STE video chip

[Steve]

Hi Steve,

AIUI (and I don't have one and haven't tried this, so YMMV), this delay board sits in line between pin 52 of the shifter (the 16MHz out line) and the trace.

So you'd have to break the trace out of pin 52, 'IN' would be the chip side of the cut and one of the two OUT lines to the far side. Presumably you try both consequtively and see which is better.

As to the how? Sorry. Dunno. Perhaps insulation tape the chip leg for a non-destructive test?

BW

Cheers man, I appreciated.

[Steve]

@exxos if you're about sometime, could you please let me know if there is a difference between output1 & output2? Also should both jumpers (SJ1 and STE clock sync) be bridged?

Thank you,

[exxos]

@Steve

IMG_0369.JPG (317.38 KiB) Viewed 3407 times

Though I doubt it will solve your problem as you're not even using the "problem shifter" ?

[Steve]

@exxos

I've actually got two STe's which are giving me grief, one is old shifter and the other is new shifter.

I'm gonna fit them on both because the one with the old shifter doesn't seem to play certain demos properly, the screen goes haywire. So yeah, just experimenting.

Thanks for the picture that's great

[Steve]

@exxos

Here's my installation, so far working well. Will do some tests. Video output seems damn fine compared to before, very crisp and stable.

PXL_20220418_162539894.MP.jpg (589.02 KiB) Viewed 3377 times

[exxos]

Here's my installation, so far working well. Will do some tests. Video output seems damn fine compared to before, very crisp and stable.

Where have you cut the track then ?

[Steve]

The board HAS fixed demo playback on my 'old' shifter STe!!! I can actually play and enjoy the 'We were @' demo for the first time!! Yay!!

ps - I have no idea why my machine couldn't play this demos before. It *does* have the 32mhz booster installed (but of course running the demo in 8mhz mode) not sure if that might have effected clock skews.

PXL_20220418_164908042.jpg (407.75 KiB) Viewed 3371 times

PXL_20220417_150004706.MP.jpg (552.62 KiB) Viewed 3371 times

[Steve]

Here's my installation, so far working well. Will do some tests. Video output seems damn fine compared to before, very crisp and stable.

Where have you cut the track then ?

I didn't cut the track. I lifted the 16mhz pin inside the PLCC socket. Soldered a wire from the shifter chip to the 16mhz input, then put the output to the Via on the mobo.

[exxos]

The board HAS fixed demo playback on my 'old' shifter STe!!! I can actually play and enjoy the 'We were @' demo for the first time!! Yay!!

ps - I have no idea why my machine couldn't play this demos before. It *does* have the 32mhz booster installed (but of course running the demo in 8mhz mode) not sure if that might have effected clock skews.

It's odd you have problems with the 588 shifter. But these machines are so fickle.. The booster could have added a bit more noise on the bus, enough to kill it. But then again, changing ROM or RAM modules can do the same thing.

[exxos]

I forgot all about this project. I guess it be useful if people can use this test program and document what shifter version they have and motherboard revision with a image of the program running.

For example:

1.JPG (56.76 KiB) Viewed 1680 times

2.JPG (61.95 KiB) Viewed 1680 times

The "Good shifter" is C300588 and the "Bad shifter" is C301712.

Its hard to round up the entire thread so newcomers I suggest starting from the first post in this thread. Mostly it seems the newer shifters have timing problems which result in all sorts of graphic related corruption / sync issues.

As a side note, I have started a revised PCB which is a bit smaller and easier to install.