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BA11-A mounting box

2025-12-19T17:12:48Z

Ethan: Removed erroneous reference to available PSUs from previous edit.

The '''BA11-A mounting box''' is a 10-1/2" [[mounting box]]; the terminal variant letter notwithstanding, it is just about the last in the line of [[BA11 mounting boxes]]. It was introduced with the [[PDP-11/44]], and was also used with the [[PDP-11/24]] and [[VAX-11/730]].

Unusually for [[PDP-11]]s, its integral [[power supply]] also provided +12V/-12V [[direct current|DC]], used for the [[MS11-M MOS memory]]'s [[Metal Oxide Semiconductor|MOS]] memory [[integrated circuit|chips]].

It came with the [[H7140 Power Supply]], mounted at the rear of the box. There were four main variants, depending on the input [[alternating current|AC]] [[voltage]], and details of the secondary output:

{| class="wikitable"
! Model !! Input !! Memory voltages
|-
| -AA || 115 || +12V, -12V
|-
| -AB || 230 || +12V, -12V
|-
| -DA || 115 || +12V, -15V
|-
| -DB || 230 || +12V, -15V
|}

Maximum power was 1350W with maximum load applied; it could provide 120A of +5V, and 10A of [[memory refresh]] +5V power to MOS memory; 3A of +15V, 3A of -15V; and 5A of +12V, 1A of -12V or -15V.

The [[H7750 Battery Backup Unit]], which provided refresh power during brief power outages to MOS memory mounted in the BA11-A, was an option.

==Power connections==

[[Image:1144Power.jpg|300px|thumb|right|PDP-11/44 setup]]

The BA11-A does not use only the standard [[DEC power distribution connectors]]; it also provided special connections on [[bus bar]]s in its power supply, and in some applications (e.g. the -11/44's [[KD11-Z CPU]]), the CPU's [[backplane]] uses unique [[Flexprint cable]]s for power, which go to the special connections (see image).

For backplanes which did not have the Flexprint cables (e.g. that of the -11/24's CPU), including the [[DD11-DK]], [[DD11-CK]], [[RK11-D]], etc., a special 'Power Distribution Board' ([[DEC part number]] 54-13815 for the 11/24 or 54-13632 for the 11/44) mounts to the bus bars and provides the needed Molex connectors.

==External links==

* [http://bitsavers.org/pdf/dec/unibus/EK-BA11A-TM-003_Aug83.pdf BA11-A Mounting Box and Power System Technical Manual] (EK-BA11A-TM-003)
* [http://www.bitsavers.org/www.computer.museum.uq.edu.au/pdf/MP00832%20BA11-A%20Field%20Maintenance%20Print%20Set.pdf BA11-A Field Maintenance Print Set] (MP00832 - May '79)
* [http://bitsavers.org/pdf/dec/unibus/MP00832_BA11-A_RevE_Engineering_Drawings_Apr87.pdf BA11-A Field Maintenance Print Set] (MP00832 - Apr '87)
* [http://retrocmp.com/pdp-11/pdp-1144/my-pdp-1144/power-supply Repairing a H7140 power supply] - informative blog entry on repairing an H7140 power supply
* [https://www.pdp-11.de/index.php/knowledge-base/fan-overhaul/ Fan Overhaul BA11-A]

[[Category: DEC Mounting Boxes]]

BA11-A mounting box

2025-12-19T17:08:12Z

Ethan: Added info that there are two Power Distribution boards depending on which CPU/PSU is installed

The '''BA11-A mounting box''' is a 10-1/2" [[mounting box]]; the terminal variant letter notwithstanding, it is just about the last in the line of [[BA11 mounting boxes]]. It was introduced with the [[PDP-11/44]], and was also used with the [[PDP-11/24]] and [[VAX-11/730]].

Unusually for [[PDP-11]]s, its integral [[power supply]] also provided +12V/-12V [[direct current|DC]], used for the [[MS11-M MOS memory]]'s [[Metal Oxide Semiconductor|MOS]] memory [[integrated circuit|chips]].

It came with the [[H7140 Power Supply]] ([[PDP-11/44]]) or [[H777 Power Supply]] ([[PDP-11/24]]), mounted at the rear of the box. There were four main variants, depending on the input [[alternating current|AC]] [[voltage]], and details of the secondary output:

{| class="wikitable"
! Model !! Input !! Memory voltages
|-
| -AA || 115 || +12V, -12V
|-
| -AB || 230 || +12V, -12V
|-
| -DA || 115 || +12V, -15V
|-
| -DB || 230 || +12V, -15V
|}

Maximum power was 1350W with maximum load applied; it could provide 120A of +5V, and 10A of [[memory refresh]] +5V power to MOS memory; 3A of +15V, 3A of -15V; and 5A of +12V, 1A of -12V or -15V.

The [[H7750 Battery Backup Unit]], which provided refresh power during brief power outages to MOS memory mounted in the BA11-A, was an option.

==Power connections==

[[Image:1144Power.jpg|300px|thumb|right|PDP-11/44 setup]]

The BA11-A does not use only the standard [[DEC power distribution connectors]]; it also provided special connections on [[bus bar]]s in its power supply, and in some applications (e.g. the -11/44's [[KD11-Z CPU]]), the CPU's [[backplane]] uses unique [[Flexprint cable]]s for power, which go to the special connections (see image).

For backplanes which did not have the Flexprint cables (e.g. that of the -11/24's CPU), including the [[DD11-DK]], [[DD11-CK]], [[RK11-D]], etc., a special 'Power Distribution Board' ([[DEC part number]] 54-13815 for the 11/24 or 54-13632 for the 11/44) mounts to the bus bars and provides the needed Molex connectors.

==External links==

* [http://bitsavers.org/pdf/dec/unibus/EK-BA11A-TM-003_Aug83.pdf BA11-A Mounting Box and Power System Technical Manual] (EK-BA11A-TM-003)
* [http://www.bitsavers.org/www.computer.museum.uq.edu.au/pdf/MP00832%20BA11-A%20Field%20Maintenance%20Print%20Set.pdf BA11-A Field Maintenance Print Set] (MP00832 - May '79)
* [http://bitsavers.org/pdf/dec/unibus/MP00832_BA11-A_RevE_Engineering_Drawings_Apr87.pdf BA11-A Field Maintenance Print Set] (MP00832 - Apr '87)
* [http://retrocmp.com/pdp-11/pdp-1144/my-pdp-1144/power-supply Repairing a H7140 power supply] - informative blog entry on repairing an H7140 power supply
* [https://www.pdp-11.de/index.php/knowledge-base/fan-overhaul/ Fan Overhaul BA11-A]

[[Category: DEC Mounting Boxes]]

H967 rack

2020-11-21T03:20:14Z

Ethan: fixed typo in link to H960

The '''H967 rack''' (officially the '''H967 Short Heavy Duty Cabinet Frame''') was the short version of the [[H960 rack|H960 cabinet]], [[Digital Equipment Corporation|DEC]]'s standard 19" wide rack (an industry-wide standard width for rack-mounted gear), used with the [[PDP-8 family|PDP-8]], [[PDP-11]], etc.

The H967 included add-ons such as the rear door, side panels, etc.

It was 4' (49.63") tall, and provided 42" of mounting space. The mounting space in the H967 was divided into 4 10-1/2" units, each of which could be further sub-divided into two 5-1/4" spaces. Most DEC gear (e.g. [[BA11 mounting boxes]]) was designed to fit in spaces of these sizes.

H967's often included an [[861 Power Controller]] for line [[Alternating current|AC]] distribution and remote control.

H967 rack

2020-11-21T03:19:45Z

Ethan: Created new page for the short racks

The '''H967 rack''' (officially the '''H967 Short Heavy Duty Cabinet Frame''') was the short version of the [[H950 rack|H950 cabinet]], [[Digital Equipment Corporation|DEC]]'s standard 19" wide rack (an industry-wide standard width for rack-mounted gear), used with the [[PDP-8 family|PDP-8]], [[PDP-11]], etc.

The H967 included add-ons such as the rear door, side panels, etc.

It was 4' (49.63") tall, and provided 42" of mounting space. The mounting space in the H967 was divided into 4 10-1/2" units, each of which could be further sub-divided into two 5-1/4" spaces. Most DEC gear (e.g. [[BA11 mounting boxes]]) was designed to fit in spaces of these sizes.

H967's often included an [[861 Power Controller]] for line [[Alternating current|AC]] distribution and remote control.

H960 rack

2020-11-21T03:12:23Z

Ethan: Added precise external height of cabinet

The '''H960 rack''' and '''H961 rack''' (officially the '''H960 cabinet''' and '''H961 cabinet'''), built around the '''H950 frame''', were [[Digital Equipment Corporation|DEC]]'s standard 19" wide rack (an industry-wide standard width for rack-mounted gear), used with the [[PDP-8 family|PDP-8]], [[PDP-11]], etc.

The H950 is the bare rack; the H960 included add-ons such as the rear door, side panels, etc. The H961 was intended mostly for expansions, and did not include the side panels, but did include a pair of filler strips (to go between the racks).

It was 6' (71.75") tall, and provided 63" of mounting space; DEC also came out with some shorter 19" racks (e.g. the [[H967 rack]]). The mounting space in the H960 was divided into 6 10-1/2" units, each of which could be further sub-divided into two 5-1/4" spaces. Most DEC gear (e.g. [[BA11 mounting boxes]]) was designed to fit in spaces of these sizes.

H960's usually included an [[861 Power Controller]] for line [[Alternating current|AC]] distribution and remote control.

==Replacement levelers==

Under the main part of the cabinet, and also at the tips of the 'stabilizer feet' (DEC's official name for the extension feet on the front a cabinet, to keep it from tipping over when units are slid out), there are 'levelers' (again, DEC's official term) - threaded rods with a metal cup holding a circular rubber pad. These are often damaged or lost, but replacements are available.

The small ones at the tips of the extension feet are 5/16"-18 thread, and a suitable replacment part is the Vlier FSE302S. They fit OK, with two caveats:

# The round foot part is a significantly larger diameter than the DEC originals, but they do fit OK on neighbouring extension feet (i.e. on a pair of H960's, both with extension feet).
# The threaded shaft is somewhat longer than the originals, so even when wound fully up, there isn't a lot of room between the foot and the floor.

The larger one under the cabinet are 1/2"-13 thread; Vlier makes suitable replacements for them, too - FSE306S. Like the smaller ones for the extensions, the pad on the bottom is somewhat wider than on the DEC originals, but they still work fine.

==External links==

* [http://www.mscdirect.com/ MSC Industrial Supply] - A source for the Vlier replacement feet

[[Category: DEC Hardware]]