7568 Power
Gearbox Power Supply Supply
   AC Power Cord Hook-Up
   Front of Power Supply
   Remove PSU
   Dead PSU, or Is It Dead?
   Status Light Meanings
Power Supply Voltages and Current
Nicad Battery
   EVM Module
Cleaning the PSU

Gearbox Power
   The GEARBOX Model 800 is a direct-wire system, using a customer-provided power cable to an applicable power source. 300 total watt worldwide, autoranging (will detect and switch for 120 or 220) power supply, with two fans to assure system cooling.

AC Power Cord Hook-Up
  7568s wired for AC power have a terminal block mounted on the left side (or upper left rear corner). The black wire (shield) on the system side of the terminal DOES NOT attach to the terminal block.

C - Terminal Cover screws
S - Terminal Block screws

Power Supply (with EVM installed)

Remove PSU

   Turn power switch off on PSU. Unscrew the three captive screws on the bottom front edge. Grab on the cutout around the EVM/Battery pack on the left and grab the right corner of the PSU (though you might try the rightmost captive screw).

Note: If you pull the rightmost shroud (#9) you can get a grip on the rear right inner corner of the PSU....

 Rock the PSU a little as you pull it out. The plug is at the back of the PSU behind the power switch. It resembles a mutant 95 planar plug. Do NOT grab the black plastic guard around the power switch!!!

Dead PSU or Is It Really Dead?
   I had two 7568s, one powered up, the other didn't. Swapped the PSUs, one worked in both cases, the other didn't work at all. These babies are built even heavier than a 95A PSU, so I was puzzled.

Dr.Jim Shorney did the office call and says:
   The tabs holding the thumbscrews at the bottom front of the PS were tweaked backwards.  Straightened them out so the PS seated fully. 

Status Lights Meaning

MAIN DC TEMP BATT FAN1 FAN2 Possible Problem
O X O O O O 1. Mains power missing
2. Defective power supply
X O O O O O Defective Power Supply
X X X O O O 1. Hi temp (poor ventilation?)
2. Defective power supply
X X O X O O 1. Battery discharged or disconnected
2. Defective power supply
X X O O X O 1. Fan 1 Malfunction
2. Defective power supply
X X O O O X 1. Fan 2 malfunction
2. Defective power supply
X X O O O O MAINS OK - Power supply OK

Standby Switch
   Run position to the left, Standby to the right. The Run-Standby switch is used when the system is disconnected from AC power for more than 72 hours. In the run mode, the battery (the big 5v 1F capacitor on the System Resource card)  preserves the setup and time-of-day clock for 72 hours. In standby, the battery preserves the setup and time-of-day information up to 60 days. Some special bid units lacked a standby switch.

Warning! Do NOT start the system in Standby mode!!! Avoid turning on the system with no AC power attached when the internal battery is installed. This will severely discharge the Ni-Cad battery... (no foolin' !)

Power Source Choices
   When the system is turned on, the PSU senses the applied power source. If AC power is present, the system starts and runs with AC as primary power. If DC power is present, it is used as a backup power source (requires EVM for extended backup time).
   If no AC power is present, the system starts and runs off DC power, if DC power is available at the battery connector (requires EVM to be installed). There is no backup capability in this configuration. Don't try running system off battery pack!!!
   The system sets operating mode (AC or DC) when the system is turned on. It remains in that mode until the power switch is turned off.

AC Specs
   120 / 220
6.0A / 2.7A
Single phase.
Power usage .75KVA

AC Power Cable
   Any cable used must be a minimum of 16AWG with ground.

Power Supply Values
Max output 288.8 W
+5V @42A   -5V @0.3A
+12V @4A   -12V @1A
+6V @5mA
Battery Charger +28V @80mA
Fan Supply 15W max

BATTERY, NICAD (INTERNAL) (#6221) (P/N 15F8625)

This internally mounted battery allows continuous operation through brief main power interruptions (nominal 1.5 seconds default). Also, if the interruption continues beyond this period, the battery maintains DC voltages to allow the system to perform an orderly shutdown.

Note 1: Battery or EVM must be installed to retain system set up information during periods when system is shut down. (though there is a whopping big 5v 1F cap on the system resource board).

Note 2: Shutdown is limited to max of 10 sec under hardware control. Software control shutdown depends on the electrical load and the battery capacity, and may be limited to 10 seconds. Longer shutdown periods require external battery backup, which requires an EVM.

The battery pack is 21 (twenty-one) Sony Cadnica KR-SCH 1.2v 1200mAh, Standard charge14-16 hrs at 120mA, recommended trickle charge 40mA.

Marked "Plainview Batteries, Inc" mfd- 9104  IBM replacement PN 15F8625

These EVM features allow the connection of an external DC voltage source either for additional battery backup to the main AC power, or as a main DC power source. No other external voltages are to be used as a main source or as a backup.
EVM #6231 24 volts DC. 
EVM #6528 48 or 60 volts DC. 

Note: Either an EVM (hooked to an external DC voltage source), or internal nicad battery (#6221) must be installed to retain system set up information during periods when the system is shut down.

The EVM provides RFI filtering, reverse polarity protection, and over voltage protection.

Warning! A fully populated Gearbox requires up to 30A on the DC line. Use a minimum of 12AWG

   ETRI Model 98DW 98DW1LP31 203, 12v (8-15v) at 5.2W (under .5A)

Filter Use
   The 7568 can use optional filters in the PSU compartment. Use of filters degrades the maximum temperature decreases by 9°F/5°C.

Changing Airflow Direction

   Remove the PSU. Flip it upside down. If you can see the ETRI sticker on the fan hub, the PSU is set to blow down through the shrouds. This direction is used for the filter configuration. Unfortunately, the heat generated by the PSU is now blown through the shrouds.
   If you see a silver hub, the PSU is set to suck air up through the shrouds and out through the grilles in the PSU compartment. This is good because the heat from the PSU is not blown through the populated shrouds.

   Remove the three standard screws in each fan housing. Pull them out and flip them over to whatever way you want. If you are unsure about the direction, there are two arrows embossed on the fan housing, showing fan rotation AND airflow direction.

Cleaning the PSU
   Hooray! I stumbled onto this working on the fans...

  At first look, it's grim. Rivets everywhere. Don't give up. Flip PSU upside-down. Unplug fan power connectors. Remove all fan screws. Pull up on grille and push the fan power connectors through using a flat bladed screwdriver. Now the grill comes off, and the majority of the PSU components are exposed.

  Copper heatsinks! Stud power diodes!

Content created and/or collected by:
Louis Ohland, Peter Wendt, William Walsh, Kevin Bowling, Jim Shorney, Tim Clarke, David Beem, Tatsuo Sunagawa, Tomáš Slavotínek, and many others.

Ardent Tool of Capitalism - MAD Edition! is maintained by Tomáš Slavotínek.
Last update: 28 Jul 2021 - Changes & Credits | Legal Info & Contact