DCC-116 E / DATA GENERAL NOVA 2/10 / Nixdorf 620 - Restoring and restarting

Dominique Carlier dce at skynet.be
Thu May 18 08:21:50 CDT 2017


Hi all,

Sorry for this long wait. Because of some family problems combined with 
a big professional project I had to put this project on hold. However I 
intend to continue this restoration with detailed photos and all the 
continuation of the adventure with a lot of informations ;-)

Since my lasts posts on cctalk I received the schematics of a DG Nova 
1200, all the information I needed to repair the power supply are in 
this documentation. However it is a very complex system of voltage 
regulation and because I am not a professional electronics technician, I 
have not yet found the origin of the power loss that results in the 
state of "Power Fail" (To be precise : it is when the computer is 
populated with more than 2 or 3 boards. Any board).

It is also because i have not currently enough time to search the 
problem in "blind mode" : De-solder all the transistors to search and 
evaluate a possible leaking, replace all the suspect capacitor (just to 
replace the big ones it cost more than 200$) etc..

But be patient ;-) I'm determined to continue the adventure soon as 
possible.

Thanks for your interest !

Dominique


On 18/05/2017 05:29, AJ Palmgren wrote:
> Dominique,
>
> I'm quite interested in seeing your Entrex/Nixdorf system restored.  
> Please keep us updated here.  Nice work saving these rare items!
>
> I've done some of my own work restoring a DG Nova-type system.  ( 
> http://Point4iris.com ). I'd love to see if there's any way I could help.
>
> I'll read Christian Kennedy's response here, as he seems FAR more 
> familiar and knowledgeable than I am here, but if I can add value in 
> any way, I would love to.
>
> Best,
> -AJ
>
> On Sat, Apr 1, 2017 at 12:33 PM, Dominique Carlier via cctalk 
> <cctalk at classiccmp.org <mailto:cctalk at classiccmp.org>> wrote:
>
>     Hi guys !
>
>     My name is Dominique, 43 , from Belgium (I apologize in advance
>     for my approximate English). I join this forum under the
>     recommendations of Curious Marc. It seems there are people here
>     who can help me to get back to life the venerable machine that I
>     have just recovered.
>
>     Some pictures of the beast :
>
>     http://www.actingmachines.com/classiccmp_forum/overview01.jpg
>     <http://www.actingmachines.com/classiccmp_forum/overview01.jpg>
>     <http://www.zeltrax.com/classiccmp_forum/overview01.jpg
>     <http://www.zeltrax.com/classiccmp_forum/overview01.jpg>>
>
>     http://www.actingmachines.com/classiccmp_forum/terminal.jpg
>     <http://www.actingmachines.com/classiccmp_forum/terminal.jpg>
>     <http://www.zeltrax.com/classiccmp_forum/terminal.jpg
>     <http://www.zeltrax.com/classiccmp_forum/terminal.jpg>>
>
>     http://www.actingmachines.com/classiccmp_forum/comrack_closeup.jpg
>     <http://www.actingmachines.com/classiccmp_forum/comrack_closeup.jpg>
>     <http://www.zeltrax.com/classiccmp_forum/comrack_closeup.jpg
>     <http://www.zeltrax.com/classiccmp_forum/comrack_closeup.jpg>>
>
>     It is a "Nixdor 600 series" (Apparently a Nixdorf 620/35),
>     upgraded several times until 1980, the CPU board is dated from
>     this year. So I do not know exactly what machine it is today the
>     equivalent.
>
>     Anyway, the Nixdorf 620 is actually built by "Digital Computer
>     Controls" and after some researches it seems that it is a "DCC-116
>     E", the 17 slot version of the "DCC-116" which Is a clone of the
>     "Data General Nova 2/10".
>
>     http://www.actingmachines.com/classiccmp_forum/DCC.jpg
>     <http://www.actingmachines.com/classiccmp_forum/DCC.jpg>
>     <http://www.zeltrax.com/classiccmp_forum/DCC.jpg
>     <http://www.zeltrax.com/classiccmp_forum/DCC.jpg>>
>
>     The machine has five Key-stations (ENTREX DATA/SCOPE), a Mag-tape
>     Pertec 8840A - A Disk Cartridge Diablo Model 40 and a big line
>     drum printer (Data Products model 2230), strange machine, there is
>     a tape reader inside the printer.
>
>     Here is the list of the boards I have with the references written
>     on them and their position in the machine:
>
>     *17    HEX 0 – 15                 ENTREX INC 62 00 01842 002 REV A*
>
>     *16    HEX 16 30 31             ENTREX INC 62 00 01842 002 REV A**
>     15    OPTION 2                  Empty**
>     14    OPTION 1                  Empty**
>     13    PRINTER                   ENTREX INC SN598**
>     12    TAPE 556/800 BPI     2433 LFI 213**
>     11    TAPE 1600 BPI          Empty**
>     10    DISK                           2456 00 MP-Kontroller
>     D44an620 6393500215 <tel:6393500215> 2456 7 0 1577**
>     09    COMMO                     Empty**
>     08    SCANNER                  Scanner BD 2431 NCAG 54147.1.15
>     2431 02394**
>     07    MEM                           1609 0 7 02616**
>     06    MEM                           Empty**
>     05    MEM                           1609 0 8 02367**
>     04    MEM                           1615 01 9 5596**
>     03    TTY                             Empty**
>     02    DO NOT USE             Empty**
>     01    C.P.                              1509 05 4 04436*
>
>     Concerning this I also ask a few questions:
>
>      *
>
>        What are the boards in slots 16 and 17 for?
>
>      *
>
>        I do not have a COM card, does that mean that I could not attempt a
>        serial transmission (type rs232) with this actual setup ?
>
>      *
>
>        I have no idea how many kilobytes are present, apparently there are
>        two core memory cards (8kb each? 16Kb each?), And non-core RAM
>     board.
>
>     I first solved a problem with the power supply of the disk pack
>     (bad HF filter, short-circuited with the chassis, then it is also
>     dead HF filter in the "multi-plug" of the chassis that start to
>     burn, once these problems were solved, I cleaned the machine
>     thoroughly, cleaning the heads of readings with isopropyl alcohol,
>     I Not yet cleaned the disc himself which at first glance looks
>     extremely clean, it has not left the machine for 30 years.
>
>     http://www.actingmachines.com/classiccmp_forum/disckpack01.jpg
>     <http://www.actingmachines.com/classiccmp_forum/disckpack01.jpg>
>     <http://www.zeltrax.com/classiccmp_forum/disckpack01.jpg
>     <http://www.zeltrax.com/classiccmp_forum/disckpack01.jpg>>
>
>     I cleaned all the guides and the heads of the nine track tape
>     Pertec 8840A. There was also a false contact in the ON-LINE
>     button. I did a first cleanup. I think there is always a problem
>     with the HI-DEN button used to set the magtape to 800BPI. It is
>     currently ineffective, but I have a doubt about the contacts of
>     the lamp socket).
>
>     http://www.actingmachines.com/classiccmp_forum/ninetrack.jpg
>     <http://www.actingmachines.com/classiccmp_forum/ninetrack.jpg>
>     <http://www.zeltrax.com/classiccmp_forum/ninetrack.jpg
>     <http://www.zeltrax.com/classiccmp_forum/ninetrack.jpg>>
>
>     I then cleaned all the sockets and contacts at the boards of the
>     computer (logic and PSU)
>
>     http://www.actingmachines.com/classiccmp_forum/clean_contact.jpg
>     <http://www.actingmachines.com/classiccmp_forum/clean_contact.jpg>
>     <http://www.zeltrax.com/classiccmp_forum/clean_contact.jpg
>     <http://www.zeltrax.com/classiccmp_forum/clean_contact.jpg>>
>
>
>     Unfortunately, after a couple of hours, the "POWER FAIL" light has
>     started to light up. The problem here is that I have no
>     schematics, it is a modular power supply consisting of two elements:
>
>     http://www.actingmachines.com/classiccmp_forum/psus.jpg
>     <http://www.actingmachines.com/classiccmp_forum/psus.jpg>
>     <http://www.zeltrax.com/classiccmp_forum/psus.jpg
>     <http://www.zeltrax.com/classiccmp_forum/psus.jpg>>
>
>     One seems to be dedicated to the 15 VDC regulated, the second
>     module is in charge of the regulated 5VDC. Both elements have a
>     "Power fail module". When the machine is completely populated I
>     now observe that the + 5VDC collapses at +1,9VDC.
>
>     Here what I measured out, you will also see what the boards of
>     these power supply look like.
>
>     http://www.actingmachines.com/classiccmp_forum/psu_module_1.jpg
>     <http://www.actingmachines.com/classiccmp_forum/psu_module_1.jpg>
>     <http://www.zeltrax.com/classiccmp_forum/psu_module_1.jpg
>     <http://www.zeltrax.com/classiccmp_forum/psu_module_1.jpg>>
>
>     http://www.actingmachines.com/classiccmp_forum/psu_module_2.jpg
>     <http://www.actingmachines.com/classiccmp_forum/psu_module_2.jpg>
>     <http://www.zeltrax.com/classiccmp_forum/psu_module_2.jpg
>     <http://www.zeltrax.com/classiccmp_forum/psu_module_2.jpg>>
>
>     Another thing I noted during my measurements, where I should (I
>     think) measure 15V, I have 18V, looking at the documentation on
>     the NOVA 2 (4 slots), I observed according to the diagrams below
>     That there is 18V but before a zener diode and not at the level of
>     connectors where there must be 15VDC, should I warn me ? Would the
>     diode be dead ?
>
>     I tried to join temporarily a secondary regulated power supply to
>     reinforce the + 5VDC so as to be sure that the problem did not
>     come from the logical part of the computer which checks these
>     voltages and triggers the Power Fail status. By coupling this
>     external regulated power supply, the computer restarts again, thus
>     it is definitively the power supply (or the comparator
>     component(s) of the power fail module)
>
>     If I removes all the boards (printer, core memory, scanner, disk
>     controller, etc.), the Power Fail light eventually goes out, I get
>     again the 5VDC, so the power has become "too weak" to power the
>     computer when it is fully populated.
>
>     Despite the temporary (and dangerous) look of my assembly with
>     secondary power supply, I could not stop myself and attempt a boot
>     procedure via the Cold Start button of the machine from the Disk
>     Pack, and it works! :-)
>
>     http://www.zeltrax.com/classiccmp_forum/first_boot.jpg
>     <http://www.zeltrax.com/classiccmp_forum/first_boot.jpg>
>
>     It seems that I still have problems with the magtape, I had errors
>     trying to read a backup, but it may be simply because I still
>     cannot get the machine in 800BPI because of the capricious buttons
>     of the front panel. I also wrote a tape mark via a "WRITE TAPE
>     MARK AND REWIND" function, the mark seems to be written but does
>     not do the Rewind, however if I launch a REWIND only function, it
>     executes the action appropriately. In short, still things to
>     investigate on this side.
>
>     Notes that the Operating system I used to make these tests is a
>     very limited OS named DIDOS which was distributed by Nixdorf for
>     his 620 Serie. As the machine is a clone of DG NOVA 2/10, I wonder
>     if the computer is compatible with programs for the NOVA series of
>     Data General? So I wonder if the DCC-116 was compatible with the
>     software for NOVAs?
>
>     The other questions I ask myself at this point are the ways to
>     transfer softwares or bootable OS on this machine? I have no other
>     disk pack on another system but I have a nine track tape TU81 +
>     connected to a VAX 4000-605A under OpenVMS 6.2, and I can put this
>     computer on my network. Do you think there's a way to make a
>     bootable tape for my NOVA 2 clone with the Pertec 8840A from a VAX
>     4000 with a TU81+ ?
>
>     Well, to continue, I have to repair this PSU, all information is
>     welcome, schematics would be ideal of course.
>
>     Finally, note that I am not a professional electronics technician,
>     I fixed a lot of machines basic knowledge, intuition, researches,
>     comparisons and logic, it is effective but full of limitations
>     too, so forgive me in advance If I do not always understand the
>     possible answers of electronics in "high engineering" mode ;-)
>
>     As a bonus, the V1 of a small video mounted with a few clips
>     captured during a session of my nocturnal repairs, during the
>     first boot of the machine since 3 decades ! (on my music, yes, I'm
>     also a composer ;-) )
>
>     https://youtu.be/5jWOUtLKRIU
>
>     Thanks a lot to all in advance ;-)
>
>     Dominique
>
>
>
>
> -- 
>
> Thanks,
> AJ Palmgren
> http://fb.me/SelmaTrainWreck
> https://www.facebook.com/profile.php?id=100010931314283
> https://www.linkedin.com/in/aj-palmgren-4a085516/
>



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