To my surprise, I find I have a Pet which works - all apart from the
keyboard, that is. So I have a query about fixing it.

So far, I have removed the keyboard and found that the PCB contacts work
if shorted with something conductive. Therefore the problem is with the
little black pads that a keystroke presses against the PCB. I have tried
these things:

* cleaning with isopropyl alcohol
* cleaning with contact cleaner
* abrading with a pen eraser

The latter was not really effective as there is too much give in the
part of the key which supports the pad so I would say that the operation
failed to abrade the pad successfully.

Where I am now is that a few pads work but most do not. I have tried
putting two meter test prods on the pads to measure resistance and found
that some only become conducive with significant pressure. I guess that
the rubber of some of them has become too hard with age.

So what can I do to fix them? Any ideas?


One idea I've had so far is to apply some conductive matter to the pads.
I have tried a product called Keypad Fix on a remote but found it dries
to be too inflexible and crumbles on use, albeit that that was on larger contacts.

Another option is conductive paint such as

https://uk.rs-online.com/web/p/solder-pastes/8352699/

A further option is to cut tiny copper-film discs and stick them to the existing pads.

Any of those good options? Other suggestions welcome.


--
James Harris

--- SoupGate-Win32 v1.05
* Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)

On Wednesday, January 10, 2018 at 12:17:06 PM UTC-5, James Harris wrote:

To my surprise, I find I have a Pet which works - all apart from the keyboard, that is. So I have a query about fixing it.

So far, I have removed the keyboard and found that the PCB contacts work
if shorted with something conductive. Therefore the problem is with the little black pads that a keystroke presses against the PCB. I have tried these things:

* cleaning with isopropyl alcohol
* cleaning with contact cleaner
* abrading with a pen eraser

The latter was not really effective as there is too much give in the
part of the key which supports the pad so I would say that the operation failed to abrade the pad successfully.

Where I am now is that a few pads work but most do not. I have tried
putting two meter test prods on the pads to measure resistance and found
that some only become conducive with significant pressure. I guess that
the rubber of some of them has become too hard with age.

So what can I do to fix them? Any ideas?

One idea I've had so far is to apply some conductive matter to the pads.
I have tried a product called Keypad Fix on a remote but found it dries
to be too inflexible and crumbles on use, albeit that that was on larger contacts.

Another option is conductive paint such as

https://uk.rs-online.com/web/p/solder-pastes/8352699/

A further option is to cut tiny copper-film discs and stick them to the existing pads.

Any of those good options? Other suggestions welcome.

--
James Harris

I have seen the 8-bit Guy use that keypad fix (or whatever it was called) before and it seemed to work. However, I highly doubt he tested it much beyond
the making of the video and who knows how long it would last.

I like the idea of using some copper foil or discs. Perhaps epoxy a small copper pad on the bottom and try that?

--- SoupGate-Win32 v1.05
* Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)

James Harris <james.harris.1@gmail.com> wrote:

To my surprise, I find I have a Pet which works - all apart from the keyboard, that is. So I have a query about fixing it.

So far, I have removed the keyboard and found that the PCB contacts work
if shorted with something conductive. Therefore the problem is with the little black pads that a keystroke presses against the PCB. I have tried these things:

* cleaning with isopropyl alcohol
* cleaning with contact cleaner
* abrading with a pen eraser

The technology is the same as that used for remote controls, see here for
lots of potential repair methods: http://www.repairfaq.org/sam/irrfaq.htm#irrwcm

--
__ __
#_ < |\| |< _#

--- SoupGate-Win32 v1.05
* Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)

01-10-18 17:17 James Harris wrote to All about Commodore Pet keyboard re
Howdy! James,

I was wondering if the Keyboard Switches are called "Cherry Switches"?

A Cherry Switch (as I remember them being called) is a (almost) 3/4 Inch Plastic Box with two contacts on the bottom.

I built a Netronics ASCII Keyboard kit and after I finished one of the
Keys didn't do anything when I pressed it.

A friend used a knife to cut the bottom plastic piece from the rest of
the Switch.

I can't remember what He did (probably bent the contacts a little bit),
and then glued the bottom part with plastic glue from a tube and then
soldered the assembled Switch back on the PC Board, put the Key Cap on
it and the Switch worked when pressed.

Hope this idea is of help.

If a NEW Cherry Switch is what You need they may still be available at
Digi-Key or JamesCo or other Parts Stores.

@MSGID: <5A5689A0.2429.cbm@capitolcityonline.net>
To my surprise, I find I have a Pet which works - all apart from the keyboard, that is. So I have a query about fixing it.

So far, I have removed the keyboard and found that the PCB contacts
work if shorted with something conductive. Therefore the problem is
with the little black pads that a keystroke presses against the PCB. I have tried these things:

* cleaning with isopropyl alcohol
* cleaning with contact cleaner
* abrading with a pen eraser

The latter was not really effective as there is too much give in the
part of the key which supports the pad so I would say that the
operation failed to abrade the pad successfully.

Where I am now is that a few pads work but most do not. I have tried putting two meter test prods on the pads to measure resistance and
found that some only become conducive with significant pressure. I
guess that the rubber of some of them has become too hard with age.

So what can I do to fix them? Any ideas?

One idea I've had so far is to apply some conductive matter to the
pads. I have tried a product called Keypad Fix on a remote but found it dries to be too inflexible and crumbles on use, albeit that that was on larger contacts.

Another option is conductive paint such as

https://uk.rs-online.com/web/p/solder-pastes/8352699/

A further option is to cut tiny copper-film discs and stick them to the existing pads.

Any of those good options? Other suggestions welcome.

--
James Harris

--- SoupGate-Win32 v1.05
* Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)

... A Pseudonym is a nym that is not your real nym.
--- MultiMail/MS-DOS v0.49
* Origin: CCO BBS - capcity2.synchro.net - 1-502-875-8938 (1:2320/105)

On Thursday, January 11, 2018 at 10:04:18 AM UTC-6, Jim_64 wrote:

On Wednesday, January 10, 2018 at 11:17:06 AM UTC-6, James Harris wrote:

To my surprise, I find I have a Pet which works - all apart from the keyboard, that is. So I have a query about fixing it.

So far, I have removed the keyboard and found that the PCB contacts work if shorted with something conductive. Therefore the problem is with the little black pads that a keystroke presses against the PCB. I have tried these things:

* cleaning with isopropyl alcohol
* cleaning with contact cleaner
* abrading with a pen eraser

The latter was not really effective as there is too much give in the
part of the key which supports the pad so I would say that the operation failed to abrade the pad successfully.

Where I am now is that a few pads work but most do not. I have tried putting two meter test prods on the pads to measure resistance and found that some only become conducive with significant pressure. I guess that the rubber of some of them has become too hard with age.

So what can I do to fix them? Any ideas?

One idea I've had so far is to apply some conductive matter to the pads.
I have tried a product called Keypad Fix on a remote but found it dries
to be too inflexible and crumbles on use, albeit that that was on larger contacts.

Another option is conductive paint such as

https://uk.rs-online.com/web/p/solder-pastes/8352699/

A further option is to cut tiny copper-film discs and stick them to the existing pads.

Any of those good options? Other suggestions welcome.

--
James Harris

Hi, I work for a company that makes keypads and I have refurbished c64 and

VIC-20 (PET style) keyboards.

The contacts are usually (maybe always?) conductive rubber. There are two

ways to make conductive rubber, impregnation of the base rubber with conductive
material or a surface conductive paint. I am pretty sure the typical c64 uses the impregnated
conductive material. I'd be surprised if the PET was different. I don't remember the PET VIC-20 being that different.

Cleaning with isopropyl alcohol is really all I've ever done to restore

commodore keyboards to like new condition. I am surprised that didn't do the trick for you. Make sure you clean both the bottom of the conductive rubber pad AND the contacts on
the circuit board. You can use some force.

You are cleaning off any build up of surface films etc. that affect the

contact resistance. This is the same method used to clean the contacts of the "newer" membrane keyboard contacts used in the sx-64 and I think the Amiga (I'm
strictly 8 bit, so I
don't know Amiga that well...).

I haven't researched it, but I would avoid using contact cleaners. i would

think those are designed to clean plated surfaces and might attack rubber in a bad way.

Abrading with an eraser could work to clean the surface films off but I don't

think it is necessary.

If the rubber contacts were made with surface conductive paint (really cheap

way to go by the way), that ink can were off over time. Abrasion cleaning would be bad for these. If the rubber is any color than black, you can see the
wear patterns for
this. Pretty sure though, that the commodore parts will be black...

If you really think you want to try conductive ink again, this looks like the

right stuff. Usually some conductive material is mixed with a silicone paint so that it flexes with the rubber. Don't try anything that doesn't claim to stretch with the
rubber. The surface should be cleaned before application.

https://www.amazon.com/CaiKot-Conductive-Silver-Coating-surfaces/dp/B003D8G8SY/ref=pd_sbs_201_1?_encoding=UTF8&pd_rd_i=B003D8G8SY&pd_rd_r=FAXQRX7Y9CCEFSA99NT1&pd_rd_w=3RbXX&pd_rd_wg=P5wSL&psc=1&refRID=FAXQRX7Y9CCEFSA99NT1

But, please try the alcohol cleaning again first. It really should work.

You could also move some contact around to see if the issues follow the contacts or there is some issue with the PCB/cabling.

Good luck!

Jim

Also, I would not try to use any metal bits for contact pads. This would just be an ugly hack that might not work and ruin the feel of a cool old PET computer...

--- SoupGate-Win32 v1.05
* Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)

On Wednesday, January 10, 2018 at 11:17:06 AM UTC-6, James Harris wrote:

To my surprise, I find I have a Pet which works - all apart from the keyboard, that is. So I have a query about fixing it.

So far, I have removed the keyboard and found that the PCB contacts work
if shorted with something conductive. Therefore the problem is with the little black pads that a keystroke presses against the PCB. I have tried these things:

* cleaning with isopropyl alcohol
* cleaning with contact cleaner
* abrading with a pen eraser

The latter was not really effective as there is too much give in the
part of the key which supports the pad so I would say that the operation failed to abrade the pad successfully.

Where I am now is that a few pads work but most do not. I have tried
putting two meter test prods on the pads to measure resistance and found that some only become conducive with significant pressure. I guess that
the rubber of some of them has become too hard with age.

So what can I do to fix them? Any ideas?

One idea I've had so far is to apply some conductive matter to the pads.
I have tried a product called Keypad Fix on a remote but found it dries
to be too inflexible and crumbles on use, albeit that that was on larger contacts.

Another option is conductive paint such as

https://uk.rs-online.com/web/p/solder-pastes/8352699/

A further option is to cut tiny copper-film discs and stick them to the existing pads.

Any of those good options? Other suggestions welcome.

--
James Harris

Hi, I work for a company that makes keypads and I have refurbished c64 and VIC-20 (PET style) keyboards.

The contacts are usually (maybe always?) conductive rubber. There are two ways
to make conductive rubber, impregnation of the base rubber with conductive material or a surface conductive paint. I am pretty sure the typical c64 uses the impregnated
conductive material. I'd be surprised if the PET was different. I don't remember the PET VIC-20 being that different.

Cleaning with isopropyl alcohol is really all I've ever done to restore commodore keyboards to like new condition. I am surprised that didn't do the trick for you. Make sure you clean both the bottom of the conductive rubber pad AND the contacts on the
circuit board. You can use some force.
You are cleaning off any build up of surface films etc. that affect the contact resistance. This is the same method used to clean the contacts of the "newer" membrane keyboard contacts used in the sx-64 and I think the Amiga (I'm
strictly 8 bit, so I
don't know Amiga that well...).

I haven't researched it, but I would avoid using contact cleaners. i would think those are designed to clean plated surfaces and might attack rubber in a bad way.

Abrading with an eraser could work to clean the surface films off but I don't think it is necessary.

If the rubber contacts were made with surface conductive paint (really cheap way to go by the way), that ink can were off over time. Abrasion cleaning would be bad for these. If the rubber is any color than black, you can see the
wear patterns for this.
Pretty sure though, that the commodore parts will be black...

If you really think you want to try conductive ink again, this looks like the right stuff. Usually some conductive material is mixed with a silicone paint so that it flexes with the rubber. Don't try anything that doesn't claim to stretch with the
rubber. The surface should be cleaned before application.

https://www.amazon.com/CaiKot-Conductive-Silver-Coating-surfaces/dp/B003D8G8SY/ref=pd_sbs_201_1?_encoding=UTF8&pd_rd_i=B003D8G8SY&pd_rd_r=FAXQRX7Y9CCEFSA99NT1&pd_rd_w=3RbXX&pd_rd_wg=P5wSL&psc=1&refRID=FAXQRX7Y9CCEFSA99NT1

But, please try the alcohol cleaning again first. It really should work. You could also move some contact around to see if the issues follow the contacts or
there is some issue with the PCB/cabling.

Good luck!

Jim

--- SoupGate-Win32 v1.05
* Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)

On 11/01/2018 16:04, Jim_64 wrote:

On Wednesday, January 10, 2018 at 11:17:06 AM UTC-6, James Harris wrote:

To my surprise, I find I have a Pet which works - all apart from the
keyboard, that is. So I have a query about fixing it.

I'll just reply here but thanks to all for the helpful advice.

So far, I have removed the keyboard and found that the PCB contacts work
if shorted with something conductive. Therefore the problem is with the
little black pads that a keystroke presses against the PCB. I have tried
these things:

* cleaning with isopropyl alcohol
* cleaning with contact cleaner
* abrading with a pen eraser

The latter was not really effective as there is too much give in the
part of the key which supports the pad so I would say that the operation
failed to abrade the pad successfully.

Where I am now is that a few pads work but most do not. I have tried
putting two meter test prods on the pads to measure resistance and found
that some only become conducive with significant pressure. I guess that
the rubber of some of them has become too hard with age.

So what can I do to fix them? Any ideas?


One idea I've had so far is to apply some conductive matter to the pads.
I have tried a product called Keypad Fix on a remote but found it dries
to be too inflexible and crumbles on use, albeit that that was on larger
contacts.

Another option is conductive paint such as

https://uk.rs-online.com/web/p/solder-pastes/8352699/

A further option is to cut tiny copper-film discs and stick them to the
existing pads.

Any of those good options? Other suggestions welcome.


--
James Harris

Hi, I work for a company that makes keypads and I have refurbished c64 and

VIC-20 (PET style) keyboards.

The contacts are usually (maybe always?) conductive rubber. There are two

ways to make conductive rubber, impregnation of the base rubber with conductive
material or a surface conductive paint. I am pretty sure the typical c64 uses the impregnated
conductive material. I'd be surprised if the PET was different. I don't remember the PET VIC-20 being that different.

To my great surprise I seem to have found some similar conductive pads.
They are the same 4mm diameter and 0.5mm thick. Pack ordered!

http://termopasty.pl/en/produkty/rubbers-for-remote-controllers-en/

Cleaning with isopropyl alcohol is really all I've ever done to restore

commodore keyboards to like new condition. I am surprised that didn't do the trick for you. Make sure you clean both the bottom of the conductive rubber pad AND the contacts on
the circuit board. You can use some force.

You are cleaning off any build up of surface films etc. that affect the

contact resistance. This is the same method used to clean the contacts of the "newer" membrane keyboard contacts used in the sx-64 and I think the Amiga (I'm
strictly 8 bit, so
I don't know Amiga that well...).

I haven't researched it, but I would avoid using contact cleaners. i would

think those are designed to clean plated surfaces and might attack rubber in a bad way.

Abrading with an eraser could work to clean the surface films off but I don't

think it is necessary.

If the rubber contacts were made with surface conductive paint (really cheap

way to go by the way), that ink can were off over time. Abrasion cleaning would be bad for these. If the rubber is any color than black, you can see the
wear patterns for
this. Pretty sure though, that the commodore parts will be black...

If you really think you want to try conductive ink again, this looks like the

right stuff. Usually some conductive material is mixed with a silicone paint so that it flexes with the rubber. Don't try anything that doesn't claim to stretch with the
rubber. The surface should be cleaned before application.

https://www.amazon.com/CaiKot-Conductive-Silver-Coating-surfaces/dp/B003D8G8SY/ref=pd_sbs_201_1?_encoding=UTF8&pd_rd_i=B003D8G8SY&pd_rd_r=FAXQRX7Y9CCEFSA99NT1&pd_rd_w=3RbXX&pd_rd_wg=P5wSL&psc=1&refRID=FAXQRX7Y9CCEFSA99NT1

But, please try the alcohol cleaning again first. It really should work.

You could also move some contact around to see if the issues follow the contacts or there is some issue with the PCB/cabling.

Again, that's good advice. I have cleaned them a few times with the
isopropyl alcohol and some more keys are working. There is no great
staining coming off on to the cotton buds but I guess there could be
enough which has built up over time.

They are not all working yet but I'll keep at it - at least until the
new pads arrive.


--
James Harris

--- SoupGate-Win32 v1.05
* Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)

On 12/01/2018 22:56, James Harris wrote:

On 11/01/2018 16:04, Jim_64 wrote:

...

But, please try the alcohol cleaning again first. It really should work. You could also move some contact around to see if the issues follow the contacts or there is some issue with the PCB/cabling.

Again, that's good advice. I have cleaned them a few times with the
isopropyl alcohol and some more keys are working. There is no great
staining coming off on to the cotton buds but I guess there could be
enough which has built up over time.

They are not all working yet but I'll keep at it - at least until the
new pads arrive.

Success! I have a working Pet. Lots and lots of rubbing the black pads
with a cotton bud dipped in isopropyl alcohol did it.

This must be the first time I have used a Pet in decades and it's a
really strange nostalgic experience. For example:

I'd forgotten how one has to make space to insert characters but I
remember how cursor movement characters show up if too many spaces are
inserted - similar to the effect of typing an odd number of double
quotes on a line.

It was really weird that keyboard shortcuts like typing L shift I as a
shortcut for LIST came back to me immediately as if it was more a muscle
memory that a mental one.

I remembered Pets being ready as soon as the phosphor glowed but I'd
forgotten how slow they are in Basic; characters appear on the screen as
if they were coming over a modem! When I was of school age a friend and
I wrote some machine code and were blown away with how fast it was
compared with the Basic programming we were used to. Speaking of which,
I remember, with regret, the absence of a repeat key and writing a
machine code routine to try to provide autorepeat - unsuccessfully, IIRC.

I took a look at the character set and I'd forgotten that some Pets -
like this one - had no lower case. IIRC later Pets did but I'm not sure
what they did with the graphics characters which they presumably
displaced to make the lower case chars available.

Anyway, just a few reminiscences. This has transported me back to many,
many years ago!


--
James Harris

--- SoupGate-Win32 v1.05
* Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)

"James Harris" <james.harris.1@gmail.com> wrote in message news:p3guas$7vd$1@dont-email.me...

On 12/01/2018 22:56, James Harris wrote:

On 11/01/2018 16:04, Jim_64 wrote:

...

But, please try the alcohol cleaning again first. It really should
work. You could also move some contact around to see if the issues
follow the contacts or there is some issue with the PCB/cabling.

Again, that's good advice. I have cleaned them a few times with the
isopropyl alcohol and some more keys are working. There is no great
staining coming off on to the cotton buds but I guess there could be
enough which has built up over time.

They are not all working yet but I'll keep at it - at least until the
new pads arrive.

Success! I have a working Pet. Lots and lots of rubbing the black pads
with a cotton bud dipped in isopropyl alcohol did it.

This must be the first time I have used a Pet in decades and it's a really strange nostalgic experience. For example:

I'd forgotten how one has to make space to insert characters but I
remember how cursor movement characters show up if too many spaces are inserted - similar to the effect of typing an odd number of double quotes
on a line.

It was really weird that keyboard shortcuts like typing L shift I as a shortcut for LIST came back to me immediately as if it was more a muscle memory that a mental one.

I remembered Pets being ready as soon as the phosphor glowed but I'd forgotten how slow they are in Basic; characters appear on the screen as
if they were coming over a modem! When I was of school age a friend and I wrote some machine code and were blown away with how fast it was compared with the Basic programming we were used to. Speaking of which, I remember, with regret, the absence of a repeat key and writing a machine code
routine to try to provide autorepeat - unsuccessfully, IIRC.

I took a look at the character set and I'd forgotten that some Pets - like this one - had no lower case. IIRC later Pets did but I'm not sure what
they did with the graphics characters which they presumably displaced to
make the lower case chars available.

Anyway, just a few reminiscences. This has transported me back to many,
many years ago!

--
James Harris

All Pets have lower case. You have a choice between upper-case/graphics or upper-case/lower-case (graphics retained on the non-alpha keys). I can't remember what the pokes were to change the character set.

With the earlier Pets you would have to use the shift key to get lower-case.

Steve

--- SoupGate-Win32 v1.05
* Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3)