Tony,
You've given me the other answer that I had come up with (and the one I was
hoping was wrong). First, he is now running USB2 from an add on board in a
PCI slot, so it seems unlikely that the problem is the hardware interface -
although, as you say, there are some situations where the voltage is just
not enough.
I intentionally left out one datum that supports a mobo problem. His sound
system is not working correctly, it isn't stereo, he only has one channel,
somehow the other channel has quit, the sound is built into the mobo. I've
had sound systems go without affecting anything else, but given the things
he has done to try to fix the scanner problem, I am very suspicious of the
board. Even more so now that you have made your comments. I was hoping that
there was a known software glitch that would account for it - it is usually
cheaper to fix than replacing the motherboard. Of course blown capacitor
could add a nice voltage, and a high frequency voltage would account for
what is showing up.
I will prolly try running it on my P4, but I will be very surprised if I see
any problems there. The only problem with that as a test is that I am
running windows 2000 - it really doesn't handle USB as well as XP does.
Thanks for taking the time - I have no experience with XP, it is good to
know that there aren't any bugs hanging around like that. As for USB, it
works well on my G4 Dual MAC, I've never tried to use it on the P4. There I
have a SCSI card and that seems to work well with my scanners. While I do
scan with the P4, it is really dedicated to running Neural Network models
nearly constantly, I don't even know if my audio works on it.
Brad
> Brad Davis wrote:
>
>> I wouldn't expect the interface to put in such an even (if random)
>> dot pattern. I have no idea how XP might be at fault, but the one thing
>> that would seem to be common is the XP driver for USB(1&2).
>
> No such problems here with XP USB2 and scanners or anything else. If he's
> tried different interfaces and scanners, it sounds like dirty/bad mains
> supply or RFI, or low volts on the USB perhaps. Early VIA chipsets were
> awful for this, they'd sag badly if asked to supply anything like the 500mA
> USB is specced for, and some peripherals just wouldn't work at all. But
> that will only apply if he's using USB hung off the PC's internal USB ports
> (powered from the mobo). If he's using a PCI card with USB ports he'll have
> to look deeper (and if he isn't, he should try one as a priority, as they
> circumvent the mobo USB chipset's limitations).
>
> It may also be worth trying the scanner hung off a *mains powered* USB2
> hub, in case the power supply from the mobo chipset is dirty or failing.
> Not all scanner drivers like hubs though, so this could create new
> problems.
>
> If none of that helps, I think he's going to have to
> - try the scanner on a different PC in his home
> - try the scanner on a different PC somewhere else
> - try his PC and scanner somewhere else
> - try the PC and scanner at home on a decent UPS
> to establish whether it's the PC or his mains supply.
>
> If it is his PC, and a PCI USB card doesn't fix it, I think he's then
> looking at establishing whether it's the PSU or mobo, by substitution.
>
> Check the voltages in the BIOS. A careful visual inspection of the mobo may
> help pin it down. Look for leaking/bulging/corrosion-covered electrolytic
> capacitors especially.
>
>
>
> Regards
>
> Tony Sleep -
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