Search found 40 matches

by quokkaz
Sun May 24, 2020 7:40 pm
Forum: 8-bit acorn hardware
Topic: BBC Master outputs green text
Replies: 11
Views: 699

Re: BBC Master outputs green text

Just to close this one off, I didn't get round to trying anything else and have now put it up for sale on eBay with this known fault.
by quokkaz
Tue Aug 13, 2019 7:34 pm
Forum: 8-bit acorn hardware
Topic: BBC Master outputs green text
Replies: 11
Views: 699

Re: BBC Master outputs green text

Yep, I can get colour using RF.
by quokkaz
Fri Aug 09, 2019 7:45 am
Forum: 8-bit acorn hardware
Topic: BBC Master outputs green text
Replies: 11
Views: 699

Re: BBC Master outputs green text

Thanks for the extra info 🙂

I've now tested with RF and get white text in modes 4 and 7 so moved on to look at the board. There are no obvious signs of dry joints or damaged tracks in those areas so I'll look at swapping the transistors out and go from there.
by quokkaz
Thu Aug 08, 2019 9:33 am
Forum: 8-bit acorn hardware
Topic: BBC Master outputs green text
Replies: 11
Views: 699

Re: BBC Master outputs green text

Thanks for that. I'll give an RF lead a go.
by quokkaz
Wed Aug 07, 2019 8:12 pm
Forum: 8-bit acorn hardware
Topic: BBC Master outputs green text
Replies: 11
Views: 699

Re: BBC Master outputs green text

Yes, I have another Master and a few Bs which all work fine with same cable.
by quokkaz
Wed Aug 07, 2019 7:58 pm
Forum: 8-bit acorn hardware
Topic: BBC Master outputs green text
Replies: 11
Views: 699

BBC Master outputs green text

I have a BBC Master 128 which is outputting text via RGB in green, from booting. When I first got it, it was fine, then the text output turned to yellow, then green, and has been like that ever since. I don't really know where to start with this one, and can't find any reference to this issue anywhe...
by quokkaz
Sat Nov 21, 2015 4:20 pm
Forum: 8-bit acorn hardware
Topic: What the Beeb!
Replies: 14
Views: 1369

Re: What the Beeb!

Eventually got round to fixing the PSU in the dodgy B. From this: https://s3-eu-west-1.amazonaws.com/quokkaz/bbc/cashbeeb-blown-cap.jpg To this: https://s3-eu-west-1.amazonaws.com/quokkaz/bbc/cashbeeb-new-caps.jpg I removed the SWR and croc clips and checked that links S20, 21 and 22 were to their d...
by quokkaz
Tue Nov 10, 2015 2:46 pm
Forum: 8-bit acorn hardware
Topic: Master 128 LEDs Not Working
Replies: 3
Views: 471

Re: Master 128 LEDs Not Working

Moved the connector back a couple of mm and all's well :D
Image
by quokkaz
Tue Nov 10, 2015 1:30 pm
Forum: 8-bit acorn hardware
Topic: Master 128 LEDs Not Working
Replies: 3
Views: 471

Re: Master 128 LEDs Not Working

Think I've found the problem. Power light comes on if I wiggle the ribbon cable connector :(
by quokkaz
Mon Nov 09, 2015 3:32 pm
Forum: 8-bit acorn hardware
Topic: Master 128 LEDs Not Working
Replies: 3
Views: 471

Master 128 LEDs Not Working

While fixing the floppy drive control on a Master 128, I've found that the keyboard LEDs have failed. Initially just the Caps Lock and Shi f t :oops: Lock but now also the Power LED. When I first bought it, all three worked fine. The Lock keys do do what they are supposed to and the rest of the keyb...
by quokkaz
Wed Nov 04, 2015 2:18 pm
Forum: 8-bit acorn hardware
Topic: Problem with dual floppy drives on Master 128
Replies: 26
Views: 3096

Re: Problem with dual floppy drives on Master 128

It's been a while but I finally got round swapping ICs to try and fix the floppy problem, after also replacing the 2 broken capacitors, and started with IC4. Removing the old one was proving difficult until I bought a desoldering iron which made short work of it. I found a broken trace underneath (t...
by quokkaz
Fri Oct 09, 2015 3:50 pm
Forum: 8-bit acorn hardware
Topic: What the Beeb!
Replies: 14
Views: 1369

Re: What the Beeb!

May have to come back to this one a little later:
Image
Off to eBay for a capacitor kit...
by quokkaz
Thu Oct 08, 2015 9:23 pm
Forum: 8-bit acorn hardware
Topic: What the Beeb!
Replies: 14
Views: 1369

Re: What the Beeb!

steve3000 wrote:Had something similar to this on mine and it turned out to be due to a bad contact/surface corrosion on one of the RAM chips. Solved by simply taking out the chip and putting it back on again... Hope it's that simple on yours. :)
Thanks, I'll give that a go.
by quokkaz
Thu Oct 08, 2015 9:10 pm
Forum: 8-bit acorn hardware
Topic: What the Beeb!
Replies: 14
Views: 1369

Re: What the Beeb!

Found this http://www.stardot.org.uk/forums/viewto ... 71&p=12583 and will give the test code a go tommorow.
by quokkaz
Thu Oct 08, 2015 8:57 pm
Forum: 8-bit acorn hardware
Topic: What the Beeb!
Replies: 14
Views: 1369

Re: What the Beeb!

Hi, It looks like a RAM fault to me. I can't however figure out which IC it may be off the top of my head, and I am out at the moment. Try setting S25 to the south position and see if mode7 clears up... Lee. Thanks Lee. Moved to south I get random red/white blocks, continuous tone and no keyboard. ...
by quokkaz
Thu Oct 08, 2015 6:52 pm
Forum: 8-bit acorn hardware
Topic: What the Beeb!
Replies: 14
Views: 1369

Re: What the Beeb!

The knob by the keyboard is wired into the speaker so it'll be a crude volume control. Yep, verified that that's what it is. The other switch is connected to a chip with a label saying "Sideways Ram" so it'll be probably be a write enable switch so you can load a rom image into the chip and then lo...
by quokkaz
Thu Oct 08, 2015 6:50 pm
Forum: 8-bit acorn hardware
Topic: What the Beeb!
Replies: 14
Views: 1369

Re: What the Beeb!

hoglet wrote:If it seems to be accepting commands, try changing to a different screen mode, e.g. MODE 6.

It may be the fault just affects MODE 7.

Dave
MODE 7 didn't make any difference. MODE 9 I get a prompt in some clear space at the top of the screen but then the same kind of corruption lower down.
by quokkaz
Thu Oct 08, 2015 5:48 pm
Forum: 8-bit acorn hardware
Topic: What the Beeb!
Replies: 14
Views: 1369

What the Beeb!

Just had delivered a Model B I bought on spec for £22 as it sounded as if it might be in working condition. It turns out that it does work, in that it beeps and outputs to a monitor, but the result is odd (see below) and it looks to be crudely modified. https://s3-eu-west-1.amazonaws.com/quokkaz/bbc...
by quokkaz
Wed Sep 23, 2015 2:15 pm
Forum: 8-bit acorn hardware
Topic: Problem with dual floppy drives on Master 128
Replies: 26
Views: 3096

Re: Problem with dual floppy drives on Master 128

Interesting probe results from IC2 and IC4 with the new board (previous results from original board on the right):
Image - Image
by quokkaz
Tue Sep 22, 2015 3:22 pm
Forum: 8-bit acorn hardware
Topic: Problem with dual floppy drives on Master 128
Replies: 26
Views: 3096

Re: Problem with dual floppy drives on Master 128

I've moved the goalposts slightly... I saw another Master on eBay that was being sold as faulty but looked like the motherboard might be OK - it looked in better condition than the one I've got. I bought it and it arrived earlier today. https://s3-eu-west-1.amazonaws.com/quokkaz/bbc/master2-faulty.j...
by quokkaz
Mon Sep 21, 2015 8:56 pm
Forum: general
Topic: Today I received.....
Replies: 5828
Views: 512014

Re: Today I received.....

Not the usual Sinclair kit: https://s3-eu-west-1.amazonaws.com/quokkaz/sinclair/dm2-3.jpg Still had a (dead) PP9 inside: https://s3-eu-west-1.amazonaws.com/quokkaz/sinclair/dm2-2.jpg Soldered in a PP3 connector: https://s3-eu-west-1.amazonaws.com/quokkaz/sinclair/dm2-4.jpg And it works: https://s3-e...
by quokkaz
Sun Aug 30, 2015 7:12 pm
Forum: 8-bit acorn hardware
Topic: Problem with dual floppy drives on Master 128
Replies: 26
Views: 3096

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. Thanks. That's sort of what I'd figured but wasn't sure if the fault was actually in one of these ICs. Is the only way to swap one at a time? The...
by quokkaz
Sun Aug 30, 2015 12:32 pm
Forum: 8-bit acorn hardware
Topic: Problem with dual floppy drives on Master 128
Replies: 26
Views: 3096

Re: Problem with dual floppy drives on Master 128

This morning I've taken some readings with the logic probe with both drives connected which I've summarised here: https://s3-eu-west-1.amazonaws.com/quokkaz/bbc/probe-results-1.jpg Column B shows the status at startup, then C and D are after doing a *CAT on each drive. Drive 1 works consistently and...
by quokkaz
Sat Aug 29, 2015 4:45 pm
Forum: 8-bit acorn hardware
Topic: Problem with dual floppy drives on Master 128
Replies: 26
Views: 3096

Re: Problem with dual floppy drives on Master 128

If you disconnect both drives, and disable both DFS and ADFS, it should be safe to poke any test values to &FE24 to test IC2 and IC4 (unless the MOS gets in the way). Otherwise be careful that you don't try to do something silly like activate both drives at once! :mrgreen: Mark I now have a probe a...
by quokkaz
Thu Aug 27, 2015 7:28 pm
Forum: general
Topic: Today I received.....
Replies: 5828
Views: 512014

Re: Today I received.....

A Series 3a and the hinge donor 3c:
Image
by quokkaz
Thu Aug 27, 2015 7:24 pm
Forum: general
Topic: Today I received.....
Replies: 5828
Views: 512014

Re: Today I received.....

Edit: but wait... 3c? What's the difference between that and the Series 3? From Wikipedia: "It has a slightly different external appearance to the earlier variants because a redesigned badge is placed centrally on the lid, the lid has fewer undulations, and a port for an infrared connection is visi...
by quokkaz
Thu Aug 27, 2015 4:11 pm
Forum: general
Topic: Today I received.....
Replies: 5828
Views: 512014

Re: Today I received.....

I've not seen a Psion 3c in the "flesh", so to speak, but does it by any chance have one of those "rubbery" type coverings? If so I've known a few devices with such "grip finishes" where the coating has started to break down and goes very very sticky. One was a Microsoft wireless mouse no less! Yes...
by quokkaz
Wed Aug 26, 2015 8:57 pm
Forum: general
Topic: Today I received.....
Replies: 5828
Views: 512014

Re: Today I received.....

Received today: an extremely sticky Psion 3c needing a new hinge (for which I have a donor). Can't imagine where it's been - it's like fly paper.
by quokkaz
Wed Aug 26, 2015 8:49 pm
Forum: 8-bit acorn hardware
Topic: Problem with dual floppy drives on Master 128
Replies: 26
Views: 3096

Re: Problem with dual floppy drives on Master 128

Looks like I'll be investing in some clippage too, thanks.
by quokkaz
Wed Aug 26, 2015 8:47 pm
Forum: 8-bit acorn hardware
Topic: Problem with dual floppy drives on Master 128
Replies: 26
Views: 3096

Re: Problem with dual floppy drives on Master 128

in your intro with pic of master insides, there is another unknown rom in the bank below WORD, and maybe something else? a *ROMS list may help. If it's a MMC interface (user port) rom, then weird things do happen :shock: Here's the list of ROMs ROM F TERMINAL 01 ROM E View 04 ROM D Acorn ADFS 50 RO...

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