Uh Oh.Electron inbound

Any 8bit repairs, images, cool things, upgrades etc.
stephen_usher
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Re: Uh Oh.Electron inbound

Post by stephen_usher » Fri Jun 11, 2021 4:24 pm

I always just look for dodgy looking data on the data line. That's the first one. Of course this doesn't help with addressing faults but weird data line pulses is my first test. I hope your toy 'scope is good enough for that!
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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rubber_jonnie
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Re: Uh Oh.Electron inbound

Post by rubber_jonnie » Fri Jun 11, 2021 4:33 pm

stephen_usher wrote:
Fri Jun 11, 2021 4:24 pm
I always just look for dodgy looking data on the data line. That's the first one. Of course this doesn't help with addressing faults but weird data line pulses is my first test. I hope your toy 'scope is good enough for that!
We'll find out I guess!!

Fisher Price awaaaaaay
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

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rubber_jonnie
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Re: Uh Oh.Electron inbound

Post by rubber_jonnie » Fri Jun 11, 2021 4:40 pm

@stephen_usher Good call, I just checked and IC4 has nothing on data out, 5, 6 & 7 are all showing signs of life.

We'll go with that one first.
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

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arkadiusz.makarenko
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Re: Uh Oh.Electron inbound

Post by arkadiusz.makarenko » Sat Jun 12, 2021 9:24 am

From my experience most common faults on electron
  • not connected keyboard.
  • ula socket (if you have one - replacement was available from Bulgarian demobile 😮 )
  • ram
You need pretty very bad luck to have ula damaged.

Sometimes piggybacking ram can help you find which one is damaged, but never worked for me. Personally I would replace all chips, but that's me.
Do not trust people. They are capable of greatness.
~ Stanislaw Lem

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rubber_jonnie
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Re: Uh Oh.Electron inbound

Post by rubber_jonnie » Sat Jun 12, 2021 10:30 am

arkadiusz.makarenko wrote:
Sat Jun 12, 2021 9:24 am
From my experience most common faults on electron
  • not connected keyboard.
  • ula socket (if you have one - replacement was available from Bulgarian demobile 😮 )
  • ram
You need pretty very bad luck to have ula damaged.

Sometimes piggybacking ram can help you find which one is damaged, but never worked for me. Personally I would replace all chips, but that's me.
Yeah, it seems like a BBC with respect to the keyboard needing to be plugged in, though in this case it makes no difference. Having had a keyboard fault with my BBC B I did think this might be a possibility.

I have buzzed out all the switches which all worked, and the ribbon, despite obvious corrosion, has good continuity and no shorts between wires. If it fails later I'll just make a replacement.

As for the ULA, it's a glop top and directly soldered in, so I can guarantee that the socket isn't a problem! :)

Replacement RAM is in the post, so I'll do the prep whilst I'm waiting and fit a socket. Due to my limited workshop at the moment, I will just do the RAM IC that has no D Out activity, unless of course that doesn't fix it, then I will review.

I've not had any luck with piggybacking myself, but I know it can sometimes help.
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

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rubber_jonnie
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Re: Uh Oh.Electron inbound

Post by rubber_jonnie » Sat Jun 12, 2021 12:00 pm

Ok, IC4 is gone and has a socket in it's place, just have to wait for the RAM to arrive so I can test.
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

stephen_usher
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Re: Uh Oh.Electron inbound

Post by stephen_usher » Sat Jun 12, 2021 12:14 pm

Well, you could power on and see if the fault has changed without the chip in there. :-)
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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rubber_jonnie
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Re: Uh Oh.Electron inbound

Post by rubber_jonnie » Sat Jun 12, 2021 12:24 pm

stephen_usher wrote:
Sat Jun 12, 2021 12:14 pm
Well, you could power on and see if the fault has changed without the chip in there. :-)
I will later on, but first, lunch :)
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

User avatar
rubber_jonnie
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Re: Uh Oh.Electron inbound

Post by rubber_jonnie » Sat Jun 12, 2021 3:19 pm

stephen_usher wrote:
Sat Jun 12, 2021 12:14 pm
Well, you could power on and see if the fault has changed without the chip in there. :-)
Problem is identical with the RAM chip gone, at least I didn't make it any worse :)

That, to me at least, suggests that chip was bad anyway, just have to wait for the new ICs now.
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

stephen_usher
Posts: 1690
Joined: Mon Nov 13, 2017 7:19 pm
Location: Oxford, UK.
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Re: Uh Oh.Electron inbound

Post by stephen_usher » Sat Jun 12, 2021 3:53 pm

Yeah. It's always good to check. Maybe check what signals the RAM chip is getting from the ULA whilst you have the socket there and maybe buzz out the data path to the ULA. (Being paranoid.)
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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