Dart star Dartboard video monitor

NT-1431 information

It's been a long time since I last saw one of these monitors, but one just came in for repair. I'm photographing it now and preparing lots more information to go into my repair guide for this model.

The NT-1431 was one of the monitors (VGA resolution) to be installed into the Medalist "Spectrum" (a.k.a. Spectrum Genesis) coin op dart machines. I have not been able to locate a manual or schematics for this particular model, but you can use either the Neotec NT-27V or the NT-2702 (Li-Chin version) manuals and schematics to troubleshoot this monitor. Notice the neckboard says, "Li-Chin" on it.

This model is installed in a special custom made frame specifically to fit the odd shape of the Medalist Spectrum dart machine cabinets. The remote adjustment board is long and skinny with trimpots R503, R502, and R501 NOT installed.
 

Attachments

  • NT1431 complete.JPG
    NT1431 complete.JPG
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  • NT1431 Nameplate.JPG
    NT1431 Nameplate.JPG
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  • NT1431 neckboard.JPG
    NT1431 neckboard.JPG
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  • NT1431 neck closeup.JPG
    NT1431 neck closeup.JPG
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  • NT1431 remote front.JPG
    NT1431 remote front.JPG
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NT-1431 burnt parts

The NT-1431 is known to develop some burnt components after several years of operation.

Resistor R428 near the center of the main board burns because it is run close to it's upper limits of it's specifications. R428 should be a 330 ohm @ a half watt. Probably would be a good idea to bump up the wattage of this resistor to one watt.

Resistor R431 (10k @ a quarter watt) burns because the electrolytic capacitor located directly to the left of this resistor has gone bad. It's capacitor C424 that has gone bad. The value of that capacitor is 10 uf @ 50 volts. However, I strongly suggest bumping up the voltage rating of this capacitor to either 100 volts or 160 volts to prevent future failures. Be sure to note that the "C424" silkscreened designations on both sides of the board are obscured by the cable clamp on the parts side and by the metal frame surrounding the board on the foil side. Sometimes resistor R432 (located directly to the left of C424) might have changed value too. R432 should be 12k @ a half watt.

If you have a "No vertical deflection" symptom and the vertical output IC301 is good, then resistor R307 is open. R307 is located next to electrolytic capacitor C312 and is a 33k @ a quarter watt resistor.
 

Attachments

  • NT1431 R428.JPG
    NT1431 R428.JPG
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  • NT1431 C424.JPG
    NT1431 C424.JPG
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  • NT1431 main board.JPG
    NT1431 main board.JPG
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  • NT1431 working.JPG
    NT1431 working.JPG
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