Help me figure out how to fit Cherry MX on a board it doesn't belong on

[happylacquer]

I have a synthesizer made by Yamaha which was made between 1999 and 2002. It has 16 buttons on bottom row which are known to die easily after a few years. It was a common replacement something like 15 years ago. I saw a forum once I haven't been able to dig back up of a guy who had most of his bottom row died and he replaced them all with cherry mx. He said it worked great and it sounded nice too.

Here is what the pcb looks like when switches are removed from the PCB. I'm not sure  mx even works as a drop in replacement (doesnt look like it) or what the guy did to get mx on his rm1x. or if his claim was all bs?




And the buttons that come on it:

[tp4tissue]

if the pin width is correct. just drill out the hole in the middle it should fit..

Use high speed drill (preferably drill press)

And use the smallest drill bit,  and size up slowly till you get to the final size.  DO NOT drill the final size hole in the pcb right away.  It might bite too deep and rip out traces..


High rpm, drill slowly..

[Findecanor]

Are you absolutely sure that that other guy replaced the switches with Cherry MX specifically? Cherry does not only make key-switches but also micro-switches.
That looks like a standard 6.5×4.5 mm rectangle hole pattern and there are lots of microswitches that would fit that footprint. Cherry MX does not.

If you still want to mount Cherry MX, then yes, there are people who have mounted Cherry MX switches in places on PCBs that were not designed to fit them. The pinout is in the datasheet on Cherry's web site. There are switches with or without fixing pins for better fix into PCBs, and there are switches with or without a jumper wire or a diode that would also make it sturdier if present.

You would have to make sure that any holes you would drill would not break any existing traces on any layer of the PCB, or that those traces could be replaced with wires. If your PCB has more than two layers then there could be traces that you can't see.
You may have to use glue or a mounting plate to get a switch to stick if there is no suitable trace/pad on the bottom of the PCB.
I once fit Cherry MX switches where there was a grounding plane on the back side. I used a Dremel tool to grind away excess grounding plane around the holes I made and covered the exposed metal with lacquer to prevent a short from happening.

When drilling PCBs, because they are made of fibreglass be very sure that you don't inhale any fibreglass dust: Work in an area where you can collect all dust, even from the air. Wear a dust mask and protective clothing. Inhaling fibreglass dust can lead to lung cancer.

[tp4tissue]

The safety concern over fiberglass dust is overblown..

Unless you drill pcbs all the time..  it's not gonna kill you.. hahahahahha



It's not like cocaine, where you do it once,  Love it,  boom homeless..

[Findecanor]

Don't listen to tp4. He is our resident troll. He gets away with a lot of things here that he wouldn't on other forums.
Most of the time, we don't take him seriously, and neither should you. We keep him around because he is funny sometimes.

You don't skimp on safety. You just don't.

[tp4tissue]

Don't listen to tp4. He is our resident troll. He gets away with a lot of things here that he wouldn't on other forums.
Most of the time, we don't take him seriously, and neither should you. We keep him around because he is funny sometimes.

Tell that to all them asbestos miners who have 0 problems having inhaled asbestos all their life..

hahahahaha

[OfTheWild]

I did a little research (modding and music are two favorite activities of mine) and to help clear things up it looks like yes, even though there are 4 solder points, its still just a STSP-NO switch... just like a cherry mx. From the bottom view you can see the trace is just a bridge between the legs:



I was thinking the same thing about drilling two tiny holes and then soldering a bridge over to one of the pads. You would probably want to install the cherry switch sideways and get the ~.25" spacing of the cherry poles to line up with the 7.4mm spacing of the switches... which could actually be spot on: http://www.digikey.com/products/en?lang=en&site=US&KeyWords=401-1796-ND&x=0&y=0
The other thing i thought about would be to bend the cherry poles flat and try to connect to existing pads. Maybe with a lead from each pad. Another option would be to hot glue the switch to the hole in the board and then run wire leads out of small holes in the side of the cherry switch. I'm much more inclined to mod a cheap cherry switch than an expensive pcb.

The only thing that i think might become a deal breaker is the switch height of the cherry vs. these flat pcb button switches. but maybe they'd just sit up high on the board and stuff a key cap on top. Got any photos of someone who's done this already?

[tp4tissue]

You can make a breakout board.

[OfTheWild]

You can make a breakout board.

yeah i thought about that too but i dont imagine theres enough room there.