My QXT640 thread

[Chr$]

This is my Sandy QXT640 project, received the Wednesday and tried out for the first time today.

I had to change the filter caps on the PSU and that works now. It's a bit dodgy as it was only held down with one screw and some hot glue and is obviously quite exposed on the top. I connected the PSU to the QL board with nothing else plugged in (apart from a screen) and it didn't work. ZX8301 was bad, swapped out, QL board works now.

It also came with a 3.5in FDD and metal bracket to hold it. The metal bracket also has an original microdrive attached underneath with appropriately sized cut-out on the right side of the case. Unfortunately the front metal face-plate is a bit worn out and a lot of the white stripes etc are scratched - you can see that it was originally used with a 5.25in drive and 3.5in.

It also came with Sandy keyboard interface (not tested yet), Sandy RAM/FDD interface (not tested yet - the RAM part is certainly bad as shown in my other recent post). There is also a QIMI mouse interface and a SPEM 'QL Keyboard' (checked - has some non functioning keys, hope it's not a membrane type) plus a bag of various ribbon cables, screws etc.

I know that it basically works so all I need to do is clean up, probably retro-brite the plastics, perhaps add some standoffs to fit the PSU properly, change the power switch to one that doesn't rely entirely on hot glue as insulation, check and connect the expansion cards, FDD etc and then see if I can somehow make that front face-plate prettier and fill that 5.25in bay hole.

[dilwyn]

Thank you chr$. Nice to see pictures of these old systems.
Many years ago, I was at an International QL Meeting with a few other Quanta members. We travelled there in a minibus, driven (I think) by Phil Borman, former Quanta Chair. I remember seeing a QXT640 at that fair and it got me thinking I should have bought either one of those or a CST Thor. Quite simply, I was convinced that this sort of machine was what the QL should have been from day 1.
At one stage, I was looking to put a QL into a PC case. Someone gave me a case for next to nothing which turned out to be the same case as used for the QXT640 (not sure if it was a real QXT640 or just a matching case... Maybe Dave could tell us if Sandy made the cases or bought them in?). After a while, I decided I had too much QL stuff and gave a lot away, including that case.
Memories.

[Chr$]

Someone gave me a case for next to nothing which turned out to be the same case as used for the QXT640 (not sure if it was a real QXT640 or just a matching case... Maybe Dave could tell us if Sandy made the cases or bought them in?). After a while, I decided I had too much QL stuff and gave a lot away, including that case.
Memories.

I wondered about the case too, it's clearly properly made injection moulded plastic or whatever. I came to the conclusion that they must have been sourced from somewhere and were probably generic cases for some general purpose. Dave will correct me if I'm wrong. The flat aluminium front and rear panels were no doubt custom made.

[Dave]

They were generic cases sourced by SPEM. The cases came with the front and back panels, which were all milled by hand. They were then powder coated and had the logos applied. Some of them, a step was skipped and they shed the white like crazy. A shame, really.

The keyboard interface is absolutely worth cloning - with minimal changes it will accept a PS/2 keyboard. It was IIRC designed and sourced from SPEM. The keyboards were (memory don't fail me now) Olivetti(?) made, or something really generic. They weren't great, but they didn't have to be. The QL keyboard was so poor it just didn't matter. I thought at the time that the size and font of the logos and writing on the machine was tacky. Tony and Arnie thought it was trendy. At the time we thought the machines would all be dumpstered within five years since everything was moving and developing so fast.

The Astec power supplies were very grumpy, and I would recommend in a heartbeat that you replace them with a mini PC PSU or a Meanwell cage PSU. They were temperamental, and electrically VERY noisy.

Notice the snapped off screw mounts?

Was the XTAL on this QL changed from 15 MHz?

Sadly, I remember the day Arnie bought me a QL thru-con RAM card and asked me to munge it to fit in an Amiga 500. The addition of a battery backed RTC, and the beginnings of an exit from the QL market saw fruit. That was the same day I accidentally plugged one of those keyboard interfaces into a QL and blew it up in a moment of lack of concentration. Almost 40 years later, I still lose sleep over that.

[RalfR]

The keyboards were (memory don't fail me now) Olivetti(?) made, or something really generic. They weren't great, but they didn't have to be.

Sandy advertised them "To meet the highest specifications for the Futura .

[Chr$]

The keyboard interface is absolutely worth cloning - with minimal changes it will accept a PS/2 keyboard. It was IIRC designed and sourced from SPEM. The keyboards were (memory don't fail me now) Olivetti(?) made, or something really generic. They weren't great, but they didn't have to be. The QL keyboard was so poor it just didn't matter. I thought at the time that the size and font of the logos and writing on the machine was tacky. Tony and Arnie thought it was trendy. At the time we thought the machines would all be dumpstered within five years since everything was moving and developing so fast.

Hopefully the k/b interface works then. It had a couple of broken wires to the k/b socket and a broken transistor. Fixed now, need to test. Not entirely sure if the part that plugs into the original QL k/b connectors is making a good connection. I quite like the logo and stripes, it's very much of the time but hasn't aged too badly.

The Astec power supplies were very grumpy, and I would recommend in a heartbeat that you replace them with a mini PC PSU or a Meanwell cage PSU. They were temperamental, and electrically VERY noisy.

I'm pleased it works for now. Can always fit a Meanwell in the future if needed.

Notice the snapped off screw mounts?

Yeah, I've tapped some new holes and fitted standoffs for the PSU. Will do the same where needed elsewhere.

Was the XTAL on this QL changed from 15 MHz?

No, it's a 15 MHz, just has hot glue around it for some reason.

[Dave]

Was the XTAL on this QL changed from 15 MHz?

No, it's a 15 MHz, just has hot glue around it for some reason.

The first few machines people got, they would look in them and ooh and ahh a lot, and touch things, and the commonest problem was people breaking the xtal. Hot glue was an elegant solution to this problem. The ones without hot glue were either the very earliest or the very latest.

There is one, possibly two QXT640s that have a DIN ribbon cable and the expansion cards rotated 90 degrees so their interfaces show on the back panel. They were problematic because signal quality was..... well, I was going to say "in the toilet" but that was the QL's default state, so I'd have to say "round the U-bend". If anyone has a QXT with one of those (ribbon cable, proper cut-outs and a parallel port on the back) it's an extremely rare custom mod.

There's also a single machine out there that had the inside of the body sprayed with zinc spray to make an RF shield. It was used in an NHS facility and was causing interference to a nearby Very Expensive Machine (don't know what) and we had to Fix It™. I remember Arnie went and bought the rattle can of spray from a welding supply store on the same industrial unit on Manton Heights. I didn't understand the wisdom of this at the time, but then he took apart his own personal QL and did this to it and I wondered what he knew that I didn't.

[Chr$]

I've just been trying out the Sandy K/b interface card. It doesn't work, but seems partially willing, symptoms are:

(The backplane is powered with 5, 12, -12 separately from the PSU. I have Minerva fitted (so that it at least gets past the F1/F2 screen without having to press anything). TKII is disabled, in case it interfered with the ROM in the SANDY card...)

Upon turning on, it always gets stuck on the screen with the Minerva logo bottom right (or plain black screen after the tweed pattern when using JS).

When reset in that state, it will get further and show the F1/F2 etc screen and it lists the 'SANDY QXT 640 Upgrade V0.06'. Pressing F1/F2 does nothing.

Minerva autoboots to F2 mode and I get a flashing cursor.

Pressing keys on the attached real AT k/b results in either nothing or a character that does not correspond to the key pressed. Very often it's an 'i' or a ';'. Sometimes a space, sometimes 2 characters appear. Very often the cursor completely disappears or stops flashing - both of these result in a locked up QL. I assume that's the RAM buffer on the k/b card getting full and confused. Does that mean that the keypresses are not being passed to where they should go?

Assuming the connection to the original QL k/b connectors is good, what else could it be? I also noticed that with the connection to the QL k/b connectors left off that it produces similar results with nonsense characters appearing, so in that sense it is almost as if the connection to the QL connectors isn't making much difference. I've done my best to make sure the connections are good.

There's also a single machine out there that had the inside of the body sprayed with zinc spray to make an RF shield. It was used in an NHS facility and was causing interference to a nearby Very Expensive Machine (don't know what) and we had to Fix It™. I remember Arnie went and bought the rattle can of spray from a welding supply store on the same industrial unit on Manton Heights. I didn't understand the wisdom of this at the time, but then he took apart his own personal QL and did this to it and I wondered what he knew that I didn't.

Thanks for the interesting insights Dave.

[Crud3]

Just got a tip that this thread popped up here! Lovely to see more of these beautiful beasts being brought back to life!

I have way to many Sinclair QL's to be considered sane but...


Then I also have a set of redeeming features:


/Anders

[Dave]

Let’s add to this family picture.