Screw at MTX case bottom

About original Memotech hardware.
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protek
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Screw at MTX case bottom

Post by protek » 06 Aug 2015 13:15

What type should the screw at the bottom of the MTX case, apparently securing the motherboard, be? I've been looking at the screw in mine and I'm not sure whether it's an original screw or not.

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Dave
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Re: Screw at MTX case bottom

Post by Dave » 06 Aug 2015 13:41

Look on the page .....
http://www.primrosebank.net/computers/mtx/mtxphoto.htm

Just below the video board photos, the bolt goes through the base and is fixed with a nut job n the heat sink tab. I'd need to check the size, but it's probably a small BA sized bolt.

I'll try and get measurements later

Regards
Dave

protek
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Location: Oulu, Finland

Re: Screw at MTX case bottom

Post by protek » 06 Aug 2015 13:49

I take you mean this one: http://www.primrosebank.net/computers/m ... emoved.jpg

Well it shows that the screw is anodized. Mine isn't. Is it supposed to be a countersink screw?

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Dave
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Re: Screw at MTX case bottom

Post by Dave » 06 Aug 2015 14:11

Hi, yes, that's the photo.

Just to be clear, the screw that you are talking about should "appear" through the hole in the 7805 regulator, it is not fitted in the photo, but this is the best photo that I have of the regulators and heat sink. They are usually obscured by C56.

No, it isn't normally a countersunk screw, it's a pan head bolt. Normally it is silver/steel coloured,

Regards
Dave

protek
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Location: Oulu, Finland

Re: Screw at MTX case bottom

Post by protek » 06 Aug 2015 14:14

Ok, then I think I have the correct screw in mine.

Thanks!

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1024MAK
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Re: Screw at MTX case bottom

Post by 1024MAK » 07 Aug 2015 05:38

It has to be a M3 machine screw or an equivalent that has the same (or slightly smaller) diameter so that it fits the hole in the regulator. Mind, it is possible that you could use a slightly larger one, as the M3 machine screw and regulator are designed to have an insulating shaped washer fitted (not needed for the 7805 and 7812 regulators, the boost transistor does need insulating).

I don't know the length, as I have never bothered to measure it. When I needed to renew one (the existing one had become rather bent :shock: ) I selected a replacement of the correct length from my stock of spare machine screws.

The screw head can be either pan head or cheese head.

You will need a matching nut also.

Mark

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