Computers in Collection

DEC MicroVAX II, serial … {#…}

Initial Bring-Up

20190625 Photographed the system as configured when received. Removed all the cards and photographed them. Followed the Owner’s Manual (MicroVAX II 630QB):

Halt Enable/Disable switch to disable (down) position.
Mode switch to middle (language inquiry) position.
Baud control knob for the console terminal to 4800.

Attached a USB-serial adapter between my laptop and the system and started “screen” at 4800 baud. Disconnected power to the hard drive and tape drive. Booted system with only processor card installed. The system powered up and sounded decidedly anemic. LEDs were lit on processer card, as was the single digit LED display on the back. It showed “F”. I got no activity via the console. A null modem adapter didn’t help. I tested the voltages at the hard drive connector, and both 5V and 12V were low – about 3.5V. So whatever supply was driving those voltages requires more load, or is plain busted. I daringly tried booting with the tape drive plugged in, but that didn’t help. Then I tried with the hard drive plugged in too. The hard drive spun, but there was a frequent clicking noise, presumably the head servo or parking mechanism. Voltages still looked low – 10.5V on the 12V rail, and it dipped every time the hard drive clicked. I also noticed the green LED labeled “DC OK” was not lit. Well, OK. Feeling more brazen, I decided to plug in a RAM board. If anything would draw a lot of current, that would. Upon powering up, the fan motors sounded quite a bit more vigorous, and I got console output. I continued to noodle with the system, trying to get past the “2..” point on the console. The hard drive would periodically spin down for a second and then back up again. And booting would end this way:

KA630-A.V1.3

Performing normal system tests.

  7..6..5..4..3..

Tests completed.


Loading system software.

  2..
?40 NOSUCHDEV
?06 HLT INST
    PC = 00800EE6
Failure.
>>> 

I removed the front panel earlier, to see what was up with the two “aftermarket” switches on the front of the system. One of them was not connected at all. The other looked to be connecting or interrupting a pair of signals in the hard drive. Upon putting the switch in the other position, the drive stopped periodically spinning down for a moment, which I imagine makes reading data from the drive a bit easier… Now, boot would reach “2..” on the console (and “1” on the LED), but eventually spit a “?P54 TIMEOUT”, try again, and spit P54 again, then stop. It’s possible there’s nothing on that drive, so I should expect that error. But perhaps there is an operating system on the drive, and the drive is mechanically unhealthy. I’ve heard of MFM/RLL drives of this era getting sticky in their head servos. So perhaps I’ll lube it tomorrow and see if that doesn’t get things moving.