I’m getting a BOOT ERROR DC (disk controller) on my TRS-80 Model II.
I’ve read about the error here:
I’m not always getting that error message.
Sometimes when I turn on the power, I get INSERT DISKETTE, but when I insert the disk nothing happens. Other times, I get the BOOT ERROR DC message. There doesn’t seem to any rhyme or reason as to when either message pops up. It’s hit or miss, and I can’t do anything to make one or the other happen at any particular time.
When the BOOT ERROR DC message pops up, I notice that the head on the Shugart loads, but the head never moves (note: the head loads sometimes but not always). I thought maybe the stepper motor was bad or not getting power, so I removed the drive and checked it, and the stepper motor is fine. When the power is off, I can move the head easily by turning the stepper shaft where it sticks out of the back of the motor – it moves easily, and isn’t binding. When the power is on, I can’t manually move the stepper shaft as the motor is energized, which is as it should be.
I get this BOOT ERROR DC whether the disk expansion unit is connected and turned on first or not.
So far I’ve done / checked the following:
- checked the drive, as mentioned above
- tried three different disks that I made from images provided by others and Bitsavers
- removed all socketed chips on the four cards in the card cage, and reseated all those chips
- removed and reseated all RAM
- replaced each row of RAM with known good RAM (one row at a time), reinserted the card and rebooted after each row was replaced – it made no difference
- removed and cleaned (with electronics cleaner) the connectors on the backplane
- used an eraser (to clean the contacts) on the connectors on the four cards in the card cage
The Model II Boot Errors Table says the BOOT ERROR DC occurs because of:
1) Defective diskette – try a different diskette
2) Floppy disk expansion unit not on –turn on the floppy disk expansion unit
3) Defective FDC Chip or drive – Contact RSSC
Would the errors I’m getting be representative of a failed Western Digital 1791 or some failed SN74LS chips on the FDC, or could I be looking at some other problem?
I feel like I’m headed down a dead end street which I’m hoping is really a cul-de-sac.
I’m now thinking I’ve got two directions I can go in – borrow or buy another FDC to see if that is really the problem, or replace the Western Digital 1791 and all the SN74LS chips on my FDC.
Does anyone have any other suggestions/directions I should go in?