OSI 600D Superboard Build

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rubber_jonnie
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Re: OSI 600D Superboard Build

Post by rubber_jonnie »

PhilC wrote: Mon Mar 25, 2024 1:35 pm Well done. Complete nightmare with those logic chips.
I'll say. Just wondering if I powered on with the wrong voltage at some point, as an LS00 for the video circuit died this morning as well, and that is too many to be a coincidence.

Just need to jump this last flickery video keyboard issue and it should be good.

Been a bit of a marathon for sure.
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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PhilC
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Re: OSI 600D Superboard Build

Post by PhilC »

rubber_jonnie wrote: Mon Mar 25, 2024 3:39 pm
PhilC wrote: Mon Mar 25, 2024 1:35 pm Well done. Complete nightmare with those logic chips.
I'll say. Just wondering if I powered on with the wrong voltage at some point, as an LS00 for the video circuit died this morning as well, and that is too many to be a coincidence.

Just need to jump this last flickery video keyboard issue and it should be good.

Been a bit of a marathon for sure.
* I'm sure we've all done it " he says whilst thinking "oh yeah I blew up my video Adaptor last week, oops"
If it ain't broke, test it to Destruction.
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rubber_jonnie
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Re: OSI 600D Superboard Build

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PhilC wrote: Mon Mar 25, 2024 3:47 pm
rubber_jonnie wrote: Mon Mar 25, 2024 3:39 pm

I'll say. Just wondering if I powered on with the wrong voltage at some point, as an LS00 for the video circuit died this morning as well, and that is too many to be a coincidence.

Just need to jump this last flickery video keyboard issue and it should be good.

Been a bit of a marathon for sure.
* I'm sure we've all done it " he says whilst thinking "oh yeah I blew up my video Adaptor last week, oops"
At some point I was using the bench PSU for powering on the PS2 Slim, which is 8.5v. Now I don't recall powering the OSI on with that voltage, but I suppose if I forgot to select 5v on memory 1 I could have easily done so if I wasn't paying attention.
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: OSI 600D Superboard Build

Post by stephen_usher »

Time to add a zener diode and a quick blow fuse to the power input?
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: OSI 600D Superboard Build

Post by rubber_jonnie »

stephen_usher wrote: Mon Mar 25, 2024 3:54 pm Time to add a zener diode and a quick blow fuse to the power input?
Indeed, and potentially put a label on my bench PSU reminding me to check voltages before turning power on. There may already be a Zener in there, need to double check.
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: OSI 600D Superboard Build

Post by rubber_jonnie »

OK, so it's fixed.

IMG20240328134336.jpg
IMG20240328134336.jpg (198.23 KiB) Viewed 184 times

The solution? I replaced the 74LS04 at U21 with a 74S04.

According to the build doc I have it should be an an LS, but as soon as I swapped it out, the problem went away. I then looked at other schematics and BoMs and all state an LS04.

I tried a bunch of LS04's and the results were always the same, fuzzy screen.

Now I need to test a few other things, like saving basic progs, but for now it's built and running.
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: OSI 600D Superboard Build

Post by stephen_usher »

Oh, so marginal timings... What fun.
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: OSI 600D Superboard Build

Post by rubber_jonnie »

stephen_usher wrote: Thu Mar 28, 2024 2:59 pm Oh, so marginal timings... What fun.
Indeed...
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: OSI 600D Superboard Build

Post by rubber_jonnie »

So here is the list of things that caused me problems during my build.

Everybody will be different, and I'm happy to say I didn't have any shorts at all, but what I did have were some errors of my own making, and some that were baked in to the info I had in front of me.
  1. Clock circuit problem 1 - I used a 74LS92 for U29. This is what the BoM said, though the schematic said it was a 74LS93. I followed the BoM. Fixed by using a 74LS93
  2. Clock circuit problem 2 - I had inserted a 150nF cap at C65, it should have been 150pF and it was effectively filtering the clock signal.
  3. Video circuit - I had a placement diagram that showed 3 holes for the position of C8, with the middle pin indicated, so I connected the right and middle pins. This is incorrect and should have been the left and right pins, ignoring the middle marked pin. This led to 15Khz on the vertical sync instead of 60Hz and a rolling image.
  4. Fuzzy video - this was an odd one, but ultimately turned out to be the use of a 74LS04 at U21. I swapped for a 74S04 and the fuzziness went away, so clearly some sort of timing issue. This is a bit of a gotcha as the BoM and schematic agree it should be an LS part.
  5. Initial memory location - My misinterpretation, but the 2 RAM chips used for initial testing need to go into sockets U31 & U45, not U38 & U52.
  6. Shift lock - There are 3 apparent connections for the shift lock switch. The middle connection is irrelevant and the switch needs to connect the left and right pins only for shift lock to function correctly.
I think that's about it so far, but if I hit any more issues going forwards I'll extend this list.

Hopefully it may help others with issues doing this build.
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: OSI 600D Superboard Build

Post by stephen_usher »

I think the fuzzy video thing is due to the change in speed (and manufacturing process) between now and the 1970s. Indeed, I'm surprised that the BoM didn't state a specific manufacturer's part as the timings differed so greatly back in the day. There are many systems where the service manual states manufacturer and even down to build date for replacement parts.
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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