The best working Kaypro 2 stopped booting last night. Today I logic tested all the 74xx ICs on my T48 (minipro on the Mac FTW!) and found a bad 74LS373 that was causing it.
That unit is now seemingly stable. A second one usually boots, but one drive is extra flakey and the whole thing semi-locks up when it sits idle. The third one is a parts donor box now, especially after I accidentally fried one of the two custom ICs today.
Kaypro project done for now.
#retrocomputing #kaypro2 #cpm
Last note tonight: I have cleaned drive heads, lubricated rails, etc.
For the notorious TEC FB-501 drives, I have replaced all the electrolytic caps on the main boards and found minimal corrosion. Traces seem good where it was just starting. I need to do the motor boards next, but they seem currently clean and stable.
Regardless, things work and then they suddenly don’t and either the drives are the cause or the symptom. More analysis…
I will say that the state of the floppy drives seems very prone to disks getting corrupted when moved around between drives. One minute you’re good, then a drive stops working right and the disk throws errors in drives that were reading fine a minute ago.
Go rewrite the disk freshly in #greaseweazle and you’re back in business until the next odd drive freak out scenario.
I have learned a lot and the drives gave me the hardware and the need/excuse to finally use #greaseweazle.
So I’ve repeatedly made working book disks to aid me in the saga.
And tonight, I made a Kaypro floppy from scratch as an image on my Mac, copied files onto it with cpmtools, wrote a disk from it with greaseweazle and got Zork running on two of the units.
Then one stopped booting properly and the other gets unstable after it’s on for a bit. Progress.
Much progress made and many things learned on these Kaypro machines. Most of my time is spent getting the various floppy drives happy. One minute all is well, the next something won’t read or boot or write that was fine just a bit ago.
Fortunately, with three systems and six drives, I have lots of comparative swap ability for debugging.
I thought I had one fully working and a second close. Now both of those have issues again. A bit tiresome.
Opened up the second Kaypro 2 machine. Prior owner had a note on it: “no power - worked for a while”.
Yep. Dead. Then I happened to feel the back and realized the fuse holder was empty and open. So I swapped one over from the first machine.
Power flows now, but it makes a metallic tink tonk tink tonk sound with the rhythm of a clock ticking. No lights. Guessing something on the power board.
But this motherboard swapped into the first has me booting again.
@WoodooProd I did clean the heads before I ever tried a disk in them and they worked briefly on that machine. Working great on #greaseweazle every time. My floppies are factory sealed new old stock, so clean as well.
I just swapped the main board of the second unit into this one and it boots again with its same drives… so increasingly think something drive controller related died minutes into my first use on the first unit’s main board. :(
Well, that's fun. Popped the drives back on the Kaypro 2, inserted the floppy and it booted right into CP/M 2.2.
Ran a couple of commands. Worked nicely. Then on the next command I ran the prompt hung. Restarted it and it prompts for the boot disk but doesn't read from the either floppy now. Drives still both work fine directly on #greaseweazle.
So... worked for a few minutes, then the drive controller or something in it seems to have crapped out. <sigh>
Whoa - this worked better than I ever dreamed! #greaseweazle seems happy with this Hi-Tech DSDD drive. I wrote out a .td0 Kaypro boot disk seemingly without error. I'm about to go test it on the computer.
On a whim, I stuck in a floppy of M.U.L.E. that I made on my 1541 last night (from a .d64 on a pi1541). Greaseweazle wrote out a .d64 very quickly. I attached the image to VICE on my Mac and it's playing perfectly in the background as I write this.
At a glance, this first Kaypro 2 machine seems to have a SSDD drive A and a DSDD drive B, so that crosses the wires a bit on ID between 2/84 and 2X. More digging to do...
Meanwhile, I have pulled the DSDD drive B and am giving it a thorough once over as a potential #greaseweazle drive. It's a HI-TECH "Echo" 548-50. Have to go steal a 4-pin molex off some PC carcass in the basement to rig up a convenient bench power supply for it.
Will try to make a boot disk. #cpm #kaypro2 #retrocomputing
Aaron Mahler