Lexicon PCM 42 up arrow button not working

Hi there,

I know the usual suspects don't service these lovely PCM42s anymore and mine has a stuck "up" arrow button not functioning.
The "down" arrow button works as it should, though.
Is there any way to either restore that button or could anyone point me to a spare  button by any chance?

Thanks!

Often buttons of that type can become stuck due to a spillage or contamination from liquids ,sugary stuff in particular when it dries out . Id try a shot of isopropyl alcohol on it ,maybe use an old tooth brush to get down the side of the switch button .If that doesnt work ,probably best to dismantle the front panel from the unit and examine the switch itself more closely , theres many different sorts of tactile switches ,so while you have it appart take a few pics and someone here might be able to indentify the type and a source for you.

Thank you so much - here are pictures

Trying close-ups ;-)

The display section

More circuit shots

Hmmm , not a common switch type ,I certainly dont recognise it .
Looks like the switch sub assembly might easily plug out of the circuit board below it ,
Try dipping the small board in switch cleaner or isopropyl and see if the switch frees up .
It does look like the switch might have got hit and slightly pushed in , there could be some physical damage inside ,you could try pulling the switch button out ,but bear in mind theres likely to be small parts inside ,so be carefull not to loose anything ,there could be a small spring between the button and the switch contact or sometimes a plastic actuator ,this might be damaged or misaligned

Looks to me like the two slots on the sides of the switch might allow you to pop the button out using a very small screw driver , either way try the switch cleaner first and see if that helps

OK - will do, thanks!

Hi team,

Gary (the original designer of the PCM 42) was kind enough to reply to my inquiries about that faulty button, here what he said:

Hmm...off hand I don't know a source. It's no longer a common style for a button.

You may be able to fix the switch, though. Pop the top cap out by inserting a thin blade (such as an 'xacto' knife') at an edge of the button top. Underneath is a metal piece that also comes out and under that is the contacts themselves. You can see how the switch works. The metal piece bridges the 2 contacts and also serves as the 'spring' to push the button cap up.

If you clean the contacts and the metal 'bridge' piece with a pencil erasure or other, then reassemble the switch, there's a very good chance the switch will work again.

This was the standard fix for a problem with those switches at Lexicon and a lot easier than replacement, even if you have the part. Give it a try, and let me know how it works out.

Gary

Wow thats pretty good detective work tracking down the designer ,
Let us know how how get on with fixing it .

Hey gang,

I also got a reply from Mr. Bob Sellon (who took over from Gary):

"Unfortunately I don't have any further information on the parts except to say that the buttons are simple normally-open momentary switches. Nearly any momentary switch will work as a replacement though you may need to have wires go out to the switch leads and mount the switches with silicone epoxy."

So, there you go!

Let me try to fix that button following these instructions and report here.
I guess pictures would be useful for future reference?

So, I was able to remove the button cap, as per Gary's instructions.
See picture

Button and metal spring.

But simple cleaning did not make it, there seems to be a mechanical contact problem as the values change when a contact is made inside the button (using a wire).
So I tried another method: the Swiss Chocolate fix

The idea is to create an extra metal layer behind the metal spring.
It kind of works now and will be good enough until the next better solution.

So, I've basically wrapped the metal spring piece in a Swiss chocolate aluminium foil to help with the contact.