Mike's PCjr Page

Okay, I had time to try and adjust the RPM on the drive and could not get it to the correct RPM. I even took my good drive out under the same fluorescent tubes and saw that it was showing a good solid 300 RPM. But for the life of me I could not get this drive to the right speed. Having watched a vid...

I think it’s interesting that you see the same problem when using two different motherboards. Things to try: If you have a normal, full-size ATX power supply, try using it instead of the picoATX. The full-size supply probably has less noise, will be at a greater distance, and will be enclosed in a ...

I also ran the built in tests for the floppy drive and got an error “C”…which I don’t see listed in the PCjr hardware manual as to what that means…other than it failed. Try running the tests when the “JJ” service plug is plugged in. That will give you more detailed codes : DISKETTE DIAGNOSTIC ERROR...

Is it not reading disks at all or is it not reading disks from other drives? I have had drives go out of alignment where they cant read disks from other drives but can read disks that are formatted on them and read them just back fine. Alright, I had some time today to tinker with my non-working 5 ...

If I’m reading you correctly, your two systems do have shared components: power supply diskette drive diskettes jr-IDE I do have a jrATX power supply and the original long board, so I do have 2 different power supplies, although the King's Quest problem follows the jrATX every time (almost, I did g...

Take my advice - avoid it like the plague. Do not start desoldering things for fun, only darkness and despair lies on that path. (1) Chips are heat sensitive. Motherboard traces can be lifted and damaged. It's a labor intensive process and you run a high risk of damaging something. Even just gettin...

I usually suspect RAM when a system is unstable, but diagnosing RAM on the motherboard is pretty difficult without removing it. It's also not worth the risk of damage. Based on that, go with what DoctorOctal just wrote ... use the built-in diagnostics to see if you can force the error. Bad RAM is i...

I think your RAM is probably OK. If you ran the POST loop 15 to 20 times with the service plug and didn’t get any errors, that’s a good sign. To test further, plug in the “JJ” service plug, press Ctrl-Alt-Ins to get into the diagnostics, and let the RAM test run in the background for a while. You’l...

I'll post "jrMD" later tonight - it's a memory tester specifically for the Jr. EDIT: Find it under jrMD.zip at https://www.brutman.com/PCjr/pcjr_downloads.html I was attempting to run the jrmd tool today and ran into an issue. It says the range of memory couldn't be tested (it defaults to...

Thanks much! I'll try to give that a shot when I have time. (background: I have a 1.5 year old so I rarely get time to work on the machine). I did manage to get some testing done today: System + 64k internal card and jrATX power supply. I ran the repeated POST test using the service plug in the PCjr...