18 Oct
2012
18 Oct
'12
9:56 a.m.
We also had problems with our 9900/4's 24V/+-12V power supply (needed for
the SMD 8" disk drive). It turned out that
1. the metal clamps that press the transistor cases to the heat sink were
corroded and fell off (and may produce a short circuit!)
2. some electrolytics in both PSUs were shorted and needed replacement
3. a CMOS NAND gate (CD4011) was bad
4. later on (after the PSU did work again), the TDA4718 went bad
I think 3. and 4. were caused by the short circuit described in 1.
On Wed, 17 Oct 2012, P Gebhardt wrote:
and?applying power to?the switching supply turned
on?the
blinkening?kight of the ?green "RUN" button, but pressing it did not do
anything. Afterwards, I deconnected the supply, checked that power
The RUN button is only to halt the machine in combination with the INIT
key switch position.
just seems dead. I guess that the supply has a
problem. It's difficult
to check it, though, without schematics. It has a small ribbon cable
which connects to a small PCB with several ICs on which can be found the
"RUN"-button. I have no idea, which signals that supply needs in order
to enter a state at which it should be on. The small PCB with the
buttons and ICs could also be defective. ?There is also a key-switch,
That key switch is the power-on and reset switch. If really nothing
happens, check the standby voltage (12V).
but I played with both positions and it does not
influence anything on
my system. The systems seem rare. At least, I could find only little
information on the net and not documentation at all.Has anybody a clue
Then you haven't looked hard enough ;-)
From our museum's site, there's the following
links to our PCS docs:
ftp://ftp.informatik.uni-stuttgart.de/pub/cm/pcs/
on how to power-up this thing?Are there other owners
of PCS systems, who
can tell me who the system behaves upon applying power to the PSU and if
it is sufficient to press the RUN-button to turn it on? ? Kind regards,
As said, the RUN button does essentially nothing. But have a look at the
documents, they describe quite well how everything works, and they contain
the description and pinout of the various connectors.
If you search the usenet archive, you'll find a posting on d.a.f.c.
from somebody, dated 29.3.2005, that sais
"[...]
Elkos sind generell ein Problem, ich habe ja bei meiner Sammlung
auch die Tage schon mehrere repariert:
PCS Cadmus 9700 - Elko mit Kurzschlu?, Nebeneffekt abgebrannte Leiterbahn,
sonst nix.
[...]"
Christian