Yamaha CS50 #1251 Part 2: closer, much closer

Calibrating and tuning a CS50 (and I assume the other nearest siblings) is an iterative process.  There are pitfalls at every step, and when you finally reach the end you get a nice easter egg -a tuned 4 (or more) voice synth!  In the last post I quickly diagnosed why my CS50 didn’t make a sound -having the TU (tuning) voltage jumped to ground.  This post is about other problems.  The CS50 circuitry has a lot of functions that are distributed among a couple of boards, so you may find you have a tuning problem originating in your SUB board, or a portamento problem originating from your PRA board.  Well, I had a TU problem coming from my SUB board – no matter what I tried, I got 6.5 volts at the TU terminal -trim pots had no effect… this terminal is supposed to be 4.000 volts.  Lots of head scratching and component replacement later I decided to just order a CS50 SUB board from synthparts.com -a handy side effect of CS50 voice boards being worth $400 – $500 each, making the CS50 worth about 2x it’s ‘complete working’ value in parts is that CS50 specific parts are CHEAP.  I got a complete front panel and lower chassis in like new condition for $150 while I was at it.  Too much money probably, but not bad really if you just want to fix your cheaply obtained synth that just happens to be worth more as parts.

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Part way through a power supply recap.  I am told the small value green caps don’t really tend to fail, and to leave them alone.  After the recap it’s a good idea to look at the rail voltages again just in case. Continue reading

Yamaha CS50 #1251 Part 1: Bringing home strays

I decided to be ‘one of those guys’ and placed an ad on Craigslist looking for an ARP Odyssey (really want one!!), anyway -responses were thin and expensive except for a ‘broken Yamaha CS50’.  I went for a look and hey-ho next thing I knew I had a $600 CS50 in the back of my car.  Considering perfect ones sell for $1200 – $2000, the price was probably high for how little worked on it, but I decided to take a chance since I like a challenge.  It came with a lid and legs.

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A good looking specimen.  All slider caps are present.  The keyboard is in great shape.  Not too many scratches.  Even came with the legs.  The LFO control board has a bunch of paint loss in the lower left corner -like the PO played with a metal band watch on.

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Yamaha CS-80’s on eBay right now!

Update 5/15/2013:  CS80 number 1259 is on eBay right now.  Used by Little Feat, not sure anyone buying a CS80 is going to care about this.  Asking price is $17,999!

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Update 8/16/11: The $17,999 CS-80 from Perfect Circuit has sold for asking price.  A new record?

I keep an eye on the search term ‘Yamaha CS*’ since I have a CS-50 and am always looking for parts to squirrel away.  Tonight I was surprised to see there is a CS-80 arms race going on.  What’s all the fuss?  Check out some Vangelis CS-80 demo’s on YouTube and you’ll see.

First up is this guy from Perfect Circuit Audio for $17,999 out of Southern California.

Someone’s got some solid Photoshop skills.  That is a mighty fine looking keyboard.  $17,999 is the Buy it Now.

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