35, 40, 56, 57, 76 & 77 - Front Panel Connector

aka Control Assembly or Control Panel Connector

Control Panel Connector Variants
Control Panel Connector Pinout
8-pin Cable on 12-pin Header
12-pin Cable on 8-pin Header


Control Panel Connector Variants

The 8540 systems used a "Control Panel" with an 8-pin "Control Panel" header on the system board for the power switch, power/HD LEDs, and PC speaker:

  • Control assembly w/o volume control - 92F0002 (Power switch, Cable, Speaker)

The 95xx Premium systems used a 12-pin "Control Panel" header that adds a symmetrical +/-12 V supply for the power audio amp used by the speakers. The "Ultimedia Control Panel" had a speaker jack, microphone jack, volume knob, and a power audio amp for external speakers:

The following planars feature the compatible 8-pin or 12-pin Control Panel header:

Planar # of pins Reference
8535 / 8540 (SX) 8 J12
8556 / 8557 (SX, SLC Ultimedia M57 SLC) 8 J19
9556 / 9557 (SLC2, SLC3 & Ultimedia M57 SLC2) 12 J19
9533, 9535, and 9540 12 J13
9576 and 9577 (Bermuda) 12 J19
9576 and 9577 i/s (Lacuna) 12 J21


Control Panel Connector Pinout

Pinout information provided by Daniel Hamilton.

The pin arrangement on the 8-pin header forms the center of the 12-pin headers. This allowed IBM to continue using the existing "Control Panels" on both 8-pin and 12-pin "Control Panel" headers.

85xx Models 95xx Models

Pin Description Pin Description
1 PWR LED - 2 PWR LED +
3 HD LED + 4 PWR Sense +
5 HD LED - 6 PWR Sense -
7 Audio - 8 Audio +
Pin Description Pin Description
1 N/C 2 N/C
3 PWR LED - 4 PWR LED +
5 HD LED + 6 PWR Sense +
7 HD LED - 8 PWR Sense -
9 Audio - 10 Audio +
11 -12 V (Amp) 12 +12 V (Amp)

Note: Both views are at the face of the plug or socket. So, the oddity of the numbers being "flipped" top to bottom is correct. Think of plugging the plug into the socket, now the pins match.

Warning: Pay attention to the pin numbering (the pins were previously marked in a non-standard order). Incorrect cable wiring may lead to damage! Dan Hamilton blew one of the LM386 amp ICs on his Ultimedia module by mis-wiring the cable following the misleading (now corrected) numbering scheme.


8-pin Cable on 12-pin Header

Why a 12-pin connector? Not all 9557/9577 were Ultimedia, so it was cheaper to use a 12 pin header for both 8 pin [2x4] and 12 pin [2x6] cables. Can't do that with a 10 pin [2x5] header, odd number of columns, the older 8 pin cables would not fit (key would be offset).


12-pin Cable on 8-pin Header

It's possible to use the 12-pin Ultimedia Panel connector with a 8-pin planar header. See HERE for more information.

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Louis F. Ohland, Peter H. Wendt, David L. Beem, William R. Walsh, Tatsuo Sunagawa, Tomáš Slavotínek, Jim Shorney, Tim N. Clarke, Kevin Bowling, and many others.

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Last update: 29 Sep 2024 - Changelog | About | Legal & Contact