TC 2068 weird colors

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amateus
Posts: 57
Joined: Wed Mar 21, 2018 2:28 pm

TC 2068 weird colors

Post by amateus »

Hi,

I got a TC 2068 which has a problem and I wonder if any of you can help me.

Blue, yellow, black and white colors are fine, but the other ones give weird colors. Red, Magenta Green and Cyan are all wrong.

I didn't made any tests yet (not sure what tests I can do - I can't find info on internet about TC2068 diagnostics).

Thanks in advance

Shots bellow:
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153764784_1642804779263865_7760647022486252639_n.jpg
153586419_3832398460152572_5682548986311368824_n.jpg
153365835_334487717941228_4137074583686206931_n.jpg
153349678_755988588665867_1339051547940724482_n.jpg
Last edited by amateus on Wed Feb 24, 2021 8:30 pm, edited 1 time in total.
amateus
Posts: 57
Joined: Wed Mar 21, 2018 2:28 pm

Re: TC 2068 weird colors

Post by amateus »

154592165_1340703266309465_4501432281733045776_n.jpg
154110293_265553268266905_8128831650988990283_n.jpg
153493613_766647520644497_6138520077505454408_n.jpg
amateus
Posts: 57
Joined: Wed Mar 21, 2018 2:28 pm

Re: TC 2068 weird colors

Post by amateus »

I'm in the process of replacing all the capacitors in the video circuit, but have to pause as there's a couple missing from my inventory :)
McKlaud
Posts: 337
Joined: Tue Dec 19, 2017 10:02 pm
Location: St Albans, UK

Re: TC 2068 weird colors

Post by McKlaud »

Hi,

Nice board and all IC's socked. Anyway, when you finish re-cap, all colours should be back to normal. If not, check continuity of traces between the SCLD (ULA) and 22uF capacitors and between these capacitors and the PAL encoder (MC1377 type) inputs.

I would suggest cleaning both RCA connectors (TV and monitor outputs) because they look very dirty and rusty. 1000 grit wet sandpaper would do the job.

Bear in mind that any TS/TC2068 has a flaw in the design. BRIGHT is visible in BLACK, so TC2068 shows 16 colours instead of 15.

For diagnostic purposes you can you any diagnostic ROM available on the net and the demo called "Timmy" (https://www.pouet.net/prod.php?which=64102). For my own purpose and testing AY in any Timex machine I've cracked DiagROM I hope Phill wouldn't mind (https://www.youtube.com/watch?v=dC0ZgcBu8rQ).
Claudius
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amateus
Posts: 57
Joined: Wed Mar 21, 2018 2:28 pm

Re: TC 2068 weird colors

Post by amateus »

Thank you for your comment. I'll try everything after the recap :)
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