Bad Control key on keyboard

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bjjones37
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Bad Control key on keyboard

Postby bjjones37 » Tue Sep 14, 2004 1:12 am

I have just one key that is not working on my MegaSTE - the Control key. Every other key seems to be working although I was not sure how to fully check out the function keys. I took it apart and removed all the dust from the inside, even removed the plastic template the keys make contact with using their rubber feet, but everthing looked good. How could one key not work? And how could I fix it? I would think that if a conductive track on the template were open it would affect a row of keys, at least that is my assumption. Any ideas?
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Gryzor
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Postby Gryzor » Tue Sep 14, 2004 7:38 am

Would it? I think every key has a contact track running off to the controller or at least some more central point, so the problem might be there...?

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aktiv8
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Postby aktiv8 » Tue Sep 14, 2004 8:03 am

Been a while since I;ve looked at the tracks etc on my ST keyboards - but I think Gryzor is right. I think every key has its own track. Otherwise I can't see why this one key is not working when all others are...

Have a close look with a magnifying glass if needbeand if anything gone - try a test repair job with some aluminium foil if the tracks are exposed to see if it solves the problem.... then you can fix the break properly if it works
>>> Trust me, I'm a Research Chemist.... <<<

simbo

Postby simbo » Fri Sep 17, 2004 2:30 am

hum

go to maplin and buy a little bottle of silver membraine repair paint
cost 7 quid

but its worth it

you can bridge tracks and repair pads and also the pcb ferrite pads

sure one key can stop working


but a keypad is a matrix like 8by 4 bits wide
and is scanned to form dwords you dumb clots above

so ... its easy just to loose one
usualy caused by black pcb desease spots

a common bacteria that lives on copper and the nice green paint
pcb maker use

its a funny bacteria smells of beer when you burn it with an iron {subtle hint} and eats the tracks


look for the black spots and scrape them off carefully
then "tin " the area with some solder and a low wattage iron
{12watts only here}

read simbos faq s on keyboard
repair
and if you get stuck
take a good photo or a scan of the print side and ill tell you where to solder

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Gryzor
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Postby Gryzor » Fri Sep 17, 2004 6:24 am

Er... I think we all got a pretty good idea of what to do :D

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Postby manicx » Fri Sep 17, 2004 8:23 am

The info was enough to fix not one but five keys!
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bjjones37
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Postby bjjones37 » Fri Sep 17, 2004 1:11 pm

Thanks Simbo,
I'll try that. I just happen to have some of that silver paint to use if it has not dried up over the past seven years. It never has been opened. I cannot do any soldering because the traces are painted onto a thin clear plastic membrane. I am going to open another topic now because I have another much more serious problem.
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Bad Control key fixed and add to Bad Hard drive controller

Postby bjjones37 » Mon Sep 20, 2004 1:42 pm

Guess you can lock this topic now too! Get this, when I fixed my problem with the hard drive controller by reseating all of the chips, the Control key started working too! :) I guess there is a reason they called it a GLUE chip. For those interested, it was a SCSI 2 drive I installed and it works fine on my MegaSTE. It has a Parity Disable jumper on it which is why I managed to get it to work. I could only get one gigabyte of the two gigabyte drive to actually work but for an ST, that is fantastic. A third party controller probably would have seen all of it. I used HDX 5.00 to format it (HDX 5.02 and 5.04 seemed to have problems with it, not sure why.) I used CBHD to partition it into eight 128M partitions and HINSTALL with AHDI6061 to put the driver on it. Had to manually rename the AHDI file of course so HINSTALL could install it. Now to try to fill up that hard drive :D
Oh and thanks to Simbo and everyone else who helped out while I was panicking and going through my learning curve.
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simbo

Postby simbo » Wed Sep 22, 2004 10:57 pm

lol its great to see so much success

to rejuvinate the silver paint you need a small bottle of celulose thinners from a model maker shop use a pipet from an old ear wax disolver bottle or something

look down the tins take a whiff of the paint first as a referance
and find the closest match smell wise

its 60p for thinners or 7 quid for more silver paint {any celulose thinners will do,,,,}
i always dress the pcb if needed to remove the section of green paint

and use then acitone form the chemist

ask for the plain deal no added crap to make ladies nails soft

just plain white acitone


this will realy clean the area so use a cotton bud not a cloth

and dont spend all day at it just a quick swab round and let it dry

then the paint realy sticks on


but dont use this on the plastic membrane type's as you sussed out its better to use pure paint and do a few thin coat's

you can use acetone one some type's of plastic but for celulose thinners also be carefull
to test a small area somehwere it dosn't matter
to guage what the plastic does.... first!!!
Last edited by simbo on Thu Sep 23, 2004 1:43 am, edited 3 times in total.

simbo

Postby simbo » Wed Sep 22, 2004 11:29 pm

to the posters galore on the chips and drop technique

this is all well and good but no substitute

for a good body earth and a burnish brush


essental tools
http://www.maplin.co.uk/

first version for flux removal

Two pens for precise removal of flux from printed circuit boards.
· Completely removes flux in seconds
· Spot cleans tight tolerance areas on circuit boards
· Marker dispenser provides controlled and exact application
· Dries fast
· 9g pen No Clean Flux Remover (Order Code N64AA)
· 8g pen Rosin Flux Remover (Order Code N66AA)


flux around ics and connections even power {esp power} causes sproggies and strange effects so clean it off completely in computer land


this is a burnish to clean chips pins esp the plug in fga types

A fibreglass abrasive stick housed in a propelling pencil type case. Designed for removing protective lacquer coatings on PCB board, prior to repair, and generally cleaning copper track for soldering. A spare fibreglass stick is available (Order Code KR62S) Warning: A certain amount of fibreglass dust is produced which should be removed with great care. Avoid touching with exposed skin as the particles can easily penetrate flesh and be extremely uncomfortable. Avoid contact with eyes.

{this means you wear glasses to do ANY job with this pen and use an electical dust vacum ..... same supplier...}
if you think flesh contact is "extremely uncomfortable" try your eye's
!!!!! and never see again ... chance of....

code KR61R




dont be daft here
use a GOLD CLOTH its blue you can buy one from the jewler

and use it to clean ram and sensative parts contacts

its also great for high density connector strips
{made of plastic with a bar of connector ribbions on a stiff back that plugs into and locks into side connectors in cameras etc fine connectors need tender treatments ...!!!! and small fine hands so ask someone else if you have sausages for fingers

BUT .. for chips mostly i use the burnish

{always buy a pak of refills with a first time buy youll find all sorts of uses for this so keep a stock of spare brush elements}




be warned keep a static earth at all times

buy a snap on wrist band and not to the electrical earth
use a down pipe outside or your water system only !!!! BE WARNED
5 out of 10 houses electical supply is sub standard.... in europe and the u/s
with japan the best earthed



spend a few quid if your taking a tinkering with old chips
buy a conductive pad or use a few layers of folded tin foil glues with copydex to a bit of conductive foam {also maplin}
as a placement zone
i also order from small firms via adverts in
epe magazine local news agents

http://www.epemag.wimborne.co.uk/

or buy a copy online for a few quid



like a nappy for the elderly its essental to avoid sensative earth gate spillage.....

http://mp3.cloudfactory.org/%7Edjstonie ... de_vii.mp3

3rd or 4th tune




chips die if you abuse them but not right away
they live a few years and run like a geriatric dog and get hotter so
have signed the death certificate as soon as you unplug them

so earth all parts first inc you!!! TO THE SAME POINT then to the earth

static dosnt destroy the chip
it destroys the gates on the output pins like buffers that arent ecd protected mostly pre 1987 chips
Last edited by simbo on Thu Sep 23, 2004 1:25 am, edited 4 times in total.

simbo

Re: Bad Control key fixed and add to Bad Hard drive controll

Postby simbo » Thu Sep 23, 2004 12:11 am

bjjones37 wrote:Guess you can lock this topic now too!



i only lock topics once all the info on a topic is aquired or yielded
this allows others to see
solved topic list

as topics with idiot posts i mark in a log and would only remove after getting approval ... etc,,,,

if i lock a topic and you disagree
please post me a pm


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