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VLB Graphics Card Sync Problems

Anonymous Coward

Anonymous Coward

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Joined
Aug 11, 2004
Messages
1,557
Location
Shandong, China
I currently have a dead s3 964 based Diamond Stealth 64 VLB graphics adapter that I would like to repair. When the card is plugged into a monitor will analogue controls, I am able to get a picture by making some adjustments. However I am only able to use low resolution video modes. Going into higher modes produces only distortion.

If I plug the card into a monitor with digital controls and automatic adjustments, I am not able to see a picture at all. The monitor just shows an "out of sync" or "sync not supported" message.

I am pretty inexperience with electronics, and I am not sure how to begin trouble shooting this. I did a little searching, and I am under the impression that I may have bad capacitors. They are of the ceramic disc variety. 10uF, 16V. None of them appear to be scorched or leaking though. I currently do not have the equipment to test them.

Before I waste my time and order some new ones, is there anyone in here that has had any luck repairing graphics adapters that can give me a few suggestions on how to fix mine?
 
By low resolution how low are you talking aka 640x480???

I owned an old Diamond Stealth at one point and none of my monitors at that time would sync with it above 640x480 (my svga screens all topped out at 800x600x56hz or 1024x768 interlaced), I later found the cards default refresh rate was WAYY too high, somebouts around 90hz. Not sure if this applies or not in your case.

To answer your other question, I have never tried to troubleshoot a video card with damage, I have changed jumpers and pinouts but never tried to resolder the card. Though I have replaced video memory on several occasions with fairly good success, of coarse we're talking antiques with dipps.

Good Luck
 
It won't sync at all on any of my current displays. At one point I had it going on a Sony CPD-1393 14" display, but I could only get text mode and 4-bit colour 640x480 working. By low resolution I mean 640x480x4 and lower.
 
Is that old SONY one of the ones that you can use at 15Khz? I have an old NEC 3ds that will sync at 15Khz and I use it on my Amiga 1200, just about all VGA monitors built after the early 90's are standard 31Khz and above. So maybe the card has a bad ramdac and is screwing up the output frequency.
 
I don't know that the monitor supported 15KHz vertical refresh rate. What I do know is that the horizontal refresh was fixed at 70Hz, as it was a fixed frequency display. I guess it doesn't matter much any longer since I tossed the thing 7 years ago. I wish I had a nice NEC Multisync II. That is my ideal vintage display.

Anyway, what do you think the likelihood of a bad RAMDAC is? I hope it's not the case, since otherwise it looks like a nice card. It's a BrookTree bt485 135MHz. it seems to have some resistors and capacitors orbiting it. Perhaps one of those went bad. I also noticed there is a component labelled "FB1" connected directly to the pins of a RAMDAC. I could be wrong, but I believe this is a fuse. It is in a small black cylindrical casing. I've had fuses go on motherboards before, and this sounds like a possibility at least. However, using a multimeter the output doesn't seem characteristic of a fuse. However, according to internets sources, circuit board notation "FB" can designate a fuse. Also... I tried to look for a datasheet for this RAMDAC, but came up empty handed.

I'm going to try shorting it to see what happens.
 
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