• Please review our updated Terms and Rules here

DEC Rainbow PC100 restoring

D

demonlg

Veteran Member
Joined
May 22, 2016
Messages
521
Location
Italy
Hello to all.

I have another computer to restoring, the DEC Rainbow 100. This computer is powered off many yer ago, i dont' know if it stored in working condition or not, but now is not relevant.

The original monitor have a very strange problem, i have found other photo on google with same issue, the front have a bubbles on all surface, i don't know if secure to turn on int, but internally is very clean and apparently with not blowned components, really clean and really with very little black powder deposited as in the usual CRTs.
Now, i have a similar tube, but i don't find any documentation of this original tube, i need to try replacement of only tube and with installing the original deflection yoke on my tube. I have noted a perticulary on original tube, the high voltage headset of the eat is on the bottom of the monitor, unlike others where I find it in the upper part or at most lateral left or right.

Now i think so probably the deflection yoke are inverted too, and if i try to replace tube i have to asemble the original yoke on the new tube with correct way.

Can anyone have a full complete schematic for this computer and our monitor?
Then, what do you recommend to proceed for the restoration of this computer? disassemble it into pieces, clean it and which checks to do first?
Thanks

Emanuel
 
Regarding the bubbles, these defects are referred to as cataracts. It is from the safety layer delaminating from the glass due to failed adhesive.

It is safe to use, just very cosmetically ugly.

Repairing this might not be as hard as you think. Usage electric has a recent video where he repairs a monitor with this condition:

 
WOW, thanks silver, it's a very good guide from you, i will try this. Very very thanks for now.
 
Yes, i have resolved the monitor issue with this guide, very strange operation but the result is very fine, now i restoring and test other computer component. If have a problem i write here.

Thanks

Emanuele
 
Hi again.

The computer is working! Fantastic, i have recapped the psu, system boot up from original 10mb hdd after 30 year of stop, incredible, it say first TESTING then i have a boot select screen and 2 selection, cpm or ms dos, cpm won't boot because is lost a file during startup, msdos boots perfectly, request date and time and then go into a software selection tools with file manager, lotus 123, printing and other.

keyboard worling perfectly.

only little problem on a monitor, it have a little restriction of vertical amplitude and the other problem is on the contrast and brightness.

the rear contrast regulation is to the max value and brightness at middle but are present the retracing lines. i think so the brightness is ok but the contrast is low.

Any idea to check on the monitor?

The drive a try to format disk but then its not complete formatting and say formatting failure

The drive b wont start to format, the motor spinup but led stay off and say formatting failure.

Thanks

Emanuele
 
I have checked and clieaned drive, checked belt and PCB capacitors, all are ok, then the drive B need a floppy inserted to b side to work, drive B reading correctly original system disks, but both drives not formatting and Drive A won't read and formatting disks, i have tested more floppy working on a pc or commodore computer, and i have tested 48tpi and 96 tpi disks but nothing, il try to format, heads move to sector, but then it says Formatting Failure.

I have connected the drive into a BLUE connector on the mainboard controller, it's correct or i have to use black connector?

Emanuele
 
Also remember that on an RX50, the disk inserted into the lower slot needs to be put in upside down !

800px-DEC_RX50-AA_5_%C2%BC%E2%80%9D_dual_floppy_disk_drive.jpg
 
demonlg said:
I have checked and clieaned drive, checked belt and PCB capacitors, all are ok, then the drive B need a floppy inserted to b side to work, drive B reading correctly original system disks, but both drives not formatting and Drive A won't read and formatting disks, i have tested more floppy working on a pc or commodore computer, and i have tested 48tpi and 96 tpi disks but nothing, il try to format, heads move to sector, but then it says Formatting Failure.

I have connected the drive into a BLUE connector on the mainboard controller, it's correct or i have to use black connector?

Emanuele
Click to expand...
Hi Emanuele, have you tried reading an original DEC Rainbow floppy disk?
the new RX50 floppies are preformatted at a low level and it is normal that generic ones cannot be formatted.
It is however possible to restore a CPM disk image (TD0) using a PC and teledisk. later you can format this with DOS and CPM on the rainbow.

Nicola
 
Yes Na 103, i have raded original disk of dos 2.0 but only on bottom bay and with disk in upside down, in the bottom drive it's don't readable, drive is cleaned and lubricated and heads seems to be ok with multimeter testing and confronted with the bottom heads.

And what is the correct way to format a new disk? i have tried with dos command format b:/i the /i because without it says initialize disk needed, but the formatting disk start but not completed (on bottom drive) on the upper side drive won't start anything!

Emanuele
 
Hi gary, i have recapped all monitor board, any capacitor in loss of capacitance, now the screen is correctly vertically opened and contrast is good, not perfect, i have tried to move the CUT OFF trimmer but is at the maximum at default, i don't have checked the trimmer rear external regulation, i will check it.

Emanuele
 
demonlg said:
Yes Na 103, i have raded original disk of dos 2.0 but only on bottom bay and with disk in upside down, in the bottom drive it's don't readable, drive is cleaned and lubricated and heads seems to be ok with multimeter testing and confronted with the bottom heads.

And what is the correct way to format a new disk? i have tried with dos command format b:/i the /i because without it says initialize disk needed, but the formatting disk start but not completed (on bottom drive) on the upper side drive won't start anything!

Emanuele
Click to expand...
You can't format a generic floppy disk unless it has been low-level formatted first.
You can't do low level formatting from Rainbow. they were sold by DEC ready-made
one solution is to restore an original disk image of a disk (from the PC with a 1.2MB drive) with teledisk and then format it from the Rainbow.
Sunday 8 October I will be at Brusaporto Retrocomputing with my Rainbow 100, I will be happy to show you this and other things if you are present.
 
Wow, you are Italian... not probably i'm not present, but i have now idea of this, i have the GREASEWEAZLE tool, can i have to made disk from image file with this?
 
You can format a floppy on the rainbow from MS-DOS 2.05 and later using "format a: /I". The /I (Initialize) flag will do both a physical and logical format, allowing non-RX50 formatted disks to be formatted for the RX50. Normal double density floppys are fine. Rainbow MS-DOS 2.01's format command doesn't have the /I option. See page 59 (document page 3-6) of this PDF: http://www.bitsavers.org/pdf/dec/ra...S-DOS_V2.05_Technical_Documentation_Nov84.pdf
 
Nice to know. I had tried to format a "new" floppy. It never complained but it would not read on the Pro-350. So I will try this to see if it works. Thanks.
 
For the Pro-350, you'll need to format the disk on the Rainbow with the /I option to get the physical format, then format again on the Pro-350 to write the logical formatting the Pro-350 expects.
 
Did not know any of this. Will try the next time I am on the Rainbow and Pro. Now if I could just figure out how to transfer files to the Rainbow via the serial port. Tried running Kermit that I have on disk on the Rainbow and sending the file from my laptop. It never sent. I am sure I did this once, but can't remember what I did back then. And I likely sent the file the other direction.
 
Back in 1993 or so I used my 1.2MB HD 5.25 floppy to read/write Rainbow disks. Teledisk to write images, and if I remember correctly there was a device driver that allowed DOS to read/write the Rainbow disks directly.
 
You must log in or register to reply here.
Back
Top