Search found 2795 matches

by jonb
Sun May 02, 2021 5:31 pm
Forum: off-topic
Topic: What a crappy day I've had.
Replies: 3
Views: 231

What a crappy day I've had.

Eh up chums Today I decided I'd better get a shift on and list some computers on eBay. Well, I am sure you all know what a pain in the bottom that is. First up, a Memotech MTX 512, in absolutely mint condition boxed, etc, just as the collectors like them. So I pull it out and set it up, plug it in a...
by jonb
Wed Apr 07, 2021 2:37 pm
Forum: off-topic
Topic: 3D printing advice
Replies: 244
Views: 16880

Re: 3D printing advice

Elminster, check under the four bed clips for the Kapton tape fix (extra insulation that prevents a short between 24v and ground if the heater element's lacquer wears off under one of the clips). That's the vital fix to prevent USB devices getting toasted when connected. I put Kapton on the bed and ...
by jonb
Thu Mar 25, 2021 5:02 pm
Forum: introduce yourself
Topic: Hi from Sussex
Replies: 10
Views: 237

Re: Hi from Sussex

Worvin' me too though I moved here after completing a Software Engineering HND and getting a job at Link Miles (remember them?) Still in Worvin' innit, and looking forward to moviung somewhere else. Been here for 30 years... time for a change! CJE Micros still going strong. Respect is due (but they ...
by jonb
Thu Mar 18, 2021 11:49 am
Forum: other vintage hardware, software and languages
Topic: Memotech MTX 512 questions
Replies: 21
Views: 648

Re: Memotech MTX 512 questions

I saw a train game for this machine that looked really good! Like a 3d thing. Hextrain? I think it streams from disc by the looks of it. It streams from a flash storage device such as a Compact Flash. And yes, it’s Andy’s Hextrain 8) Mark I remember when he demonstrated it at Memofest (2017?). I wa...
by jonb
Sat Feb 27, 2021 9:41 pm
Forum: general
Topic: Today I received.....
Replies: 6210
Views: 744346

Re: Today I received.....

Nice motor Jon 8) Remember: essential journeys only, and you must stay local until March the 29th at the earliest :D Lee. Yes, Lee. I had some essential shopping to do this morning, and was not very surprised by the large number of other road users in classic cars, soft tops and on motorcycles doin...
by jonb
Sat Feb 27, 2021 9:15 am
Forum: general
Topic: Today I received.....
Replies: 6210
Views: 744346

Re: Today I received.....

A proper toy..

Yellow Elise.jpg

:P

(PS, I like the drive units, Ken. Nice!)
by jonb
Thu Feb 25, 2021 9:09 am
Forum: other vintage hardware, software and languages
Topic: Micro UK101
Replies: 20
Views: 2428

Re: Micro UK101

I expect Grant would be OK about it as the seller is openly crediting his work. And that's a good price for a board like that (even though you can get them made for about 25% if you know how to lay it out).
by jonb
Thu Feb 18, 2021 12:49 pm
Forum: general
Topic: Have you ever had one of those Hot-Collar moments?
Replies: 18
Views: 771

Re: Have you ever had one of those Hot-Collar moments?

"Have you ever had one of those Hot-Collar moments?" Many times as my scribblings on this very forum will evidence. But the scariest instance occurred when I was working nights, in charge of a £10M+ Airbus A320 flight simulator. Engineers were allocated time slots to do integration testing...
by jonb
Thu Feb 18, 2021 12:39 pm
Forum: other vintage hardware, software and languages
Topic: Anyone know what this is?
Replies: 6
Views: 509

Re: Anyone know what this is?

Yikes. Rare, valuable. Don't scrap it...
by jonb
Wed Feb 10, 2021 10:42 am
Forum: other vintage hardware, software and languages
Topic: Help me identifying power transistors
Replies: 5
Views: 323

Re: Help me identifying power transistors

Thanks for looking them up, Mark. Typically for this sort of PSU (I surmise), the transistors themselves are mounted on a flat aluminium panel in a pattern matching the PCB layout; then the PCB is fitted to the legs and it's all soldered. Hence, the transistors are not mounted on the component side ...
by jonb
Tue Feb 09, 2021 11:01 am
Forum: other vintage hardware, software and languages
Topic: Help me identifying power transistors
Replies: 5
Views: 323

Help me identifying power transistors

Hi I am looking at the MDS-II PSUs. They are meaty old things from the late '70s with multiple outputs, implemented on separate modules. One of them has a faulty 5v rail and as the current output is high, it has multiple output transistors in parallel. These are big TO-3 cased components. On one of ...
by jonb
Mon Feb 01, 2021 6:10 pm
Forum: 8-bit acorn hardware
Topic: Disk drive head cleaner
Replies: 9
Views: 474

Re: Disk drive head cleaner

You need a fibrous surface like this

0E1FA77E-16B2-406A-8D19-C858F8916C89.jpeg

It’s like a coffee filter, slightly stiff and absorbent.
by jonb
Fri Jan 29, 2021 3:05 pm
Forum: wanted
Topic: Wanted: TM100-2A floppy drive
Replies: 0
Views: 152

Wanted: TM100-2A floppy drive

Hi I'm searching for a TM100 floppy disk for my Superbrain II. I have a pair here but neither are working. Heads are misaligned. I know that some BBC micro floppy drives are TM100s (such as were fitted to the original IBM PC, TRS-80s and many other machines of the time). It must be a TM100 because t...
by jonb
Fri Jan 22, 2021 5:28 pm
Forum: other vintage hardware, software and languages
Topic: Superbrain #3 : The Superbrain II board
Replies: 186
Views: 13569

Re: Superbrain #3 : The Superbrain II board

I’m still left with a non working B: drive. A: is fine, and this is why I hadn’t considered the SB II’s drive circuitry. But eventually it dawned on me that, if the B: drive from the SB I worked fine in the SB I, but not in the SB II, it must be the SB II’s board. Oh dear. I had a look at the schema...
by jonb
Thu Jan 21, 2021 5:27 pm
Forum: for sale / freebies
Topic: Free to collector Archimedes swag
Replies: 27
Views: 3984

Re: Free to collector Archimedes swag

Hello again dear Acorn chums!

I just noticed that (most of) this stuff is still up for grabs. Anyone?

Gosh, retrocomputing stuff, you can't give it away these days! :lol:
by jonb
Thu Jan 21, 2021 5:10 pm
Forum: for sale / freebies
Topic: FS: P.R.E.S. Advanced Plus 3 disk interface for Electrons
Replies: 2
Views: 221

FS: P.R.E.S. Advanced Plus 3 disk interface for Electrons

Hi all I have a (working) PRES Advanced Plus 3 disk interface for sale. It's a plug-in module for the Electron that contains a DFS ROM and floppy drive interface. Has a 34 way drive port - see pictures below. Note, it plugs into the Acorn Plus 1 expansion box, so your Electron will need one, and of ...
by jonb
Thu Jan 21, 2021 12:31 pm
Forum: other vintage hardware, software and languages
Topic: Superbrain #3 : The Superbrain II board
Replies: 186
Views: 13569

Re: Superbrain #3 : The Superbrain II board

Fitted the adapter board last night, after spending a long, long time trying to get the uIDE port on it working. IMG_7353.jpg The adapter is the purple board to the left of the fan. It's providing the connection between the PSU board (main / aux serial ports, video signals and power) and the SB II m...
by jonb
Wed Jan 20, 2021 12:17 pm
Forum: 8-bit acorn hardware
Topic: Acorn Electron pr0n
Replies: 4
Views: 445

Acorn Electron pr0n

Some pictures of my Electron and Plus 3 rig (requested by another member).

Front view. It has Plus 3 and Plus 1 interfaces attached.
Front view. It has Plus 3 and Plus 1 interfaces attached.
Right hand side, showing the noraml Electron ports (UHF TV, Composite View, RGB Video and Cassette), plus the power socket on the Plus 3.
Right hand side, showing the noraml Electron ports (UHF TV, Composite View, RGB Video and Cassette), plus the power socket on the Plus 3.
Rear, showing Plus 1 ports - Joystick (analogue BBC type) and printer.
Rear, showing Plus 1 ports - Joystick (analogue BBC type) and printer.
Plus 3 has a connector for a second external drive at its rear.
Plus 3 has a connector for a second external drive at its rear.
Close up of the Plus 3 drive.
Close up of the Plus 3 drive.
Manuals.
Manuals.
Manuals.
Manuals.
Underside, showing how they are all bolted together.
Underside, showing how they are all bolted together.
Acornsoft games.
Acornsoft games.
by jonb
Wed Jan 20, 2021 11:55 am
Forum: acorn atom and acorn system series
Topic: Some Atom pr0n...
Replies: 0
Views: 231

Some Atom pr0n...

Hi

Some pictures of my Acorn Atom for a new StarDot member.

Case underside.
Case underside.
Close up of the printer port.
Close up of the printer port.
Rear view. AtoMMC on left, Composite then TGB video trailing leads on right.
Rear view. AtoMMC on left, Composite then TGB video trailing leads on right.
Front view, Issue 4
Front view, Issue 4
Documents - Getting Acquainted with your Acorn Atom and Willow Utility ROM manual.
Documents - Getting Acquainted with your Acorn Atom and Willow Utility ROM manual.
Documents - Atomic Theory and Practice / Atom Technical Manual.
Documents - Atomic Theory and Practice / Atom Technical Manual.
Spare chips (replaced by ROM/RAM board).
Spare chips (replaced by ROM/RAM board).
Interior. From left to right: AtoMMC attached to top lid, RAM/ROM board, Colour board.
Interior. From left to right: AtoMMC attached to top lid, RAM/ROM board, Colour board.
Acorn promotional leaflets.
Acorn promotional leaflets.
by jonb
Mon Jan 18, 2021 5:23 pm
Forum: other vintage hardware, software and languages
Topic: Superbrain #3 : The Superbrain II board
Replies: 186
Views: 13569

Re: Superbrain #3 : The Superbrain II board

Quick update. 2xTIP110s arrived, soldered in and drives running again. New SCR arrived, soldered into the PSU and that is working too. Adapter boards arrived but the uIDE port is wired wrong. Fixed that with some patching on the PCB, but I am getting dropped bytes on the read operation. It's probabl...
by jonb
Sun Jan 17, 2021 6:41 pm
Forum: off-topic
Topic: The 8bit Guy
Replies: 9
Views: 694

Re: The 8bit Guy

8 bit guy?

I’m not a fan. People send him stuff for free which he goes on to sell. Hardly preservation. And he just got his mitts on a Kim-1. Gah...
by jonb
Thu Jan 14, 2021 3:30 pm
Forum: other vintage hardware, software and languages
Topic: Superbrain #3 : The Superbrain II board
Replies: 186
Views: 13569

Re: Superbrain #3 : The Superbrain II board

As I'm going to be messing around with the drives in the SB I I thought it'd be a good idea to print another shield... SB Drive Bay shield.jpg Although the slot isn't quite positioned correctly, it is only 2 layers so very easy to trim with a pair of scissors. And now we come to the interesting part...
by jonb
Tue Jan 12, 2021 9:55 am
Forum: other vintage hardware, software and languages
Topic: Superbrain #3 : The Superbrain II board
Replies: 186
Views: 13569

Re: Superbrain #3 : The Superbrain II board

Hi Mark

I did consider that but the TIP110 bolted to the heatsink does get quite hot, so I insulated the rear of the chassis instead (with a 3D printed cover).

I have a little more troubleshooting to do on the one servo board, then I can move on at last.
by jonb
Mon Jan 11, 2021 4:37 pm
Forum: other vintage hardware, software and languages
Topic: Superbrain #3 : The Superbrain II board
Replies: 186
Views: 13569

Re: Superbrain #3 : The Superbrain II board

Well, anyway.. after a couple of hours swapping components in and out of the TM100 servo boards, I have discovered that the culprit is the TIP-110 Darlington transistors, which are connected to the heatsinks that shorted out. I thought I'd done a successful substitution test on these already, but it...
by jonb
Sun Jan 10, 2021 4:16 pm
Forum: general
Topic: Magnifiers for help with working on PCBs
Replies: 10
Views: 638

Re: Magnifiers for help with working on PCBs

I've got a lap with a big glass in it but it does get in the way a bit when soldering. Plus, if the lamp is not square to the board it makes my eyes go funny, so I am always having to adjust it.

I might try that £20 set from Amazon.
by jonb
Sun Jan 10, 2021 10:24 am
Forum: other vintage hardware, software and languages
Topic: Superbrain #3 : The Superbrain II board
Replies: 186
Views: 13569

Re: Superbrain #3 : The Superbrain II board

Yeah, your deflection is a bit squished on the right hand side. Check those caps and adjust V-HEIGHT... you can achieve a much straighter image if you want to. :)
by jonb
Sat Jan 09, 2021 1:09 pm
Forum: other vintage hardware, software and languages
Topic: Superbrain #3 : The Superbrain II board
Replies: 186
Views: 13569

Re: Superbrain #3 : The Superbrain II board

Oh no, I recapped it entirely (all electrolytics). And found a supplier of bipolar caps that don't explode, so my boards (both) have the correct electrolytic at C441 (and they are titchy compared to the old ones - 63v as well). God, no, not old Macs. Worthless junk. Even old PCs are more valuable. I...
by jonb
Sat Jan 09, 2021 10:44 am
Forum: other vintage hardware, software and languages
Topic: Superbrain #3 : The Superbrain II board
Replies: 186
Views: 13569

Re: Superbrain #3 : The Superbrain II board

I'm not convinced your problem is the BU406. Your screen looks quite different to mine when I had the bad 406 fitted. I had compressed characters on the right third of the screen that got more and more squished the further to the right you looked, ending in a vertical white line. That looks like wha...

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