Saturday, March 29, 2008

Yamaha TG33 rack mounted

Matrixsynth has up a post on the Yamaha TG33, which is basically a tabletop version of the SY22 keyboard.  It is possible, although a bit awkward, to rack mount the TG33.  Here it is:

The rack ears are apparently hard to find.  Where the ears fasten to the side of the synth, they provide two sets of holes so the synth can be mounted horizontally, as seen here, or tilted forwards at about 30 degrees.  Here is a close-up of the mounting:

It isn't possible to mount it vertically, and there's a reason why: the display, which is already at an angle, would be facing the floor.  As you can see, some space has to be left above the TG33 in order to see the display and reach the power switch, volume knob, and data entry knob.  And, unless it's near the top of the rack, you  have to leave some space under it also, because it obviously overhangs whatever is below it.  Nonetheless, it's still more convenient than having to find surface space for it.  

Sunday, March 23, 2008

Vintage synths with reliability issues

Everyone who plays or collects vintage synths knows that it's a labor of love. Some are difficult to keep in tune; some contain parts that are hard to find replacements for, and some are just cranky and unpredictable. However, there are a few synths with known failure mechanisms to watch out for. The shame of it is, all of these are well-regarded for their sounds and playability. Still, there are things that owners and potential buyers should be aware of. Here's a guide to these problematic synths.

Roland Juno-106, MKS-30, and GR-700

Failure mechanism: The Roland 800017A VCF/VCA hybrid IC suffers from internal metal migration, which eventually causes internal shorts.

Failure signature: A voice crackles, cuts in and out, or continues to sound when no key is pressed. Rustling noises may be heard when playing or when no key is pressed. Less commonly, a filter may behave erratically or refuse to stay in calibration. Symptoms may get either better or worse as the synth warms up. On the Juno-106 or the MKS-30, in Poly 1 mode, every sixth note played exhibits the symptoms. On the GR-700 guitar synth, one particular string exhibits the symptoms.

Advice for buyers: If you can get access to the synth, power it up in test mode (or tuning mode for the GR-700)and test all six voices. Do this once when the synth is cold, and again after it has warmed up for about ten minutes. If you can't get access to the synth (e.g., an Ebay deal), insist that the seller disclose whether or not all six voices work and stand behind his word.

Advice for owners: Despite some Internet speculation, no one has managed to identify any particular date codes that will or won't fail. Owners are advised to stockpile a couple of spares. Currently 80017A's are going for about $65 US on Ebay. An alternative is to buy a broken 106 for parts; a used 106 with problems will often sell for less than the cost of a full set of 80017A's. Another alternative is a clone part. There are several available, but the one I recommend is the D80017 from Analog Renaissance. It's nearly the same size as the real thing, so it won't cause any clearance or heating problems inside the case, and the manufacturer claims that calibration trimming will be similar.

Difficulty of repair: Not difficult. Anyone with soldering skills should be able to do it. The board is clearly labeled as to which ICs go with which voices. For the Juno-106, see my previous post for the location and layout of the module board. For the MKS-30 and the GR-700 (which use the same board), see this page from Wayne Scott Jones.

Korg Polysix

Failure mechanism: A NiCad memory backup battery installed at the factory leaks onto the CPU board, eating the copper traces off the board and damaging the substrate.

Failure signature: Random behavior; panel buttons don't work, lights flash randomly, voices don't play. Or, the synth doesn't boot up at all. Note that serious damage can be done before the battery fails to the point where patch memory doesn't retain.

Advice for buyers: Ask the seller if the battery has been replaced and the CPU board inspected and/or repaired. If the answer is no, or if the seller doesn't know what you are talking about, don't buy unless you have a good tech or advanced electronics repair skills.

Advice for owners: If you don't know that your Polysix has been previously repaired and a lithium battery fitted, open it up and inspect the CPU board. This page from "The Old Crow" (Scott Rider) shows how to open the synth up and what to look for; it also contains the detailed repair procedure.

Difficulty of repair: Replacing the battery, in itself, is not difficult. However, by now, chances are that any Polysix that still has its original battery has suffered significant damage to the CPU board. The battery acid can be neutralized by cleaning the board with baking soda and water, but damaged board traces have to be identified and jumpered. It's a tedious job that requires some knowledge of the circuits, and advanced soldering skills.

Update: Commenter "steamy vicks" advises that the Kawai SX-240, and possibly also the SX-210, suffers from this same issue.

Rhodes Chroma Polaris

Failure mechanism: Ribbon cables which are molded into the membrane panel have been embrittled with age, and crack or split when moved or subject to vibration.

Failure signature: Some or all panel buttons don't work.

Advice for buyers: Frankly, unless you absolutely have to have one, or you are handy with electronics and you want something to experiment on, don't buy. If you do find one cheap, be aware that the Curtis IC's in the synth are probably worth more than the synth itself.

Advice for owners: Don't gig with your Polaris; in fact, don't move it at all if you can avoid it. Don't open up the synth unless you have to; opening it flexes the ribbon cables.

Difficulty of repair: Because the ribbon cables are one piece with the membrane panel, the easiest path of repair is to replace the whole membrane. This is not a difficult repair; the difficult part is finding a replacement. Here is a list of service centers from, but it is my understanding that there aren't many Polaris panels left. And, be aware that any replacement panels that do exist are as old as the originals, and are likely to also have the embrittlement problem. Attempts to splice the ribbons back together usually fail because handling the ribbons cause them to crack further. In this thread from Harmony Central, a poster succeeded in soldering wires onto the end of the ribbon cable and connecting them to a bulkhead connector. However, as you can see from reading the thread, it was a very exacting job requiring, among other things, a temperature-controlled soldering iron. The best way to address the problem appears to be to just use a software editor and edit via MIDI. I've seen talk about designing a replacement panel using real switches, but I haven't found anyone who has actually done this.

Ensoniq Fizmo

Failure mechanism: The LM2940 voltage regulator on the DSP board shorts out and applies a high voltage to the DSP board, which fries the processors on the board.

Failure signature: The synth displays an "ESP" message in the display on power up, and won't play.

Advice for buyers: Ask the seller if the LM2940 has been replaced. If the answer is no, or if the seller doesn't know, do the following: (1) Make the seller assure you that the synth was working the last time it was powered up; (2) Instruct the seller to not power it up again before shipping, and (3) when you receive it, do not power it up until you inspect it and replace the regulator if necessary.

Advice for owners: If you don't know for sure that the regulator in your Fizmo has been replaced, do not power it up again until you have inspected it and replaced the regulator if necessary. If you do know that the regulator has been replaced, you're home free. Note that apparently some Fizmos had th regulator replaced at the factory before shipping; if the regulator in your Fizmo is something other than an LM2940, it's probably OK. Also note: There are a number of threads in various places speculating as to whether the factory supplied wall wart was responsible for these failures. This turned out to be not true, but there are Fizmos around with wall warts that don't supply enough current, which can cause erratic behavior. See Carbon111's page referenced below for more information.

Difficulty of repair: It depends on whether or not the LM2940 has failed. If the synth is still working, anyone who is handy with a soldering iron and a drill can replace the regulator. Carbon111 has an excellent page showing how to inspect the regulator, and it contains a link to a page with the detailed repair procedure. Unfortunately, if the regulator has failed and the synth is displaying the "DSP" error, repair is all but impossible. The DSP's are small-pitch surface mount parts that cannot be soldered or unsoldered without specialized equipment and advanced skills, and the cost of the repair would likely exceed the synth's market value. There is no known source for replacement DSP boards.

Friday, March 14, 2008

Who owns Minimoog serial #1001?

While looking into the lineage of an early-production Minimoog that was on Ebay last week, I got curious as to the whereabouts of Minimoog serial number 1001, the first production unit. We know this much: According to the Moog Archives, Mini #1001 was shipped to Walter Sear on November 19, 1970 (about a year before Bob sold the company to Musonics). Now, Walter was an interesting character, worthy of a future blog post himself. He was involved in marketing Moogs to the New York entertainment industry, and he also did some soundtrack work with synths (electronic scores were the new hip thing that every movie producer wanted in the early '70s). So he purchased several Minis out of the early production run; in addition to #1001, he was also the customer for units 1024, 1033, 1051, and 1062.

Given the number of units that passed through his hands, it wouldn't be a surprise if there was some swapping around of parts in a pinch. But I'm not sure this explains why there appear to be two Minis staking claim to being #1001 now. Contestant number one is in possession of the Eboard Museum in Austria. (I've provided a link to their page that describes most of their extensive collection; unfortunately it's all on one page and there appear to be no anchors in the page to link to. Scroll about 3/4 down.) Here's a photo from the page:

Contestant number two is from the Audities Foundation (which is also in possession of severa Mini prototypes). It should be noted that Audities does not itself claim that this is #1001; however, a Google search revealed three other Web sites (including Raymond Scott's site) claiming that it is. Here's a photo:

The main difference that jumps out at me is that black-on-white badge on the Emuseum one. I don't believe I've ever seen that on any other piece of Moog gear from the R.A. era. I'm not at all sure what to make of that. The other thing that I spot is that the switches near the pitch/mod wheels on the Emuseum one appear to be some kind of generic toggle switch, while the switches on the Audities one look like the switches used on the Model D prototype. Again, I don't at all know what to make of this.
Did Moog make two units numbered 1001? Possibly. It wouldn't be the first time that a company built a set of prototypes under a given set of serial numbers, and then used those numbers again at the beginning of the production run. If one of these is really a prototype, I'd bet on the Emuseum one, based on the fact that it looks rather well used, and the woodwork appears to be a different kind of wood or finish. But if it is a prototype, that raises the question of its lineage and how it got to be where it is now. Did Moog sell it to someone at some point? Did a Moog employee take it home? Did it get dragged from Trumansburg to Williamsville to Buffalo, get stuffed in a corner there, and then sit until the company went under and the assets were sold off? If so, it's kind of remarkable that it still exists at all.

Thursday, March 6, 2008

Rhode Island

 A Statescape, done with the Boss DD-20 GigaDelay:

The Roland JD800 is the main synth.  Also used is the Oberheim Matrix-1000 for the bass parts, played via Studiologic MP-113 pedals.  This is a live performance with no editing or overdubs.

A higher-resolution audio file is available on the Source Code Web site here.