T800 Tx Woes

[ChrisS]

Hi,

Was wondering if anyone has had any experience with a Tx module that will not
shut down after the trigger input has been removed.
Unit is a T881, all programmed and aligned but constantly putting out a carrier.
All four inputs, TX Key input, Carrier button, Mic Tx and opto coupler operate
as normal, ( activating any of them will light Red Tx Led ) and dropping them activates the tail timer as normal. Tail timer is adjustable.
The main TX timer does appear to be operating and adjusting it drops the input but not the carrier
Passing an audio signal through the main input from the receiver puts it on the
air as normal but dropping any of the normal triggers causes it to stay
transmitting a carrier.
Unit does not have a CTCSS board installed and is stock with no modifications.
Unit starts transmitting as soon as power is applied.
I have a Circuit diagram for a T856 and located the TX Ex op pad on the board,
grounding this pad operates the TX led and the timer as above.
TP5 ( Tx Reg ) test point is showing 8.95 Volts with any of the triggers activated and still shows 1.78 V approx after the tail timer or Tx timer has dropped the input.
Disconnecting the white lead from the exciter compartment to the power amp section seems to have no effect. ( Carrier remains after the two are seperated )

Unit is a series one ( Eprom channel programming )

Any thoughts would be appreciated, especially if any one has any ideas which way i might proceed next with it

Regards,