Hi,
a few weeks ago, I was able to get some of my old hardware to where I live now. It was stored in the attic for the last 10~15 years, and probably saw temperatures between 0°C in winter and +45°C in summer.
One of the things I brought was a PCCHIPS M326 mainboard (basically a 386DX/40 board) with a Ti486DLC/40 and coprocessor. The board works correctly, but unfortunately, both ISA graphics cards I had fail (they also fail in a different mainboard). They are not identical, but very similar and carry the same FCC-ID (HNG2YPTVGA06X4LT2).
Card 1 is labelled "TVGA9016X2/4 LT2 REV.B". It contains 512 KB DRAM (256 KB soldered), a "Music TR9C1710" RAMDAC and a Quadtel BIOS. When plugged into the mainboard, it starts but my TV does not detect a video signal. I used an old (fixed-frequency) cash register VGA CRT, and it shows an image - but it appears as if the vsync signal is missing (the image runs from bottom to top, overlaying on itself). It contains a few electrolytic capacitors.
Card 2 is labelled "9016X2/4 LT2 REV.B" and contains 512 KB DRAM, all socketed. The Quadtel BIOS looks to be the same, but the RAMDAC is labelled "KDA0476BCN". If I plug this card into the mainboard, I just get beep codes telling me about a video error. No output on the CRT either. This card does not contain any electrolytic capacitors, but uses the brown blob-type ones (Tantalum?) instead.
So far, I tried swapping the DRAM chips, as well as the BIOS and the RAMDAC. No change, the semi-working card did detect all RAM chips, but never produced a vsync signal. Changing the jumper positions did not help either.
I traced the connection from the VGA VSYNC pin to the TVGA chip, and it appears to be a direct connection. So I guess that one of my TVGA chips is broken. I also attempted to measure the frequency on the clock generator chip (Trident TCK9002NP) on both cards, and as far as I can tell without having the pinout, they work correctly - at least, I found some expected clocks (25 MHz, 28 MHz, 36 MHz).
And this is where my knowledge ends.
How would I continue from here, to get at least one working ISA card?
Is there a way to restore the vsync signal somehow?
What faults would cause the system BIOS to fail, assuming that DRAM, BIOS and RAMDAC are fine?
Swapping the TVGA chips exceeds my capabilities, though.
Best Regards,
Svenska
a few weeks ago, I was able to get some of my old hardware to where I live now. It was stored in the attic for the last 10~15 years, and probably saw temperatures between 0°C in winter and +45°C in summer.
One of the things I brought was a PCCHIPS M326 mainboard (basically a 386DX/40 board) with a Ti486DLC/40 and coprocessor. The board works correctly, but unfortunately, both ISA graphics cards I had fail (they also fail in a different mainboard). They are not identical, but very similar and carry the same FCC-ID (HNG2YPTVGA06X4LT2).
Card 1 is labelled "TVGA9016X2/4 LT2 REV.B". It contains 512 KB DRAM (256 KB soldered), a "Music TR9C1710" RAMDAC and a Quadtel BIOS. When plugged into the mainboard, it starts but my TV does not detect a video signal. I used an old (fixed-frequency) cash register VGA CRT, and it shows an image - but it appears as if the vsync signal is missing (the image runs from bottom to top, overlaying on itself). It contains a few electrolytic capacitors.
Card 2 is labelled "9016X2/4 LT2 REV.B" and contains 512 KB DRAM, all socketed. The Quadtel BIOS looks to be the same, but the RAMDAC is labelled "KDA0476BCN". If I plug this card into the mainboard, I just get beep codes telling me about a video error. No output on the CRT either. This card does not contain any electrolytic capacitors, but uses the brown blob-type ones (Tantalum?) instead.
So far, I tried swapping the DRAM chips, as well as the BIOS and the RAMDAC. No change, the semi-working card did detect all RAM chips, but never produced a vsync signal. Changing the jumper positions did not help either.
I traced the connection from the VGA VSYNC pin to the TVGA chip, and it appears to be a direct connection. So I guess that one of my TVGA chips is broken. I also attempted to measure the frequency on the clock generator chip (Trident TCK9002NP) on both cards, and as far as I can tell without having the pinout, they work correctly - at least, I found some expected clocks (25 MHz, 28 MHz, 36 MHz).
And this is where my knowledge ends.
How would I continue from here, to get at least one working ISA card?
Is there a way to restore the vsync signal somehow?
What faults would cause the system BIOS to fail, assuming that DRAM, BIOS and RAMDAC are fine?
Swapping the TVGA chips exceeds my capabilities, though.
Best Regards,
Svenska