Posts Tagged Nova 3/12

The Nova 3/12 Console is repaired

Posted by Tommie in Data General Minicomputer Projects, The Data General Nova 3 Restoration Project on Wednesday 24 February, 2010

The ”Stop/Reset” toggle switch wouldn’t toggle back to its center position so I took a switch from my other Nova 3 console. Turns out that this switch would not make contact in the “Stop” position and I had to grab yet another switch from my other front panel. Looks as this front panel rapidly is becoming an assembly to salvage parts from.

All indicator lights are now replaced. The leads of the ones that did work where extremely brittle and since incandescent lamps have limited lifetime I decided to replace all lamps. Lights 7 – 12 would not lit or if they did, they lit very dimly and sporadic. The driver chip, DG part # 113-7748 was faulty and I replaced it with a NTE74LS06 chip (Hex Inverter Buffers/Drivers With Open-Collector High-Voltage Outputs).

Now that the console is working (apart from lacking the XX2065 key which I have ordered), I can start testing the cpu and memory.

Nova 3 Console disassembled

Nova 3 Console Lamp Driver DG part 113-7748

Nova 3 Console Lights works fine after replacing all lamps and a driver IC

Data General, DGC NOVA, Minicomputers, Nova 3, Nova 3 Console, Nova 3/12

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Powered up my Nova 3/12 today

Posted by Tommie in Data General Minicomputer Projects, The Data General Nova 3 Restoration Project on Sunday 14 February, 2010

After sitting in my hallway for 3 months now, I finally got around to do some work on my Nova 3/12. The installed power supply was faulty. 5 VDC worked fine while all voltages based on the raw 15 VDC was missing. I did some trouble shooting but decided to use the power supply from my other Nova 3/12 chassis. This power supply worked fine after replacing the 5VDC and 15VDC capacitors on the Power Supply board and adjusting the 5VDC and the 15VDC voltage levels.

With only the front panel installed I applied power to the chassis and a plume of smoke rose from the front panel logic board and the typical smell of burnt electronics spread throughout my apartment. I quickly pulled the power plug and disassembled to front panel. One of the decoupling capacitors on the 15VDC power bus had its plastic coating melted and of the internals only a black crust remained. Not unusual for old capacitors to develop a short. I decided to use the front panel from my empty Nova 3/12 chassis and voila – the light bulbs that were not broken came on.

I’ve ordered 30 sets of 28V .04A Hudson 2187D equivalent lamp bulbs and a fan that needs replacing.

Data General, Nova 3/12

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Data General Nova 3/12 Power Supply drawings

Posted by Tommie in Data General Minicomputer Projects, The Data General Nova 3 Restoration Project on Sunday 7 February, 2010

I have two Nova 3/12’s. One equipped with:

NOVA 3 CPU, PWRFAIL, PRLOAD, 256KW
NOVA 3 TRIPPLE OPT, MMPU, PAR, MUL/DIV, RTC
64KW Plessey, 128K SC, W PAR, 0-127
DGC NOVA CASSETTE I/O, $TTI/O, 9600 B, RTC
DISK CARTRIDGE CONTROL DGC NOVA, DKP, 4234, 6030
DGC NOVA CASSETTE I/O, $TTI/O, 9600 B, RTC

The other is an empty chassis, both with faulty power supplies. I contacted Bruce Ray of Wild Hare Computer Systems and Bruce provided me with Nova 3/12 Power Supply and backplane drawings. I still have to troubleshoot and repair the power supplies, but at least I now have the drawings and the tools.

$TTI/O, 128k Plessey memory, 256KW, Data General, DGC NOVA, DGC NOVA CASSETTE I/O, DISK CARTRIDGE CONTROL, DKP, Minicomputers, MMPU, Nova 3, NOVA 3 CPU, Nova 3/12, PAR, PRLOAD, PWRFAIL, RTC, TRIPPLE OPT, Wild Hare Computer Systems

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Hauling it all home

Posted by Tommie in Data General Minicomputer Projects on Friday 7 August, 2009

Well, I missed out on the S/280 system which Bjarni, another collector of Data General computers and a very nice guy, now has, but brought home the following: