Scottie, we need more power! Couldn't resist...
Reset Switch Attempts
Device Power Draw
Repairs on ASTEC Power Supplies
System Power-On Logic
Power LED on Front Panel
95A Power Supply Specifications
Parts for PS/2 Power Supplies
If you have a rare IBM system (aren't they all?) that
has a dead PS and you just can't find one, try contacting ASTEC's Tech
"If you are inquiring about replacement power supplies
or adaptors for computers manufactured by [IBM], please note that these
are custom power supplies, and the terms of our contracts ... prohibits
us from supplying replacements or schematics, BUT our product support group
can repair the units."
The main support page is HERE,
or you can call (760) 930-4600 and ask for the Astec Custom Power Product
The power supply responds to a 'power-on request' signal
to control the power to the system. While this signal is inactive,
the system is in the standby mode. When the signal is active, the
power supply is on and produces its output voltage. The 'power-on request'
signal is controlled by logic on the system board, as represented in the
System Power-On Logic
Note: The Remote Maintenance
Jumper is present on the 85N and 95A planars It is a four pin header, surrounded
by a keyed white shroud. On the 95A/85N planars, it is in the upper left
corner of the planar (JMP6)
Sometimes, the system had a ServerGuard
adapter removed, but the Remote Maintenance Jumper is left open. The system
will not start, because it cannot get the Power-Good signal. Jumper the
pins1-2 and the system should power up.
Power LED on Front
The power switch and two light-emitting diodes (LED) are
on the front of the system unit. When the green LED is lit, the power
supply is operating properly. When the amber LED is lit, the hard
disk is actively accessing data on the disk (this LED is not used on the
95A Power Supply
||Range automatically sensed
Sinewave input is required.
||Low:90 (min)-137 (max) Vac
||High:180 (min)-265 (max) Vac
||50 Hz ± 3 Hz or 60 Hz± 3 Hz
|Max amp draw
||Low:6.4 A-90 V / 4.1 A-137 V
||High:3.1 A-180 V / 2.1-@ 265 V
|Input in kVA
||Min configuration:0.077 kVA
||Max configuration:0.578 kVA
Reset Switch Attempts
Hi Stephan !
>I´ve done a modification on a mod80 in the powersupply.
It connects ground to the power-good-signal and that makes the box reset
(yes, and sometimes (very rare) the powersupply goes off). May be it is
possible on a 9595 too, but not tested at the moment. I will see ... (I
got my 95a 8 weeks (or so) ago).
Now - that works fine on "generic" power supplies ...
using a 10 microfarad condensor with a 1K resistor across in line with
a switch (to prevent a longer short-circuit of the PWRGOOD line). But if
you try that on PS/2 you have a good chance to run into a 301/8601 keyboard/pointing-device
error after you hit the button. The time sequence when PWRGOOD is
pulled low and released is different to that when the system is restarted
with the "power switch". The keyboard port *holds* the +5V for longer and
the keyboard microcontroller gets bad signals and barfs.
At least that was what *I* got on my 8595 when I had that
"good idea". It didn't work on a Mod. 60 much earlier ... nontheless I
tried it on the 95. Or maybe I had only bad luck ... (?)
The system board voltages are +5 V dc, +12 V dc,
and -12 V dc. The system provides a separate power source for internal
SCSI drives through three 4-pin connectors on the power supply (see Power
Supply Connectors). The drive voltages are +5 V dc and +12 V dc.
(Ed. The 95 series PS (maybe others)
also supplies -5v to the planar. The -5v was used in early AT/XT machines
to power serial ports. As such, it is not needed by the microchannel system,
which has always needed +5v only for serial ports. Artifact)
Note Some adapters and drives draw
more current than the recommended limits. These adapters and drives can
be installed in the system; however, the power supply will shut down if
the total power used exceeds the maximum available power.
A short circuit that is placed on any dc output (between
outputs or between an output and dc return) latches all dc outputs into
a shutdown state, with no damage to the power supply.
If an overvoltage fault occurs in the power supply, the
power supply latches all dc outputs into a shutdown state before any output
exceeds 130% of the nominal value of the power supply.
If either of these shutdown states occurs, the power supply
returns to normal operation only after the fault has been removed and the
power switch has been turned off.
All PS/2 power supplies are designed to operate at No
Most PS/2 power supplies have an automatic restart feature.
This allows the power supply to restart after an AC voltage power outage.
Beginning with products announced in October 1990, a 3 to 6 second delay
was added to enable all subsystems and peripherals ample time to reset,
prior to sequencing power back to the system.
PS/2 power supplies can be operated continuously over
the following ranges: 100V Range (90 to 137 VAC) and 200V Range (180 to
265 VAC) with a sine wave input with maximum 5% total harmonic distortion.
On some models, the power supply automatically switches to the required
voltage, and on others, there is a manual switch.
NOTE An important "gotcha"
is the sine wave input. If you are using a "modified sine wave" UPS, you
may experience random power-downs, followed by power-ups. The UPS will
not trip because it sees nothing wrong.
At power-on time, the output voltages track within 50
milliseconds of each other when measured at the 50% points.