Acorn electron 'stuff' - free

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acp
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Re: Acorn electron 'stuff' - free

Post by acp »

Ronin47 wrote:
Thu Jun 10, 2021 11:43 pm
baz4096 wrote:
Thu Jun 10, 2021 8:56 pm
I was thinking perhaps I got the "better" machine here, given the switch problems and general clean up you guys had; mine was super clean, all things considered.

However, after my PSU order arrived, it looks like I might have a dead ULA. It's a socketed Issue 4 one, with the little metal plate. There was some residue between the contacts on the chip, and the socket wasn't spotless, but even after a gentle application of IPA, I'm still getting a solid grey rectangle on screen. I'm not giving up though! Any suggestions where to start? I should probably open a new thread over in 8-bit Hardware...
I've read:

Keyboard
ULA
RAM
CPU
Mine is an issue 6, the ULA is soldered in, I can't help but think that's better than the socket. Might be worth looking at the CPU, I had a dead one in a BBC B recently, they are pretty cheap.
Mine’s also an issue 6 with the soldered epoxy blob style ULA. The ULA was actually my main worry waiting for it to arrive, since I’d seen some stories before of that being a source of problems. Fortunately, mine seems to work fine as-is.

I ordered a handful of key switches from Mr. RetroClinic this morning along with the keyboard ribbon, so once those arrive I should have a fully working Electron (minus the RF modulator that I’m not replacing for now). :)
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Re: Acorn electron 'stuff' - free

Post by daveejhitchins »

I've ordered 5 of Budgie's ULA replacement PCBs - So anyone with a dead ULA - fingers crossed :D

Dave H.
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Re: Acorn electron 'stuff' - free

Post by Ronin47 »

In terms of keyboard switches, I think I got a good one, as I just did a continuity test and all of them work fine. The only remaining concern is the ribbon, but it does have end to end continuity, and it doesn't have any shorts between lines, so I'm feeling quite hopeful that once the power problem is done it'll run just fine.

I'm hoping my capacitors come today or tomorrow so I can get the PSU board fixed and get power on, see what's what.

I have an urge to get a BBC Master as well, but with only 3 weeks until our potential house move, I need to stop buying stuff!!

I've already bought 2 Model Bs, the Electron and an Amstrad NC100 in the last 12 weeks.....
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Re: Acorn electron 'stuff' - free

Post by Ronin47 »

daveejhitchins wrote:
Fri Jun 11, 2021 8:04 am
I've ordered 5 of Budgie's ULA replacement PCBs - So anyone with a dead ULA - fingers crossed :D

Dave H.
I like your forward thinking :)
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Re: Acorn electron 'stuff' - free

Post by acp »

Ronin47 wrote:
Fri Jun 11, 2021 9:11 am
In terms of keyboard switches, I think I got a good one, as I just did a continuity test and all of them work fine. The only remaining concern is the ribbon, but it does have end to end continuity, and it doesn't have any shorts between lines, so I'm feeling quite hopeful that once the power problem is done it'll run just fine.
My ribbon seems fine continuity-wise, but there's a fair bit of corrosion on it, so it seems sensible to swap it out anyway. Since I was ordering some switches from RetroClinic, I might as well get the ribbon at the same time and then it's done.
I have an urge to get a BBC Master as well, but with only 3 weeks until our potential house move, I need to stop buying stuff!!

I've already bought 2 Model Bs, the Electron and an Amstrad NC100 in the last 12 weeks.....
Blimey, sounds like you're worse than me! I moved at the end of last year and finally had room to spread my retro stuff out and set it all up. Now I have too many projects! :)
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Re: Acorn electron 'stuff' - free

Post by Ronin47 »

acp wrote:
Fri Jun 11, 2021 9:25 am

My ribbon seems fine continuity-wise, but there's a fair bit of corrosion on it, so it seems sensible to swap it out anyway. Since I was ordering some switches from RetroClinic, I might as well get the ribbon at the same time and then it's done.

Blimey, sounds like you're worse than me! I moved at the end of last year and finally had room to spread my retro stuff out and set it all up. Now I have too many projects! :)
My ribbon is corroded too, but I'm going to leave as is until it dies, then I'll make a new one. If you were ordering switches anyway, it makes perfect sense to get one at the same time.

I am quite bad, I have something like 15 or so STs of various flavours, another BBC B that arrived just as we were packing and is still packed and in storage!! Then there's the consoles......

I suspect in total I must have going on for 40-50 machines of various types, but luckily we're going to a much bigger house with a lot more storage and space to spread out the machines I want to have permanently set up.

I already have a number of projects in storage that I need to get on as soon as I've reassembled my workshop.
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Re: Acorn electron 'stuff' - free

Post by baz4096 »

Ronin47 wrote:
Fri Jun 11, 2021 9:39 am
I suspect in total I must have going on for 40-50 machines of various types, but luckily we're going to a much bigger house with a lot more storage and space to spread out the machines I want to have permanently set up.
I'll be showing this post to my other half, makes my dozen assorted machines look positively tame :)

daveejhitchins wrote:
Fri Jun 11, 2021 8:04 am
I've ordered 5 of Budgie's ULA replacement PCBs - So anyone with a dead ULA - fingers crossed :D

Dave H.
Raises Hand That might be me :)

Still got some other bits to tick off first though :)
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Re: Acorn electron 'stuff' - free

Post by Ronin47 »

baz4096 wrote:
Fri Jun 11, 2021 9:52 am
Ronin47 wrote:
Fri Jun 11, 2021 9:39 am
I suspect in total I must have going on for 40-50 machines of various types, but luckily we're going to a much bigger house with a lot more storage and space to spread out the machines I want to have permanently set up.
I'll be showing this post to my other half, makes my dozen assorted machines look positively tame :)
I have a problem.....
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Re: Acorn electron 'stuff' - free

Post by HughF »

Ronin47 wrote:
Fri Jun 11, 2021 9:39 am
acp wrote:
Fri Jun 11, 2021 9:25 am

My ribbon seems fine continuity-wise, but there's a fair bit of corrosion on it, so it seems sensible to swap it out anyway. Since I was ordering some switches from RetroClinic, I might as well get the ribbon at the same time and then it's done.

Blimey, sounds like you're worse than me! I moved at the end of last year and finally had room to spread my retro stuff out and set it all up. Now I have too many projects! :)
My ribbon is corroded too, but I'm going to leave as is until it dies, then I'll make a new one. If you were ordering switches anyway, it makes perfect sense to get one at the same time.

I am quite bad, I have something like 15 or so STs of various flavours, another BBC B that arrived just as we were packing and is still packed and in storage!! Then there's the consoles......

I suspect in total I must have going on for 40-50 machines of various types, but luckily we're going to a much bigger house with a lot more storage and space to spread out the machines I want to have permanently set up.

I already have a number of projects in storage that I need to get on as soon as I've reassembled my workshop.
Pretty much the same as me... My dad is a hoarder, we have 10 acres covered in containers and lorry bodies. I 'got into computers' in the mid 90's so we would go to car boot sales every sunday and buy pretty much anything and everything as it was so cheap back then. We also would help ourselves to everything from the local recycling center.

I went away to University in 2001, parents moved all the stuff (with the exception of all the consoles and cartridges) out of my bedroom and put it into a container and it's only now that I am sorting through it all and either selling it (in the case of the C64 and Sinclair stuff) or giving it away on here.

Anyone want a boxed dragon32? :D :D :lol: :lol: (or 7.... for some reason I have 7)
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Re: Acorn electron 'stuff' - free

Post by Ronin47 »

I'm kind of interested in a Dragon, yes.

The move is now so close I need to put things on hold a bit, but if you could give me an idea of price I can have a think about it.

Thanks.
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Re: Acorn electron 'stuff' - free

Post by Ronin47 »

Ok, so good news/bad news on the Electron Front.

The caps arrived and I now have good power, however it's not all roses.

The screen looks like this:

Stripey.jpeg

So more troubleshooting required, but it's a start, because it shows me that the video circuit is working, and it's also likely the CPU is good too, and a quick check shows me that the clocks seem good too.

So at this point I'm thinking RAM, but can't discount ROM or possibly the ULA.

I think RAM at this point unless anybody has any other thoughts?
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Re: Acorn electron 'stuff' - free

Post by acp »

Ronin47 wrote:
Fri Jun 11, 2021 1:08 pm
Ok, so good news/bad news on the Electron Front.

The caps arrived and I now have good power, however it's not all roses.

The screen looks like this:

So more troubleshooting required, but it's a start, because it shows me that the video circuit is working, and it's also likely the CPU is good too, and a quick check shows me that the clocks seem good too.

So at this point I'm thinking RAM, but can't discount ROM or possibly the ULA.

I think RAM at this point unless anybody has any other thoughts?
Erk, that doesn't look right.

If you've not found it yet, the service manual for the Electron is available here: http://chrisacorns.computinghistory.org ... tronSM.pdf

Page 21 suggests looking at the ULA and/or PCB tracks if the video output isn't correct. Might be worth having a nosey through that manual at other bits to check, too?
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Re: Acorn electron 'stuff' - free

Post by Ronin47 »

acp wrote:
Fri Jun 11, 2021 1:51 pm

Erk, that doesn't look right.

If you've not found it yet, the service manual for the Electron is available here: http://chrisacorns.computinghistory.org ... tronSM.pdf

Page 21 suggests looking at the ULA and/or PCB tracks if the video output isn't correct. Might be worth having a nosey through that manual at other bits to check, too?
No, it's not good. I've had the service manual a couple of days now and just got a really nice quality all in one schematic downloaded.

Clocks are good, I have checked at the ULA and CPU and they are as expected, with /RESET high at the CPU. The tracks all look fine around the ULA and as it's a glop top, the socket is not going to be a problem.

Thing is, the video output is sharp and really clear, and my inclination is to think that what's being displayed is corrupt RAM. It looks similar to other machines I've repaired with similar on-screen corruption where RAM was bad.

I've left it running to see what, if anything gets hot and I'll have a probe around the address lines to see if anything seems stuck.

What is interesting is that the RAM is directly connected to the ULA, and there is nothing else there. If that ULA goes, you're in trouble.

All the other logic seems mostly there for the video generation.
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Re: Acorn electron 'stuff' - free

Post by 1024MAK »

The ULA is the absolute key to this machine. The only thing the 6502 directly accesses is the ROM, but even then the control circuits are in the ULA…

ALL 6502 RAM accesses are via the ULA because the DRAM data bus is only four bits wide.

Mark
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Re: Acorn electron 'stuff' - free

Post by roland »

HughF wrote:
Fri Jun 11, 2021 10:41 am
Anyone want a boxed dragon32? (or 7.... for some reason I have 7)
For some reason a Dragon attracts me: 6809 CPU, 6847 VDG but on the other hand I am quite sure that I won't use it very much. It took me about 35 years before I started to use the Electron :lol: And since I just received the Plus3 I don't want to be too greedy. So if, and only if, end up with one that nobody wants, I probably want one. Just to prevent they end up in a recycle bin....

Thanks again for the Plus3. I'll give it a good cleaning.
HughF wrote:
Fri Jun 11, 2021 10:41 am
I went away to University in 2001, parents moved all the stuff (with the exception of all the consoles and cartridges) out of my bedroom and put it into a container ...
Ah, that explains the rusty parts :lol:

Last question, for now: is the Electron power brick good enough to power an Electron with Plus1 and Plus3 attached or do I need another power supply?
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:
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Re: Acorn electron 'stuff' - free

Post by Ronin47 »

Looking through the service manual and following the diagnostics, I really think this is DRAM that's broken.

The video is clear as day, clocks are good and so are CAS/RAS.

Plus the service manual states: 'Is there a screen display, albeit an incorrect one' and if it is then the answer is DRAM.

It's been running for about an hour now and none of the chips are hot, but if DRAM is bad for video output, which chip would I swap? The service manual doesn't seem clear on that one.
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Re: Acorn electron 'stuff' - free

Post by stephen_usher »

Ronin47 wrote:
Fri Jun 11, 2021 3:09 pm
Looking through the service manual and following the diagnostics, I really think this is DRAM that's broken.

The video is clear as day, clocks are good and so are CAS/RAS.

Plus the service manual states: 'Is there a screen display, albeit an incorrect one' and if it is then the answer is DRAM.

It's been running for about an hour now and none of the chips are hot, but if DRAM is bad for video output, which chip would I swap? The service manual doesn't seem clear on that one.
And I see on another forum that you took my advice and used your toy oscilloscope on the memory data pins and found one with no traffic... So maybe that's the culprit, eh?

I'm guessing that because of the ULA you'd not have any other data bus chatter from the other parts of the machine, which makes this a pretty simple system to diagnose memory faults in circuit.
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Re: Acorn electron 'stuff' - free

Post by Ronin47 »

stephen_usher wrote:
Fri Jun 11, 2021 8:14 pm

And I see on another forum that you took my advice and used your toy oscilloscope on the memory data pins and found one with no traffic... So maybe that's the culprit, eh?

I'm guessing that because of the ULA you'd not have any other data bus chatter from the other parts of the machine, which makes this a pretty simple system to diagnose memory faults in circuit.
Indeed, just didn't get time to post on here earlier.

Nice to see you here too Mr Usher :)

IC4 has no data activity, so I'll go with that first, but it does seem to have the hallmarks of bad RAM.

The ULA does seem to have it's good points in that it really does isolate the RAM from any other chips.
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Re: Acorn electron 'stuff' - free

Post by Ronin47 »

1024MAK wrote:
Fri Jun 11, 2021 2:44 pm
The ULA is the absolute key to this machine. The only thing the 6502 directly accesses is the ROM, but even then the control circuits are in the ULA…

ALL 6502 RAM accesses are via the ULA because the DRAM data bus is only four bits wide.

Mark
I can see why ULA problems kill this machine completely. It really is its beating heart.
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Re: Acorn electron 'stuff' - free

Post by Ronin47 »

IC4 is removed and a socket in it's place, just need the RAM to arrive and fingers crossed we'll be good to go.

EDIT: I also later checked it with the RAM IC removed, and the fault remains, suggesting that was the bad IC. Just got to wait for the replacements now.
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Re: Acorn electron 'stuff' - free

Post by acp »

The switches and replacement ribbon from RetroClinic arrived this morning. Soldered them in over lunchtime and now I have a fully working Electron (well, minus the RF modulator, but that doesn't matter). :)
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Re: Acorn electron 'stuff' - free

Post by MrGpG »

HughF wrote:
Fri Jun 11, 2021 10:41 am
Anyone want a boxed dragon32? :D :D :lol: :lol: (or 7.... for some reason I have 7)
I'd be interested from a perspective of trying I/O via the analogue joystick port :D :D

Glen
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Re: Acorn electron 'stuff' - free

Post by Ronin47 »

acp wrote:
Mon Jun 14, 2021 12:37 pm
The switches and replacement ribbon from RetroClinic arrived this morning. Soldered them in over lunchtime and now I have a fully working Electron (well, minus the RF modulator, but that doesn't matter). :)
Nice one. Always good when another machine is resurrected :)

Still waiting for my RAM to arrive, but removing the one I suspected as dead has not changed the symptoms, so fingers crossed the new IC4 will do the trick.

I was hoping it would be here today, but sadly no luck.
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