STE video synchronisation problem

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exxos
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Re: STE video synchronisation problem

Post by exxos » Sun Oct 01, 2017 6:31 pm

Lift one end of R470 and see if GCLK comes back up ? Also check CCLK both sides of C427.. and R489.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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Number_Nine
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Re: STE video synchronisation problem

Post by Number_Nine » Sun Oct 01, 2017 7:52 pm

exxos wrote:
Sun Oct 01, 2017 6:31 pm
Lift one end of R470 and see if GCLK comes back up ? Also check CCLK both sides of C427.. and R489.
I've tried removing R470, and after removing - input of R489 (it's R469, I believe though) 4.6V, after R469 - 2.6V, on input of C427 it's 2.6V and on the side connected to pin 17 of 1377 it's same 5V.

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Re: STE video synchronisation problem

Post by exxos » Sun Oct 01, 2017 9:36 pm

Number_Nine wrote:
Sun Oct 01, 2017 7:52 pm
I've tried removing R470, and after removing - input of R489 (it's R469, I believe though) 4.6V, after R469 - 2.6V, on input of C427 it's 2.6V and on the side connected to pin 17 of 1377 it's same 5V.
So just a flat DC voltage there, no signal ?

So to recap, input to R469 has the clock, but the output does not ?

Also with the IC end of R469 lifted, do you still see CCLK on both sides of the resistor ?
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
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Re: STE video synchronisation problem

Post by exxos » Sun Oct 01, 2017 9:53 pm

This is what I get "left side input" of R469..
c1.png
c1.png (3.9 KiB) Viewed 446 times
3V p-p. Bias 0v.

Output side of R469 (IC side).
c2.png
c2.png (3.85 KiB) Viewed 446 times
about 0.2V p-p (200mV) with 0.4V (400mv ). DC offset.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

Number_Nine
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Re: STE video synchronisation problem

Post by Number_Nine » Sun Oct 01, 2017 10:00 pm

exxos wrote:
Sun Oct 01, 2017 9:36 pm
Number_Nine wrote:
Sun Oct 01, 2017 7:52 pm
I've tried removing R470, and after removing - input of R489 (it's R469, I believe though) 4.6V, after R469 - 2.6V, on input of C427 it's 2.6V and on the side connected to pin 17 of 1377 it's same 5V.
So just a flat DC voltage there, no signal ?

So to recap, input to R469 has the clock, but the output does not ?

Also with the IC end of R469 lifted, do you still see CCLK on both sides of the resistor ?
Yep, no signal, I was blaming that from the beginning, but then I've checked on a good Atari and that was the same flat signal.
Both input and output of R469 have clock, output has it much weaker (~300mV), though, regardless of the IC side soldered or desoldered.
On schematics R469 is 5.0K, but on the board it's almost 6K, but I don't think that matters as I've tried shorting it out and got no difference.

And what's more interesting - it's all absolutely the same on my second Atari.

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Re: STE video synchronisation problem

Post by exxos » Sun Oct 01, 2017 10:07 pm

Number_Nine wrote:
Sun Oct 01, 2017 10:00 pm

Yep, no signal, I was blaming that from the beginning, but then I've checked on a good Atari and that was the same flat signal.
Both input and output of R469 have clock, output has it much weaker (~300mV), though, regardless of the IC side soldered or desoldered.
On schematics R469 is 5.0K, but on the board it's almost 6K, but I don't think that matters as I've tried shorting it out and got no difference.

And what's more interesting - it's all absolutely the same on my second Atari.
I think you need to switch to 100mV on your scope and re-check, as you probably won't see the signal else. See my previous images, if I use 5V/div It would appear flat also on my scope.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

Number_Nine
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Re: STE video synchronisation problem

Post by Number_Nine » Sun Oct 01, 2017 10:09 pm

exxos wrote:
Sun Oct 01, 2017 9:53 pm
This is what I get "left side input" of R469..

c1.png

3V p-p. Bias 0v.

Output side of R469 (IC side).

c2.png

about 0.2V p-p (200mV) with 0.4V (400mv ). DC offset.
Input R469:
SDS00001.jpg
SDS00001.jpg (28.46 KiB) Viewed 443 times
Output R469:
SDS00002.jpg
SDS00002.jpg (28.58 KiB) Viewed 443 times
Input C427:
SDS00004.jpg
SDS00004.jpg (28.78 KiB) Viewed 443 times
Output C427:
SDS00005.jpg
SDS00005.jpg (26.49 KiB) Viewed 443 times

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Re: STE video synchronisation problem

Post by exxos » Sun Oct 01, 2017 10:18 pm

Number_Nine wrote:
Sun Oct 01, 2017 10:09 pm
Output C427:
You need to be in x10 mode with your probe, and 100mV/div on scope...

c3.png
c3.png (3.42 KiB) Viewed 443 times
I don't think you will see it with the modes you are using.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

Number_Nine
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Re: STE video synchronisation problem

Post by Number_Nine » Sun Oct 01, 2017 10:20 pm

exxos wrote:
Sun Oct 01, 2017 10:07 pm
Number_Nine wrote:
Sun Oct 01, 2017 10:00 pm

Yep, no signal, I was blaming that from the beginning, but then I've checked on a good Atari and that was the same flat signal.
Both input and output of R469 have clock, output has it much weaker (~300mV), though, regardless of the IC side soldered or desoldered.
On schematics R469 is 5.0K, but on the board it's almost 6K, but I don't think that matters as I've tried shorting it out and got no difference.

And what's more interesting - it's all absolutely the same on my second Atari.
I think you need to switch to 100mV on your scope and re-check, as you probably won't see the signal else. See my previous images, if I use 5V/div It would appear flat also on my scope.
Sorry, I meant flat 5V on 17 pin of 1377 (well, it's also a pulse-ish, but with 5V bias and p-p some very few mV).

Number_Nine
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Re: STE video synchronisation problem

Post by Number_Nine » Sun Oct 01, 2017 10:29 pm

exxos wrote:
Sun Oct 01, 2017 10:18 pm
Number_Nine wrote:
Sun Oct 01, 2017 10:09 pm
Output C427:
You need to be in x10 mode with your probe, and 100mV/div on scope...


c3.png

I don't think you will see it with the modes you are using.
I see it, but it's very unstable and jerky. Is it fairly stable on your machine?
SDS00006.jpg
SDS00006.jpg (28.13 KiB) Viewed 439 times

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