Jump to content
johndias

VIC-20 Keyboard Mostly not working

Recommended Posts

Hi all, my new power supply from Ray arrived today so I got a chance to boot up for the first time.

 

System comes up, no problem, but the keyboard ... probably 80% of the keys don't work.  I had pulled them and cleaned them while I was retrobriting the case (and lost one spring - anyone got a spare?).

 

I saw another thread @carlsson recommended swapping the 6522 chips, which I will do. What else can I check?

Share this post


Link to post
Share on other sites

Is there a pattern to which keys are not working? Like it was mentioned in the other thread, every second key worked and the rest didn't. If you have a massive fail of up to 80%, sure it could be a toasted 6522 but it makes me wonder what other causes it could be.

 

In case you own a C64, the keyboard is mechanically (*) and electrically compatible with the VIC-20 one so you could swap keyboards to rule out sources of error.

 

(*) The white C64C keyboard may have different mounting points so it would be difficult to fit physically, but loose out of the case it works the same way.

  • Like 1

Share this post


Link to post
Share on other sites

I pulled the keyboard PCB out and cleaned it with IPA. Then I plugged it back in and used a wire to jump the contacts to see if that would respond. The keys did (I didn't do a complete test but enough to convince me that I had a mechanical problem).

 

Then I took a plunger (the commodore key) and used it to connect each of the contacts. No bueno, the key presses did not show up. So, I think my plungers are bad, what to do? These are NOT the rubber dome ones but rather like this one

 

 

Share this post


Link to post
Share on other sites
17 hours ago, carlsson said:

Is there a pattern to which keys are not working? Like it was mentioned in the other thread, every second key worked and the rest didn't. If you have a massive fail of up to 80%, sure it could be a toasted 6522 but it makes me wonder what other causes it could be.

 

In case you own a C64, the keyboard is mechanically (*) and electrically compatible with the VIC-20 one so you could swap keyboards to rule out sources of error.

 

(*) The white C64C keyboard may have different mounting points so it would be difficult to fit physically, but loose out of the case it works the same way.

There's no pattern, that I can determine. The working ones are scattered about.

Share this post


Link to post
Share on other sites

There are a few smaller variations on the keyboard mechanism, but all have some sort of plungers. I believe you can use graphite spray or draw with a pencil on the rubber to make it conductive, but if most (80%) of the plungers don't register, it must be quite worn.

Share this post


Link to post
Share on other sites

Hmm, I have some graphite powder and was attempting to make conductive paint for an electroplating project - I might play around with that and see if I can re-surface those plungers.

Share this post


Link to post
Share on other sites

Oh man, rookie mistake! Short story, while I thought the contacts were clean I put them under my microscope and realized there was corrosion on most of them. So, with extra diligence I cleaned them all up and for kicks tested the resistance on all of the plungers (they were all around 100 ohm which I guess is good?) and tested - all the keys work!

 

Well, except for the Commodore key, for which I lost the spring. Anyone know where I can buy one?

20200919_125756.jpg

  • Like 2

Share this post


Link to post
Share on other sites
Just now, evg2000 said:

cool!
what did you use to clean off the corrosion?

 

IPA and a paper towel. I think the problem before is that I was using a non-cotton fiber swab like the ones here and it wasn't doing much scrubbing. They're great for general grime and cleaning tape and disk heads, though.

s-l64.jpg

Share this post


Link to post
Share on other sites

Probably someone has spare keyboards in parts from where you could source a spring if that is all you're missing. I suppose measuring an existing one might allow you to find somewhere selling springs only, though I don't know if hardware stores have that.

Share this post


Link to post
Share on other sites
3 hours ago, carlsson said:

Probably someone has spare keyboards in parts from where you could source a spring if that is all you're missing. I suppose measuring an existing one might allow you to find somewhere selling springs only, though I don't know if hardware stores have that.

I've had to match springs before, it's challenging. There are online places that sell springs. That's my last resort, I'm hoping to find a kind soul with a spare VIC-20.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...