cherry keyboard issue

[Julian H. Stacey]

Paul Douglas wrote:
> I recently posted a query on the peripheral hardware forum about a problem

It's not always software at fault ...

Did you measure the current each keyboard uses ?  They do vary a
lot.  The PS2 mini keyboard I'm using uses 46 mA, other PS2 full
sizers on shelf here pull 63 & 70 & 83, another mini PS2 here pulls
88 mA, one PS2 I recall pulled 150 or so & was troublesome on some
PCs so I dumped it.

Then add whatever a USB to PS2 converter draws.

I havent measued what my one USB2 keyboard drawa. Or my USB to PS2
or PS2 to USB converters.

I went through various other kit & & wrote cconsumption under devices.

USB-2 is spec'd at 0.5 Amp, but I suspect some sockets (on PCs & hubs)
dont deliver enough & some devs (disks) obviously draw 0.7+
& need doubler cables. Keyboards shouldnt be near 0.5A but
conside dried out electolytic capacitors on USB power supplies etc.

Certainly seen that on hubs & transformer (for USB & ethernet)

Cheers,
Julian
-- 
Julian Stacey, BSD Unix Linux C Sys Eng Consultants Munich http://berklix.com
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