> Hi Joerg,
> Cooling would be the fix in my opinion. None of the original machines would
> have been without a case and without cooling for more than a brief time. If
> you have an IR camera you could check the temps of the chips in your setup;
> the DS8641 datasheet specs a maximum temp of 70C.
"Warm" feels more like enhanced body temperature, far far below the 70°.
> Have you noticed if it's always the same chip on the board every time? If
> you're able to measure power draw for that one chip, that would be
I'll have a look at it, when the 3rd fails.
>> Perhaps the russian clones are bad, or the 8641 generally need cooling.
>> 8641s also tend to break on vintage DEC boards ... maybe UniBone/QBone
>> is just too compatible here.
>> You suffer from this issue too?
> When we build QBones we do a burn-in test on the drivers for an hour or two
> for regular units, and we did 24+ hours for the Gold units. So far this
> hasn't failed any chip -- chips fail within the first 10 seconds if they're
> going to fail. Overall failure rate of the КР559ИП3 is higher than the
> DS8641 chip, but both are in the single-digit percentages.
I also do an >1h selftest burn-in for every board.
Can't remember any ebay-chip failed there, not even the КР559ИП3.