TT and Mega STE: check your LED brackets!

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stephen_usher
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TT and Mega STE: check your LED brackets!

Post by stephen_usher » Sun Nov 17, 2019 3:29 pm

It's long been known that the LED brackets for the power and HD are prone to rusting but until this week I didn't realise just how bad mine had become.

Earlier in the week I noticed that the HD light wasn't showing so I took the HD module out and had a look. I knew it was rusty but what I hadn't realised was that the rust had curled around the grommet holding the LED and had corroded the leads and one had fallen off.

So, I ordered a new LED and replacement PVC grommets (RS Components stock No. 6664593).

Today I started work and wanted to check the power LED as well. It's as well I did as that bracket, although superficially less rusty than the HD one was actually worse. After removing it, poking the LED out and removing the remains of the (now hard) grommet I discovered that I was only just in time and the end of the brackets had very little metal left! As I was removing the old grommet part of the socket started to crack and tear.

After an initial clean-up with sandpaper I popped it into rust removal gel, which got rid of some of the haematite but because it had built up so slowly it was crystalline so the citric acid did little to dissolve it. But it was enough that I could support the very thin steel with some solder.
IMG_1669.jpg
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Eventually, after more physical removal using a file and more bathing in acid I got the bracket into a state where I could finally cover it in anti-rust primer, fit a new PVC grommet and re-install.

Thankfully the HD bracket, being thicker metal, wasn't in such a precarious state, but it did take a lot of filing and chemical treatment to get that in a state where it could be primed and reinstalled (and new LED fitted).
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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Icky
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Re: TT and Mega STE: check your LED brackets!

Post by Icky » Sun Nov 17, 2019 4:48 pm

I had exactly the same corrosion on my brackets and it seemed to be a reaction of the rubber grommets used to hold the LED. The rubber was almost like a sticky goo when I touched it the first time and the rust seemed to start from the rubber goo.

stephen_usher
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Re: TT and Mega STE: check your LED brackets!

Post by stephen_usher » Sun Nov 17, 2019 5:06 pm

Icky wrote:
Sun Nov 17, 2019 4:48 pm
I had exactly the same corrosion on my brackets and it seemed to be a reaction of the rubber grommets used to hold the LED. The rubber was almost like a sticky goo when I touched it the first time and the rust seemed to start from the rubber goo.
The grommets on my TT were as hard as rock. I'm guessing that the PVC broke down and released chlorine which catalysed the rusting.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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ari.tao
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Re: TT and Mega STE: check your LED brackets!

Post by ari.tao » Sun Nov 17, 2019 9:15 pm

Have a look what I did when the same problem arrived at me.
The new LED which I purchased from my local dealer did not fit into the old bracket.
So I bent a new holdering from a piece of copper wire. Will never be rusty again, and is easily to remove & stickon again when I need to open the case.
(I apologize for the picture quality - could not manage to zoom out for smaller size...)
LED+Rost.jpg
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Alt+neu.jpg
Alt+neu.jpg (17.22 KiB) Viewed 166 times
Buegel neu.jpg
Buegel neu.jpg (26.1 KiB) Viewed 166 times
neue LED.jpg
neue LED.jpg (13.67 KiB) Viewed 166 times
Falcon, TT & some more

stephen_usher
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Re: TT and Mega STE: check your LED brackets!

Post by stephen_usher » Sun Nov 17, 2019 10:00 pm

Yes, you have to get the correct sized LED if you want to do a direct replacement. The ones Atari used are 3mm diameter with 3mm hole, 5-6mm hole diameter (8mm total diameter) PVC grommets.

Of course, if Atari had painted the steel we wouldn't have half the problems. Even better used grommets which didn't leak corrosive substances would have been better. Still, they probably thought the lifetime of the product was only a few years anyway, so it was good enough.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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TimNaber
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Re: TT and Mega STE: check your LED brackets!

Post by TimNaber » Wed Nov 20, 2019 7:30 pm

I bought a Mega STe cover with HD bracket from Brad at Best. It arrived with the corrosion and one of the wires just fell off. These were NOS, so it will most likely happen to all of them. Brad replaced it no problem.
ST: TT030 10/32 MB; Falcon 030 14MB(2); Mega STe 4 MB; Mga 4 stock(3), 1040STf 4 MB(3); ST 4MB (2); Megafile 44 (3); Megafile 30(4)

8-Bit: 320XE w/Ultraspeed+/FIXXL; 320XE; 130XE w/Ultimate 1MB; 600XL w/Ultimate 1MB; 800XL w/Omnimon XL/Boss XL/Omniview XL; 800 w/Incognito; 48K 800; Black Box Enhanced (3); 1050 Super Archiver II; 1050 Happy (2); XF551 360K(2); XF551 720K; 8-bit Hard Drive Tower 480 MBs.

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Icky
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Re: TT and Mega STE: check your LED brackets!

Post by Icky » Wed Nov 20, 2019 8:35 pm

If I get time I may design a bracket to 3D print :)

I did find a model on thingiverse for the MegaSTE / TT disk cover viewtopic.php?f=62&t=1732.

Never got round to printing it out as it was too big for my printer but now with the Giant Panda viewtopic.php?f=18&t=2086 I should be able to refine the design and print a few out to see how they turn out.

stephen_usher
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Re: TT and Mega STE: check your LED brackets!

Post by stephen_usher » Wed Nov 20, 2019 10:39 pm

TimNaber wrote:
Wed Nov 20, 2019 7:30 pm
I bought a Mega STe cover with HD bracket from Brad at Best. It arrived with the corrosion and one of the wires just fell off. These were NOS, so it will most likely happen to all of them. Brad replaced it no problem.
Yes, it's a systemic problem with the plastic of the grommet seemingly releasing chlorine ions catalysing the rusting of the steel.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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