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Atari 800 Space Bar not working


Lardo Boffin

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Hello all

 

I finally got a mostly working PAL Atari 800 from eBay (sold untested hence I could afford it ?). Unfortunately the space bar doesn't work. A quick google suggest that this is a fairly common issue but with varying causes. 
I have taken the computer apart as  below. The keyboard is a HI-TEK. As far as I can tell the mechanical part of the keyboard is fine - if I push the plunger down it looks look like the plate on the left makes contact with the four fingers on the right although I will confirm this with a continuity tester at some point. 
Any ideas where I start with this?

Any help greatly appreciated!

Thanks!

Lardo

BE7F5463-C87C-480D-97B0-65C5F968684D.jpeg

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59 minutes ago, Lardo Boffin said:

Hello all

 

I finally got a mostly working PAL Atari 800 from eBay (sold untested hence I could afford it ?). Unfortunately the space bar doesn't work. A quick google suggest that this is a fairly common issue but with varying causes. 
I have taken the computer apart as  below. The keyboard is a HI-TEK. As far as I can tell the mechanical part of the keyboard is fine - if I push the plunger down it looks look like the plate on the left makes contact with the four fingers on the right although I will confirm this with a continuity tester at some point. 
Any ideas where I start with this?

Any help greatly appreciated!

Thanks!

Lardo

BE7F5463-C87C-480D-97B0-65C5F968684D.jpeg

You can see the problem on the photo.  Look at solder pad 57 just to the right of the ribbon cable.  You can see that the two solder holes are open (the pins fell out).  Pad 57 is for the space bar.  This is the common flaw of the Hi Tek keyboard.  It is fixable.  You need to insert two pins back in, but there is a trick.  I use a metal pin constructed from those cheap Christmas ornament wire hooks since they are malleable and not too rigid.  You need a multimeter to test continuity.  Insert the two pins and you will have to feel around until you get continuity when you press the spacebar.   When they are positioned to get continuity when the spacebar is pressed, very carefully solder them without moving the pins.  I've done this on three Hi Tek and had a 100% success rate.  You need patients to insert them in the right position.  No continuity when the space bar is not pressed and continuity when it is.  This failure is usually attributed to too many enthusiastic sessions of Defender smacking the spacebar (smart bomb) too hard.  The load is passed into the PCB and it eventually de-bonds and the solder pad releases the pin.  You have both pins to contend with.

 

One warning:  Be careful not to leave the solder iron on the PCB Pads (location 57) too long.  You might be-bond the trace on the PCB if it gets too hot for too long (been there, done that). 

Edited by ACML
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2 hours ago, TGB1718 said:

I had a similar issue with my 800 but wasn't aware of this issue, but I did find it, I used a piece of copper core from 

house wiring mains cable (solid conductor) and now it works fine.

could you give a bit more detail, I think I have the same issue with one of my 800 keyboards

 

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I have had a look on the underside of the keyboard and was wondering what the missing pins look like?


I can see the base of the contactor through the solderless hole (see the ‘artists’ rendition below) but I am not sure how the pin connected to it? 
I got continuity by putting a cut off capacitor leg into the hole and against the base of the contactor but if I just do that and solder it, it doesn’t seem like it will be a very sturdy connection?

Are the pins shaped to maybe go round the base of the contactor or similar?

Many thanks!

8483B27C-0B67-48A1-A833-4CD85259BA1C.jpeg

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4 hours ago, Lardo Boffin said:

I have had a look on the underside of the keyboard and was wondering what the missing pins look like?


I can see the base of the contactor through the solderless hole (see the ‘artists’ rendition below) but I am not sure how the pin connected to it? 
I got continuity by putting a cut off capacitor leg into the hole and against the base of the contactor but if I just do that and solder it, it doesn’t seem like it will be a very sturdy connection?

Are the pins shaped to maybe go round the base of the contactor or similar?

Many thanks!

8483B27C-0B67-48A1-A833-4CD85259BA1C.jpeg

If its making descent contact and is soldered in place, it should hold up.  One of the reasons I like to use a wire/pin made of a malleable (not too stiff) metal is that it is more likely to stay in contact and when it takes a load against the PCB, it gives a little (bend, but not yield).  I think it can take cyclic loads better than a thick stiff pin.  It's a matter of cycle fatigue.  It can take thousands of light impacts before crack initiation (solder pad).  Propagation of the crack is also likely delayed as the softer material acts as an energy absorber.  A stiff rigid pin imparts almost all of the load directly into the PCB.  I know, enough cycle fatigue already (give me a break, I'm an AE).    

Edited by ACML
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So I bodged it. I did one side fine and that gives continuity to the key side. 
The other side went wrong when I tried to remove the remaining solder - the track lifted. Argh. Not done that for a long time. 
Any thoughts on best process of repair? The last time I did this I had the luxury of being able to see the other side of the PCB and be able to solder that side and then put a jumper cable in place. This - not so easy!

One immediate crazy thought was hot melt glue to hold the pin and then jumper from that but I have no idea if that will be strong enough or even if the glue will stick to the PCB! Not to mention once the glue is there there will be no repositioning of the pin should it be necessary. 

Did I say argh?

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9 minutes ago, TGB1718 said:

Lardo Boffin, you could try pushing the wire to make contact through the hole, then wedge it in place with another

piece of wire in the same hole, solder up a patch to the old track, make sure its all working, then bite the bullet and glue it in place.

Thanks. I am at this point seriously considering sending it off to an expert and pay them to do it. Its one of those questions - ‘at what point do I cut my losses?’ If I ruin the keyboard the only other one for sale on eBay (from MyAtari) is from the USA so will be far from cheap to buy and import to the UK! Its £50 just for postage!!!

Are there any web sites still selling these does anyone know?

Many thanks!

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23 minutes ago, Lardo Boffin said:

Thanks. I am at this point seriously considering sending it off to an expert and pay them to do it. Its one of those questions - ‘at what point do I cut my losses?’ If I ruin the keyboard the only other one for sale on eBay (from MyAtari) is from the USA so will be far from cheap to buy and import to the UK! Its £50 just for postage!!!

Are there any web sites still selling these does anyone know?

Many thanks!

Best Electrics, again in the USA so cost is $$$

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11 hours ago, Lardo Boffin said:

So I bodged it. I did one side fine and that gives continuity to the key side. 
The other side went wrong when I tried to remove the remaining solder - the track lifted. Argh. Not done that for a long time. 
Any thoughts on best process of repair? The last time I did this I had the luxury of being able to see the other side of the PCB and be able to solder that side and then put a jumper cable in place. This - not so easy!

One immediate crazy thought was hot melt glue to hold the pin and then jumper from that but I have no idea if that will be strong enough or even if the glue will stick to the PCB! Not to mention once the glue is there there will be no repositioning of the pin should it be necessary. 

Did I say argh?

Can you upload a photo of what it looks like now?

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On 10/6/2019 at 10:58 AM, ACML said:

This failure is usually attributed to too many enthusiastic sessions of Defender smacking the spacebar (smart bomb) too hard.  The load is passed into the PCB and it eventually de-bonds and the solder pad releases the pin.

Hehe, I recalled this was mentioned in ANTIC Interview 33 - Louis Massucci, Atari Bench Tech just after the 9 minute mark. :P

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14 hours ago, Lardo Boffin said:

I went the bunny ear route for one side. ?

 

image.png.7c790187e7833cd91bad647bc35a6c93.png

Yes, I see.  What can you do to hold the pin in place with the pad lifted, that is the question.

 

1)  You might try hot glue to hold the pin in position and then solder a 30 gauge wire from the new pin to the other pin on the lifted trace.  Glue may not hold to PCB

 

2)  Super glue trace back on PCB? 

 

3)  Replace the lifted trace with a thick solid wire (20 gauge or thicker) between the lift pad/new pin and the pin at the other end of the lifter trace (laid flat on PCB where trace was).  Now its thinker and more robust, just hot glue the new 20 gauge wire segment to PCB.  Now it might have enough mass and surface area to hold. 

 

Edited by ACML
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use high temperature epoxy/crazy glue.... available for cheap on all the auction sites for trace repair... the trace you lifted looked fully intact... if you do a careful job no one might notice... use a matching or clear solder mask (available  same way) to seal and bond it further...

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On 10/11/2019 at 9:42 PM, ACML said:

image.png.7c790187e7833cd91bad647bc35a6c93.png

Yes, I see.  What can you do to hold the pin in place with the pad lifted, that is the question.

 

1)  You might try hot glue to hold the pin in position and then solder a 30 gauge wire from the new pin to the other pin on the lifted trace.  Glue may not hold to PCB

 

2)  Super glue trace back on PCB? 

 

3)  Replace the lifted trace with a thick solid wire (20 gauge or thicker) between the lift pad/new pin and the pin at the other end of the lifter trace (laid flat on PCB where trace was).  Now its thinker and more robust, just hot glue the new 20 gauge wire segment to PCB.  Now it might have enough mass and surface area to hold. 

 

The bunny ears were not intentional but I found that a stiff piece of wire bent over gave the best contact. 

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