Troubleshooting an Unresponsive Control Displaying 8's

Overview

Why is my control displaying only 8's and not responding?

This is an indication that the control is stuck in startup process. There are four potential causes for this:

• Bad connection on one of the harnesses between the I/O board and display board

• Defective I/O board

• Defective display board

• Low voltage output from the transformer

Procedure

SHOCK HAZARD To avoid electrical shock, perform relay checks or transformer checks as described as instructions.

The following checks are performed with the wall circuit breaker closed and the main power switch in the ON position. Extreme caution should be taken. Make connections before applying power, take reading, and remove power before removing meter leads, or electrical shock could result.

1. Measure output voltage on the secondary side of the transformer.

   Voltage should be between 22-26 volts.

   1. If the voltage is outside of 22-26 volts, then verify supply voltage is correct.

   2. If supply voltage is correct but output voltage is not correct, replace the transformer.

2. Take the harnesses off between the I/O board and the display board and then re-connect.

3. If the issue is still present, then move the control board to another vat.

   1. If the issue continues on a different vat, then replace the control board.

   2. If the issue only occurs on one vat, then replace the I/O board.