DCC-116 E / DATA GENERAL NOVA 2/10 / Nixdorf 620 - Restoring and restarting
dce at skynet.be
Thu May 18 08:21:50 CDT 2017
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
Thanks for your interest !
On 18/05/2017 05:29, AJ Palmgren wrote:
> 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.
> 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 :
> 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
> 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".
> 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
> 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.
> 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).
> I then cleaned all the sockets and contacts at the boards of the
> computer (logic and PSU)
> 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:
> 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.
> 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! :-)
> 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 ;-) )
> Thanks a lot to all in advance ;-)
> AJ Palmgren
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