Mike's PCjr Page

As I told you Chuck, the floppy drive power wire came off at some point in time and whoever tried to resolder it put it on wrong.. instead of wiring them 12V G G 5V they were 5V 12V G G. Horrible solder job too.. The 12V was always shorted to ground. Once I had the wiring corrected, the Racore PS ca...

You have a modem, an 8087 coprocessor daughter board, and wrap plugs from the maintenance manual there. Oh, and a loose BIOS ROM chip. I have never seen the coprocessor daughter board in real life. Take good care of it, it is extremely rare. Is that a modem? It has an RJ jack of some kind, but it j...

I want to be sure the small board in the last picture that is close to the large yellow cap is not touching the Heat sink it looks to be leaning against. The small board has a backing on it that protects is from touching the heat sink. Now your comment about the 110 v drop tells me that the switchi...

Hi Chuck, Here is some info that kind of explains the situation. I know it's difficult to resolve problems like this by description and pictures. I sometimes have customers that hold the phone up to the Automatic Doors I work on and say "Can you hear that? What do you think?" :lol: I reall...

Hi Chuck, Trouble shooting my Racore power supply.. After performing some tests too monotonous to go into, I really feel this power supply is the problem. I'm thinking about the PT-65-B switching power supply you mentioned. The DC voltages I would need are +5 (x2), +12, -12. I am not sure of the cur...

I followed the instructions and installed the drive. It was just sitting on top disconnected. The original owned could not get it to work. I couldn't get it to work either. Something seems to be loose as the hard drive suddenly started to spin, but then stopped when I jiggled the cable. I could not ...

ChuckB wrote:I find the one with the toggle switch interesting and the same as on yours(?) What is it's function?

Figured it out:

Quite a few upgrades you have going on there Chuck, although some of them are over my head, being the PCjr novice I am. Nice sanitary job on the switches. That internal power supply will be nice! As many would agree, I am sure, those bricks are a pain! Amazing are those 3D printers. Yes that is a du...

I had planned to wait for my keyboard to arrive, but I booted up my PCjr.. booted as it should... went to basic without a disk, booted up with a DOS disk and wanted a new time and date. I have the Racore fixed disk upgrade, but it's seemed to be dead. I checked the voltages at the register chips and...

Brutman wrote: You find this interesting for background: http://www.brutman.com/Mouse_Systems_Op ... Mouse.html


Mike

Nicely written Mike.. very informative.