Sparkly pixels

[Lardo Boffin]

Is the +5V power OK? Or is there a lot of "noise" or peaks or voltage drops? Maybe you have to replace old capacitors (if not already done) ...

Regards
Siggi

Not sure about the power but I imagine that they would have checked such things.

The capacitors have been changed while they had it (as well as the ULA being heat sinked - don't tell Moggy!!) but that didn't fix the issue.

[PokeMon]

Well - take it sporty. Nobody else has this type of machine. What ever caused the effect, you have an unique machine, that's what counts.

I don't think that this is a timing issue. If data would be read wrong there should be distortions char wide (8 pixels following each other) at least partly. Here is just one single pixel down. I would say this could be an ULA issue even if it does not occur without ZXpand. Did you ever try another ULA ?

[Lardo Boffin]

Did you ever try another ULA ?

I tried one and I think MCG who fixed it tried some different ones as well. It was changing the ROM that seems to have finally fixed it.

[1024MAK]

I'm not sure the numbers of ZXpand and ZX81 are as you suggest.
Some ZXpands are being used with ZX80 computers.
And in my case, the ZX81 ZXpands that I have normally stay attached to the same ZX81 machines. So it is possible that some of mine may have similar symptoms but I would not know.

Mark

[Lardo Boffin]

I'm not sure the numbers of ZXpand and ZX81 are as you suggest.
Some ZXpands are being used with ZX80 computers.
And in my case, the ZX81 ZXpands that I have normally stay attached to the same ZX81 machines. So it is possible that some of mine may have similar symptoms but I would not know.

Mark

Fair comment - I was potentially exaggerating a bit to emphasise the fact that in reality not many zeddys have been near a ZXPand as a percentage of how many there are.

[PokeMon]

Maybe good idea for a retro meeting and exchanging components between different users.

[Lardo Boffin]

I have just had another sparkly pixel zeddy. This time with a vULA81 fitted.

The cure was to change the ROM. Sadly I am now out of spare ROMs.