Sun3 19" monochrome monitor

Technical data

View

Here comes a schematic view of the monitor from thr rear with opened case and tin.

IMPORTANT: Remove power cord and let the monitor alone for some hours. Otherwise there might be deadly voltages inside!

        ---------------------------------------
        |            Valve (Clinton)          |
        |                                     |
        \...                               .../
         \  .....                     .O...  /  Connector (O)
          \      ...               ...      /   for the thick red
           \        ...         ...        /    cable to the valve
            \          ..     ..          /
high        | #          .   .        +--+|
voltage     | #           . .         | $||  power supply
board (#)   | #       ****. .         | $ |  with
with        | #%%%%       . .         | $ |  shield tin 
flyback     | #           ...         | $ |  and
(% oder *)  | #                       | $||  printed circuit ($)
            | #        @@@@@@@@@      +--+|
            -------------------------------
                   printed circuit (@)
                   is placed at the
                   rear tin or on the
                   shaft of the valve

Parts known to become defective

1. Power supply
   The condensators loose capacity. Look for condensators which have lost electrolyte or which have become "thick".
2. Brightness
   There are two potentiometers to tune brightness, if the external brightness knob (on the rear near the power switch) is exhausted.
   One is on the small printed circuit near (or on) the shaft of the valve and the other is on the high voltage board near the rear end at half height and named "pre bright".
3. Unsharp
   If the picture is unsharp in the corners only, you can adjust the "focus". If the whole picture is unsharp, then the valve is defective.
4. High voltage board
   The flyback transformator is a known broken part here. If you hear a bizzling sound, the picture gets black and it smells, then immediately turn the power off. With some luck, only the flyback transformator is defective now.

   The flyback is the big black thing where the thick red cable ends which is fastened at the side of the valve. If you want to remove the cable from the valve, be careful. Do not fiddle with the screwdriver under the plastic lid! Press the knob from both sides and turn it gently until it pops out.

   It is very easy to solder the flyback in or out, because it has only a few and big pins. Sometimes the flyback is placed on a separate printed circuit on the bottom.

   The flyback is of the type 5107-140-02151, replacement type is HR 46036.