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 10:33 pm

Number_Nine wrote:
Sun Oct 01, 2017 10:29 pm
I see it, but it's very unstable and jerky. Is it fairly stable on your machine?
It's not great no. Though the scope will be loading the signal and causing some issues anyway.

So I think your input to pin 17 is just fine by the looks for it. ..


As for pin 9, I see this... again with 100mV/DIV X10 probe.

c4.png
c4.png (3.45 KiB) Viewed 602 times
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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Number_Nine
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Re: STE video synchronisation problem

Post by Number_Nine » Sun Oct 01, 2017 10:44 pm

exxos wrote:
Sun Oct 01, 2017 10:33 pm
Number_Nine wrote:
Sun Oct 01, 2017 10:29 pm
I see it, but it's very unstable and jerky. Is it fairly stable on your machine?
It's not great no. Though the scope will be loading the signal and causing some issues anyway.

So I think your input to pin 17 is just fine by the looks for it. ..


As for pin 9, I see this... again with 100mV/DIV X10 probe.


c4.png
Yeah, so you see composite PAL signal (with colours from pins 3,4,5 added onto composite sync after colour burst), and on pin 2 you'll see only composite sync of the same form, but without colours.
On my machine I see this on pin 2 (correct form):
SDS00007.jpg
SDS00007.jpg (26.35 KiB) Viewed 599 times
But only this on pin 9:
SDS00008.jpg
SDS00008.jpg (28.28 KiB) Viewed 599 times

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Re: STE video synchronisation problem

Post by exxos » Sun Oct 01, 2017 10:48 pm

Number_Nine wrote:
Sun Oct 01, 2017 10:44 pm
But only this on pin 9:
SDS00008.jpg
are you using x10 probe and 100mV/DIV on your scope ? If so , try 10mV and see if you can see anything..

I also assume you have pin 9 still bent upwards out of the socket ?
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
Posts: 21
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Location: UK

Re: STE video synchronisation problem

Post by Number_Nine » Sun Oct 01, 2017 10:50 pm

Number_Nine wrote:
Sun Oct 01, 2017 10:44 pm
exxos wrote:
Sun Oct 01, 2017 10:33 pm
Number_Nine wrote:
Sun Oct 01, 2017 10:29 pm
I see it, but it's very unstable and jerky. Is it fairly stable on your machine?
It's not great no. Though the scope will be loading the signal and causing some issues anyway.

So I think your input to pin 17 is just fine by the looks for it. ..


As for pin 9, I see this... again with 100mV/DIV X10 probe.


c4.png
Yeah, so you see composite PAL signal (with colours from pins 3,4,5 added onto composite sync after colour burst), and on pin 2 you'll see only composite sync of the same form, but without colours.
On my machine I see this on pin 2 (correct form):
SDS00007.jpg

But only this on pin 9:
SDS00008.jpg
It looks a bit like an audio signal, maybe it's trying to say something:
SDS00009.jpg
SDS00009.jpg (27.59 KiB) Viewed 595 times

Number_Nine
Posts: 21
Joined: Tue Sep 19, 2017 1:48 pm
Location: UK

Re: STE video synchronisation problem

Post by Number_Nine » Sun Oct 01, 2017 10:53 pm

Number_Nine wrote:
Sun Oct 01, 2017 10:50 pm
Number_Nine wrote:
Sun Oct 01, 2017 10:44 pm
exxos wrote:
Sun Oct 01, 2017 10:33 pm


It's not great no. Though the scope will be loading the signal and causing some issues anyway.

So I think your input to pin 17 is just fine by the looks for it. ..


As for pin 9, I see this... again with 100mV/DIV X10 probe.


c4.png
Yeah, so you see composite PAL signal (with colours from pins 3,4,5 added onto composite sync after colour burst), and on pin 2 you'll see only composite sync of the same form, but without colours.
On my machine I see this on pin 2 (correct form):
SDS00007.jpg

But only this on pin 9:
SDS00008.jpg
It looks a bit like an audio signal, maybe it's trying to say something:
SDS00009.jpg
Jokes aside, with the same time frame as your picture:
SDS00011.jpg
SDS00011.jpg (30.74 KiB) Viewed 592 times

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Re: STE video synchronisation problem

Post by exxos » Sun Oct 01, 2017 10:57 pm

Hold up..

SDS00008.jpg
SDS00008.jpg (28.28 KiB) Viewed 590 times

If that is 6.7V there, then the IC is getting a external DC bias somewhere. Like Q404 C-B short.. feeding 12V into 1377 pin 9...

I think you need to try one of the IC's like you are using now in your working ST and see if you have composite there..

I have a feeling now that every IC you put in your faulty machine is getting blown up by something around Q404... you need to see if such 1377 works in your known working ST...

If the IC does not work, then you know what the problem is... then you will need to try a known good 1377 in your faulty machine, but lift pin 9 before powering up.. and re-check the output..
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
Posts: 21
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Location: UK

Re: STE video synchronisation problem

Post by Number_Nine » Sun Oct 01, 2017 10:58 pm

Number_Nine wrote:
Sun Oct 01, 2017 10:53 pm
Number_Nine wrote:
Sun Oct 01, 2017 10:50 pm
Number_Nine wrote:
Sun Oct 01, 2017 10:44 pm


Yeah, so you see composite PAL signal (with colours from pins 3,4,5 added onto composite sync after colour burst), and on pin 2 you'll see only composite sync of the same form, but without colours.
On my machine I see this on pin 2 (correct form):
SDS00007.jpg

But only this on pin 9:
SDS00008.jpg
It looks a bit like an audio signal, maybe it's trying to say something:
SDS00009.jpg
Jokes aside, with the same time frame as your picture:
SDS00011.jpg
Same with pin 9 upwards:
SDS00001.jpg
SDS00001.jpg (30.86 KiB) Viewed 589 times

Number_Nine
Posts: 21
Joined: Tue Sep 19, 2017 1:48 pm
Location: UK

Re: STE video synchronisation problem

Post by Number_Nine » Sun Oct 01, 2017 11:04 pm

exxos wrote:
Sun Oct 01, 2017 10:57 pm
Hold up..


SDS00008.jpg


If that is 6.7V there, then the IC is getting a external DC bias somewhere. Like Q404 C-B short.. feeding 12V into 1377 pin 9...

I think you need to try one of the IC's like you are using now in your working ST and see if you have composite there..

I have a feeling now that every IC you put in your faulty machine is getting blown up by something around Q404... you need to see if such 1377 works in your known working ST...

If the IC does not work, then you know what the problem is... then you will need to try a known good 1377 in your faulty machine, but lift pin 9 before powering up.. and re-check the output..
I thought that too and have even bought more MC1377s, but then if I'd just measure pin 9 on socket without the IC, then I should have seen something like >5-6VDC, but I see only this:
SDS00002.jpg
SDS00002.jpg (29.85 KiB) Viewed 588 times

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Re: STE video synchronisation problem

Post by exxos » Sun Oct 01, 2017 11:08 pm

Number_Nine wrote:
Sun Oct 01, 2017 11:04 pm

I thought that too and have even bought more MC1377s, but if I just measure pin 9 on socket without the IC, then I should see something like >5-6VDC, but I see only this:

I would confirm your IC's are "blown" on your other machine before anything else..

or try a brand new IC (never before being used) and lift pin 9 and re-check..

I suspect every IC you are putting in that faulty STE is blowing your 1377's up.

You clearly have all the inputs as I do, but no outputs, so , IC faulty or something is blowing the IC up, IE, CB short on Q404.

So if you make sure you lift pin 9, or remove R442... and try a new never before used IC... and see what happens...
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
Posts: 21
Joined: Tue Sep 19, 2017 1:48 pm
Location: UK

Re: STE video synchronisation problem

Post by Number_Nine » Sun Oct 01, 2017 11:11 pm

exxos wrote:
Sun Oct 01, 2017 11:08 pm
Number_Nine wrote:
Sun Oct 01, 2017 11:04 pm

I thought that too and have even bought more MC1377s, but if I just measure pin 9 on socket without the IC, then I should see something like >5-6VDC, but I see only this:

I would confirm your IC's are "blown" on your other machine before anything else..

or try a brand new IC (never before being used) and lift pin 9 and re-check..

I suspect every IC you are putting in that faulty STE is blowing your 1377's up.

You clearly have all the inputs as I do, but no outputs, so , IC faulty or something is blowing the IC up, IE, CB short on Q404.

So if you make sure you lift pin 9, or remove R442... and try a new never before used IC... and see what happens...
I've ordered some more Chinese 1377, let's wait for them to have delivered, honestly I don't want to experiment much with my good Atari as I want at least one good Atari STE at home ;)

My current theory is that just these 1377 off ebay were all dodgy, although it's unlikely as their pins looked never soldered, so your theory definitely fits better.

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