TechNote  40T-034

4400  Series

4000 Series Using Southern Systems Channel Interface
4-29-91 Pat Hennigan

Models: 4410 / 4440 / 4470 / 4490

Summary:
 SYMPTOM: 4410 / 4440 / 4470 / 4490 printers fail to operate with a Southern Systems Channel Interface box. This box uses a Dataproducts short line interface to communicate with the printer.

CAUSE: The Channel Interface box uses the FAULT OUT circuit from the printer for STATUS or READY and requires a + 5 volts level at printer output B3 (READY). However the Interface Box input for READY signal has a 330 ohm pull down resistor. The + 5 volt output level to the box looks more like O volts.

Resolution:
 ACTION: A modification needs to be installed to the SMPI board to satisfy the protocol converters input requirement. The following modification should be performed:

 Add a jumper wire across R41. This will keep +5 volts on connector output B3.

 Cut pin #2 of chip U36. This will prevent a premature failure of U36.

NOTE: Southern Systems is also known as N.B.S.


Specifications subject to change without notice.
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