Many thanks for these detailed answers ! :)
Indeed, I finally do not know exactly what Nova my DCC is the clone.
Another specialist suggested that it was rather a clone of NOVA 1200?
Note that in Nixdorf contracts for the 600 series, these machines were
sometimes updated with a new CPU over the years of service.
In the doubt here are pictures of the board in slot 01 dedicated to the CPU:
http://www.actingmachines.com/classiccmp_forum/cpu01.jpg
http://www.actingmachines.com/classiccmp_forum/cpu02.jpg
http://www.actingmachines.com/classiccmp_forum/cpu03.jpg
Do you have any idea what that is?
Concerning the PSU I will analyze your suggestions.
Concerning the memory, I analyzed more in detail, I think finally that
all the memory is core type, 1 X 16KW (it is marked on it) and 2 X 8KW
(according to the size of the core package in comparison with the 16KW
board). Thus a total of 32KW.
For transmission via serial port, unfortunately I do not have this
"basic board" in slot 3 (TTY), it's empty. Can we still find board like
this?
Dominique
Er. My DCC-116 is more a clone of the mapped Nova 840 than the Nova 2,
with the DCC/Keronix "64Kword" hack that gives up more than one level of
indirect memory reference in exchange for having 16, rather than 15,
bits of logical memory reference.
IIRC the functionality of the basic I/O board normally found in slot
three is subsumed into the CPU card of the DCC116, so you should be fine
as long as you can find the signals on the back of the machine.
It's a word oriented machine, so memory is sized in KW, not KB. You can
probably tell how big the boards are by looking at the physical address
jumpers; core boards were typically 8KW, MOS boards were typically 16 or
32KW, depending on vintage. Hint: The more jumpers, the smaller the board.
I have no idea how this machine packages things, but in jumbo-chassis
Novas the lower PS generates five and 15 volt supplies, the top PS
generates only five. The reason for this is that the 15 volt supply is
only used by core memory boards and the memory bus is only available in
the lower chassis.
Sounds like one of the +5V switchers is having issues.
+/-5V and +15V but not -15V should be regulated. In the original DG
power supply both five and 15 volt supplies were derived from a common
+30V unregulated supply, but it's not clear that DCC followed that
model. It may be helpful to know that the +15V supply is not regulated
to 15V but temperature compensated downward with increasing temperature,
such that at 55C it's closer to 14.4V; this is done to maintain margins
on the core planes. The consequence is that you're probably looking at
something having drifted in the voltage divider that feeds the voltage
comparator or something having drifted in the temperature compensation
stuff (if it's actually there) rather than a simple zener gone bad.
/POWER FAIL is asserted by the power supply itself, as is MEM OK.
It's a switcher; look at the caps in the LC filter (downstream of the
series pass transistor) that, together with the inductor, form the
energy storage mechanism of the power supply; check the source supply as
well. The fact that it eventually comes back suggests that the
reference, comparator and pass device are probably functioning.
Should be, as long as the machine isn't running in extended logical
address mode (my DCC has a front panel switch to enable/disable this
feature).
Nice job on getting the machine to boot!
Cheers,
Chris
