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ADB Information

To do ADB, you'll need

  1. A CPU board with the Turbo chipset. The Turbo chipset includes the ADB transceiver. Most Turbo systems are 33 MHz 68040 boxes. There are a few hundred systems with the Turbo chipset that run at 25 MHz.
  2. A v74 or later ROM. This is the first production ROM that contains the code that probes for the presence of the ADB keyboard. (I've run across a few machines in the field that do ADB with v73 ROMs, but these were pre-production 'science experiment' ROMs, complete with bugs.)
  3. A new cable. The ADB bus uses a previously unused pin on the cable between the Sound Box or monochrome monitor and the CPU board. The newer cable adds a conductor on the previously unused pin. The newer cables will also work with non-ADB equipment.
        Cable                    ADB            Old Non-ADB
          NeXTcube                4534            150
          NeXTstation             4535            1532
          NeXTstation color       4536            2286
  1. ADB sound card. You'll need an ADB sound card in your Sound Box or monochrome monitor. These can be identified by the ADB jack (4 pins + locator) used for the keyboard connector, and by serial number prefix. Sound boxes manufactured with the ADB sound card are series ADD. Monochrome monitors with the ADB sound card are series ACX (going by the one sample I found!)

When using ADB peripherals with the NeXTStation Turbo Color, the monitor vertical refresh rate is set to 72 Hz rather than 68 Hz. NeXT switched monitor models when the ADB keyboard was introduced, and used the keyboard type as a cue for what monitor was connected. When used with a 68 Hz refresh 17 inch display, the only visible effect is a slight distortion of the top 1/2 inch of the display. (Assuming the hardware was OK before, of course!)


Mono slab monitor won't stay off

 I have just obtained an old mono slab and, to protect the monitor from
dimming problems, I'd like to turn it off when it's not in use. However, the
slab doesn't seem too happy about this, and turns itself back on shortly after
powering off :-)

   Is this a feature (i.e. can I stop it doing this), or is there Something


Log in as root, open the Preferences application, and turn off the
"auto-power on after shutdown."

That feature is there for sysadmins who didn't want the users to be able
to turn the machine off.


I turned that checkbox off already, with no effect. What does ticking that box do, set a
flag in a config file somewhere, or do something to the hardware (PRAM or something?)?


It sets a hardware register.

Try opening up the machine, remove the battery overnight, and then
replace it and try again (This will have the side effect of deleting
your hardware password, if you set one.)

Using a cheap PC Power Supply for a NeXTstation

I performed the above procedure now twice, but my power supply only lasted 5 mins the last time. Either something else is broken, too, or the little chopper ceramic plate is cracked too much and too uneven now to make proper heat contact. Since Sony, who made the original power supply, decided to use these thick film modules, further repair is made impossible, especially since I could not find any source of these very special replacement parts. Therefore I decided to use a cheap (< DM 100) PC power supply for my NeXTstation.

Obvious drawbacks are:

  • it won't fit into the NeXT housing and has to be placed outside
  • it does not support the electronic power on/off (but see below!)
  • less obvious is that the b&w-NeXT needs at least 2A @ -12V, during startup up to 3.3A @ -12V are consumed for a few seconds (for the monitor!), while most PC power supplies only supply 0.3A @ -12V. This does not apply to the color NeXTs, as the huge current on -12V is only consumed by the black&white monitor, which is powered by the NeXT directly (the monitor is also the one part that increases the +12V current to 4A).

Before you start, be warned: there are lethal voltages inside a power supply! Only do this if you know what you are doing! I am not liable for any damages you might incur. This is only information for the expert, i.e., a trained TV service repair man.

How to increase the -12V current rating

So first you have to increase the rating of the power supply at -12V (only for b&w NeXTs, not color NeXTs, where the monitor has its own power supply). Luckily, sometimes the same coil of the transformer is used for +12V and -12V and only the rectifiers are the current limiting parts.

I should be very clear here: to increase the 12V current rating for b&w-NeXTs you must have a type that uses the same coil for +12V and -12V!! Otherwise you could ruin your NeXT! And I learned that these (older) PC power supplies are hard to find these days. So be warned, not all PC power supplies are usable!

It is hard to give general instructions here since the PC power supplies vary a lot, so you are basically on your own. Replace the -12V diodes with stronger Schottky-type diodes. I used those in a TO220 housing (MBR1030) and mounted them to the wall of the metal housing of the power supply, for cooling. Of course you must mount them isolated as otherwise you would shorten out your new power supply. In Germany the company B├╝rklin has isolation kits, but I am sure Radio Shack will have them, too. You can also use axial Shottky diodes, e.g., SB530 should do. I my case I also had to bridge a low-Ohm resistor in the -12V path. It is a good idea to ramp up the -12V smoothing capacitor: use a 1000F, 16V capacitor in parallel to whatever is already in there.

Next, test your new power supply using lamps of the appropriate rating. Test it at full load (see specs of the old power supply above) and for a long time, I recommend one hour. Measure voltages and currents.

If all is fine, you have to cut the power connector from the old power supply, remove the old supply from the NeXT, solder new, strong (1.5mm^2) wires to it (use the hole of the former AC connector to get the wires outside), and connect it to your new supply. Make the wires as short as possible, best less than one meter. For isolation of the soldering joints I recommend "Schrumpfschlauch" (called "shrink wrap" or "heat shrink tubing": black rubber sleeves that you put on the wire, and then shrink down with heat). Watch out for the color coding of the wires: the NeXT uses a different scheme than most PC-type supplies:

line	NeXT	PC
+12V	red	yellow
+5V	yellow	red

Do not connect equal colors but equal voltages!! Look at the pinout of the power supply connector.

Reset/PowerGood for the NeXT

The one thing left is the PowerGood pin of the NeXT. I tried connecting it to the PowerGood outlet of my new power supply but it did not work. The NeXT expects a long (1 sec) low signal here while the PC power supply sets PowerGood to high much too fast. I am still working on this, but I hope that a simple 555-reset timer will be good enough. ...YES, indeed I tested it and it works just fine! Have a look at the circuit diagram (also as GIF if you can't handle tiff!).

Adding electronic on/off switching capability

Since I was tired of switching the supply on and off manually, I devised a simple circuit with triacs to switch the new power supply on and off electronically from the NeXT power button. Here is the circuit diagram I am using (works like a charm). The MUC3043 is a special zero-crossing opto-triac. This works for 230V AC line voltage, but could also work for 110V (I am not sure about the current rating of the triac).

Now I have the same functionality (keyboard power on/off, no manual intervention required) as with the old power supply. I leave my NeXT running almost all the time and the PC-type supply works without any problems now for over a year. Highly recommended!

Slab will not power down

This is usually a symptom of a process which has not died properly. Several daemons can do this.

Try this.

Logout. Login as 'console' with no password. run 'ps -auxwww' and see what is still hanging around. There will be a certain amount of processes always running. There are some which stand out. Hopefully it will be clear. Try sending a 'kill -15 PID' (where PID is the process number, which you'll see when you do 'ps'). If 'kill -15' doesn't work, try 'kill -2 PID' and then 'kill -1 PID'

If and only if that all doesn't work, use 'kill -9 PID'.

i had a similar problem and i finally realized what was going on after doing some tests. In my case, a modem which was connected to the serial port but not working correctly was hanging my box.

try disconnecting whatever peripherals you have and see if it shutsdown properly.

See Also