SB-810

TR-2400 Display or Keyboard trouble                        2-20-80


Display

An intermittent or blank digit may be caused by either a broken lead, or
intermittently shorting lead on the PLL unit.

On the PLL unit, look in the area of Q12, the touchtone generator.  Between
Q12 and the board edge locate the D1-D4 lines.  Inspect this area for
either an open (Broken) lead, or shorted (pinched) lead.  Repair as
necessary, and check lead dress before reassembly.

Keyboard

An intermittent or inoperative keyboard row or column may be caused by a
torn or pinched lead, or a cracked diode.

Again, in the area of Q12, inspect the "T" and "Y" lines for shorts or open
connections, and inspect diodes D19-D26 for physical breakage.




JEB/yn
(c) 22080TKC