How to repair a ZX81XT extender board (or slot edge connector)

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PokeMon
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How to repair a ZX81XT extender board (or slot edge connector)

Post by PokeMon » Mon May 01, 2017 4:27 pm

* HOWTO instruction *

Well - one day with bad luck, to much force, bad angle or whatever it may happen, that one of the contacts of slot edge connector is bended and moved inside the connector and while trying to fit it deeper onto the edge connector you press it more inside like this:
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The repair is quite simple with few tools and a soldering iron. Contacts can be removed and replaced easily. First heat the soldering of the contact and bend it back into the straight position.
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Then you can move the contact outside in slightly pushing it to the connector open side. Avoid bending - best to do this is to use a side cutter, grab it and push it in the desired direction. Be careful not to cut it accidently ...
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PokeMon
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Re: How to repair a ZX81XT extender board (or slot edge connector)

Post by PokeMon » Mon May 01, 2017 4:32 pm

Here it comes and now you can easily grab it from the front side with a tweezer or a side cutter or a small screwdriver to pull it out completely.
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Then you need a new contact feather or spring (don't know the correct name of this) - I have a small box and collected many over the time, so easy for me to find. You may also take another unused connector to take from. Be sure it is of same type, there are different types used ... (the upper one is the bad contact and below shown a new contact)
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Then you can simply put it back into the edge connector from frontside while carefully moving it deeper into it's hole and see coming out from the other side.
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Last edited by PokeMon on Mon May 01, 2017 4:40 pm, edited 1 time in total.

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PokeMon
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Re: How to repair a ZX81XT extender board (or slot edge connector)

Post by PokeMon » Mon May 01, 2017 4:35 pm

You may take it now from the other side and pull it deeper into the connector until the right position is found (as deep as the others). Better to pull then to push it too much from the other side as it has to be handled carefully.
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Then bend it back to reach the pcb and heat the soldering and move it near the board and let it solder back again.
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That's it - now it looks fantastic again like new and (most important) will work again. 8-)
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Last edited by PokeMon on Tue May 02, 2017 12:33 am, edited 1 time in total.

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1024MAK
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Re: How to repair a ZX81XT extender board (or slot edge connector)

Post by 1024MAK » Mon May 01, 2017 4:43 pm

Edge connector surgery with Doctor PokeMon :ugeek:

With new edge-connectors that need cutting down to size, I keep the spare bit for this very reason ;)

Mark

sirmorris
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Re: How to repair a ZX81XT extender board (or slot edge connector)

Post by sirmorris » Mon May 01, 2017 11:08 pm

Ha! Yes, _exactly_ what I do when that happens (all too often) to me. My own boards get a lot of abuse and a damaged edgey is a common complaint.

Sometimes I find that the spring wants to escape into the central space, especially if the plastic around the spring's position is slightly damaged. When this happens I insert a piece of PCB material into the connector before inserting the spring, so that the new spring is pushed/pulled into its seat properly.

Great guide Karl!

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mrtinb
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Re: How to repair a ZX81XT extender board (or slot edge connector)

Post by mrtinb » Thu Apr 19, 2018 3:36 pm

I have used a ZX81XT to get space between my Lambda 8300 and the ZXBKBv3 keyboard controller I've built. But yesterday all kinds of chars came randomly on the screen, but the computer worked. It was hard to use, as most of the chars on the screen were corrupted.

This was very frustrating. Finally I saw that one of these connectors was broken. I replaced the ZX81XT with a UDG-for-ZXpand card, and everything worked.

Thanks for the great dokumentation to fix this. I need the ZX81XT to use my ZXblast.
Martin
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube

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