kbs1

Vintage - MFM data connector on ST-251-1 plugged in backwards - dead?

8 posts in this topic

I own an old 286 PC made by DTK, it's called 'Mini 286'. It's equipped with 1mb ram and it's made in 1989. It was laying in my closet for 6 years now. I've remembered it might be a good time to change the CMOS battery. I was too late, it has already leaked. I disasambled the whole PC, resoldered a new battery, cleaned out the corrosion and it works just fine. I gave it a perfect clean. There is not a dust particle left. I disassembled and cleaned everything, including the power supply. I've never cleaned the PC before, so now it was a good time as I had to completely disassemble it to remove the main board from the case.

Eager to get it working again, I plugged in the data cable of the ST-251-1 the other way around (on the controller side, as the disk side is keyed). Now the bios was dead (obviously since I've changed the battery). I did not remember the "hard disk type" off hand. So I googled. I found this drive should be either type 30 or type 44 on my system. It has 820 cylinders and 6 heads. 44 and 30 are the only two types that match up in my bios.

However the drive is still dead. The green led comes on a couple of times at bootup, and the drive spins up, but the system says Physical disk 0 failure. What exactly has failed and can I ever know? It was plugged in the opposite side the first ~6 bootups before I gave up with the bios settings and started looking for a problem elsewhere. That's when I've found the flipped data cable.

The drive certainly did work before (6 years ago). Could I have blown something when I reversed the connector? The drive sounds normal and healthy.

Thanks

Share this post


Link to post
Share on other sites

Dear Lord...why are you even bothering ;)

This is way outside of my expertise but flipping the cable is never good. Regardless if it was that or the drive just died inside...they do that...it seems extremely unlikely you're going to get the drive you have in hand working again. eBay may be your best bet at this point.

Share this post


Link to post
Share on other sites

Well because I like vintage computing and I'd like to use the programs I have stored on that harddrive :) Any other folks with particular experience on MFM drives? Thanks :)

Share this post


Link to post
Share on other sites

I blew some ST-225s back in the day with reversed cables. Those older drives have some serious current going through the cables and powering them flipped even for a second often cooks something.

Also happens with older unkeyed floppy drives - some fry instantly.

Best case scenario is finding an identical drive on eBay and doing a board swap.

My vintage computers and stuff

Sorry :-(

Edited by FastMHz

Share this post


Link to post
Share on other sites

Thank you, drive is toast confirmed. Took me this long to find another drive in my area :) And that one works. At least nothing else is toast and the computer, HDD and floppy drive A works perfectly! :)) Thanks all for your help,

Regards,

kbs1

Share this post


Link to post
Share on other sites

Plugging in a MFM cable backwards will destroy the drive if memory serves.

Ten years ago I had enough of them laying around I probably could've sacrificed one to check. Tossed everything since then tho. :P:(

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now