new conductive paint to fix 800/1200XL Mitsumi keyboards

[ACML]

I went to Radio Shack reluctantly expecting to pay the $22 for the Craig Circuit Writer conductive pen, but alas, my Radio Shack no longer carried them and on the shelf I noticed a "Bare Paint" conductive paint pen for $9.95. Its acrylic based (not waterproof) and is thick like artist paint (it uses graphite as the conductive material). I applied it with a tooth pick to repair a Mitsumi 800 keyboard and it works pretty good. Best to have a blow dryer on LOW to speed up curing. It gets more conductive as it dries. It also has a resistance and sometimes it doesn't show continuity on my multiplier, but it will still do the job (its intended for DC voltages <= 12 VDC). If you put it on thick, it will dry hard (i.e. brittle) and may not be a good idea to put directly on the mylar pad contact point where the plastic plunger consistently hits. All I needed to do was re-trace the terminal points where the mylar contacts the circuit board and repair one trace.

Edited July 8, 2013 by ACML

[RodLightning]

My first 600XL has this problem but is pretty far gone. I trimmed the mylar cable shorter as the end contacts failed over time. At this point, I would need to glue on a piece of mylar and paint all new traces onto the extension. I also removed the 64k ram upgrade and put it in a newer 600XL that I found years later so it is back to 16k.

 

In spite of my poor old 600XL's sad condition, I would very much like to restore it to working order one day It is the first home computer I ever owned and was a xmas gift in the mid 1980's. This paint (or something similar) might be a good start. It's funny how some of us still suffer from Atari's cheap build quality, decades later.

[RodLightning]

Bumping with more information:

 

Bare Conductive Pen - Radio Shack Part #276-267

 

A search for "bare paint" returns zero results on their website. Thanks again Rat Shack. The pens do appear to be in stock for $9.99 usd at many local stores.

This does indeed beat the $22.99 price tag on CAIG CircuitWriter pens, also supposedly stocked in stores.

 

I want to try fixing a 5200 controller with this material to see if it beats the foil and super glue repair.

 

 

 

[ACML]

Let us know if it works on repairing your 5200 controller.

[+Guitarman]

The ribbon on the 600XL can usually be brought back to life with some alcohol and an eraser. Use the eraser to clean the contact ends on the ribbon and then wipe with alcohol to get rid of any residue. This has worked well for me with the 600XL/800XL keyboard ribbons.

 

My first 600XL has this problem but is pretty far gone. I trimmed the mylar cable shorter as the end contacts failed over time. At this point, I would need to glue on a piece of mylar and paint all new traces onto the extension. I also removed the 64k ram upgrade and put it in a newer 600XL that I found years later so it is back to 16k.

 

In spite of my poor old 600XL's sad condition, I would very much like to restore it to working order one day It is the first home computer I ever owned and was a xmas gift in the mid 1980's. This paint (or something similar) might be a good start. It's funny how some of us still suffer from Atari's cheap build quality, decades later.

[ACML]

Just revived two more 1200XL keyboards. This stuff works great. Just remember, since it has some resistance, your multi meter won't beep on continuity if the trace is broken (but it still works). Just measure resistance.

[boxpressed]

I bought some of this at my local Radio Shack and used it to repair a 5200 controller. The substance is quite viscous but easy to apply with the pen. I probably should have waited a day for it to dry, but I tested it after a couple of hours. Seems to work great. I still have some doubts about it, though. I'm afraid the substance will eventually flake off, so the tin foil method may still be the best. It may be best for circuits that are not intended to contact something on a repetitive basis, like a fire button.

[telengard]

I used something like this a few years ago to fix an 800 keyboard, worked a treat!

[cfernan]

Has anyone tried conductive tape?

 

http://www.ebay.com/itm/1pc-One-Side-Conductive-Adhesive-Tape-Shielded-5mmX20m-/200729799577?pt=LH_DefaultDomain_0&hash=item2ebc6dab99

 

[ACML]

I've now revived nine 1200XL and three 800 Mitsumi keyboards using the same Bare conductive paint I bought almost two years ago. Still hasn't dried up. Best $10 I've spent at Radio Shack in a while. My 800 has a Mitsumi again? I think the Hi-Tek mechanical keyboards are the best for the long haul, but you just can't beat the feel of a Mitsumi. It's a 48K 1200XL with the best stock video of any Atari 8-bit!

Edited March 28, 2015 by ACML

[+bob1200xl]

I tried your paint...

 

Works great!

 

I mask the connector (a 1200XL) with 1/32' map tape and then just paint on the goo. Make it textured rather than smooth. Peel off the tape when it is dry. No shorts, nice look.

 

Very nice, thanks!

 

Bob

[AMC4x4]

Just pulled out my 1200XL after many many years. The power was finicky at first, but seems OK now, but (of course) the keyboard doesn't work. I'll be trying the keyboard fix with this paint next weekend. Terrified to try it, but I guess it's not going to fix itself.

 

I just want to take some video of all the old BASIC programs I made before selling it all.

 

Thanks for the tips!

[ACML]

Just pulled out my 1200XL after many many years. The power was finicky at first, but seems OK now, but (of course) the keyboard doesn't work. I'll be trying the keyboard fix with this paint next weekend. Terrified to try it, but I guess it's not going to fix itself.

 

I just want to take some video of all the old BASIC programs I made before selling it all.

 

Thanks for the tips!

Make sure you have an Exacto knife and multimeter. When "gently & slowly" pulling the mylar/silicon sheet away from the PCB, use the Exacto knife to free the sticking white silicon from the green PCB. The white silicon spacer must stay with the mylar sheet. If a few keys still won't respond, the multimeter can be used to find a broken trace.

[+DrVenkman]

Listen to ACML's advice - take your time peeling apart the silicone sheet. A few minor tears won't hurt so long as you lay them back into place carefully when you reassemble things. I used this same Bare conductive paint to repair two 1200XL keyboards of my own last summer. Stuff works great but it is rather thin (not very viscous. I actually used a fine paintbrush to paint the stuff across the connector traces since the tip of the "pen" is far too large and coarse for that kind of small work.