Need help: DSD-440 with unresponsive formatter/control board

[Julian Wolfe]

So the DSD-440 I got at VCF is completely unresponsive.  All of the LEDs are on and never go out, which is bizarre - they are supposed to go out in 1/10 of a second after power on.



I tried disconnecting everything but power to the card, and it still lights all LEDs.  No jumpers that I could find are in the wrong spot, but many are seemingly undocumented ( I looked in both the 1981 user manual and 1984 service manual on Bitsavers).



The drive just spins and does nothing else.  Altering the switches on the control board do nothing to change the state of the LEDs.



I measured voltages at the power supply, and they seem to be within spec according to the manual.



Are there any other things I can try before I start digging into things on a component level?