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mehguy

Timex Sinclair 1000 repair

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I own a Timex Sinclair 1000 (NTSC version of the ZX81) and it displays no video... from what I've researched, the ULA chip is to blame for this. Are their replacements out there or are there substitutes?

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Are you sure there is no video? The reason I ask is I got my Timex Sinclair 1000 just a bit ago and thought the same thing but I found out that the ULA doesn't work well with most TV's and so to get a pic you generally have to crank the brightness up to 11 to see anything.
As JamesD mentioned, there are replacements, either to buy or make. Personally, the replacement is so simple to do that I'm going to make mine to save myself the cash. IF you're sure the ULA's completely fried, then just Google "Replacement ULA zx81". I just did that search and found this (http://www.sinclairzxworld.com/viewtopic.php?t=680&start=20)

 

Have fun!

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There are 2 possibilities for the ULA chip: ULA2C184E or the newer ULA2C210E

 

The older 184E doesn't have the back porch on the NTSC signal and many TVs display a very dark screen because of that. You can either try an old B&W TV or a composite video kit that recreates the missing signal.

 

This composite video mod board works great and I've used 3 of them in the past: http://www.sellmyretro.com/offer/details/ZX8-CCB---video-output-for-ZX81-3712

 

It fits inside the RF Modulator if you pull the guts out of it. :)

 

RJ

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Hey, that's a pretty reasonable price. Sure it's fun to build your own but at that price, I think I'll just get one of those. Thx for that!

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That web site is a cool place to buy parts and new aftermarket items from Europe. You can find replacement mylar keyboards over there to replace the originals that like to crack.

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Yeah I did the Composite video mod so I could use it on a B&W security monitor I picked up. It looks really well but I'm at a stand still!. I'm making a new keyboard for my Timex 1000 with some actual buttons!

 

I've got the buttons put in a way where they all sit right under the same keys as the membrane! Since I've already messed the heck out of this computer and I've got a working NTSC zx81 I was thinking about cutting a hole in the case to mount the new keyboard..... OR! Make it's on wooden case as a joke. like an Apple I!

 

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:thumbsup:

Is there a way to maybe brace the switches against the bottom of the case so that the membrane itself pushes against them?

It wouldn't do anything to actually fix a broken keyboard membrane or anything like that, but with a good keyboard you'd at least have some tactile feedback from the switches, even though it's actually the membrane that's being actuated.

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I want to cut a hole in in the case of the T1000 so I can mount the new keyboard inside and lay the membrane against it. so we get the click of the buttons but the flush of the original keyboard. The last thing I need to replace is the voltage regulator. I want to go with a new more efficient one. to well drop the heat sink on that bad boy.

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