Search found 72 matches

by sfdNut
Tue Oct 06, 2020 12:54 am
Forum: 8-bit acorn hardware
Topic: Master 128 Power supply caps are blue?
Replies: 2
Views: 158

Master 128 Power supply caps are blue?

Opening up a recently acquired master power supply for refurb I found these x2 caps
823B4E65-D8E4-43CE-B23F-A0A468177395.jpeg
823B4E65-D8E4-43CE-B23F-A0A468177395.jpeg (40.12 KiB) Viewed 158 times
DA64307F-E777-4CF4-A7D7-CA7791AB2BEC.jpeg
DA64307F-E777-4CF4-A7D7-CA7791AB2BEC.jpeg (30.07 KiB) Viewed 158 times
Obviously these don’t look like the explody-stinky type so...
Question: Do they need replacing as a matter of course?
Thanks
by sfdNut
Tue Oct 06, 2020 12:46 am
Forum: 8-bit acorn hardware
Topic: Help! Master 128 Resurrection (hopefully)
Replies: 20
Views: 1114

Re: Help! Master 128 Resurrection (hopefully)

Progress! It's not unusual for some keys not to work - the remedy is to use them, pretty firmly, for 100 times. They should come good. Yeah, got some working by doing that so can now reset the CMOS 😊 Some are resisting and one is auto repeating without seemingly being pressed! I have ordered some r...
by sfdNut
Sun Sep 27, 2020 1:47 am
Forum: 8-bit acorn hardware
Topic: Help! Master 128 Resurrection (hopefully)
Replies: 20
Views: 1114

Re: Help! Master 128 Resurrection (hopefully)

Old 74s04n removed and new socket and chip added. Success! I get the correct beep and a display. Unfortunately it says "This is not a language" and some of the keys don't work, including 'R" which means I can't reset the CMOS. I'll do some keyboard cleaning and see if I can resurrect all of the keys...
by sfdNut
Fri Sep 18, 2020 11:14 am
Forum: 8-bit acorn hardware
Topic: Help! Master 128 Resurrection (hopefully)
Replies: 20
Views: 1114

Re: Help! Master 128 Resurrection (hopefully)

dp11 wrote:
Wed Sep 16, 2020 10:34 pm
You do can try a 74LS04 but it might not work, you should really should use 74S04
Ok, I've ordered an S04. I'll remove the old chip and add a socket.

Thanks for your help so far. I'll probably be back soon with the next issue ;)
by sfdNut
Wed Sep 16, 2020 8:37 am
Forum: 8-bit acorn hardware
Topic: Help! Master 128 Resurrection (hopefully)
Replies: 20
Views: 1114

Re: Help! Master 128 Resurrection (hopefully)

Excellent now try probing pin 2 . If that doesn't give you a signal and there is no obvious signs of damage I think you need a new 74S04 . Changed the scope to not limit to 20MHz and saw no real change. Checked pin2 - got absolutely nothing. I have 74LS04Ns available. Can I use that instead of a 74...
by sfdNut
Tue Sep 15, 2020 10:33 am
Forum: 8-bit acorn hardware
Topic: Help! Master 128 Resurrection (hopefully)
Replies: 20
Views: 1114

Re: Help! Master 128 Resurrection (hopefully)

dp11 wrote:
Mon Sep 14, 2020 2:15 pm
Excellent can you now go back and look at the clock pins now the scope is setup in a suitable way
OK here we go:
Pin1 (should be a 16MHz signal?)
IC43-Pin1.JPEG
and pin13 (17.7MHz):
by sfdNut
Mon Sep 14, 2020 12:43 pm
Forum: 8-bit acorn hardware
Topic: Help! Master 128 Resurrection (hopefully)
Replies: 20
Views: 1114

Re: Help! Master 128 Resurrection (hopefully)

I'd like to see how the scope displays it. The scope probes should be set to X10. I don't know how the scope does its vertical maths. But what you want is to adjust the the vertical gain and positioning of the trace to be say 5 divisions different from nothing connected to the probe tip. The go bac...
by sfdNut
Mon Sep 14, 2020 12:06 am
Forum: 8-bit acorn hardware
Topic: Help! Master 128 Resurrection (hopefully)
Replies: 20
Views: 1114

Re: Help! Master 128 Resurrection (hopefully)

dp11 wrote:
Sun Sep 13, 2020 7:22 pm
Can i have a scope trace of pin 14 too the 5v pin.

To see the clocks the time base needs to be be some like 0.1us per division.
I checked pin 14 at the start. Solid 5v

Thanks for the tip :)
by sfdNut
Sun Sep 13, 2020 12:49 pm
Forum: 8-bit acorn hardware
Topic: Help! Master 128 Resurrection (hopefully)
Replies: 20
Views: 1114

Re: Help! Master 128 Resurrection (hopefully)

Sorry for the delay. I thought I should learn a bit more first. However the output from IC43 pin 1 is
IC43-Pin1.JPEG
and Pin 13 is:
IC43-Pin13.JPEG
These should be showing the oscillator outputs I think. There's something but the auto measure on the scope couldn't resolve it.
by sfdNut
Tue Sep 08, 2020 2:35 pm
Forum: 8-bit acorn hardware
Topic: Help! Master 128 Resurrection (hopefully)
Replies: 20
Views: 1114

Re: Help! Master 128 Resurrection (hopefully)

Firstly are you an experienced scope user ? No. Just starting out with this. What do you see at pin1 and Pin 13 of IC43 I see nothing at either. I checked first to see if the scope was working by hooking it up to a ZX81 ULA video out pin and could see the correct output. Nothing from the Master tho...
by sfdNut
Mon Sep 07, 2020 2:45 pm
Forum: 8-bit acorn hardware
Topic: Help! Master 128 Resurrection (hopefully)
Replies: 20
Views: 1114

Help! Master 128 Resurrection (hopefully)

Hi All, Bought my first Master 128 off eBay. Description said "spares - not working" so I knew I was in for a challenging time. The guy also said it switches on ok but needs a PSU to which I decided he mean't -"you need to replace the blown 30 odd year old capacitors". I'd already encountered (and s...
by sfdNut
Tue May 01, 2018 8:24 am
Forum: for sale / freebies
Topic: 2 x GBC Vs-104 Video Sensors
Replies: 1
Views: 601

Re: 2 x GBC Vs-104 Video Sensors

How about a picture or two :)
by sfdNut
Thu Oct 19, 2017 5:22 pm
Forum: 32-bit acorn emulators
Topic: Mac Arculator
Replies: 31
Views: 5285

Re: Mac Arculator

I'm interested.
I have a Mac and X-Code and am currently learning Swift programming, although I suspect the current code will be in Objective-C?

I'd like to get involved at least :D
by sfdNut
Thu Aug 24, 2017 9:05 am
Forum: introduce yourself
Topic: Retro computing tensions
Replies: 16
Views: 3012

Re: Retro computing tensions

Welcome Mark :)
I would suggest some off-site storage containers...for those pesky sofas, dining tables, and beds that keep getting in the way :wink: :wink:
by sfdNut
Thu Jul 20, 2017 11:57 pm
Forum: 8-bit acorn software: other
Topic: Odd Message; Tube On! with SD Card/MMFS/PiTubeDirect
Replies: 4
Views: 1367

Re: Odd Message; Tube On! with SD Card/MMFS/PiTubeDirect

Fair enough, so you can't play Tube Elite with this menu system? I need a tutorial on how to use SD cards on a BBC system ... Thanks You can't use the menu system to play tube elite but it's on disc 45 (I think) so try the following: *DIN 45 *TUBEELT This will run the game. It would be a good idea ...
by sfdNut
Thu Jul 20, 2017 8:07 pm
Forum: 8-bit acorn software: other
Topic: Odd Message; Tube On! with SD Card/MMFS/PiTubeDirect
Replies: 4
Views: 1367

Re: Odd Message; Tube On! with SD Card/MMFS/PiTubeDirect

Fair enough, so you can't play Tube Elite with this menu system?

I need a tutorial on how to use SD cards on a BBC system ...

Thanks
by sfdNut
Thu Jul 20, 2017 5:54 pm
Forum: 8-bit acorn software: other
Topic: Odd Message; Tube On! with SD Card/MMFS/PiTubeDirect
Replies: 4
Views: 1367

Odd Message; Tube On! with SD Card/MMFS/PiTubeDirect

Hi All; This was working before (i.e. yesterday) and today it doesn't. BBC Micro Issue 7 board + SD Card (SirMorris) + MMFS + PiTubeDirect(Diamondback) on Pi Zero with Interface board from Kjell Yesterday got the tube running and was able to run the BBC.MMB games disk without issue. Today however wh...
by sfdNut
Tue Oct 18, 2016 12:28 pm
Forum: past physical ABug events
Topic: ABug North 18/19/20 November 2016, Bolton
Replies: 199
Views: 32034

Re: ABug North 18/19/20 November 2016, Bolton

sydney wrote:
sfdNut wrote:As this is my first event I don't want to upset anybody so....If I have an item to sell, say a RiscPC 600 with Acorn monitor, is it ok just to bring it along?
That's fine.
Thanks :)
by sfdNut
Tue Oct 18, 2016 11:01 am
Forum: past physical ABug events
Topic: ABug North 18/19/20 November 2016, Bolton
Replies: 199
Views: 32034

Re: ABug North 18/19/20 November 2016, Bolton

As this is my first event I don't want to upset anybody so....If I have an item to sell, say a RiscPC 600 with Acorn monitor, is it ok just to bring it along?
by sfdNut
Thu Oct 13, 2016 9:14 am
Forum: past physical ABug events
Topic: ABug North 18/19/20 November 2016, Bolton
Replies: 199
Views: 32034

Re: ABug North 18/19/20 November 2016, Bolton

I've paid too and didn't realise I needed to post the fact :shock:

So, Simon, I have paid :)
by sfdNut
Sat Sep 10, 2016 12:26 am
Forum: 32-bit acorn hardware
Topic: RiscPC CMOS check (SOLVED)
Replies: 8
Views: 1100

Re: RiscPC CMOS check

Update: It looks like I've fixed it. The track from 47R to IC20 must have been broken somewhere as the meter did not register. The surrounding tracks tested ok and so I replaced the 47R surface mounted resistor with a wired job linked between Pin 8 of IC20 and the + side of D3. All seems better. No ...
by sfdNut
Tue Aug 30, 2016 4:52 pm
Forum: 32-bit acorn hardware
Topic: RiscPC CMOS check (SOLVED)
Replies: 8
Views: 1100

Re: RiscPC CMOS check

It is a 47R ( 47 with zero zeros after it). Your meter should say 180R form that pad of the 47R to the battery. Check also the other side of the 47R is connected to pin 8 of IC20 Will do, although it will be the weekend now. If I don't get a reading at one or more positions, is there anything I can...
by sfdNut
Tue Aug 30, 2016 4:50 pm
Forum: 32-bit acorn hardware
Topic: RiscPC CMOS check (SOLVED)
Replies: 8
Views: 1100

Re: RiscPC CMOS check

This is at odds with the TRM circuit diagram Be careful, it's yours a RiscPC 600 with 8-bit sound? There are, I understand, two later RiscPC PCB revisions - the first redesign was when 16-bit sound was added, but the only TRM circuit diagram is for the original RiscPC 600 and as far as I know, no d...
by sfdNut
Tue Aug 30, 2016 3:24 pm
Forum: 32-bit acorn hardware
Topic: RiscPC CMOS check (SOLVED)
Replies: 8
Views: 1100

Re: RiscPC CMOS check

The only one I have at the moment - can get more but not until the weekend. After this pic was taken I took a cotton bud soaked with nail varnish remover to the lump of fuzz next to the battery (-) terminal. Turns out it's a surface mount resistor with 470 written on it (470 Ohms?). This is at odds ...
by sfdNut
Tue Aug 30, 2016 1:55 pm
Forum: 32-bit acorn hardware
Topic: RiscPC CMOS check (SOLVED)
Replies: 8
Views: 1100

RiscPC CMOS check (SOLVED)

Hi All After working through a couple of the other threads on here related to CMOS issues after battery replacement I am left with a motherboard that looks very clean, a new battery which is being charged and is delivering 1.2v to somewhere but I'm still getting CMOS unreadable floppy flashes. I hav...
by sfdNut
Mon Aug 22, 2016 11:08 pm
Forum: 8-bit acorn hardware
Topic: Pace 5.25 inch FD PSD3P Issue
Replies: 47
Views: 5793

Re: Pace 5.25 inch FD PSD3P Issue

Well, it's always hard to model these things but the 1770 FDC clock may well become fecked up which will lead to a lack of response (enough?) and I /think/ there was another IC86 function when I looked (can't remember just now) which will potentially cause more upset. Basically though, if it's left...
by sfdNut
Mon Aug 22, 2016 9:59 pm
Forum: 8-bit acorn hardware
Topic: Pace 5.25 inch FD PSD3P Issue
Replies: 47
Views: 5793

Re: Pace 5.25 inch FD PSD3P Issue

MartinB wrote:Thus, you can't leave IC86 fitted, bad things will surely follow... [-X [-(
Such as? Although I think I may already know the answer...
by sfdNut
Mon Aug 22, 2016 9:58 pm
Forum: 8-bit acorn hardware
Topic: Pace 5.25 inch FD PSD3P Issue
Replies: 47
Views: 5793

Re: Pace 5.25 inch FD PSD3P Issue

Suggested solution. Warning, try this at your own risk... Cut all the pins of the 74LS393 chip in position IC86 as close to the body of the chip as possible. Remove the chip. Then carefully solder a wire on the remains of pins 1 and 4 so that the wire links only these pins and no others. No need to...
by sfdNut
Mon Aug 15, 2016 10:30 am
Forum: 8-bit acorn hardware
Topic: Pace 5.25 inch FD PSD3P Issue
Replies: 47
Views: 5793

Re: Pace 5.25 inch FD PSD3P Issue

Right then, I think I've found a smoking gun in the Beeb setup (better than a smoking PSU :) ). Reading the 1772 Disk upgrade manual and checking against the PCB I spotted a possible issue where the instructions say "Check for the presence of a 14pin IC DIL socket at location IC86". I checked. There...
by sfdNut
Mon Aug 15, 2016 8:47 am
Forum: introduce yourself
Topic: Beeb's big adventure / hello
Replies: 11
Views: 2383

Re: Beeb's big adventure / hello

Hello and welcome 8)

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