Yamaha CS-60 part 2: The capacitor list

Replacing capacitors in an old piece of electronics has become a somewhat frequent endeavor in my world. I am woefully behind on recapping all the stuff I have that should have it done for reliability and worry free service, so I do it as needed rather than because I want to. The CS-60 could probably soldier on for years with its old capacitors, but I would feel a lot better about using it regularly if I knew it was less likely to experience a failure, and there is always a chance that a failure would result in damage to nearly impossible to find ICs. You could say it is cheap but time consuming insurance to replace the caps.

What’s in the box? A lot of wires, circuit boards and very carefully tied little string loops and knots to keep the wiring harness organized.

Generating a capacitor list is an iterative process that starts with an assessment of what you have and ends with an order placed to your favorite electronic component dealer. The steps I follow are below. Mouser and Digikey seem to be the go-to folks for us here in the USA.

  1. Determine if any capacitors have been replaced before. You can do this by looking at the caps themselves: are they all the same type by rating and appropriate age? Or looking at the solder pads: are there any that are extra shiny? If any capacitors have been replaced before you need to make sure the new ones are the right ratings by cross referencing the service manual or an original unit.
  2. Identify what is in the unit you are going to recap. Make your list by circuit board so if you lose track of where you are, you don’t have to start at the beginning. If the unit you are going to recap has them identified by number (C1, C2, C3 etc) use this nomenclature so that again, its easy to go back and double check stuff without starting over. Service manuals are notorious for containing mistakes. You need to look at what is physically present. Be careful handling the boards, don’t pull on the harnesses and don’t try to bend stuff out of the way so you can read the caps. Take your time and use a flashlight and magnifying glass. On the CS-60 the boards themselves are marked with the ratings of the components right by the components.
  3. Compare what you identified with what’s in the manual as a sanity check. If there are any discrepancies try to figure out why. Did you misidentify a capacitor? Is there a mistake in the manual or a mistake in manufacturing assembly? Is it something someone changed that you didn’t identify as such? In the end, you need to be sure that the capacitor you are going to solder in there is correct.
  4. Condense your list from board lists to a master list and by rating. If you have a 10uf 16v and a 10uf 25v – condense that to 2x 10uf 25v. If there was also a 10uf 50v you could order 3 of those. You can up the voltage a step or two. Generally speaking, higher voltage rating equals higher cost and larger size. In manufacturing you want to minimize these two things. Capacitors have gotten smaller and lower cost in the 40+ years since this was new, and you probably don’t care about saving a few pennies.
  5. Choose your replacements by grade, temp rating, hours of expected life etc. Asking around on forums is a great way to get help picking the best caps for each application. Mouser and Digikey have size listed on the ordering pages. It’s good to confirm lead spacing, height and diameter of caps. There are specialty short/fat or tall/narrow caps you can order on accident that wont fit.
  6. Get your order in a cart at Mouser or Digikey. Both allow you to save carts. It takes a while to get the order together due to the ratings discussed above, what they have in stock and making sure you didn’t choose a specialty cap. You want to triple check your order count math. Sucks to get your order only to find you don’t have enough of one size. Sellers offer price breaks at qty, so I usually end up rounding up to the next quantity cost break if I’m close. Gives me some spares in case I screw up, and helps build stock for future jobs.
One of the M voice boards. This looks scary to me mostly because I have never replaced the capacitors in a synthesizer this valuable.

Below is my capacitor list generated per above steps – with a magnifying glass and pencil then cross checked on the circuit board illustrations in the manual. There isn’t much of a parts list in the factory service manual – though there are images of the PCBs where you can confirm any caps you are having trouble identifying. After I got this done I received a capacitor list from Emanuel on gearspace who replaced the capacitors in his CS-60 a few years ago.

First list is by board and is what is physically present in the CS-60 from factory and confirmed in the manual. All caps are radial electrolytic unless noted otherwise.

Power Supply

  • 1x 22uf 16v
  • 2x 220uf 16v
  • 2x 220uf 25v
  • 2x 1000uf 25v
  • 2x 3300uf 35v

SH sample and hold

  • 2x 47uf 16v

Key Assigner

  • 1x 22uf 16v tantalum
  • 2x 47uf 16v

Sub

  • 1x 1uf 16v
  • 1x 10uf 16v non-polar
  • 3x 10uf 16v

T61

  • 1x 47uf 16v
  • 1x 100uf 16v

M1-8

  • 5x each 40x total 1uf 50v non-polar
  • 3x each 24x total 4.7uf 50v non-polar
  • 2x each 16x total 4.7uf 50v
  • 2x each 16x total 10uf 16v
  • 4x each 32x total 100uf 16v

PRA

  • 4x 10uf 16v
  • 1x 10uf 35v non-polar
  • 6x 33uf 16v
  • 1x 33uf 25v non polar
  • 2x 47uf 16v
  • 4x 100uf 16v

KBC; T62; R6

  • No capacitors to replace

Adding all like values above and combining ones I can uprate voltage I get the following:

Polar capacitors

  • 1x 1uf 16v
  • 16x 4.7uf 50v
  • 23x 10uf 16v
  • 2x 22uf 16v (1 of these is originally a tantalum)
  • 6x 33uf 16v
  • 7x 47uf 16v
  • 37x 100uf 16v
  • 3x 220uf 25v (the 1x 220uf 16v is added here)
  • 2x 1000uf 25v
  • 2x 3300uf 35v

Non-Polar capacitors

  • 40x 1uf 50v NP
  • 24x 4.7uf 50v NP
  • 2x 10uf 35v NP (the 1x 10uf 16v NP is added here)
  • 1x 33uf 25v NP

Next post I will convert these lists to an order at Mouser.

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