Search found 868 matches

by station240
Sun Mar 13, 2016 9:22 pm
Forum: hardware
Topic: header pins for Master keyboard
Replies: 5
Views: 506

Re: header pins for Master keyboard

A standard Molex brand connector fits (I've used them myself) Pitch is 2.54mm A no one makes a 15 way version, you have to buy 2x 3 way, and 2x 12 way. http://uk.farnell.com//molex/22-01-3037/housing-female-3way/dp/1462838 http://uk.farnell.com//molex/22-01-2125/housing-crimp-receptacle-2-54mm/dp/25...
by station240
Tue Feb 02, 2016 10:40 am
Forum: off-topic
Topic: Virgin Media Super Hub
Replies: 20
Views: 2695

Re: Virgin Media Super Hub

My only thought is it's done some automatic or remotely triggered firmware update. The engineers that make these sorts of devices are lazy, and don't bother to read the current config so it can be kept.
by station240
Tue Dec 29, 2015 4:04 pm
Forum: hardware
Topic: Vine Master to B conversion board
Replies: 11
Views: 925

Re: Vine Master to B conversion board

Finally got some time to look at this again today :oops: In case any one has the same issue, the lead goes to pin 2 of IC33 (ROM output enable). Pin 2 of IC 33 is also wired to pin 2 IC 29, so technically we are both right. The circuit calls this signal AA16 which is connected to ROM output enable ...
by station240
Mon Dec 21, 2015 5:06 pm
Forum: hardware
Topic: Microvitec Cub PTC problems
Replies: 9
Views: 749

Re: Microvitec Cub PTC problems

The PTC is designed to heat up internally and go open circuit. That it blows the fuse proves it's faulty.

The coil design is pretty standard for TV's/monitors, so any PTC from a TV or VGA monitor the same size would do.
by station240
Sat Nov 28, 2015 3:16 pm
Forum: hardware
Topic: Vine Master to B conversion board
Replies: 11
Views: 925

Re: Vine Master to B conversion board

On line it's a black wire, rather than a brown. Used the scientific methods that involve: 1) Wire only reaches certain ICs 2) Signal must make sense, eg something not present on other ICs the boards already connect with. The notes I keep for the installation black wire (connects to pin 22 of the 3 a...
by station240
Wed Nov 25, 2015 2:33 pm
Forum: hardware
Topic: Fix your Beeb Chip
Replies: 10
Views: 754

Re: Fix your Beeb Chip

What I'd like to see is a beeb version of a port 80 tester (google it). That is something able to deal with almost all the hardware being dead. Given the most common IC failure is the 6522, followed by ram and 74254 buffer chips, being able to determine if those are faulty would help greatly. Why no...
by station240
Mon Nov 16, 2015 3:56 am
Forum: hardware
Topic: Econet in a Box
Replies: 27
Views: 1205

Re: Econet in a Box

I've tried making my own econet clock, trust me it's not as easy as it seems. Unless you have a working network, you have no idea if various components actually work. Say you get "no clock" is it actually the clock, the cables, the junction box, or the terminators ? A 100% reliable clock r...
by station240
Sun Nov 08, 2015 2:54 am
Forum: hardware
Topic: Master Compact EEPROM
Replies: 2
Views: 363

Re: Master Compact EEPROM

Been discussed before, the 24LC014 is a cheap replacement.
See Mark's post
http://www.stardot.org.uk/forums/viewtopic.php?p=89210#p89210
by station240
Fri Oct 30, 2015 1:03 pm
Forum: hardware
Topic: My new beeb is really quite old
Replies: 9
Views: 732

Re: My new beeb is really quite old

Just run it with an externally powered disc drive, and leave the original PSU in the machine. The term "linear" refers to the voltage regulation, in this case series regulation. As opposed to the more modern switch mode PSU, which varies the input voltage to the output stages directly. Lin...
by station240
Thu Oct 29, 2015 2:00 am
Forum: hardware
Topic: Sourceing spare pins for Watford/ATPL ROM boards
Replies: 8
Views: 756

Re: Sourceing spare pins for Watford/ATPL ROM boards

I did find a pretty close match to the 28pin version http://uk.mouser.com/ProductDetail/Harwin/D95028-42/?qs=sGAEpiMZZMs%2fSh%2fkjph1tiOpk5oEEfXAfSLcm6%252binMw= it's not the proper width, but can always cut it in half. They have others like 14, 16 pins which are an exact match. Digikey also have th...
by station240
Sun Oct 11, 2015 1:50 am
Forum: hardware
Topic: Micro SD SCSI interface for MDFS File Server
Replies: 68
Views: 4647

Re: Micro SD SCSI interface for MDFS File Server

Still waiting on Ottly to test the 1mhz to SASI bridge board I sent him with this adapter. I'd like to resurrect and old filestore type case that has the controller but no SASI drive.
by station240
Fri Oct 09, 2015 2:34 pm
Forum: hardware
Topic: Ripping ADFS disks
Replies: 8
Views: 681

Re: Ripping ADFS disks

Not sure if BBCzip can do this
http://mdfs.net/Apps/Archivers/BBCZip/
the man(ual) pages mention spanned archives, but a quick look didn't show how to create them.
by station240
Wed Oct 07, 2015 12:43 am
Forum: hardware
Topic: Scans of Microfilm Circuit Diagrams
Replies: 29
Views: 1450

Re: Scans of Microfilm Circuit Diagrams

No one seems to really know the connections for the PET, hence the need to get the circuit. best guess however considering how the pins are wired. PL6 1Mhz bus PL5 Printer port PL4 User port PL3 unknown (not wired correctly for a Disc Drive) PL2 Tube??? http://chrisacorns.computinghistory.org.uk/8bi...
by station240
Sun Sep 20, 2015 12:38 pm
Forum: hardware
Topic: Cheese wedges
Replies: 7
Views: 505

Re: Cheese wedges

The only difference is the Teletext adapter has a row of vents at the back removed to fit the channel tuner adjustments. Those are the 4 red cylinders show in the pics below. http://chrisacorns.computinghistory.org.uk/8bit_Upgrades/Acorn_ANE01_TeletextAdapter.html If you don't care about the small h...
by station240
Sat Sep 19, 2015 2:12 am
Forum: hardware
Topic: Electron / Atom inline power switch.
Replies: 15
Views: 1285

Re: Electron / Atom inline power switch.

Is it so difficult to google "12Vdc inline switch" and choose one with the correct plug/socket size (or just rewire it) ?
by station240
Sun Sep 13, 2015 7:30 pm
Forum: hardware
Topic: Cleaning a 'cheese wedge'
Replies: 22
Views: 1644

Re: Cleaning a 'cheese wedge'

Zaphod wrote:If that is spray paint, then brake fluid will take it off and leave the plastic alone


Simple Green does much the same job, but is non toxic.
Basic way either work, is to dislodge the paint from the plastic. Some scrubbing is required to get the paint to actually come away completely.
by station240
Sat Sep 12, 2015 2:09 am
Forum: hardware
Topic: Idea for Project: Econet / Ethernet FileServer
Replies: 12
Views: 817

Re: Idea for Project: Econet / Ethernet FileServer

On the Ethernet side: An ethernet NAS with 1 or many 512Mb "hardfiles" each hardfile being editable via the ethernet side through ADFS / DFS explorer. On the Econet side - a box which has both Econet and Ethernet which can "see" the hardfiles and give the Beebs access to them vi...
by station240
Tue Sep 01, 2015 10:59 am
Forum: hardware
Topic: BBC B restoration - help please!
Replies: 4
Views: 482

Re: BBC B restoration - help please!

Most likely the startup capacitor in the PSU is dead, is the 220uf one near the middle. The two X2 caps would also need replacement.

mark@retroclinic.com can repair the PSU/machine, if you can't find anyone nearby.
by station240
Sun Aug 30, 2015 5:53 pm
Forum: hardware
Topic: Problem with dual floppy drives on Master 128
Replies: 26
Views: 1772

Re: Problem with dual floppy drives on Master 128

Pin 5 on IC2 and IC4 is where the fault lies, hence IC2 pin 6 is not producing a correct output. Fun part is figuring out which of the two ICs is faulty.
by station240
Thu Aug 27, 2015 11:56 am
Forum: hardware
Topic: R/nW signal confused :(
Replies: 56
Views: 2812

Re: R/nW signal confused :(

buffering is fine , but why ? , even the very much used USERPORT is not buffered oke it is not directly on the main lines , but blowing up 6522 is also not good The printer port is buffered, as people tend to put noisy printers some distance from their computer. The buffer chip is there to ensure t...
by station240
Wed Aug 26, 2015 4:10 pm
Forum: hardware
Topic: Problem with dual floppy drives on Master 128
Replies: 26
Views: 1772

Re: Problem with dual floppy drives on Master 128

While this isn't my usual field, I'm pretty clear what needs doing but (forgive me if this a daft question) what's the practical solution to checking results while typing in the pokes given that IC2 and IC4 are under the keyboard? :| The trick is to attach wires to the IC pins, then put everything ...
by station240
Tue Aug 25, 2015 3:27 pm
Forum: hardware
Topic: Problem with dual floppy drives on Master 128
Replies: 26
Views: 1772

Re: Problem with dual floppy drives on Master 128

Also test:
pin 16 (motor)
pin 32 (head select)
both of which go via IC1 (7406)
by station240
Tue Aug 25, 2015 5:55 am
Forum: hardware
Topic: Problem with dual floppy drives on Master 128
Replies: 26
Views: 1772

Re: Problem with dual floppy drives on Master 128

The bang and puff of smoke is from noise filter caps in the master PSU blowing up. Should be about 10,000 threads about that around here, it's a very common failure. The drive problems could (partially) also due to dirty heads. To be expected with 30 year old gear people sometimes store in attics. Y...
by station240
Mon Aug 24, 2015 1:39 pm
Forum: hardware
Topic: dead GOMMC, have questions.
Replies: 3
Views: 438

Re: dead GOMMC, have questions.

I tried using MMCUP to update the software on the board, did nothing. The 3.3v rail is working.

Best guess is the ROM is completely dead, I've emailed John for advice.
by station240
Fri Aug 21, 2015 4:58 pm
Forum: hardware
Topic: dead GOMMC, have questions.
Replies: 3
Views: 438

dead GOMMC, have questions.

I've got a GoMMC card, trying to get it to come to life. It appears dead, not seeing the ROM at all, so obviously it doesn't read the card. I've already replaced a damaged DIL header in the hope that fixed it, no change. Anyone know if reprogramming the rom is enough to fix it ? I have the disk util...
by station240
Sat Aug 15, 2015 1:24 pm
Forum: hardware
Topic: Arm evaluation system
Replies: 8
Views: 966

Re: Arm evaluation system

Must be for SneakerNet support.
by station240
Wed Aug 05, 2015 12:49 pm
Forum: hardware
Topic: Master Key Not Working
Replies: 7
Views: 591

Re: Master Key Not Working

Trick here is to take one pin out at a time, so there is something holding the internal contacts in place.
by station240
Sun Aug 02, 2015 3:31 pm
Forum: hardware
Topic: Noisy Beeb
Replies: 15
Views: 1231

Re: Noisy Beeb

Lucky I have dead PSUs not kept in their cases :wink:

C16,C19,C20 1000uF 16V
C17 2200uF 16V
C18,C21 100uF 25V
All should be 105C low ESR types

C21 is the -5V rail.
by station240
Sun Aug 02, 2015 3:17 pm
Forum: hardware
Topic: Microvitec Cub parts list may not match reality.
Replies: 3
Views: 367

Re: Microvitec Cub parts list may not match reality.

Looks to me like the circuit is minimum values, someone discovered higher values of uF and voltage still worked. One of these caps is right next to the main drive transistor, the other is next to a 5W resistor. Guess someone decided to over engineer to stop the caps dying too soon. Now I have to won...
by station240
Sun Aug 02, 2015 1:57 pm
Forum: hardware
Topic: Microvitec Cub parts list may not match reality.
Replies: 3
Views: 367

Microvitec Cub parts list may not match reality.

I'm in the process of servicing a Microvitec Cub 1451, replacing caps to fix issues in the E-W circuitry. Found an odd thing in the Electrolytic caps in this part of the circuit. According to the manual (which covers this exact model) the caps I replaced are: C311 470uf 25V C312 220uf 25V C224 1000u...

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