Image instability with STE booster and system memory over 512k

[DementED]

I have rerouted the clock wire and it's made a big improvement. The distortion and blue screens are gone, but the whole image is shifting left and right rapidly by about 1 pixel. I tried to take a video but could not get the camera to focus.

I'll look through the forums for video fixes.

[exxos]

I have rerouted the clock wire and it's made a big improvement. The distortion and blue screens are gone, but the whole image is shifting left and right rapidly by about 1 pixel. I tried to take a video but could not get the camera to focus.

Like towards the end of this video ? viewtopic.php?p=73580#p73580

[DementED]

Hi Exxos - the whole image is shifting slightly to the left and then back again several times a second. The vertical lines (e.g. on the desktop icons and the sides of the desktop itself) remain straight. They are not wavy like the display at the end of that video.
Thanks again for your help.

[Steve]

@DementED do you have the booster enable/disable on a switch? It's good to flick the machine into 32mhz then to 8mhz to see if the behaviour changes.

[DementED]

Hi Steve - sorry for the late reply. I've been busy with RetCon (we had a good Atari showing this year). I haven't added the 8mhz/32mhz switch - I only just found out how to add it on another post. I'll try that and see. I'm also going to try the STE Ghosting Fix. I wonder if insulating the clock wire with a sleeve might improve things further...

Hi mrbombermillzy - the SIMMs all have silver contacts and are brand new from the exxos store.

[DementED]

I'm back again after a long break (family stuff).

I have added a 47uF capacitor to C411 (I don't have a 1uF ceramic). I also added a heat shrink shroud to the clock wire.

IMG_20231025_114507.jpg (394.77 KiB) Viewed 1235 times

The graphical corruption is now minimised, but the whole image is still shifting rapidly left and right by about 1 pixel every second. It's very hard to film (especially with my shaky hands), but it's very noticeable and distracting with the naked eye.

https://youtu.be/MxhwfCuoS2s?si=HD3QDPMcmGWw4Qaj


Interestingly, the same issue happens when I change the booster back to 8mhz mode. I have tried connecting the machine to 3 different displays and it has the same issue on every one. I didn't notice the issue before I made the upgrades.

My machine has the C301712-001 shifter (dated 1990). Could this be the problem? I haven't got an oscilloscope and wouldn't know how to use it anyway.

IMG_20231025_114529.jpg (361.09 KiB) Viewed 1235 times

Many thanks again everyone.

[Steve]

It's got to be something to do with noise on the clock line. All I can suggest is perhaps source some micro-coax which has shielding, solder one end of the shielding to ground leave the other end unsoldered. Then run it the same as you have before, or try even more directly since the shielding should absorb any electrical noise.

[exxos]

Maybe it's this problem again viewtopic.php?p=80133#p80133

[rubber_jonnie]

Personally I think your clock wire is too long and it's also going past the main power input, the large capacitor and numerous other components.

I've installed two boosters now, and run 4MB of RAM in both machines, and I don't have any issues, but my clock wire is the original in both cases and runs the shortest route possible.

I'll try and find a picture, or take a new one.

[DementED]

Personally I think your clock wire is too long and it's also going past the main power input, the large capacitor and numerous other components.

I've installed two boosters now, and run 4MB of RAM in both machines, and I don't have any issues, but my clock wire is the original in both cases and runs the shortest route possible.

I'll try and find a picture, or take a new one.

Thank you. Looking forward to seeing it. Just to confirm, I'm using the clock wire that came with the Exxos kit. I tried running it exactly as shown in the post with installation instructions here on the forum (i.e. A bit closer to the SIMMs) but this made the interference worse.

It's got to be something to do with noise on the clock line. All I can suggest is perhaps source some micro-coax which has shielding, solder one end of the shielding to ground leave the other end unsoldered. Then run it the same as you have before, or try even more directly since the shielding should absorb any electrical noise.

I'll try to find some micro_coax cable. @exxos is there any that would be approved for use here? You mentioned before that different wires create a different kit and would be an experiment.

Thanks again.