BBC Master 128 Circuit Schematics (Remastered PDF) Mainboard and keyboard
BBC Master 128 Circuit Schematics (Remastered PDF) Mainboard and keyboard
As an admirer of the work of dv8 with the remastered pdf manuals, the only thing missing was the circuit diagrams.
As a result I decided to do my bit towards this preservation task and started to redraw the Circuit/Schematic Diagrams.
So as a first presentation, I give you the BBC Master 128 Diagram, completely re-drawn, Hi-res, full size (A0) PDF.
I've already started work on the BBC Micro version and I'll add that to this post as soon as I have it completed.
Printed out onto A3 or better still A2, these plans look super clean compared to any scans out there.
Although I've checked the drawings many times, if anyone notices any errors please let me know and I'll correct them.
Enjoy !
Update :24/04/24 - I've also added the BBC Master Keyboard schematic now which I've also corrected and colour coded to make it easier to see each trace
BBC Master 128 Circuit Schematic (latest update 24/04/2024)
Log of corrections completed:
26/05/2021 22:20 : corrected CO to CQ and Added A5/A6 ( missing from original ) on ICs 17/18/23/26
26/05/2021 22:36 : corrected L1 value to 33μH
27/05/2021 12:50 : correct C40 and C43 to 4n7
07/07/2021 : changed crystal near C86 on page 1 to X2
13/08/2022 : Pin 7 of IC49 changed to GD / Pin 2 of IC4 changed to "Q1" / couple of capitalisation errors fixed
09/01/2023 : Fixed missing RW track
23/08/2023 : corrected R36 to R38 / fixed searchable text layer
10/09/2023 : corrected SC1/SC0 labels on IC10 ( should have been SC1&2)
04/01/2024 : corrected DMA 0,1,2,3 to remove space
24/04/2024: corrections: IC40-Pin2>3 'BLANK', IC11 pin 16>18, Q11 & Q13 Graphic to PNP rather than NPN - added Keyboard Schematic
As a result I decided to do my bit towards this preservation task and started to redraw the Circuit/Schematic Diagrams.
So as a first presentation, I give you the BBC Master 128 Diagram, completely re-drawn, Hi-res, full size (A0) PDF.
I've already started work on the BBC Micro version and I'll add that to this post as soon as I have it completed.
Printed out onto A3 or better still A2, these plans look super clean compared to any scans out there.
Although I've checked the drawings many times, if anyone notices any errors please let me know and I'll correct them.
Enjoy !
Update :24/04/24 - I've also added the BBC Master Keyboard schematic now which I've also corrected and colour coded to make it easier to see each trace
BBC Master 128 Circuit Schematic (latest update 24/04/2024)
Log of corrections completed:
26/05/2021 22:20 : corrected CO to CQ and Added A5/A6 ( missing from original ) on ICs 17/18/23/26
26/05/2021 22:36 : corrected L1 value to 33μH
27/05/2021 12:50 : correct C40 and C43 to 4n7
07/07/2021 : changed crystal near C86 on page 1 to X2
13/08/2022 : Pin 7 of IC49 changed to GD / Pin 2 of IC4 changed to "Q1" / couple of capitalisation errors fixed
09/01/2023 : Fixed missing RW track
23/08/2023 : corrected R36 to R38 / fixed searchable text layer
10/09/2023 : corrected SC1/SC0 labels on IC10 ( should have been SC1&2)
04/01/2024 : corrected DMA 0,1,2,3 to remove space
24/04/2024: corrections: IC40-Pin2>3 'BLANK', IC11 pin 16>18, Q11 & Q13 Graphic to PNP rather than NPN - added Keyboard Schematic
- Attachments
-
- bbc master circuit diagram APR2024.pdf
- (1.57 MiB) Downloaded 42 times
Last edited by Ukwebb on Wed Apr 24, 2024 11:03 pm, edited 18 times in total.
BBC Bs, Master 128s, Master Compact, and Electrons, and an A3000 with an ARM3
Don’t Panic and Always Carry a Towel
Don’t Panic and Always Carry a Towel
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
Looks incredible, well done.
I haven't checked the original, but was curious why the A5/A6 pins are not labelled on the RAM (IC17/18/23/26). Aren't the data pins D0-D3, rather than all D0?
I haven't checked the original, but was curious why the A5/A6 pins are not labelled on the RAM (IC17/18/23/26). Aren't the data pins D0-D3, rather than all D0?
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
Thats a very good question - I dont know.
BBC Bs, Master 128s, Master Compact, and Electrons, and an A3000 with an ARM3
Don’t Panic and Always Carry a Towel
Don’t Panic and Always Carry a Towel
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
Ah, the data pins should be labelled DQ, not D0.
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
on which chip ? --
edit : forget that - I see now ! I'll edit that now !
BBC Bs, Master 128s, Master Compact, and Electrons, and an A3000 with an ARM3
Don’t Panic and Always Carry a Towel
Don’t Panic and Always Carry a Towel
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
Just wondering if you're following the Copywrite and asked Acorn first.......
Ed......
3 working Beebs, 1 RetroClinic Master, 1 normal Master, 1 A3010, 1 Pi2 RISC OS, 2 broken Beeb Motherboards, 1 Omnibus A7000+ server, 1 A7000+ Desktop, 1 PET, 1 C64, 1 C128, 1 Amiga 500 and 1 Roamer.
3 working Beebs, 1 RetroClinic Master, 1 normal Master, 1 A3010, 1 Pi2 RISC OS, 2 broken Beeb Motherboards, 1 Omnibus A7000+ server, 1 A7000+ Desktop, 1 PET, 1 C64, 1 C128, 1 Amiga 500 and 1 Roamer.
- Multiwizard
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Re: BBC Master 128 Circuit Schematics (Remastered PDF)
I just saw it on FB,, nice work...
Greetings, Wim...
Greetings, Wim...
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
thankyou
BBC Bs, Master 128s, Master Compact, and Electrons, and an A3000 with an ARM3
Don’t Panic and Always Carry a Towel
Don’t Panic and Always Carry a Towel
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
C40 and C43 should be 4.7nf caps.
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
Great work, a fantastic resource...
Electron, Plus 3 and plus 1, AP6 and Home made MMFS PP SD interface
Electron Plus 1 Pres AP3/4 AP5 MGC ELKWiFi MRB
Beeb issue 7 with IFEL 16 socket Rom/Ram board
Master 128,CoPro
Master Compact
StrongA RPC,
Atom, Music 5000 and Keyboard
Electron Plus 1 Pres AP3/4 AP5 MGC ELKWiFi MRB
Beeb issue 7 with IFEL 16 socket Rom/Ram board
Master 128,CoPro
Master Compact
StrongA RPC,
Atom, Music 5000 and Keyboard
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Re: BBC Master 128 Circuit Schematics (Remastered PDF)
Nice. See also my circuit diagram for the BBC B https://tobylobster.github.io/mos/mos/S-s25.html
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
BBC Bs, Master 128s, Master Compact, and Electrons, and an A3000 with an ARM3
Don’t Panic and Always Carry a Towel
Don’t Panic and Always Carry a Towel
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
Nice work -TobyLobster wrote: ↑Thu May 27, 2021 11:13 am Nice. See also my circuit diagram for the BBC B https://tobylobster.github.io/mos/mos/S-s25.html
nice site too
BBC Bs, Master 128s, Master Compact, and Electrons, and an A3000 with an ARM3
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- retroclinic
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Re: BBC Master 128 Circuit Schematics (Remastered PDF)
Both brilliant, well done.
Can either of you do a recreation now of the B+ and Compact schematics? The only ones available (that I know of) are really bad quality, these are the ones we could really do with having a good version of!
Thanks, Mark.
Can either of you do a recreation now of the B+ and Compact schematics? The only ones available (that I know of) are really bad quality, these are the ones we could really do with having a good version of!
Thanks, Mark.
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
Do you have the resources to produce variants for the different PCB issues (I'm not quite sure which issue yours is).TobyLobster wrote: ↑Thu May 27, 2021 11:13 am Nice. See also my circuit diagram for the BBC B https://tobylobster.github.io/mos/mos/S-s25.html
I have a dyeline print of Issue 3 BBC, though it's faded to almost unreadable having been stuck on the wall for some years. Notable differences are the Econet clock/terminator deleted from your version (empty space top right-hand corner), R172 (suppressing the audio buzz from the 1MHz bus connector), and minor changes around the printer port (the latter crudely drawn on this print - but obviously on the master from which the print was taken rather than my annotation; I think these were changes done as rework on earlier PCBs, maybe reworked on iss2 and rolled in to iss3, or maybe this print was meant to show how iss3 came out of the factory with rework done).
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Re: BBC Master 128 Circuit Schematics (Remastered PDF)
I don't, I only have the one diagram, which has no issue marked, but I would assume is Issue 7.
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
Very useful and as it's a PDF you can text search it.
Spotted page 1 top right hand corner, 16MHz crystal should be X2.
Ashley.
Spotted page 1 top right hand corner, 16MHz crystal should be X2.
Ashley.
Ashley.
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
Thanks and amended
BBC Bs, Master 128s, Master Compact, and Electrons, and an A3000 with an ARM3
Don’t Panic and Always Carry a Towel
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Re: BBC Master 128 Circuit Schematics (Remastered PDF)
Wonderful. Thanks for the effort, it is gorgeous.
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
thankyou
BBC Bs, Master 128s, Master Compact, and Electrons, and an A3000 with an ARM3
Don’t Panic and Always Carry a Towel
Don’t Panic and Always Carry a Towel
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
I've just came by the original 80s blue prints my self , They are Huge and are a pair, ill get a few more images later ,
they came direct from some who worked in Cambridge in the early 80s
they came direct from some who worked in Cambridge in the early 80s
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
oh wow ! theyre awesome ! you're very lucky !!
they belong in a museum! somewhere like TNMOC
they belong in a museum! somewhere like TNMOC
BBC Bs, Master 128s, Master Compact, and Electrons, and an A3000 with an ARM3
Don’t Panic and Always Carry a Towel
Don’t Panic and Always Carry a Towel
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
I’d love a print of these!
What a great find
What a great find
I run a little online shop called "Vintage Imitation Parts" to sell a few Acorn Archimedes and BBC Micro related bits and pieces, such as my imitation keyboard surrounds and just recently my imitation function strips.
Take a look! vintage.imitation.parts
Take a look! vintage.imitation.parts
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
I Actually could help with prints I have a Professional A3 printer , if you would like one i could see what the best wat to capture them , the only thing is the question of copyright , is there any one here that knows about reproduction info regarding Acorn stuff ,
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
I think whilst the copyright probably still belongs to someone, nobody seems to be asserting it recently. I seem to see a lot of “if you’re the copyright holder, please contact me and I’ll stop” around the Acorn themed stuff.
I run a little online shop called "Vintage Imitation Parts" to sell a few Acorn Archimedes and BBC Micro related bits and pieces, such as my imitation keyboard surrounds and just recently my imitation function strips.
Take a look! vintage.imitation.parts
Take a look! vintage.imitation.parts
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Re: BBC Master 128 Circuit Schematics (Remastered PDF)
Thanks so much for this. It really helped me out today.
I did spot a tiny mislabel on Pin 2 of IC4 (should be "Q1")... well actually I personally think it should be Q0 but that's a whole other discussion
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
I’d love a print of these! Make some Great Wall art
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
This is beautiful, thanks for drawing this.
One minor detail I noticed is that Pin 7 of IC49 (the uPD7002 ADC) should also be GD, same as pin 5. You have it as G0 (g-zero). Have checked this against an old scanned master schematic, and also the uPD7002 datasheet (https://www.farnell.com/datasheets/100687.pdf)
Aside: Acorn have implemented this (drawn and I buzzed it out on an actual master) with pin 5 and 7 open, yet the datasheet suggests shorting them with an O-shaped trace around pin 6 and the capacitor leg.
One minor detail I noticed is that Pin 7 of IC49 (the uPD7002 ADC) should also be GD, same as pin 5. You have it as G0 (g-zero). Have checked this against an old scanned master schematic, and also the uPD7002 datasheet (https://www.farnell.com/datasheets/100687.pdf)
Aside: Acorn have implemented this (drawn and I buzzed it out on an actual master) with pin 5 and 7 open, yet the datasheet suggests shorting them with an O-shaped trace around pin 6 and the capacitor leg.
Re: BBC Master 128 Circuit Schematics (Remastered PDF)
Davidmc and lushprojects - :sorry its taken a while but your noted errors have now been corrected and uploaded to the original post
Many thanks for reporting them
Richard
Many thanks for reporting them
Richard
BBC Bs, Master 128s, Master Compact, and Electrons, and an A3000 with an ARM3
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Re: BBC Master 128 Circuit Schematics (Remastered PDF)
Hi Richard,
Nice work
On my PDF viewer, the R/W circuit under the processor (IC14) from pin 34 is incomplete. It should connect to various places including TP6, IC20 pin 31, etc. Can you have a look at this please.
Also, I understand that you may not want to show a drawing version number on the drawing itself. But it would be helpful if you include a version number in the filename. Maybe in hex? That way, it will be obvious in future when your drawing spreads across the internet, which version is which... Saves confusion when someone asks for help when repairing their machine
Mark
Nice work
On my PDF viewer, the R/W circuit under the processor (IC14) from pin 34 is incomplete. It should connect to various places including TP6, IC20 pin 31, etc. Can you have a look at this please.
Also, I understand that you may not want to show a drawing version number on the drawing itself. But it would be helpful if you include a version number in the filename. Maybe in hex? That way, it will be obvious in future when your drawing spreads across the internet, which version is which... Saves confusion when someone asks for help when repairing their machine
Mark
For a "Complete BBC Games Archive" visit www.bbcmicro.co.uk NOW!
BeebWiki - for answers to many questions...
Fault finding index • Acorn BBC Model B minimal configuration • Logic Levels for 5V TTL Systems
BeebWiki - for answers to many questions...
Fault finding index • Acorn BBC Model B minimal configuration • Logic Levels for 5V TTL Systems