It's 600XL time!

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rubber_jonnie
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Re: It's 600XL time!

Post by rubber_jonnie » Fri Jan 14, 2022 1:12 pm

So, a very quick bit of lunchtime diagnosis on the 600XL and I have found that there is no address line activity at all on the RAM chips at all. No RAS or CAS activity either.

I see some on the ROMs and Sally, and though I do need to check the rest of the ICs, I need to take a closer look at the logic sitting in front of the RAM.

So that's a bunch of LS logic chips, and those I can test with my TLS866 :)
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: It's 600XL time!

Post by rubber_jonnie » Fri Jan 14, 2022 2:03 pm

And one is dead according to the TLS866, a 74LS51, quite a key component, and the one of the few 74LS logic chips I don't actually have to hand!!

Hopefully they will arrive soon!
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: It's 600XL time!

Post by rubber_jonnie » Fri Jan 14, 2022 2:36 pm

rubber_jonnie wrote:
Fri Jan 14, 2022 2:03 pm
And one is dead according to the TLS866, a 74LS51, quite a key component, and the one of the few 74LS logic chips I don't actually have to hand!!

Hopefully they will arrive soon!
EDIT - The remaining 74LS logic chips all test good, and given that the failed 74LS51, U16, is slap bang in the middle of the CAS/RAS circuit:

Screenshot 2022-01-14 at 14.35.23.png
Screenshot 2022-01-14 at 14.35.23.png (1.82 MiB) Viewed 75 times

Then I think I definitely need to change it.
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...

tzok
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Re: It's 600XL time!

Post by tzok » Fri Jan 14, 2022 4:29 pm

Don't fully trust TL866 in terms of TTL testing, especially those less common. There are mistakes in the test vectors, verify them first.

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Re: It's 600XL time!

Post by rubber_jonnie » Fri Jan 14, 2022 5:07 pm

tzok wrote:
Fri Jan 14, 2022 4:29 pm
Don't fully trust TL866 in terms of TTL testing, especially those less common. There are mistakes in the test vectors, verify them first.
Fair comment, I will have a look.
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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