Search found 226 matches

by johnkenyon
Thu Oct 19, 2017 7:44 pm
Forum: hardware
Topic: WE 32K RAM Card Repair
Replies: 70
Views: 5175

Re: WE 32K RAM Card Repair

Received new cable and 40 pin dip plugs [img]20171019_210352s.jpg[/img], can now make up a new cable for the ram board, just got to work out how I am going to crimp the cable in the plugs without damaging the pins :wink: Peter. Insert the pins into one or more pieces of veroboard/perfboard so that ...
by johnkenyon
Thu Oct 19, 2017 10:00 am
Forum: for sale / freebies
Topic: Worth Taking a Look At
Replies: 2801
Views: 288910

Re: Worth Taking a Look At

An Econet tester and software ... http://www.ebay.co.uk/itm/Acorn-Computer-Econet-Tester-/292298191627?hash=item440e54730b:g:igUAAOSwmeRZ52bl Could be one to re-engineer. It's on my list. I don't have the software, but I do have the hardware. Beebmaster also has one http://www.beebmaster.co.uk/Econ...
by johnkenyon
Thu Oct 12, 2017 12:25 pm
Forum: software: other
Topic: Variants of ADFS
Replies: 16
Views: 2286

Re: Variants of ADFS

What it really needs, is the low level hardware 'drivers' to be separated from the higher level filing system functionality. But apparently sorting out and writing such code is not much fun... As I see it the problem is as follows: 1) Shoehorning in driver code for SCSI, IDE, MMC/SD into the same 1...
by johnkenyon
Fri Sep 29, 2017 8:11 pm
Forum: hardware
Topic: Compudata Hard-drive CS-1057
Replies: 54
Views: 3641

Re: Compudata Hard-drive CS-1057

Boydie wrote:Some of the Internal Acorn Documentation I posted to the archive a while back featured Acorn's own method for hacking into an Econet system when you'd forgotten the passwords.
The post can be found at
http://www.stardot.org.uk/forums/viewto ... 9&p=174807
by johnkenyon
Thu Sep 28, 2017 8:54 pm
Forum: hardware
Topic: Compudata Hard-drive CS-1057
Replies: 54
Views: 3641

Re: Compudata Hard-drive CS-1057

danielj wrote:It looks like a disc from a level 3 fileserver!

Someone should have an idea about how to get the stuff off it?

d.
Connect the ACB SCSI interface to a Linux PC with a SCSI card and image the drive?
by johnkenyon
Mon Sep 11, 2017 12:18 pm
Forum: hardware
Topic: Troubleshooting my latest BBC B
Replies: 70
Views: 4934

Re: Troubleshooting my latest BBC B

Hi again. Checking with a VMM uncovered no problems with voltage distribution. I found no apparent breaks leading from the pins of IC3 (6522). BUT ..... when I probed IC3 with my scope, I noticed that unlike, say, the 6502 and the other 6522 (IC59), the RESET pin doesn't go LOW when the BREAK key i...
by johnkenyon
Fri Sep 08, 2017 11:29 am
Forum: general
Topic: Today I received.....
Replies: 5702
Views: 489100

Re: Today I received.....

philb wrote:
Now I need to figure out how to deal with the SCSI ones...
Have you got a PC (preferably running Linux) with a spare ISA or PCI slot?

PM me if you want to borrow a card and suitable leads for imaging (assuming you are in the UK...)

/John
by johnkenyon
Fri Aug 11, 2017 9:51 am
Forum: for sale / freebies
Topic: FS: (slightly OT) Legacy PC hardware
Replies: 0
Views: 745

FS: (slightly OT) Legacy PC hardware

Over the years I have accumulated a silly quantity of "legacy" PC hardware. These are all 16 bit ISA cards: * World's biggest pile of 3C509 (10Base2+AUI/10BaseT+10Base2+AUI)and 3C509B (All with 10BaseT+AUI, some with 10Base2 as well) (20 in total) * Handful of 3C503 (10BaseT+AUI) - (usable in 8 bit ...
by johnkenyon
Fri Jul 07, 2017 12:39 pm
Forum: hardware
Topic: Replacing Master RTC battery pack by a supercap
Replies: 17
Views: 1921

Re: Replacing Master RTC battery pack by a supercap

Here's what I'm looking at for my next 6809 motherboard. The 146818 will be used pretty much like on the beeb but I've added a MAX807 to control the battery switchover. I'm not sure, I might add a battery connector too if the supercap proves to be too weedy I'm also looking to backup some of the ra...
by johnkenyon
Fri Jun 09, 2017 10:35 am
Forum: hardware
Topic: MMC connected to something other than user port?
Replies: 22
Views: 2155

Re: MMC connected to something other than user port?

Econet sounds interesting. Probably not going to work as I've just looked at the beeb schematic and the MC6854 only has two address pins and a 6522 would need 4. I wonder why the master econet connector has 4 address pins. You can use a 6821 which has only two address pins. But that needs a bit of ...
by johnkenyon
Thu May 18, 2017 3:29 pm
Forum: hardware
Topic: Beebug external FDD podule
Replies: 5
Views: 773

Re: Beebug external FDD podule

Easy to reverse engineer. The connector is standard, the only thing you have to work out is which signals you don't need to bother buffering, as your two 7407's only allow you to buffer 12 signals, and the pinouts at Look at http://pinouts.ru/HD/InternalDisk_pinout.shtml seem to indicate that there ...
by johnkenyon
Fri May 05, 2017 11:09 am
Forum: hardware
Topic: Keyboard LED proper push-down prevention fix
Replies: 6
Views: 1055

Re: Keyboard LED proper push-down prevention fix

I think a nylon LED spacer/stand-off is what you're looking for. The following is just an example of what I mean, you'd need to measure up and get the right height: https://www.digikey.com/product-detail/en/essentra-components/LEDS2E-8-01/RP507-ND/104916 In a pinch you could just use a short piece ...
by johnkenyon
Fri Apr 28, 2017 12:32 pm
Forum: off-topic
Topic: how to desolder pcb boards ?
Replies: 16
Views: 1937

Re: how to desolder pcb boards ?

what is the melting point of normal tin parts on a pcb board i am thinking to use a oil based pan (filled with sunflower oil at 200 C ?) put a pcb board in the pan , wait a few min. are the components loose ? to remove ofcourse then are fat :) Google says that 60/40 Sn/Pb melts at 188degC, and 63/3...
by johnkenyon
Thu Apr 27, 2017 3:56 pm
Forum: off-topic
Topic: Why are domino plugs reversible?
Replies: 4
Views: 1423

Why are domino plugs reversible?

I always wondered why you would have a connector which is deliberately unpolarised, and I found this web page: https://www.vintage-radio.net/forum/showthread.php?t=59591 which includes the text There was also a 360 degree 5 pin (sometimes called a domino) used for headphones. I reckon they used this...
by johnkenyon
Fri Feb 10, 2017 7:02 pm
Forum: hardware
Topic: battery atpl sidewise rom/ram
Replies: 14
Views: 1273

Re: battery atpl sidewise rom/ram

oke still a question what is the value of the battery ?? 4.5 volt or 4.8 volt (2x 2.4 volt now) what is the amp After looking at some pics of the ATPL board on t'interweb I reckon that one of these should fit in directly onto the PCB: http://cpc.farnell.com/varta/3-v150h/battery-ni-mh-mempac-pcb-3-...
by johnkenyon
Wed Feb 08, 2017 7:08 pm
Forum: hardware
Topic: battery atpl sidewise rom/ram
Replies: 14
Views: 1273

Re: atpl sidewise rom/ram exp parts value ?

duikkie wrote:little bit confused about the use of T1 ?? S6 switch is beter
It write protects the RAM as the main power is removed - so you don't get transients on the write line causing RAM corruption as the power goes off.

/John
by johnkenyon
Fri Feb 03, 2017 3:27 pm
Forum: other vintage computer hardware, software and games
Topic: Sony PlayStation1 laser replace?
Replies: 22
Views: 3413

Re: Sony PlayStation1 laser replace?

sbadger wrote:two things come to mind

Just a dirty laser?

or if i recall back to the mod chips of the day, wasn't there a pot that needed adjustment to get cdrs working? that may have died.
Is this of any interest? - http://dogbreath.de/PS1/LaserAlignment/Laser.html
by johnkenyon
Thu Feb 02, 2017 10:23 am
Forum: other vintage computer hardware, software and games
Topic: Single transistor NOT gate
Replies: 8
Views: 1258

Re: Single transistor NOT gate

Add a resistor to provide the required pull up or pull down. If no pullup/pull down is required use a small mosfet transistor to control the LED. (Hint: bipolar- current driven, mosfet - voltage driven) /john I'll change that a little bit to answer the question you actually asked... The current flo...
by johnkenyon
Thu Feb 02, 2017 9:15 am
Forum: other vintage computer hardware, software and games
Topic: Single transistor NOT gate
Replies: 8
Views: 1258

Re: Single transistor NOT gate

Add a resistor to provide the required pull up or pull down. If no pullup/pull down is required use a small mosfet transistor to control the LED. (Hint: bipolar- current driven, mosfet - voltage driven)
/jjohn
by johnkenyon
Mon Jan 16, 2017 1:58 pm
Forum: general
Topic: Ideas for repairing my Rigol DS1052E scope
Replies: 10
Views: 1354

Re: Ideas for repairing my Rigol DS1052E scope

I don't have anything technical to offer, however you could do worse than pay a visit to http://www.eevblog.com/forum/ specifically the test equipment board.

/John
by johnkenyon
Fri Jan 13, 2017 5:41 pm
Forum: other vintage computer hardware, software and games
Topic: Repairing a Speccy
Replies: 8
Views: 1410

Re: Repairing a Speccy

Off the top of my head: Check this first - no 12v usually means death to the DRAM 12v charge pump for the lower 16k DRAM - is it spitting out 12v? Are the 16k DRAM chips getting hot (usually caused by 12v supply failure - see above) Is the CPU running - check for the clock on the right pin of the CP...
by johnkenyon
Wed Jan 11, 2017 2:25 pm
Forum: hardware
Topic: Inserting and removing ROMs
Replies: 17
Views: 1917

Re: Inserting and removing ROMs

The other rule is that you insert the tool no more than 5mm and rotate the tool back and forth so that one end of the flat contacts the bottom of the chip and the other end contacts the top of the socket. Do this alternately on both ends of the chip (where physically possible), slowly slowly catchy ...
by johnkenyon
Mon Nov 14, 2016 3:04 pm
Forum: other vintage computer hardware, software and games
Topic: Resistor for slowing down a 12v fan
Replies: 7
Views: 1073

Re: Resistor for slowing down a 12v fan

Have you considered powering it from the +5v rail? or even powering it from the +12v and +5v rails (so the thing runs with 7v across its terminals.
by johnkenyon
Sat Oct 22, 2016 8:17 am
Forum: for sale / freebies
Topic: ALL SOLD: One rare unusual IO board for BBC
Replies: 14
Views: 2507

Re: FS: BBC B Case Bottom + Five rare unusual IO boards for BBC

For anyone wondering about the provenance of the boards - the coat of arms/shield on the top right hand corner of the I/O board is that of Sunderland Metropolitan Borough. I wouldn't be surprised if the board didn't originate from either the council's education department or even Sunderland Polytech...
by johnkenyon
Thu Oct 06, 2016 10:03 am
Forum: off-topic
Topic: Stag PP41 and PP42 programmer
Replies: 30
Views: 7678

Re: Stag PP41 and PP42 programmer

If you want a PP42 to repair let me know. The power supply has been completely re-capped (all electrolytics replaced), but the thing seems to lock up after being left powered up for a while.
by johnkenyon
Tue Sep 06, 2016 4:58 pm
Forum: hardware
Topic: NiMH replacement for NiCd cells in an A4 battery
Replies: 14
Views: 2755

Re: NiMH replacement for NiCd cells in an A4 battery

Looks like you already have some somewhere then. Labelled as pre charged they should have 80% after a year. Good luck finding them. You might need good luck finding industrial sized or tagged cells. For bog standard AAA or AA, 7dayshop.com sell a number of different manufacturers versions. "Good to...
by johnkenyon
Wed Aug 24, 2016 5:26 am
Forum: hardware
Topic: Cumana disc drive mystery switch
Replies: 14
Views: 1587

Re: Cumana disc drive mystery switch

what model are the drives in your cumana unit? They are Mitsubishi drives. Drive - 1.jpg Have a look for a label, usually located on the cast frame of the drive on the same end as the power and data connectors. This will help positively identify the drive - the markings on Floppy drive PCBs tend to...
by johnkenyon
Mon Aug 22, 2016 12:27 pm
Forum: hardware
Topic: Pi-based Co-Pro on the cheap - 100MHz 6502 for £10? (now 274MHz)
Replies: 1174
Views: 131476

Re: Pi-based Co-Pro on the cheap - 100MHz 6502 for £10?

the Master has a *configure option for internal/external tube. Seems to work either way round - any info on this? ISTR that you had two options for the tube - one to disable/enable the tube, and then the internal/external selection. I think the internal/external switch only has an effect if there i...
by johnkenyon
Mon Aug 22, 2016 4:58 am
Forum: hardware
Topic: Cumana disc drive mystery switch
Replies: 14
Views: 1587

Re: Cumana disc drive mystery switch

Well, I wasn't expecting that :shock: : The middle position isn't connected to anything; and the bottom position isn't either! So it is just an on/off switch: on=80T, off=40T. So naturally you'll be putting a solder blob on the back of the switch so that the slider gives you 40T-80T-80T instead of ...
by johnkenyon
Sun Aug 21, 2016 4:47 am
Forum: hardware
Topic: Cumana disc drive mystery switch
Replies: 14
Views: 1587

Re: Cumana disc drive mystery switch

I have a Cumana disc drive which is switchable between 40T and 80T. However, the switch has 3 positions. Does anyone know what (if anything) is the function of the middle position? I think is does nothing! I can think of two reasons: 1) If the switch is switching between two signals A and B, and th...