Image instability with STE booster and system memory over 512k

[exxos]

I've done some more tests with newer motherboards (001A DMA integrated blitter) , all 3 boards give the expected diagonal pattern. Ill write more in the other thread. viewtopic.php?f=23&t=4797

[rubber_jonnie]

I've done some more tests with newer motherboards (001A DMA integrated blitter) , all 3 boards give the expected diagonal pattern. Ill write more in the other thread. viewtopic.php?f=23&t=4797

Cool

[Steve]

Ok I opened up my STe which has the 32mhz booster just to see what I've done:

At some point I must have decided to use shielded Ethernet cable for the booster 32mhz line:

PXL_20231028_105427498.jpg (654.1 KiB) Viewed 2400 times

Here you can see the end of the cable, the 32mhz line going to the IC and the shielding wire being soldered to the GND part of the motherboard:

PXL_20231028_105526097.jpg (382.94 KiB) Viewed 2400 times

I also have the 32mhz stability board installed. I installed mine without having to cut any tracks, by lifting the 32mhz pin in the socket (thus disconnecting it from the motherboard) and soldering the 32mhz input to the PCB directly to the 558 Glue chip. Then the output goes to that Via. The other two wires go to positive/negative voltage points on the motherboard.

PXL_20231028_105546954.jpg (487.66 KiB) Viewed 2400 times

But just to clarify: The 32mhz stability board was not required for my STe to get stable video output, it already had stable video output (probably thanks to my shielded cable) the little 32mhz PCB fixed some demos which were blitter heavy, which previously would not work. I think it basically stopped the blitter crashing.

[Steve]

I did not replace the pull up resistors on the motherboard (which are the original values) because the booster board has "472" stamped on the resistor packs.

I just noticed this ^^

On my STe I have removed all the bus resistors except p100, because the bus resistors are already on the booster.

[DementED]

Ok I opened up my STe which has the 32mhz booster just to see what I've done:

At some point I must have decided to use shielded Ethernet cable for the booster 32mhz line:

PXL_20231028_105427498.jpg


Here you can see the end of the cable, the 32mhz line going to the IC and the shielding wire being soldered to the GND part of the motherboard:

PXL_20231028_105526097.jpg


I also have the 32mhz stability board installed. I installed mine without having to cut any tracks, by lifting the 32mhz pin in the socket (thus disconnecting it from the motherboard) and soldering the 32mhz input to the PCB directly to the 558 Glue chip. Then the output goes to that Via. The other two wires go to positive/negative voltage points on the motherboard.

PXL_20231028_105546954.jpg


But just to clarify: The 32mhz stability board was not required for my STe to get stable video output, it already had stable video output (probably thanks to my shielded cable) the little 32mhz PCB fixed some demos which were blitter heavy, which previously would not work. I think it basically stopped the blitter crashing.

Interesting. I see you've got the 588 shifter, so maybe that helped.

[DementED]

I did not replace the pull up resistors on the motherboard (which are the original values) because the booster board has "472" stamped on the resistor packs.

I just noticed this ^^

On my STe I have removed all the bus resistors except p100, because the bus resistors are already on the booster.

The instructions said it was fine to leave them installed. I noticed that @rubber_jonnie's two boards still had them installed.

Thanks for the TwiSTer PDF.

[exxos]

The early boosters has 2.2k so you had to remove the MB ones. The later boosters had 4.7k so there was not need to remove the MB ones.

[DementED]

I forgot to reconnect the floppy drive before booting it up today and noticed that the horizontal image shifting did not occur as often. I see that @rubber_jonnie has goteks connected to his boards, but not sure why it would make a difference.
I have obtained a buffer board from @exxos today, so I'll give that a try. If it works, I'll consider sourcing a 588 shifter as a long term solution.

[exxos]

I forgot to reconnect the floppy drive before booting it up today and noticed that the horizontal image shifting did not occur as often. I see that @rubber_jonnie has goteks connected to his boards, but not sure why it would make a difference.

If the floppy motor is running it adds noise on the power rails, which then couple to all signals causing noise. So its totally possible noise from the floppy can aggravate timings which are borderline to start with.

I can't remember if you tried colour test on the diagnostic cart ? I've seen it where the colours are fine on the cartridge, but are not when running TOS.. simply more bus activity when running TOS..

[DementED]

I forgot to reconnect the floppy drive before booting it up today and noticed that the horizontal image shifting did not occur as often. I see that @rubber_jonnie has goteks connected to his boards, but not sure why it would make a difference.

If the floppy motor is running it adds noise on the power rails, which then couple to all signals causing noise. So its totally possible noise from the floppy can aggravate timings which are borderline to start with.

I can't remember if you tried colour test on the diagnostic cart ? I've seen it where the colours are fine on the cartridge, but are not when running TOS.. simply more bus activity when running TOS..

Hmmm...maybe it is a factor.

Not tried the colour test - I haven't got a diagnostic cart. Still need to try the tests you mentioned earlier in this thread.