Mike's PCjr Page

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 directly off the power supply.. zero volts. Does any one have a schematic for the external power supply? It's the big black metal cased one that connects with a DB9 serial port connector to the back of the upper drive. I have the installation instructions, but everything seems to be in order. Worse case scenario, if I cant get this to work, I will remove it.. I have included some pictures.

wow first time I've seen the Racore Hard Drive unit..
I have the mem Expansion on one of my systems but I like the three stacker..

also is the hard drive side card just a 'dummy' holder for looks ? ie. is it empty ?

You may want to consider a switcher power supply, in place of the original.....
I have looked and even called some companies trying to get Racore/Rapport schematics.....no luck..
Below is my system with a switcher I am putting in..

I have a Third stack on my COLOR system

I KNOW I KNOW! COLORS....
before I get beat up again for painting the JR, this is a SPARE system I wanted to have fun with...

this system 'currently' has 5.25" 3.5" , the top unit will have a USB Floppy emulator and also I plan on
putting Alan's Jr-IDE as a side car on here..
The side car's are the Racore 512K expansion with LPT2 and a second LPT converted to LPT2 and Bi-Directional for the ZIP100 DRIVE.
the last car is an IBM 128K to bring the system up to 640K


if you look at the back you will see a 'BLACK' button on the RED chassis bottom, this is for Alan's TANDY MOD card
to turn it ON and OFF, I extended his little boards slide switch out the back for ease of access...

next you will see the small 'outboard' case with Switch and Push button. 3D printed and painted.
this is for the PC-SPRINT card, it toggles the SPEED function ON and OFF as needed and the Pushbutton is the JR - RESET
I also have the V20-10 chip in this system...

things to come:
(SORRY IF THE PICS ARE OVERSIZED, just zoom out if needed)

I plan on putting a switching power supply in the top most unit to power the entire system.
This will make the system a single power cord solution with no more 'bricks' hanging off the back.
I'll also use a small 30mm fan in the top unit for the power supply.
the power supply is a PT-65-B ( mouser) it has +5V 5.5A, 12V 2.5A, -12V 0.5A
The plug in board into the main board connector is from Shelby's efforts you can find him on YouTube 'akbkuku' is his name there.
He has another nice solution for power in the JR, but I choose to use his board as a wired solution to the switching power supply.
I plan on wiring a breakout connector for the floppy drives and Racore Power connector off the Switching power supply, still to be determined how best to do this...

Next are the ON/OFF power switch and the AC Power Jack.
As shown I made a couple 3D printed parts to help fit the switch and power jack.
these help keep the parts in place, the Switch, I used a drop of super glue to keep the 3D printed collar on the switch.
the power jack is a slide fit after you put it thru the back hole where original power cord would normally be.
PS: both the parts are an EXACT fit with no need to cut or enlarge the original Jr Case...
power rocker switch GRS-4012-0026 ( mouser )
AC power entry jack 4300.0105 ( mouser )
power cord 6010.5274 ( mouser )

Also 3D printed is the 'side plate' on the top most addition, this unit did not have a cover plate, so I had to make one, turned out ok..

Lastly is the addition of my Floppy 3 drive board that I will have coming soon..
this allows 3 drives to easily be added with individual cables and also a way to switch which drive to boot from using a selector switch if desired..

again.....this is just HAVING FUN.....

Speech Card still in the design phase..
















..

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 dummy portion of the top drive housing.

Isn't my power supply a switching power supply? Maybe it doesn't operate without a load and cannot be tested directly with a meter?

Attached are pictures of my side cars. I haven't identified them yet. I find the one with the toggle switch interesting and the same as on yours(?) What is it's function?

My other card appears to be a network card (?)

Those colors look fine to me!

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:

the switch is to place the operation in true Jr mode or PC type mode.
ths docs for Racore/Rapport are here on Mikes pages he has a download area..

There are others on this board that have a wealth of knowledge on these addons, I am also coming back after about 15 yrs away from the Jr
so I am very rusty...
Your Pwr supply may have some switching features I have not looked at it in detail.
I have repaired a few of mine but it was simple transistor changes and replacing the Caps with new ones...

not a bad task, but well worth the effort...if you clean off the old heatsink compound and apply new, tighten all the screws on regulators to allow for proper heat transfer. they usually run ok.

there are many experts here and all,are helpful, most need to make time for this hobby and that can be a problem....
but it is fun....

let me know if I can help.... one thing is to checkd the toggle switch and make sure it works solidly, I had to replace mine is was sloppy.
Also inside is a battery for the Real time clock that will need replacing...

but we are having fun...

chuck

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 get it to restart. Also during this time, I had no video. I will continue to trouble shoot it.

As not to confuse things, here are pictures of the installed fixed drive... The picture I posted of it earlier is the way it was shipped from Racore. The hard drive is removed and installed in the old (2nd) top assy, which becomes the new (3rd) top assy.

Chuck...

First thing I noticed in the picture you do not have a power brick attached to the Upper unit, this is needed for that power supply...
I'm sure you know this.... the power bricks usually put out 16vAC or close to that so you may want to check , they rarely go bad
unless they have been abused.

check the power (4 pin plug) that powers the hard drive this has ( +5 Gnd Gnd +12 )
If you have a Volt meter.... Power up the system and check the Hard drive power connected mentioned above the 4 pin to be sure you have the
correct voltages...

sometimes the inside 'barrel's get a bit too wide and don't make good contact, also where the cable attaches to the power supply pcb
be sure the wire is not broken, ( but touching sometimes) as this is caused by flexing back and forth, the wires fracture and break.
Long shot here but the power connector on the hard drive, if you can look at the back side where it is soldered to the pcb, be sure
the connections have not fractured either, this is a long shot as I mentioned but worth looking at all the items..

let me know how it goes....

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 current requirements that I would need though. My plan is to keep it external using the same box and cable and serial DB connecter from the Racore. If I can get it to work, I might mount it inside the third case as there is plenty of room.

Picture from the external power supply. Here is a look at the voltages I need. I am not sure what the "pick" wire is for. Do you??




I have many years behind the soldering iron ! It appears well within my capabilities, is there anything I'm overlooking?



And yes, I was aware that all three power cords were not plugged in.. I was just showing what the finished HD upgrade looked like.




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good picture.....
so the PICK is usually what tells 'this' power supply to 'turn on' it gets a signal, usually 5V from the downstairs power supply , this tells the upstairs power supply
that the power switch has been turned on....
it is a way to 'sync' both supplies to turn on with only one switch..... it works well...

I have not seen the Racore power supply for the Hard drive addition, but I'm assuming that the ORANGE 5V goes to the second addon unit to power the memory board
and the RED is for the Hard Drive connector, but my guess is that they are both sourced from the same driver and maybe have a separate filter cap.
but the PT65-B will work fine, there should not be an issue with driving both memory and Hard drive with a single 5V source....

I will offer to look at the power supply if you want to send it my way.....

Also, back to the PICK. make sure ALL cables are connected or the top power supply may not turn on, just a note which I'm sure you already know...

Q: have you measured any of the voltages when turned on ? PICK ? and the ORANGE 5V ?

I'd like to see pictures of where these wires are connected to also....

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?"

I really appreciate your time and effort!

I measured the Racore PS voltages with the PS unplugged:

White (-12) = 8.69V
Red (+5) = 0V
Blue (+12) = 0V
Orange (+5) = 0V
Pick= 21V

All three power supplies plugged in and with everything powered up, the Racore power supply makes a high frequency squeal, all the results are the same except the pick goes to 0V.

The orange 5V wire goes to #4 of the floppy drive , also to the green (3 wires into one) of the colored ribbon cable that plugs into the Drive Two Plus side card. Also comes off the Racore internal power supply interface and with the small ribbon cable, goes to the 5V supply for the hard drive controller board (these are the two boards that came with the HD upgrade.

The pick wire changes to the blue wire of the colored ribbon cable that plugs into the side card with the toggle switch.


This is the connector going into the computer from the Racore PS:





This is the colored ribbon cable that plugs into the Drive Two Plus side card. All the way to the left is the green 5V wire.. third from the left is the blue pick wire :



This is where the 5V wire goes besides the floppy drive #4. Both boards are the ones that came with the upgrade. The board on the left I am calling "Racore PS interface" the one on the right is the HD controller board, connected by the short gray ribbon cable.



Picture of the PS :

EDIT: Something I should add..See the white and black pig tail in the power supply picture? That is coming right off the 110V input/EMI filter. It measures 110 Volts unplugged, but when I plug it back into the connector, the 110 volts drops to 14 Volts AC! Im surprised no fuse blows or something doesn't smoke!