24 Aug
2013
24 Aug
'13
11:42 a.m.
At 04:18 PM 8/23/2013, Tony Duell wrote:
Yes, you're right (of course). As a 'Unibus man'[1] I am familiar wit hte
DEUNA cabkit and incorrectly assuemd the DEQNA one would be the same. The
DEUNA cabkit does have a little circuitry on it, according to the
printset it's an inrush current limiter. Quite why that's needed on
Unibus machnes and not Qbus ones I don't know.
[1] SOme Unibus machines have real front panels and CPUs built from
simple ICs I can understand and can still easily buy. Qbus macbines
don't.
-tony
IIRC there is a ltitle electronics in these
cabkits, something like a
linear voltae regualtor to provide the power for the transceiver. Is it
possible that this has failed. Have yuo measured the votlage ebtween the
transceiver power ins on the AUI connector using both the good and bad
cabkits (with the machine powered up, of course)?
No, those cabkits are entirely passive. The voltage supply for the
transceiver is regulated on the board and fuse protected.