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A 21-slot 6U x 160mm card cage with a VME J1 backplane is standard in the VR-21 Options include a 21-slot J1/J2 monolithic backplane (shown on page vr211). Smaller backplanes and multiple section backplanes are also offered. Any combination of backplanes that will physically fit can be provided.

The card cage is flush with the front surface of the chassis. If cables must be routed between the faceplates and the interior of the chassis, they must go over the top of the card cage. Any panel mounted above the card cage must take this into consideration, if required.

RP-5D-M drive mounting panel, as shipped RP-5-DM drive mounting panel, with drive
RP-5-DM 5¼" Drive Mounting Panel RP-5-DM 5¼" Drive Mounting Panel with drive


For systems that require mass storage, the VR-21 can be supplied with an RP-5-DM mass storage mounting panel that is placed above the card cage (instead of an exhaust grille). The RP-5-DM will allow the mounting of up to two 5¼" full height drives or four 5¼" half height drives or four 3½" drives in adapters. Power for these drives is supplied from cables running to the J1 backplane. The DC power cables for the drives are supplied with systems that include the RP-5-DM. Dummy panels, DP-5H-A, are available to seal off unused openings in the panel.

For those systems that do not require 5¼" drives, the VMEDA disk adapter can mount one or two 3½" drives in only two or three slots of the card cage. See the VMEDA data sheet for details.

Another option, for systems that do not require more than 13 VME slots, is to mount one or two 5¼" drives in a VMEDA-2X5FH adapter. This adapter occupies 8 slots of the card cage. See the VEV-15 data sheet for an example of this adapter in use.


Cooling air is drawn into the chassis through filters in the front panel below the card cage. Filtered, clean air is then blown through the card cage by three fans located just below the card cage. The air stream emerges from the top of the card cage where there must be open space for the exhaust. A fourth fan forces air through the power supply compartment in the pow-AIR-pak and it is then exhaust out the rear. Air warmed by the power supply never touches the more sensitive VME modules or mass storage devices.

For systems using less than 500 watts of power, you may request lower velocity fans to minimize acoustic noise. Fans as low as 57cfm, which reduce fan noise to virtually inaudible, are available at no extra charge. This option is not recommended when a power supply above 500 watts is used.


The VR-21 comes standard with a Power-Switch-Only front control panel. The power switch is illuminated when the AC power is on.

A "Full-Function" control panel upgrade (VR-21-CP) is an extra cost option. In addition to the power switch, this control panel includes RESET and ABORT buttons, DC POWER and SYSFAIL indicators and SYSRESET, ABORT, ACFAIL and Line Frequency signals. The full-function control panel will detect AC power failures and generate a Power-On SYSRESET. The SYSRESET and ABORT signals are debounced and programmable by jumpers to generate either a logic level or 300ms pulse, active high or low, when the signal is asserted. All of the photos in this document depict the full-function control panel. See the VX-11 document for more control panel information.


The VR-21 has two standard power supply configurations: 500W and 700W. Other configurations are available on special order.

The smaller power supply is the PS500-A:
  • 500W
  • +5V @ 80A
  • +12V @ 10A/16pk
  • -12V @ 10A
  • +24V @ 2A (typically used for DC fans)
The larger power supply is the PS700-A:
  • 700W
  • +5V @ 100A
  • +12V @ 12A/20pk
  • -12V @ 10A
  • +24V @ 2A

The DC outputs are cabled as required to the backplane and to the optional mass storage drives. The power supply is mounted in the rear of the pow-AIR-pak. It can be accessed for maintenance by removing the top cover. Adjustments are accessible through the removable rear panel.

Input power is typically 110/220 VAC 50/60Hz. Other voltages and frequencies can be accommodated on special order. The AC input voltage is nromally selected by changing a jumper inside the chassis. Autoranging power supplies are optionally available.


Basic Rack Mount ConfigurationWith Optional VCQE-D/D Desk Top Enclosure
Size19"W x 14.625"D x 15¾"H
(Clearance for exhaust is required above card cage, 5¼" minimum recommended. Clearance for exhaust and DC cables is required behind the chassis, 3" minimum.)
19¾"W x 23½"D x 22½"H
(The enclosure is completely open in the rear, allowing easy access to the backplanes. If a rear cover is required, Zoltech can provide it.)
Power Supply 500W or 700W
Card Cage 21-slot x 6U x 160mm with VME J1 backplane
Cooling 3 x 100cfm fans for card cage, 1 x 100cfm fan for power supply



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PHONE (818) 780-1800 ¤ FAX (818) 780-1978 ¤ EMAIL sales@zoltech.com