VOGONS


First post, by kaputnik

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Installed my old Diamond Monster 3D Voodoo card in my P233MMX machine a while ago.

When passing through video from the S3 Trio64v2 DX, there's narrow diagonal banding, slowly creeping over the screen. The vertical edges of the picture are wavy. Higher resolutions seems to worsen the problem, but it's clearly noticeable in low res too. It's notoriously hard to capture it in a still picture, the creeping makes it so much more obvious (and annoying), but see the attachment.

Except for the slight smeariness to be expected from old S3 cards, output directly from the Trio64 as well as 3D video from the Voodoo card is perfect, no visible interference at all.

Ruled out the passthrough cable. Tested two factory made ones, and made one myself to be certain about the quality, without any noticeable difference.

Can't remember this occurring in the 90's when I bought the card, but had a 15" CRT back then, which probably was way more forgiving when it comes to interference than a modern 19" LCD. It also maxed out at 800x600 IIRC. It could be a design problem just as well as aging components, etc.

Solved it temporarily by simply not using passthrough, got the S3 and Voodoo card connected to different inputs on the monitor, letting the monitor do the switching. This is however much slower, and I'd really like to go back to using passthrough if possible.

So, has anyone here experienced something along these lines, and found a solution? Is it just a question of replacing aging caps or something like that, can it be fixed by modding the output circuitry, etc?

There are no electromechanical relays doing the switchover on this particular card, it's all solid state stuff. Can semiconductors leaking noise perhaps be the problem?

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Reply 1 of 12, by Doornkaat

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A friend of mine has the same issue on an earlier Diamond Monster 3D (I think Rev. B). It doesn't show on CRTs but on LCDs there are vertical lines rolling through the screen.

I guess it's a design issue.😕

Reply 2 of 12, by Nexxen

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Doornkaat wrote on 2022-01-28, 11:07:

A friend of mine has the same issue on an earlier Diamond Monster 3D (I think Rev. B). It doesn't show on CRTs but on LCDs there are vertical lines rolling through the screen.

I guess it's a design issue.😕

I have a similar issue on a Voodoo 2.

PC#1 Pentium 233 MMX - 98SE
PC#2 PIII-1Ghz - 98SE/W2K

Reply 3 of 12, by kaputnik

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Doornkaat wrote on 2022-01-28, 11:07:

A friend of mine has the same issue on an earlier Diamond Monster 3D (I think Rev. B). It doesn't show on CRTs but on LCDs there are vertical lines rolling through the screen.

I guess it's a design issue.😕

Oh, crap, not what I wanted to hear 😜

Also got some very faint vertical lines, can be seen in the photo if you look closely. Those are more or less static though.

Perhaps it could be worth looking into designing some kind of inline filter to handle it?

Reply 4 of 12, by Doornkaat

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kaputnik wrote on 2022-01-28, 12:37:
Oh, crap, not what I wanted to hear :P […]
Show full quote
Doornkaat wrote on 2022-01-28, 11:07:

A friend of mine has the same issue on an earlier Diamond Monster 3D (I think Rev. B). It doesn't show on CRTs but on LCDs there are vertical lines rolling through the screen.

I guess it's a design issue.😕

Oh, crap, not what I wanted to hear 😜

Also got some very faint vertical lines, can be seen in the photo if you look closely. Those are more or less static though.

Perhaps it could be worth looking into designing some kind of inline filter to handle it?

Sorry, i miswrote. The lines on his card are diagonal as well. I believe they were rolling from the upper left to the lower right corner iirc.
I really don't know enough about analog video signals to give any useful input on designing a filter, sorry.

Reply 6 of 12, by kaputnik

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Doornkaat wrote on 2022-01-28, 13:01:
kaputnik wrote on 2022-01-28, 12:37:
Oh, crap, not what I wanted to hear :P […]
Show full quote
Doornkaat wrote on 2022-01-28, 11:07:

A friend of mine has the same issue on an earlier Diamond Monster 3D (I think Rev. B). It doesn't show on CRTs but on LCDs there are vertical lines rolling through the screen.

I guess it's a design issue.😕

Oh, crap, not what I wanted to hear 😜

Also got some very faint vertical lines, can be seen in the photo if you look closely. Those are more or less static though.

Perhaps it could be worth looking into designing some kind of inline filter to handle it?

Sorry, i miswrote. The lines on his card are diagonal as well. I believe they were rolling from the upper left to the lower right corner iirc.
I really don't know enough about analog video signals to give any useful input on designing a filter, sorry.

Sounds very much like the same problem then.

Oh, it was more of a rhetorical question, didn't expect you to serve me a solution on a silver plate or anything 😀

darry wrote on 2022-01-28, 13:12:

I suggest using a high quality VGA switch with 2 inputs instead of trying to improve the passthrough.

That would work aswell, if there are any autoswitching ones reacting significantly faster than my monitor available. Definitely worth investigating at least.

Reply 7 of 12, by maxtherabbit

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kaputnik wrote on 2022-01-28, 16:57:

That would work aswell, if there are any autoswitching ones reacting significantly faster than my monitor available. Definitely worth investigating at least.

search for "Extron VSW 2VGA A" you can get them for around $10-20USD on ebay all day long

they auto switch instantaneously (no perceived difference to using the passthrough) and the quality is impeccable

Reply 8 of 12, by darry

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maxtherabbit wrote on 2022-01-28, 18:16:
kaputnik wrote on 2022-01-28, 16:57:

That would work aswell, if there are any autoswitching ones reacting significantly faster than my monitor available. Definitely worth investigating at least.

search for "Extron VSW 2VGA A" you can get them for around $10-20USD on ebay all day long

they auto switch instantaneously (no perceived difference to using the passthrough) and the quality is impeccable

+1 to that (not because I have one, but because I trust maxtherabbit on this and the other Extron gear I do have is definitely excellent).

However, do yourself a favor and make sure you get a good quality power adapter to go with it (if the factory one is not included) . I once had to hunt down a weird source of audio hum/buzz that sounded like a ground loop but was actually due to a crappy power adapter that came with an OSSC clone (was meaning to replace the adapter, but forgot about it until issue cropped up). The issue went away as soon as I replaced the power adapter with an Amazon Basics USB charger and a USB A to barrel adapter .

Reply 9 of 12, by treeman

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I remember somebody saying when I was repairing a voodoo if you solder a second switch chip on top of the current switch chip it helps to clear the pass through distortions

Reply 10 of 12, by kaputnik

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maxtherabbit wrote on 2022-01-28, 18:16:
kaputnik wrote on 2022-01-28, 16:57:

That would work aswell, if there are any autoswitching ones reacting significantly faster than my monitor available. Definitely worth investigating at least.

search for "Extron VSW 2VGA A" you can get them for around $10-20USD on ebay all day long

they auto switch instantaneously (no perceived difference to using the passthrough) and the quality is impeccable

darry wrote on 2022-01-29, 05:02:
maxtherabbit wrote on 2022-01-28, 18:16:
kaputnik wrote on 2022-01-28, 16:57:

That would work aswell, if there are any autoswitching ones reacting significantly faster than my monitor available. Definitely worth investigating at least.

search for "Extron VSW 2VGA A" you can get them for around $10-20USD on ebay all day long

they auto switch instantaneously (no perceived difference to using the passthrough) and the quality is impeccable

+1 to that (not because I have one, but because I trust maxtherabbit on this and the other Extron gear I do have is definitely excellent).

However, do yourself a favor and make sure you get a good quality power adapter to go with it (if the factory one is not included) . I once had to hunt down a weird source of audio hum/buzz that sounded like a ground loop but was actually due to a crappy power adapter that came with an OSSC clone (was meaning to replace the adapter, but forgot about it until issue cropped up). The issue went away as soon as I replaced the power adapter with an Amazon Basics USB charger and a USB A to barrel adapter .

Had a look at Ebay, and sadly one of those would set me back ~$65 with shipping to my country. A little bit too steep. There's no hurry though since I got a workaround, at some point something more reasonably priced might turn up 😀

treeman wrote on 2022-01-29, 05:33:

I remember somebody saying when I was repairing a voodoo if you solder a second switch chip on top of the current switch chip it helps to clear the pass through distortions

Okay, sounds strange. Was it here on Vogons? Was there any kind of explanation on why it would help?

Reply 12 of 12, by kaputnik

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treeman wrote on 2022-01-29, 22:53:

Thanks 😀

The output filter mod is definitely interesting. I'm far from an expert on the subject, but wouldn't surprise me at all if the banding is caused by output impedance not being properly matched to the input.