My SCR power control has No Output or Full Output at all times with a load connected. How can I test the control?

With a load connected to the output of the SCR power control try the following:
 
1) Mark the position of the bias potentiometer so that it can be returned close to its present position.
2) Try to turn on the output by turning the bias adjustment.
       
If the bias adjustment allows for full adjustment of the output then it is likely that you just need to adjust the bias and gain for proper operation.  Please follow the following procedure:
 
Note:  There are additional inputs on most models that can disable the output.

The following applies to models:  1P, 3P, 1Z, 2Z and 3Z SCR Power Controls

1) A short across terminals 3 and 4  on TB1 causes the output to shutdown.  This is sometimes used so that other devices can disable the output.
2) A jumper is normally between terminals 7 & 8 on TB1 is normally installed.  If this jumper is removed then the bias pot is not operational.  This is used when an external manual/bias pot is connected to the unit.

The following applies to models:  1PCI, 3PCI SCR Power Controls

1) A short across terminals 3 and 4  on TB1 causes the output to shutdown.  This is sometimes used so that other devices can disable the output.