Power

Scottie, we need more power! Couldn't resist...
Reset Switch Attempts
Sound Levels
Device Power Draw
Repairs on ASTEC Power Supplies
Power-On Request
System Power-On Logic Diagram
Power LED on Front Panel
95A Power Supply Specifications
Outputs
Output Protection
No-Load Operation
Automatic Restart
Operating Voltage Range
Voltage Sequencing



Repairs/Replacement 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 Support people. 
    "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."

Contacting ASTEC
   The main support page is HERE, or you can call (760) 930-4600 and ask for the Astec Custom Power Product Support Group.



Power-On Request
   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 following figure.

System Power-On Logic Diagram

   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 Panel
   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 Server 95A).

95A Power Supply Specifications
Specification        Measurements
Input voltage Range automatically sensed
Sinewave input is required.
  Low:90 (min)-137 (max) Vac
  High:180 (min)-265 (max) Vac
Input frequency 50 Hz ± 3 Hz or 60 Hz± 3 Hz
Available power 400w (95A)
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).

From Peter
   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 ... (?)



Outputs
    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.

Output Protection
   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.

No-Load Operation
   All PS/2 power supplies are designed to operate at No Output Load.

Automatic Restart
   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. 

Operating Voltage Range
   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.

Voltage Sequencing
   At power-on time, the output voltages track within 50 milliseconds of each other when measured at the 50% points.

9595 Main Page