Faulty Acorn Electron

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os72
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Faulty Acorn Electron

Post by os72 » Sat Jul 25, 2020 7:03 pm

Hi there,

New member here - just purchased an Acorn Electron collection. The Acorn itself just shows a yellow screen with random red characters.

I have no experience with it, or the insides of it at all (see photo). This occurs with only the power supply and aerial lead connected.

Anyone seen anything like this or could point me in the right direction?

Thank you!
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rmbrowngr
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Re: Faulty Acorn Electron

Post by rmbrowngr » Sat Jul 25, 2020 8:28 pm

I would expect it’s a ULA issue. If it’s a pre-issue 6, pressing gently down on it might fix it. The alternative is removing the ULA and cleaning the pins with IPA. If you search a bit on this forum there are step-by-step instructions.

I had a similar issue with my issue 4 Elk and gently pressing the ULA cured it.
Richard B
Acorn Electrons issue 4 and 6, MRB, Plus 1, AP6, AP5, Pegasus 400, BeebSCSI, Gotek, Raspberry Pi, GoSDC MBE.
BBC B+ 64K (128K upgraded) with Duel OS, Raspberry Pi and Gotek.

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roland
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Re: Faulty Acorn Electron

Post by roland » Sat Jul 25, 2020 8:54 pm

There was recently quite a large topic about screen problems and cleaning or reseating the ULA over here.
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

os72
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Re: Faulty Acorn Electron

Post by os72 » Sun Jul 26, 2020 7:47 pm

Thanks for the tips!

I've tried pressing down, and also removing the ULA and cleaning it up, unfortunatley the screen doesn't change at all.

I was previously connecting it with an RF lead, found a RCA lead for the video output and tried that instead - exactly the same.

Time for the bin?

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roland
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Re: Faulty Acorn Electron

Post by roland » Sun Jul 26, 2020 9:52 pm

os72 wrote:
Sun Jul 26, 2020 7:47 pm
Time for the bin?
NO

It can also be a faulty memory chip. The Electron is not so complicated that it cannot be repaired. Are you able to remove IC's from the board and replace them?

I guess others will vome with good tips in this topic. So don't bin it [-o<

Maybe the service manual can help you: https://www.pa3byb.nl/wp-content/upload ... tronSM.pdf
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vanekp
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Re: Faulty Acorn Electron

Post by vanekp » Sun Jul 26, 2020 10:06 pm

also check the voltages that come from the power unit to make sure they are correct.
Peter.

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danielj
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Re: Faulty Acorn Electron

Post by danielj » Sun Jul 26, 2020 11:00 pm

The PSU very rarely goes wrong in the elk but definitely check to make sure the voltages are right. Even if it has gone south I don't think you'd be seeing this sort of display. If it's not ULA, most likely to be RAM, as Roland said. It uses 4164s - if you've got a scope you might be able to work out which one's misbehaving, but otherwise it might be easier just to replace all four? If you're not adept at IC removal, we can talk you through the destructive but safe method :)

The final possibility is the ROM, and there are a few anecdotal tales of that going south, but I think it's not too likely.

d.

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daveejhitchins
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Re: Faulty Acorn Electron

Post by daveejhitchins » Mon Jul 27, 2020 7:00 am

os72 wrote:
Sun Jul 26, 2020 7:47 pm
Thanks for the tips!

I've tried pressing down, and also removing the ULA and cleaning it up, unfortunatley the screen doesn't change at all.

I was previously connecting it with an RF lead, found a RCA lead for the video output and tried that instead - exactly the same.

Time for the bin?
As others have said . NO . . . NO . . . NO . . . NO . . . NO . . . NO . . . NO . . .

One check that hasn't been mentioned is the ULA socket. Please post a photo of your ULA. Dependant on the type you have, there could be a broken pin.

If all else fails and it does turn out to be the ULA - In the very near future there will be a replacement for it.

If you're unhappy with doing any work to find the fault - please contact me and I'll sort it out for you.

We just DON'T throw Electrons away!

Dave H.

os72
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Re: Faulty Acorn Electron

Post by os72 » Sun Aug 02, 2020 11:23 am

Hi there,

Please see photos of the pins and chip:
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IMG_3750.jpg
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daveejhitchins
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Re: Faulty Acorn Electron

Post by daveejhitchins » Sun Aug 02, 2020 2:03 pm

os72 wrote:
Sun Aug 02, 2020 11:23 am
Please see photos of the pins and chip:
The ULA connectors will be fine, however, unfortunately your photo of the ULA socket is fuzzy and at the wrong angle to make out if any of the pins are broken. What you need to do, to check for broken pins, is ensure that they are all the same height! You need to get up-close-and-personal 8)

Dave H.

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