Electron Issue 6 differences

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paulb
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Electron Issue 6 differences

Post by paulb »

I've been looking at the schematics in the Electron Advanced User Guide (various editions) and Service Manual, and it appears that the former provides the issue 6 schematic for the machine, whereas the latter provides something resembling the issue 4 schematic. Being familiar with the issue 4 myself, and having found plenty of issue 4 PCB pictures on the Web, I was wondering if there were any detailed issue 6 PCB pictures anywhere. Searching these forums with numerals is not apparently possible: search terms below a certain length are eliminated, and quoted terms are not supported. So a search for "Electron issue 6 pictures" is not particularly effective.

What I am wondering about, amongst other things, is whether IC19 was fitted on the issue 6 board and where it actually was on the board. The schematic also has a lot of "NF" markings, which I interpret as "not fitted", but the redrawn schematics (which are great, by the way, as I must have said before) show the two links involved with IC19 as "NF", which wouldn't exactly help with the apparent buffering role that this IC has. (I have found remarks about the video output signals being stronger on the issue 6 due to buffering, so I suppose that this is what facilitates that.)

Did anyone summarise differences between the different board revisions of the Electron?
paulxtr
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Re: Electron Issue 6 differences

Post by paulxtr »

paulb wrote:
Wed Jan 12, 2022 10:56 pm
Searching these forums with numerals is not apparently possible: search terms below a certain length are eliminated, and quoted terms are not supported. So a search for "Electron issue 6 pictures" is not particularly effective.
Try the following search in your favourite browser:

Code: Select all

electron issue 6 pictures site:https://stardot.org.uk/
Cheers,
Paul
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Re: Electron Issue 6 differences

Post by paulb »

paulxtr wrote:
Wed Jan 12, 2022 11:19 pm
paulb wrote:
Wed Jan 12, 2022 10:56 pm
Searching these forums with numerals is not apparently possible: search terms below a certain length are eliminated, and quoted terms are not supported. So a search for "Electron issue 6 pictures" is not particularly effective.
Try the following search in your favourite browser:

Code: Select all

electron issue 6 pictures site:https://stardot.org.uk/
I guess I wasn't in "search mode" and forgot to do this, so thanks for the suggestion! I ended up finding this:

Re: Versions of the Electron motherboard

A German Electron is pretty similar to the UK issue 6, and I see that IC19 is fitted near to the UHF circuit.

I also found this issue 6 image in the related results, showing the resemblance.
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rmbrowngr
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Re: Electron Issue 6 differences

Post by rmbrowngr »

If you are interested in pictures of an issue 6 Electron, with different memory modules, take a look at my post here: viewtopic.php?p=226308#p226308
Richard B
Acorn Electrons issue 4 and 6, MRB, Plus 1 x2, Plus 3, AP6 x2, AP5, Pegasus 400, BeebSCSI, Gotek, Raspberry Pi Co-processor, GoSDC MBE.
BBC B+ 64K (128K upgraded) with Duel OS, Raspberry Pi Co-processor and Gotek.
paulb
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Re: Electron Issue 6 differences

Post by paulb »

rmbrowngr wrote:
Thu Jan 13, 2022 9:41 am
If you are interested in pictures of an issue 6 Electron, with different memory modules, take a look at my post here: viewtopic.php?p=226308#p226308
Yes, those pictures are interesting, and I wonder about the economics of switching to those 4164EC4 devices, too. Frustratingly, IC19 is actually obscured by the Master RAM Board that has been fitted, but we know it is there!
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Re: Electron Issue 6 differences

Post by paulb »

OK, just to summarise what I can see in these pictures:
  • IC19 (74LS08) is fitted near the UHF circuit
  • IC18 (74S08) is fitted at the back right of the board, next to IC9 (which is responsible for the clock division by 13)
  • LK7 appears to have been made, next to IC19 (visible on the German issue 1), although I am not completely certain (but I think it would have to be)
  • LK8 and LK9 are not made, these having some involvement with ~NMI and PHI OUT
chrissawer
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Re: Electron Issue 6 differences

Post by chrissawer »

Quick snap of my Electron Issue 6 in case it is of interest
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ChrisElkIss6.jpg
paulb
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Re: Electron Issue 6 differences

Post by paulb »

chrissawer wrote:
Fri Jan 14, 2022 9:23 am
Quick snap of my Electron Issue 6 in case it is of interest
Thanks, Chris!

I'm still uncertain about LK7 which doesn't look bridged, but I think it must be connected to +5V somehow, just as the AUG indicates, but not in an obvious way. Otherwise, IC18 and IC19 would not function and the machine wouldn't work. The issue 4 board doesn't have this (as the SM indicates), so it is not helpful as another source of information.
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Re: Electron Issue 6 differences

Post by 1024MAK »

paulb wrote:
Fri Jan 14, 2022 11:07 pm
I'm still uncertain about LK7 which doesn't look bridged, but I think it must be connected to +5V somehow, just as the AUG indicates, but not in an obvious way. Otherwise, IC18 and IC19 would not function and the machine wouldn't work. The issue 4 board doesn't have this (as the SM indicates), so it is not helpful as another source of information.
I’ve not checked, but Acorn often provided a PCB track to join the two link positions for default link positions for latter issue Beeb boards, so it’s likely to be the same with the Elk issue 6 board.

Mark
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Re: Electron Issue 6 differences

Post by paulb »

1024MAK wrote:
Sat Jan 15, 2022 12:40 pm
paulb wrote:
Fri Jan 14, 2022 11:07 pm
I'm still uncertain about LK7 which doesn't look bridged, but I think it must be connected to +5V somehow, just as the AUG indicates, but not in an obvious way. Otherwise, IC18 and IC19 would not function and the machine wouldn't work. The issue 4 board doesn't have this (as the SM indicates), so it is not helpful as another source of information.
I’ve not checked, but Acorn often provided a PCB track to join the two link positions for default link positions for latter issue Beeb boards, so it’s likely to be the same with the Elk issue 6 board.
Right. So some kind of continuity test across the apparently unbridged link would confirm that Acorn put a track in, anyway.
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Re: Electron Issue 6 differences

Post by chrissawer »

paulb wrote:
Sat Jan 15, 2022 1:52 pm
Right. So some kind of continuity test across the apparently unbridged link would confirm that Acorn put a track in, anyway.
I took the PCB out and indeed there is a track on the underside connecting the two pads of LK7. Confirmed continuity with a multimeter.
paulb
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Re: Electron Issue 6 differences

Post by paulb »

chrissawer wrote:
Sat Jan 15, 2022 4:32 pm
paulb wrote:
Sat Jan 15, 2022 1:52 pm
Right. So some kind of continuity test across the apparently unbridged link would confirm that Acorn put a track in, anyway.
I took the PCB out and indeed there is a track on the underside connecting the two pads of LK7. Confirmed continuity with a multimeter.
Thank you so much for confirming this, and sorry for any inconvenience!
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