Model 77 - Common Devices

77 System, Front
   Ultimedia Module
   Ultimedia Module PCB
     Ultimedia Module PCB, Top
     Ultimedia Module PCB, Bottom
   DIY IBM Ultimedia-to-CT 5330

77 Case, Rear
Remove Cover

77 5.25" Drive Bay Guides
   Remove Guides
   Guide FRUs
   Original 5.25" Drive Rail
   5.25" 77 Drive Rail Hack
9577 Drive Slide

9577 Air Baffle for Fixed Disk Drive Bay 4C
   Air Baffle Pasteboard Hack


77 Case, Front (40, 57 similar) Multimedia Model shown

77 Multimedia Module (Image and info from William R. Walsh)

M Microphone Jack
H Stereo Headphones Jack
HD Hard-drive Activity LED
VOL Volume Control
PWR Power Good LED
SW Power On/Off Switch

   Both standard and MM control panels have a speaker. Only the MM control panel has Microphone and Headphone jacks (1/4" stereo jacks). The MM speaker (behind the grille) is rated 1.5 W / 8 Ω as compared to 0.5 W at 4 or 8 Ω. The shape is an oval cone set into a square frame.

92F0002 Control Assembly - Without Volume Control (Power Switch, Cable, Speaker)
41G3929 Control Assembly - With Volume Control (Power Switch, Cable, and Speaker)

Multimedia Module PCB (outline and info by William R. Walsh)

CR1 Hard-drive LED
CR2 Power Good LED
J1 Ultimedia Port
J2 Front Panel Connector
L7, L8 TDK ZJYS-4
U2 Philips TDA1015 amp
V3 PCB Printing
SW1 Power switch

   I would assume that the connection to the sound card powers the onboard amplifier. With the sound card cable unplugged the volume control ceases to function and the speaker plays all beeps as a normal front panel would.

MultiMedia Module PCB, Top FRU 41G3929

CR1 Hard-drive Activity LED
CR2 Power Good LED
JA Microphone Jack
JB Headphone Jack
L6,7 TDK ZJYS-4
U1,3 LM837M Quad Op-amp
U2 Philips TDA1015 power amp
SW1 Power Switch

MultiMedia Module PCB, Bottom FRU 41G3929

F1 Fuse for Headphone Output?
JA Microphone Jack
JB Headphone Jack
J1 Ultimedia Audio Port
J2 Front Panel Connector
J3 Module Speaker Header
R40 Volume Potentiometer

92F0113 Cable (Control Assembly to Audio Card)
96F7762 Cable (Control Assembly to System Board)

DIY IBM Ultimedia-to-CT 5330 by pleonard (original post on VOGONS)

   Those of us (un)lucky enough to have collected an Ultimedia PS/2 know that the audio features of this machine are a mix of good and bad: great front-panel amplified speaker with volume control and headphone/mic jacks, coupled to a terminally-unsupported audio card (M-ACPA or AudioVation, choose your MWAVE DSP poison). The question is: how to connect that great front-panel speaker up to a useful sound card?

As you might expect, audio is connected through a proprietary 16-pin connector that plugs into IBM's own audio cards. A few 3rd-party boards (ChipChat among them) include this "Ultimedia Header", but Creative's own SoundBlaster Pro MCV (CT-5330) does not.

But since we have the pinout, and since you can buy 2x8 dual row headers, it should be relatively easy to solder up a R/L/Gnd cable from the line out jack on the back of the SoundBlaster Pro:


(believe it or not, those pins aren't shorted :>)

Ed. pleonard connected Pins 1 (R), 2 (Gnd), and 10 (L). But the wiring doesn't quite match the pinout! Yet it supposedly worked for him... hmm. Needs verification.

As you'd expect, best results are obtained by disabling the built-in amp on the SBPro. The result is very clean sound - contemporary (1991) reviews of the Ultimedia mention how these machines' own sound hardware obviated the need for external speakers for most users. Best of all, you can completely uninstall the original DSP sound card. (Your sympathies for the original IBM sound card will dramatically decrease when you discover how many dozens of KB of RAM it requires to produce sound of any kind in DOS...!)


77 Case, rear (57SX shown)

Remove Case

  1. Have front facing away
  2. Unscrew both thumbscrews
  3. "Slap" the top of the case forward using your palms along the sides of the case.
  4. When the top of the case moves forward an inch and a half, pull up.


77 5.25" Drive Bay Guides

Post Notches on the reverse that fit into the drive bay walls.
Latch Locks the guide onto the drive bay wall.

To remove Guides

   Press in the latch on the guide (rear of the drive bay) and push the guide forward.

Guide FRUs

   These are mirror images of each other, one for the left side, the other for the right side. If you make your own guide rails, you can cut the back end of the rail square, so it wouldn't matter if you used the same FRU on both sides The cutout for the gude's latches will allow you to switch the guides to the other side and they will work.

96F7371 (Black) Left Guide
96F7372 (Ivory) Right Guide

Original 77 5.25" Drive Rail

   This was "fun". On this rail, the screw hole marked "R" was the fixed hole, and it serves as the reference point for the important surfaces. Note that the center-to-center distance is 3.115". Measured that from a drive. One hole is usually slotted so there can be some variation between mounting screw locations on drives.

   Also, with any measurement, a few thousandths here and there doesn't matter.

5.25" 77 Drive Rail Hack

   Get the ubiquitous 5.25" AT Drive Rail. Cut to fit. Note the web sticking down at the end of the guide (.469"). This web has two functions - first, limiting the 5.25" device to the proper depth. Second, it prevents upside-down installation of a drive if you use the original drive rails with the matching extensions that fit the .469" rear.
   I used a paper cutter to whack the rails off to length. Use what makes you feel good - hacksaw, sabresaw, vertical mill, ESP... You can cut the rear end off flush- that "horn" is (as noted) to keep the drive "upright".


Fixed Disk Bay 4C Drive Slide 96F7775, 71G5706, 71G5708, 79F3300

Seems this is a little long for OAL for it to fit into the Model 90's lower drive bay.

9577 Air Baffle for Fixed Disk Bay 4C FRU 92F0251

   The older 8557 and 9557 used a grey colored baffle, same FRU.

   This was used in older systems with hot running drives in 4C. Modern 1" high drives should run cool enough without it, but if you want to run a 7,200RPM (or higher) drive in your 77, you MIGHT want to help cool it as much as possible.

Pasteboard hack

   I built a baffle for a 9577 that went from the top air grill on the power supply over to the D: drive bay above the control module. Worked fine. A little duct tape, some pasteboard, and shazzam! I don't have a 77 anymore to give you dimensions.


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