Looking for a good synth repair shop in San Diego

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SixStringGeek
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Looking for a good synth repair shop in San Diego

Post by SixStringGeek »

My Alesis QS8, which has been my main controller board for years and which I love dearly has developed a problem with the bender and mod wheels getting funky. I think its maybe just dirty pots or something but when I throw up MIDI monitor on it I see lots and lots of semi-random mod and pitch wheel change events.

Not so good. Anyhow I took it to a guy in town and I'm beginning to get the idea he's in over his head. http://www.keyboardservice.com is the site and he seems to be more of a Hammond Organ tech than a synth guy. He keeps calling me with questions that could be easily googled. In fact, that's how I answer them. He's had my board 5 weeks - no progress and I'm fed up.

Anybody know anybody really good in town for this kind of thing?
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Tonio
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Re: Looking for a good synth repair shop in San Diego

Post by Tonio »

have you seen this?

http://piaznest.free.fr/FTP/Alesis%20QS ... 0Guide.pdf

didn't have any work done, but maybe call SDSMR http://www.sdsmr.com/pages/services.htm
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Prime Mover
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Re: Looking for a good synth repair shop in San Diego

Post by Prime Mover »

Holy ••••! I've just been working on my QS8 wheels tonight! I've been doing a lot of repair work on it the last week, getting ready for a tour. Maybe I can give you some pointers. Nice thing about the old QSs is that they're pretty easy to repair. Being slightly older, they're made with more modular parts and bigger cards.

Most of the pitch wheel problems stem from the same few problems: one of them is a bad "spring", another is from a loose nut holding the pot in place, and the other is poor contacts in the pot, usually caused by oxidation. You should know that the actual turn angle for the pot is pretty small, like maybe 30 degrees at most... so it's very touchy and any bit wiggle room or poor contacts can have pretty extreme consequences. What you're describing is, indeed, likely dirty pots. I was having the same problem, and some pretty weird results. Fact is, these things are touchy as hell, and a bit unpredictable when they get dirty/loose. I was sure I must be an electrical contact issue, but no, it was just a dirty pot.

The spring can be replaced by using a safety pin. I've never done this, but there are instructions online and it seems like a pretty sound fix to me, in fact, it may make the wheel a little more responsive.

My problem was being caused by a mixture of a slightly loose nut and oxidation. There's a thin nut holding the pot against it's housing plate, if it gets even the SLIGHTEST bit loose, then you will have this effect where it will zero out from one direction, but go out of tune when coming back from the other. There's also a little tiny nub that fits into a hole to supposedly secure the pot on it's housing. There's a little bit of give in that hole, and I was able to cut that down by putting a tiny bit of electrical tape in there to keep it from moving.

Lastly, oxidation. The online resources I read said to use "contact cleaner solution" (found at Radio Shack, and probably other electronic stores). It's basically a version of canned air with a bit of vinegar or other mild acid. I wanted to fix mine tonight and Radioshack was closed, so I just dipped the whole pot in white vinegar instead. I then blew it off with canned air. That did the trick. I was told by an electrician helping me out a few days ago that vinegar is a great anti-oxidation and corrosion solution, and it's very benign, so it won't dissolve surrounding parts.

QS8s are easy to get into, you just unscrew 6 screws along the bottom sides, and a number of small screws in the back (mine came with 7 screw holes, but only 5 had screws in them). Don't touch the big screws on the bottom, they hold the key bed and circuit boards to the case. Once you're in, you'll need to remove 4 screws from the wheel housing, and then the two wheels will be free to work on. Unfortunately, their connecting cables terminate in tiny, brittle plugs that I just couldn't get out for fear of breaking, so I did all my maintenance with the wheels still attached by wires.

I only had problems with my pitch wheel, although, in the course of fixing it I think I damaged the mod wheel because it doesn't register right now. But I never use the mod wheel... tending more toward expression pedal, aftertouch and sliders these days. But I'm sure it'll be an easy fix and I'll tackle it once I get back from tour.

***

I'll just mention that I made a big mistake the other day, which prompted all my repair work. I opened up the board to fix the pitch and aftertouch. Getting at the aftertouch wiring is a pain because they route the tiny leads underneath the transformer board. Okay, well, to make a long story short, I took off the transformer card and accidentally left it laying across the case when I turned the board back on to troubleshoot... sparks and smoke everywhere! Blew a piece off the back of the card. Thankfully, it had only blown the fuse and a short piece of the printed circuitry... a friend helped me re-solder the printed circuit. A helpful piece of advice: if you ever find the transformer fuse is blown... don't trust the sticker on it that says it requires a 125mA fuse (which is impossible to find). Even Alesis didn't use those, the stock one that came with my board was actually a 250mA, which most electronics stores will carry.

Anyway, let me know if you have any more questions. At the point, I think I've read just about all the official and unofficial info on the subject, so I should be able to point you in the direction you need to go if you're game for fixing it yourself (which might be your best option).
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SixStringGeek
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Re: Looking for a good synth repair shop in San Diego

Post by SixStringGeek »

Prime Mover wrote:Holy ••••! I've just been working on my QS8 wheels tonight!
Ah, a fellow devotee. Actually my guy finally came through. He needed a lot of handholding on the actual operation to see if it worked - but apparently he cleaned up the contacts and pots and it is solid as a rock once again.
Prime Mover wrote:I opened up the board to fix the pitch and aftertouch.
It has aftertouch? OK, now I'm going to look like an idiot because one of my gripes about this board is no aftertouch and now I've scored a pdf of the manual and searched it and - holy cow there's aftertouch! I really need to dig deeper into my gear manuals. I've had this thing for at least ten years but mostly used it as a combination MIDI controller/sound module (keyboard MIDI out thru the mac and back into a multitimbral one sound per MIDI channel mix).
Prime Mover wrote:Anyway, let me know if you have any more questions. At the point, I think I've read just about all the official and unofficial info on the subject, so I should be able to point you in the direction you need to go if you're game for fixing it yourself (which might be your best option).
I'm gonna read my manual again and start trying to get more out of this thing. My Korg DW 8000 had aftertouch and I really liked it when I gigged it back in the day. So here goes me trying to get aftertouch happening over MIDI to the Korg (now an EX8000 because I need the space).
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Thousands of $'s worth of vintage gear currently valued in the dozens of dollars.
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