Les Bird, H-8's and their repair

Ordering and contact information can be found in this notice.
Last updated June 4 2009. To return to the S-100 repair page click here.

Les Bird collects Heath computer like the H-8 and H-89. He not only runs them, and repairs them, but he even makes new boards for them. Check his Web site for the SEBHC archive and his hardware work. In June 2009 we had some conversations about repair and restoration. - Herb Johnson

In addition to many disk images and ROM dumps available on my website I also have several newly designed PCBs for the H8 computer that I offer to those who are interested. I designed the PCBs myself using KiCad, from the schematics of the original boards from the Heath company. The problem I was having with my H8 computers is that they were becoming unreliable due to the age of the original boards and finding replacements was getting more and more difficult. So I set out to design new boards that replicate the originals as close as possible and that can be assembled with readily available (for the most part) components. [Check his Web site to see and buy some of those H-8 boards. - Herb]

Connector failures on the H8: I discovered this problem after spending quite a bit of time trying to figure out why my H8 was so unreliable. There are two 25-pin plugs that come from the front control panel and plug into the buss directly behind the control panel and just in front of the CPU board. Sometimes the plugs in these connectors get partially pushed out of the connector housing itself and don't make good contact with the pins on the backplane. I only discovered this when I pulled off the front cover and the front control panel PCB when I was trying to isolate the problem. Just make sure they are firmly pushed into the connector housing and are making good contact with the backplane.

As for the expansion cards, be careful when plugging them in. A lot of times the pins on the backplane will get pushed through the PCB and you won't even realize it. You can get a flashlight and look behind the backplane to see if any pins are pushed through. I discovered this once when I thought I had some broken pins on the buss connectors but I realized they weren't broken after all, just pushed in.

diskette read errors I actually have "copies" of [the Corvus and Magnolia software I'm looking for] that I made way back in '84 in hopes to someday acquire a Corvus hard disk for my system. Unfortunately the disks are unreadable.

[I told him: "I work with floppy drives all the time. Some simple suggestions if you don't mind. Clean the heads of your floppy drives, with Q-tips and alcohol if you can. A little bit of iron oxide in the head gap of the drive will reduce the signal from the diskette. or try other drives, it may be an alignment issue (on the diskette when written)."]

I discovered that [trick] during my archival period when I was trying to copy all my data from my floppies. I couldn't figure out why so many of the disks were not readable until I took my drives out and looked at the heads. A Q-tip with alcohol did the job. Also, remarkably, I took your [other] suggestion and tried a couple different floppy disk drives and incredibly I was able to find one that would read the MMS floppies I had here. I was able to copy 99% of the files off to my SVD and save them as disk images. I think there were only 1 or 2 files that it wouldn't read. I think you were right about it being an alignment problem. What a relief it was to be able to save those files. The only thing I didn't have was a 32K MMS BIOS to boot from. I think I forgot to copy that file when I made these disks back in '84 but I did get all of the Corvus utilities. I will sort out the files and put the disk images up on my website soon.

Copyright © 2009 Herb Johnson