VOGONS


First post, by feipoa

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I recently acquired a pair of Voodoo2 cards from Poland/Amibay. I've attached a photo. If my memory is correct, they are of brand Atrend? I noticed that the image, when in 2D mode, sometimes exhibits these faint diagonal ghosting bars in bypass mode. A Matrox G200 is being used for 2D with a quality pass-through cable. These faint transparent ghosting bards look like noise and are across the whole screen. They sometimes go away completely and 2D image looks really clear, but some minutes later, the faint ghosting bars return.

I tried to take a photo of the monitor to show the ghosting bars but it didn't show up well.

This happens on both of the Voodoo2 cards. I have not seen this happen with my other Voodoo2 cards. It bothers me and I ultimately pulled the pair out and put in an SLI pair from STB. I am wondering if the switching circuit which handles the pass through needs to be replaced, if there is just too much noise occurring on the PCB around the switches, or if this brand is notorious for this issue? Is the issue easy to fix?

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Reply 1 of 30, by pshipkov

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Is not that the norm for all voodoo 1/2 cards ?
Not a voodoo "expert" by any means, but these pass througs affect signal phase, or something like that.
Especially obvious on LCD monitors.
Sometimes running monitor auto-adjust helps, but you need to do it every time after switching between video modes.

retro bits and bytes

Reply 2 of 30, by Warlord

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it's not the norm, I'm not an expert either, but I have experienced clean voodoo passthrough before on several cards. I'm sure not all voodoo 2s are created equal. I do have 1 voodoo 2 like yours though I can check to see what if looks like if you tell me what to look for. I'm still looking for some voodoo 2 schematics I posted up a few days asking for.

Reply 3 of 30, by feipoa

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It is definitely not the norm. I have several Voodoo2 cards and never experienced this issue until this latest acquisition. Noise on the pass-through is a lot more common with Voodoo1 cards. I've also had less than perfect signal quality on a Voodoo2 if I used a really low gauge pass-through cable, but the symptoms would be different than I describe here.

Warlord, look for diagonal ghosting bards on solid colour backgrounds, especially greys, NT4 default green, etc. You'd need to be at the computer for around a half hour to see if the bars come a bit later on. They look like faint, transparent, jail bars that go from the bottom left of the screen to the top right. They fill the screen and are parallel to each other. It is like you took a piece of lined paper from high school and held it up to the screen on the diagonal, added some transparency, and fattened the lines up. Set the background to a medium grey or forest green to aid in detection.

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Reply 4 of 30, by feipoa

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Here is the best photo I could get of the effect. You may have to zoom in/out to see it. If you see the effect, it is a bit worse in person. This type of noise is hard to capture on a monitor. Also, GIMP says my file size is 1.1 MB, but Vogons says it is 514 KB, so I'm sure whatever post-processing the website is doing doesn't help either.

Voodoo2_noise.JPG
Filename
Voodoo2_noise.JPG
File size
513.73 KiB
Views
749 views
File license
CC-BY-4.0

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Reply 5 of 30, by aaronkatrini

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I cannot tell from the picture you uploaded, maybe try a google drive link so we can download the uncompressed image.
However from experience with many V2 cards I can tell that some of them have better image than others (using same 2D card and same cable). And I remember specifically having a V2 (probably from A-Trend/Helios) with heatsinks on the TMUs that had minor, barely noticable, but present "ghosting lines", will need to go through my photos and see if I can get a photo of the card. 😀

UPDATE: I found the photos of the card I had, but from the photos I did, the problem isn't visible (moire effect is from the camera):
https://drive.google.com/drive/folders/1NiLKJ … _jB?usp=sharing

Last edited by aaronkatrini on 2021-09-04, 09:18. Edited 1 time in total.

Reply 6 of 30, by Joseph_Joestar

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How long is your pass through cable? Shorter ones with good shielding can minimize the image degradation.

Alternatively, you can use a KVM switch to toggle between your 2D graphics card and the Voodoo in order to eliminate pass through issues entirely.

PC#1: Pentium MMX 166 / Soyo SY-5BT / S3 Trio64V+ / Voodoo1 / OPTi 82C930 / AWE64 Gold / SC-155
PC#2: AthlonXP 1700+ / Abit KT7A / Voodoo3 / SBLive / Vortex2
PC#3: Athlon64 3000+ / Asus K8V-MX / GeForce4 / Audigy1
PC#4: i5-3550P / MSI Z77A-G43 / GTX 650Ti / X-Fi

Reply 7 of 30, by feipoa

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These are the cables I am using: https://www.amazon.ca/dp/B00CJRRY9M/ref=pe_30 … 6394800_TE_dp_1

Joseph_Joestar wrote on 2021-09-04, 09:17:

How long is your pass through cable? Shorter ones with good shielding can minimize the image degradation.

Alternatively, you can use a KVM switch to toggle between your 2D graphics card and the Voodoo in order to eliminate pass through issues entirely.

Perhaps you missed my previous comments; if I use STB branded V2 boards in the same setup, there is no issue with this kind of noise. It appears to be coming from the Voodoo2 card itself.

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Reply 8 of 30, by Joseph_Joestar

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feipoa wrote on 2021-09-04, 10:12:

This seems a bit longer than usual, 30 cm if I'm reading it right? Normally, a pass through cable would be 10-15 cm at most.

Perhaps you missed my previous comments; if I use STB branded V2 boards in the same setup, there is no issue with this kind of noise. It appears to be coming from the Voodoo2 card itself.

I see. In that case, a shorter cable might not necessarily help. A KVM switch would work though, assuming that your 2D card doesn't produce any artifacts when connected to the monitor directly.

PC#1: Pentium MMX 166 / Soyo SY-5BT / S3 Trio64V+ / Voodoo1 / OPTi 82C930 / AWE64 Gold / SC-155
PC#2: AthlonXP 1700+ / Abit KT7A / Voodoo3 / SBLive / Vortex2
PC#3: Athlon64 3000+ / Asus K8V-MX / GeForce4 / Audigy1
PC#4: i5-3550P / MSI Z77A-G43 / GTX 650Ti / X-Fi

Reply 9 of 30, by feipoa

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I've never seen a 10 cm VGA pass-through cable. The connectors alone are 5 cm each. Have a link? I have 20 and 30 cm cables. The shorter cable doesn't help the situation.

My goal is to fix the Voodoo2 card if this noise has somehow occurred due to age/wear. I'm also hoping someone would be willing to confirm if all these Atrend's are noisy like this.

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Reply 10 of 30, by Joseph_Joestar

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feipoa wrote on 2021-09-04, 10:42:

I've never seen a 10 cm VGA pass-through cable. The connectors alone are 5 cm each. Have a link? I have 20 and 30 cm cables.

The cables which originally came with Voodoo cards were around 10-15 cm (not counting connector length). Here's an example from the Vogons wiki.

I'm also hoping someone would be willing to confirm if all these Atrend's are noisy like this.

I have an A-Trend Voodoo1 and it doesn't display those ghosting lines as shown in your pictures. However, it does have washed out colors and fuzzy text in 800x600 resolution and above. There is no image degradation when using 640x480 and below. This is with a pass through cable of course. No issues whatsoever with a KVM switch.

PC#1: Pentium MMX 166 / Soyo SY-5BT / S3 Trio64V+ / Voodoo1 / OPTi 82C930 / AWE64 Gold / SC-155
PC#2: AthlonXP 1700+ / Abit KT7A / Voodoo3 / SBLive / Vortex2
PC#3: Athlon64 3000+ / Asus K8V-MX / GeForce4 / Audigy1
PC#4: i5-3550P / MSI Z77A-G43 / GTX 650Ti / X-Fi

Reply 11 of 30, by feipoa

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One cannot compare the noise on a Voodoo1's pass-thru to that of a Voodoo2's pass-thru. Voodoo1's are generally noisy while Voodoo2's are not.

The 30 cm referenced for my VGA pass-thru cable includes the connectors; 10 cm for connectors and 20 cm for cable. The shortest I have is 20 cm, including connectors.

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Reply 12 of 30, by Gmlb256

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That type of noise is definitely not normal with both Voodoo Graphics and Voodoo2.

I don't know how relevant is this but some of these cards are manufactured using a TI chip instead of a ICS one for the RAMDAC. It also depends of the manufacturer and the quality of the components used around the RAMDAC.

Reply 13 of 30, by maxtherabbit

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to avoid all IQ degradation issues with voodoo cards I *never* use the pass through

pick one of these up on ebay for $10-$15 and connect the voodoo to input 2 and primary VGA to input 1, set it to auto switching and it works seamlessly like the factory pass through but with no quality loss

https://www.extron.com/product/vsw2vgaa

Reply 14 of 30, by feipoa

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maxtherabbit wrote on 2021-09-04, 14:47:

to avoid all IQ degradation issues with voodoo cards I *never* use the pass through

pick one of these up on ebay for $10-$15 and connect the voodoo to input 2 and primary VGA to input 1, set it to auto switching and it works seamlessly like the factory pass through but with no quality loss

https://www.extron.com/product/vsw2vgaa

My goal is to fix the Voodoo2 card if this noise has somehow occurred due to age/wear or inferior components. With the frequency at which my PC cases go in and out of the closet, I'm not interested in connecting another box (VGA switch) for some quick tests. Pass-through on V2 cards should be pretty darn clear with a quality cable.

Gmlb256 wrote on 2021-09-04, 13:59:

That type of noise is definitely not normal with both Voodoo Graphics and Voodoo2.

I don't know how relevant is this but some of these cards are manufactured using a TI chip instead of a ICS one for the RAMDAC. It also depends of the manufacturer and the quality of the components used around the RAMDAC.

Thank you. You might be onto something. I have two dead Voodoo2's with the ICS RAMDACs that I could use to swap ICs. One of these dead Voodoo2 cards is also an Atrend, but it has "ver:2.0" silkscreened on the PCB. Before that v2.0 card died on me, I do not recall having this issue with the noise bars. Other than the TI vs. ICS ramdacs, the two PCBs look identical, although ver:2.0 is without the heatsink.

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Reply 15 of 30, by sdz

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The RAMDAC has nothing to do with the VGA passthrough. You can remove it completely and the passthrough will still work.
Involved in the passhtrough circuitry are the VGA connectors, U10 ( QST3384/ PI5C3384C) and FB6,C36,C38 (U10 power filtering). FB6, C36, C38 values can be found here: download/file.php?id=91548&mode=view .

Reply 16 of 30, by Gmlb256

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sdz wrote on 2021-09-04, 15:14:

The RAMDAC has nothing to do with the VGA passthrough. You can remove it completely and the passthrough will still work.
Involved in the passhtrough circuitry are the VGA connectors, U10 ( QST3384/ PI5C3384C) and FB6,C36,C38 (U10 power filtering). FB6, C36, C38 values can be found here: download/file.php?id=91548&mode=view .

Didn't know that the RAMDAC wasn't involved on this, but I knew that some components were affecting the passthrough.

Reply 17 of 30, by feipoa

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sdz, thank you. Looks like PI5C3384C is the switch.

I'll look into swapping these components with another board and see if it helps any with the noise.

What other spec sheets do you have, e.g. do you have the bottom PCB layout?

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Reply 19 of 30, by feipoa

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I was deliberately ambiguous, hoping to get all that you've got!

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