AZZA mainboard

[davmax]

This Azza 601BM is cheap and rare. It was filled entirely with DO brand caps made about 2001. They have lasted pretty well. However to get it working all the low ESR caps were replaced. It now computes fine however whenever the hard drive works hard the video display suffers steaking noise breakup. Because the video is on board my guess is that at least one of the ordinary caps (not low ESR) is faulty and therefore not decoupling the noise generated by hard drive action. The computer had to be pressed back into service as a server!!! I will try get it back to replace all the small caps (caps that I do not normally have to hand, low ESR I do have).

Has anyone come across this type of hard drive interaction with the display?

[kc8adu]

Re: AZZA mainboard

post a pic.
is that the dual 370 board?

[davmax]

Re: AZZA mainboard

Sorry no full pic right now as I have no access. Some pics taken and posted in the Bad cap threads yesterday https://www.badcaps.net/forum/showthread.php?t=4921. It is a single 370 microATX board AGP + 3 PCI slots.

[zandrax]

Re: AZZA mainboard

[...] whenever the hard drive works hard the video display suffers steaking noise breakup. Because the video is on board my guess is that at least one of the ordinary caps (not low ESR) is faulty and therefore not decoupling the noise generated by hard drive action. [...]

Has anyone come across this type of hard drive interaction with the display?

I had the same issue but with an old Cirrus Logic isa graphic card on a noisy 486 mobo. Since other cards worked fine and had an oscillator on board while the CL hadn't, I thought it was a side effect of card's cheapness.
On your motherboard it may be due to some unfiltered noise: since it's used as a server board, it would be interesting to find out if noise affects only the vga connector (the board is ok, screen dizziness apart: you can plug any old pci graphic card, e.g. old Ati Rage ones) or other periphericals too (e.g. hard disk controller: there is a SMART parameter called UltraDMA CRC Error count which increases if noise corrupt data transferts).

Zandrax

[davmax]

Re: AZZA mainboard

Thanks for input I am going to recall the computer in about two weeks. The PSU has already had a 150,000hr fan installed and I plan the install a new Arctic Cooling Copper Lite heatsink and fan on CPU (Fan 137,000hrs mtbf). I will then investigate this video problem.