicon), and it's an audio-frequency transistor, it should work. I've even heard of people successfully replacing a Germanium transistor with a Silicon type. Watch out, however, with Farfisa Compact and Vox UK and Italian Continentals circuits that use Germanium transistors - I don't have a lot of experience with those, but I think they're a little more finicky about having a correct substitute. The exception to this is the US Vox Continental, which uses garden-variety Silicon NPN transistors. Electrolytic caps (those with '+' markings and values greater than 1uf or so) should also be first candidates for replacement. Fortunately, most Oscillator and Divider circuits only have a few components, and replacing all of them wouldn't be a big (or expensive) job. Some people just replace every capacitor in the organ, which should certainly reduce future failures and dramatically extend the life of the organ.

Bench testing, making and using a signal tracer

In the description below, I'm assuming a removable generator board, but this procedure can also be used with the board in-circuit in the organ - you just have to be careful where you stick the probe, and obviously (I hope) you won't need the power supply!

Many organs have plug-in oscillator boards that can be removed and bench-tested. All this involves is hooking up an appropriate power supply to supply DC voltage to power the board, and using a signal tracer to check the oscillator and divider outputs. This is easiest with boards that only need a single supply voltage. Make sure you observe the correct power supply polarity - UK and Italian Continentals, for example, use a negative supply voltage, in which case the + output from your power supply will go to Ground and the - output to the DC input. Some boards have the supply voltage connection point clearly marked - it may say 'B+' or 'Vcc' or simply '+'. If not, you'll need a schematic or board diagram to guide you. Once the board is powered up, you can us a signal tracer to check oscillator and divider outputs to see where it's failing. If you don't have a signal tracer, you can make one pretty cheap and easy. Take an old 1/4' guitar cable you don't need, cut off one plug and strip the insulation back. Connect an alligator clip to the shield and a test probe of some sort to the center conductor. For the test probe, you can use a cheap meter test lead (get a set at Radio Shack for a few dollars) - cut off the banana plug end and connect it to the center conductor. For the alligator clip, you may want to use a foot or two of wire. This just gives you a little more room to move around when using it - especially when you're using it in the organ itself. Connect the alligator clip to the ground point on the board (again, it may be marked, or you can use a schematic or board diagram to guide you), plug the other end of the guitar cable into a guitar amp, Now, I must recommend that you use a cheap amp that you wouldn't mind parting with. I have never had any problems using this rig, but it's possible that if you accidentally touch the probe to a high-voltage point in the organ, that you may damage the amplifier (few organs have high DC voltages present, but the Gibson G101 does have a 100V supply for the percussion circuit). I use a cheap battery operated amp I paid $10 for. I advise you to find something comparable - DON'T use that expensive boutique amp or your precious 1960's Fender blackface or Marshall plexi!

Once it's all hooked up, turn the volume on the amp up just a bit, then touch the probe to the oscillator and divider output points (if the board isn't marked, use a schematic or board diagram to guide you). You should hear the tones as you touch each point. Start with the Oscillator output, and work down the dividers til you locate the culprit. If you get no sound at all, you may have a board with a bad oscillator - try it with a known-working board to verify that your test hookup is working properly.

Here are a couple of pictures of my Vox V301H generator board set up for bench testing. Here, I'm just using an alligator clip lead for a probe, but a regular meter probe with a pointed tip would be easier to use. (Click each picture to enlarge):

The 'Couplates' shown in the picture are often called 'resistor packs'. They're actually collections of resistors AND capacitors.

Additional info for Vox Continental and Farfisa Compact fixes

Visit Dave Barraclough's excellent web site.Once there, click the Vox and Farfisa links on the left, then the Osc. fix links under those. He has some great info specific to those models.

The following about Farfisa Compact oscillators was provided by a fellow combonaut (Thanks, Bill!):

'A word of advice to anyone trying to troubleshoot one of these, don't forget to check the oscillator inductor coil windings for continuity. I had open windings on two of my oscillator inductors, I was able to repair them without rewinding the coils; but I used a microscope at work to do it. Also, you don't want to stick your meter probes into the eyelets on the coil when taking measurements, it's to easy to sever the tiny wires that are soldered there. To troubleshoot the cards I've found the easiest method is to unsolder the card from the harness and remove the card completely from the organ. I made up a test fixture to supply power to the cards from a nine volt battery with alligator clips soldered to the leads coming from the battery clip, connected to the + and - of the circuit card; it's not necessary to apply power to the vibrato input. Regarding the earlier discussions about faulty capacitors; capacitors will sometimes become leaky, allowing DC voltage into a part of the circuit where it's not supposed to be. Bridging a suspected faulty cap with a good one will do nothing to correct this situation. If a capacitor is suspect, it's best to remove it entirely from the circuit and replace it with a new one, especially if it is an electrolytic.'

How to tune your combo organ

GENERAL PROCEDURE

Most combo organs have twelve oscillators, one for each note in the scale (A, A#, B, C, C#, D, D#, E, F, F#, G, G#). Each generates the highest octave, for it's note, that the organ is capable of playing. Lower octaves for the same note are created by one or more frequency dividers, one for each lower octave. Each divider takes the output from the previous stage, and divides it in half, producing the next lower octave.

You only have to tune each of the twelve oscillators - the dividers are not tunable. Normally tuning is accomplished via a variable inductor, or coil. It often is the largest single component on each oscillator board, usually situated near one end of the board. It usually looks like a can with a hex-key or screwdriver-head adjustment screw in the middle.

One large exception to this setup is the Melosonic/Whippany/Clark/Realistic line of organs, as well as the Magnus 3D Combo. You tune the oscillators on these with trimpots (they have little plastic thumbwheels with a small screwdriver slot in the middle), also located on the circuit boards. The trick with these is that each oscillator produces notes for three consecutive keys. So you just have to adjust for the best compromise of 'in-tuneness' for each of the 3 notes.

Some organs, notably the Rheem Mark VII, use the standard 12 oscillators/divider setup, but for tuning use trimpots rather than variable inductors. They're easy to get to, right on top of the generator boards, but they can get dirty, and the tone may shift erratically as you try to tune them. Some spray contact cleaner can be used to clean them up.

Once you've found the tuning coil (or trimpot), you need to figure out which one is for which note. Sometimes they're marked, sometimes not. If not, you'll have to use trial and error - pick one and adjust it slightly back and forth, playing each note one at a time (you only need to cover one octave) until you find out which one you're adjusting.

Now that you know where the coils are, and which is which, you're ready to tune. It's probably a good idea to let the organ warm up a bit first - 5 minutes is probably sufficient. You'll need a chromatic tuner of some sort (one capable of tuning all 12 notes - 5-note guitar tuners will not do the job). If you have a PC handy, and can plug the organ's output into your sound card, you can use this excellent free tuner from Audio Phonics. Ideally, you should use a plastic tool to adjust the coil, but a metal one will do, it'll just be a bit more trouble. First, turn off all voice tabs, vibrato, and other special effects. Turn on ONLY one voice tab - the highest whole-number footage available (typically 2' or 4'). Do NOT use a 2-2/3' or other fractional voice. Find the highest 12 notes on the keyboard that will play (if using a very high footage, like 1', you may find that some of the uppermost keys don't sound), and use those to tune with. Play each note, one at a time, observing the tuner. Adjust the coil appropriately to bring the note into tune. If using a metal adjustment tool, you'll find that just bringing the tool close to the coil causes the pitch to change (although I've found that with Vox Continental oscillators, at least some of them, you can use a metal screwdriver and it doesn't affect the pitch). In this case, you'll have to make small adjustments, backing the tool off after each to observe the change. Keep doing this until the note is in tune, then move to the next. After doing all twelve, you might want to go back and re-check each one, tweaking any if necessary. At this point, it wouldn't be a bad idea to put a few drops of wax on the adjustment screw, to keep it from working loose. Most are pretty tight, and will stay put on their own, but it doesn't hurt to do this, just to make sure.

NOTES FOR SPECIFIC ORGANS

Farfisa Compacts & Mini-Compacts:

There are 12 tuning holes in the back of a Mini-Compact (one for each note). They're arranged as follows (facing the back of the organ):

B G D#
A# F# D
A F C#
G# E C

I've been told that the early version of the Mini-Compact (the one without the grey bass keys) does not use this arrangement, but rather the one used by the Compact (below)

On the Compact and Compact Deluxe, only the bottom 6 are accessible through holes in the back of the case. To access the top six, you need to remove the plastic top (two screws, one at either end). They're not in the same arrangement as on the Mini, however, but rather are set up like this:

A C# F
E G# C
B D# G
F# A# D

The Compact Duo has a small panel of trimpots to the left of the tabs when the top cover is removed. There's also a set of tunable coils accessible from the back.

Farfisa Fast 4/5