STE video synchronisation problem

Problems with your machine in general.
Number_Nine
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Re: STE video synchronisation problem

Post by Number_Nine » Tue Oct 03, 2017 12:28 pm

Received one more 1377 39th week of year 90 and everything is the same with this one as well (w /o pin 9 connected).

So I guess 5 1377 can't be dead on arrival.

Once you've got time, could you also please show your pin 1:
SDS00003.jpg
SDS00003.jpg (30.44 KiB) Viewed 427 times
and pin 2:
SDS00004.jpg
SDS00004.jpg (25.88 KiB) Viewed 427 times

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exxos
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Re: STE video synchronisation problem

Post by exxos » Tue Oct 03, 2017 12:51 pm

Number_Nine wrote:
Tue Oct 03, 2017 12:28 pm
Received one more 1377 39th week of year 90 and everything is the same with this one as well (w /o pin 9 connected).

So I guess 5 1377 can't be dead on arrival.
If you're lifting pin nine it is still not working, then this is indeed held problem as it still suggests the IC is faulty.

Number_Nine wrote:
Tue Oct 03, 2017 12:28 pm
Once you've got time, could you also please show your pin 1:

and pin 2:
Pin one I see the same as you, pin two is almost the same only I would say that 95% high time.
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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guus.assmann
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Re: STE video synchronisation problem

Post by guus.assmann » Wed Oct 04, 2017 9:29 am

Hello,
All the way back to the beginning? Is there a 4.433Mhz crystal on the board?
The reason for this question is, that this crystal is the supply for the signal you're looking for.
And of course it's only needed for a PAL machine. ;)
I.m.h.o, the CCLK stands for "Color Clock"
If this signal fails, the picture should be steady but B/W.
The data sheet denotes this signal 4,433 mHz for Pal and 3,58mHz for NTSC.
In case of Pal, pin 20 should be left open.

What's the exact nature of the incorrect signal on the screen, in other words, what does the screen look like?

BR/
Guus

Number_Nine
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Re: STE video synchronisation problem

Post by Number_Nine » Fri Oct 06, 2017 9:04 pm

guus.assmann wrote:
Wed Oct 04, 2017 9:29 am
Hello,
All the way back to the beginning? Is there a 4.433Mhz crystal on the board?
The reason for this question is, that this crystal is the supply for the signal you're looking for.
And of course it's only needed for a PAL machine. ;)
I.m.h.o, the CCLK stands for "Color Clock"
If this signal fails, the picture should be steady but B/W.
The data sheet denotes this signal 4,433 mHz for Pal and 3,58mHz for NTSC.
In case of Pal, pin 20 should be left open.

What's the exact nature of the incorrect signal on the screen, in other words, what does the screen look like?

BR/
Guus
Hi Guus,
Yes, the crystal is there.
Oh, Color Clock, that makes sense as in non-PAL machines it comes out of COLOR pin of shifter, for some reason I thought C was for Composite :)
I think you're right wrt colors, I *think* 1377 uses CCLK to understand when to generate colour burst and start mixing colours into the signal.

So on my machine the picture has colours, I can see green TOS field and everything. I've checked pin 20 (tried also connecting it to GND - no composite output as well).

So as far as I see when using DIN video output colours come from SHIFTER directly and 1377 is only used as a supply of composite sync signal (from the same pin 9) (although it looks like it's still generating full composite signal with colour burst and colours)

In case of Modulator 1377 generates whole composite signal.

So on my machine when connected via Modulator - there's just silence (double-checked also with a scope),
when connected via DIN - picture has colours and everything, but it's completely out of both HSync and VSync.
It looks like each screen line has horizontal offset relatively to the previous one, and those like blocks of 40-50 shifted lines are randomly scattered on the vertical axis, and there's also some dark-pink borders visible when line if shifted too far.
Unfortunately can't make a photo now as I've prepared everything for moving house in couple of days...

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exxos
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Re: STE video synchronisation problem

Post by exxos » Fri Oct 06, 2017 9:21 pm

Can you send me a couple of those 1377 chips to try in my test machine here ?
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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Joined: Tue Sep 19, 2017 1:48 pm
Location: UK

Re: STE video synchronisation problem

Post by Number_Nine » Fri Oct 06, 2017 9:33 pm

exxos wrote:
Fri Oct 06, 2017 9:21 pm
Can you send me a couple of those 1377 chips to try in my test machine here ?
Sure, but somewhere next week, everything is packed now.

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