Uh Oh.Electron inbound

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stephen_usher
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Re: Uh Oh.Electron inbound

Post by stephen_usher »

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 »

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 many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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rubber_jonnie
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Re: Uh Oh.Electron inbound

Post by rubber_jonnie »

@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 many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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arkadiusz.makarenko
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Re: Uh Oh.Electron inbound

Post by arkadiusz.makarenko »

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.
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rubber_jonnie
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Re: Uh Oh.Electron inbound

Post by rubber_jonnie »

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 many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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rubber_jonnie
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Re: Uh Oh.Electron inbound

Post by rubber_jonnie »

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 many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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stephen_usher
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Re: Uh Oh.Electron inbound

Post by stephen_usher »

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 »

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 many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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rubber_jonnie
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Re: Uh Oh.Electron inbound

Post by rubber_jonnie »

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 many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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stephen_usher
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Re: Uh Oh.Electron inbound

Post by stephen_usher »

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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