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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 10th Apr 2005, 10:10 am   #1
gazstone
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Default Acorn Electron fault

Hi there.
I have an Acorn Electron with Slogger Master RAM Board fitted which when I power up there is no beep or no caps lock light.
The output to the screen is horizontal white lines from top to bottom.
Could anyone put me in touch with somebody who repairs Acorn Electrons or shed some light on the problem.
Thanks,
Gareth
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Old 10th Apr 2005, 10:45 am   #2
coredump
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Default Re: Acorn Electron fault

With a machine of this age, it's possible that a chip has failed simply by ion migration. There again, a common problem is chips "walking" out of their sockets. Many early 1980s home machines used very poor sockets. Have you tried lifting each socketed chip slightly and re-seating it? Usually makes quite a distinct "crunch" sound! There again, I seem to recall that the Electron's chips were mostly soldered in.

Could you say a bit more about the display? Is the picture properly synced? Or is it reminiscent of a TV with bad line-hold?

Lack of a beep does sound like the CPU is failing to come out of reset. But the clock must be OK, or you'd get no TV display at all.

Last edited by coredump; 10th Apr 2005 at 10:47 am. Reason: Atom/Electron mix-up
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Old 10th Apr 2005, 10:52 am   #3
Nickthedentist
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Default Re: Acorn Electron fault

Quote:
Originally Posted by coredump
There again, a common problem is chips "walking" out of their sockets. Many early 1980s home machines used very poor sockets. Have you tried lifting each socketed chip slightly and re-seating it? Usually makes quite a distinct "crunch" sound!
That's good advice.

Also check the voltage across the big smoothing capacitor inside, should be somewhat over 20V if I remember rightly.

Don't forget working Electrons turn up cheaply on eBay and at boot sales - I sold mine last year for under £15.

Nick.
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Old 10th Apr 2005, 5:55 pm   #4
Duke_Nukem
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Default Re: Acorn Electron fault

IIRC, the Electron is controlled by, what was then, a monster chip. I think it even made the 64k-by-4 RAM into 32k-by 8 ... halving the speed of the processor in the process :-(

Anyhow the same chip is also the display controller so I must admit that my suspicious are in that area.

Don't know how the processor reset is achieved, but if it is the old C-R across the supply then it's at least worth checking that first ... it is possible that the 6502 was responsible for seting up the big chip for different video modes.

Ah, I feel a nostalgia attack coming on, I'm off to the loft ...

TTFN,
Jon
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Old 11th Apr 2005, 10:29 am   #5
coredump
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Default Re: Acorn Electron fault

Quote:
Originally Posted by Duke_Nukem
IIRC, the Electron is controlled by, what was then, a monster chip. I think it even made the 64k-by-4 RAM into 32k-by 8 ... halving the speed of the processor in the process :-(
That's absolutely correct. Acorn reduced the cost of the Electron but slowed it down in the process.

But the mention of capacitors has made me think of tantalum decoupling caps on the power supply. I've seen a number of them just go shorted for no reason (apart from age). This has even happened in (shock, horror) HP test equipment!
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Old 27th Apr 2005, 11:07 pm   #6
tyward1
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Question Re: Acorn Electron fault

Tony re; your fault with the vertical lines .I think these are tuner lines and you will find a tuning switch on the electon or the card to turn this off .I hope this helps its been a while since I had the same problem

ROB
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