Hi there,
I got a PAL Atari 1040STE which has video sync problem, so I've been debugging it today and noticed that VSync and HSync are all right, but CCLK signal is suspiciously silent (both video connector pin #2 and U403 MC1377P pin 17).
According to MC1377 sheet it should be around 2-3 MHz, but on my machine it's just 4V all the time.
I've been scrolling through STE schematics many hours today and still I can't see where it comes from.
I would imagine it comes either from MCU or maybe Shifter, or something like VSync gets mixed with HSync...
Any idea, please?
PS: Poked PSU with a scope - not much noise, levels seem OK too. Dully recapped C103, C415, C417, C423, C433.
STE video synchronisation problem
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Re: STE video synchronisation problem
CCLK goes U308B pin 12 and comes from a clock circuit only present on PAL machines (I put the signal in red bellow) :
RodolpheWorking ones : MegaSTE (68020) / TT030 / Falcon with AB040 & Eclipse / 1040STF
Need testing : Falcon with CT2
Need testing : Falcon with CT2
Re: STE video synchronisation problem
Some monitors do not like st video modes.
You could try this fix where a couple people said it helped with sync issues also.
https://www.exxosforum.co.uk/forum/viewt ... f=17&t=135
You could try this fix where a couple people said it helped with sync issues also.
https://www.exxosforum.co.uk/forum/viewt ... f=17&t=135
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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- Joined: Tue Sep 19, 2017 1:48 pm
- Location: UK
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- Posts: 21
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- Location: UK
Re: STE video synchronisation problem
I am using an old CRT Philips CM 8802 which works perfectly with my other STE.exxos wrote: ↑Sun Sep 24, 2017 12:11 am Some monitors do not like st video modes.
You could try this fix where a couple people said it helped with sync issues also.
https://www.exxosforum.co.uk/forum/viewt ... f=17&t=135
Thanks for the link, I think that might be a bit different, but I'll try your fixes.
Re: STE video synchronisation problem
Its easy to try, not exactly the same no, but its the regulator for the video circuit. So its a sensible place to startNumber_Nine wrote: ↑Sun Sep 24, 2017 10:49 am I am using an old CRT Philips CM 8802 which works perfectly with my other STE.
Thanks for the link, I think that might be a bit different, but I'll try your fixes.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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- Location: UK
Re: STE video synchronisation problem
Having changed U403 (MC1377P), still no idea why is there nothing (constant 6VDC) on the composite output (pin 9 of U403), still guessing it might be because something is wrong with the Osc In signal (pin 17) - I see CCLK on R469, but after R469 it's so weak so after C 427 U403 has +5V instead of CCLK on its own (I've tried 4 MC1377Ps - all the same, I have to check this pin on a good Atari, though), but bypassing composite sync to composite output seems to work for me, as anyway I am getting RGB right from U401, but yes modulator won't work like this...
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Re: STE video synchronisation problem
Checked a working Atari STE - everything is just exactly the same, the only difference is that it has also composite out on pin 9.
I am out of ideas.
I am out of ideas.
Re: STE video synchronisation problem
Number_Nine wrote: ↑Sat Sep 30, 2017 9:31 pm Checked a working Atari STE - everything is just exactly the same, the only difference is that it has also composite out on pin 9.
I am out of ideas.
What are you seeing on cclk on working and none working machines ? Can you post scope images?
Have you lifted pin 9 out of the socket and checked that way ?
What is on pin 2 of the 1377 ?
Check q404 and make sure you have 12v there.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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- Joined: Tue Sep 19, 2017 1:48 pm
- Location: UK
Re: STE video synchronisation problem
Thanks for the reply.exxos wrote: ↑Sun Oct 01, 2017 12:41 amNumber_Nine wrote: ↑Sat Sep 30, 2017 9:31 pm Checked a working Atari STE - everything is just exactly the same, the only difference is that it has also composite out on pin 9.
I am out of ideas.
What are you seeing on cclk on working and none working machines ? Can you post scope images?
Have you lifted pin 9 out of the socket and checked that way ?
What is on pin 2 of the 1377 ?
Check q404 and make sure you have 12v there.
I have already assembled the good Atari back together as I noticed no differences earlier.
12V on collector of Q404 is there.
With pin 9 of 1377 unconnected - all the same (no Composite off it).
CCLK: Pin 2 of 1377 (VSync + HSync -> XOR (U2009A) -> Invertor (U211C)): Pin 17 (Osc In) on 1377: