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Now that the North Star Horizon motherboard and power are sorted, along with the Compupro CPU-Z and RAM-17 boards, it's time to try to revive the DJ/DMA fdc. Actually, I have two of the boards, so I'm hoping I can get at least one working. I'm starting with the one that I bought off Ebay a year...

My North Star motherboard seems to be in working order (thanks, everyone). I decided to plug in my Compupro CPU-Z board and try to sort it out. At first it seemed to be working okay, at least I was getting a good clock signal and RESET* seems to work. I installed a couple of 2kx8 EPROMS that...

I suspect the reset switch on my North Star Horizon no longer functions; I get 0L on the multimeter on both switch positions. The switch was made by Carling Tech. One position is the default, with the other temporary. I’ve had no luck trying to locate it, although I was able to locate a Carling...

This is to follow up on a thread I started a while back about my dead North Star Horizon motherboard. After repairing the traces and a bad resistor, I decided to replace the original linear power supply with a switching power supply, specifically a Meanwell HRP-75-7.5 and two RS-15-15s. That's...

Hi all. I've got a 1981 revision of the Morrow Designs DJ-DMA fdc. It used the hard-sector North Star format for its 5.25 inch disks. I suspect the chips board got fried at some point when I had power supply issues, so I'm in the process of replacing them. If any of the PROMs were trashed, I may...

About a year ago I fired up my ancient North Star Horizon. It had sat since about 1986. Lo and behold it worked...for a couple of weeks, after which it would no longer boot. I finally got myself a multimeter and started checking voltages on the motherboard (it's been 40 years since I've done...

Hello from the US! I ran across this group the other day and signed up. Way back in 1978 I built a Northstar Horizon computer from a kit, which I used up until 1986. After that it sat in the garage for 34 years gathering cobwebs and bug parts. I brought it out the other day, cleaned it up...