ECA 007 - Dual ASYNC card wired wrong


Dual ASYNC card wired wrong (ECA:007)

 

PURPOSE:
To replace the Dual ASYNC card, if required. GNK. card process checked, GNK. built cards will not exhibit this problem.

PHYSICAL check:
On some cards, one end of component "L2" is installed in the wrong hole. Compoent "L2" is located near the lower 15 pin connector (port 2). One end of "L2" is correctly connected to pin 5 of the port 2 connector. The other end should be connected to ground (the hole nearest to the port 2 connector). Some cards were manufactured with this end of "L2" connected to -12 volts. see diagram below: Dual ASYNC card

   _______________________________________________________
  |    Dual ASYNC card                                  _|_ port 1
  |                          (correct hole is ground)  |   |
  |                                      |             |   |
  |                                      |             |___|
  |                                      v     _l2_     _|_ port 2
  |      (incorrect -12 volts) ------->o o----|____|-5-|   |
  |                                                    |   |
  |________________________      ___          _______  |___|
                           |____|   |________|       |___|

The system will not Power up when an external device (printer, plotter, modem, etc.) is connected to port 2 of the Dual ASYNC card. This includes any device that has signal and frame ground connected together. If the device does not have the two grounds connected together, the system will Power up. However, the device will not be functional when connected to port 2. To determine if the device is functional, it should be tested in port 1. To identify an incorrectly wired card see "physical check" section of this ECA:.

NOTEs:

Order parts through normal distribution.

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