Grindmaster 87710 service manual Service/Troubleshooting Solid State Air Agitation

Service/Troubleshooting Solid State Air Agitation

A vibrator air pump is located in the control box. This pump supplies the air to the coffee liners. It is turned on directly by pushing the manual agitation switch, and automatically by the brew timer or solid state relay in series with the brew timer.

The manual agitation switch is a momentary contact, normally open single pole black push button switch. Depressing the button closes the switch contacts completing the circuit to the air pump. It is wired parallel to the automatic agitation circuit.

The automatic 30-second (approx.) operation of the air pump is provided by the output of the solid state brew timer or a separate solid state agitation relay in series with the brew timer. The delayed automatic agitation program (2 minute off time between end of spray and start of 30 second agitation) uses a delay solid state relay in series with the brew timer.

The following trouble shooting guide assumes that internal wiring is correct and 120V AC power is provided.

1.IF COFFEE LEVEL DOES NOT RISE BACK IN GAUGE GLASS, or is unusually slow to come back up, the very small vent hole in the clean out cap is clogged. Clear vent using a straight pin or similar object.

2.IF AGITATION DOES NOT STOP, check for sticking manual agitation switch. Where automatic agitation is built into timer, and manual switch checks okay, timer is defective and should be replaced. Where automatic agitation is a separate solid state agitation relay and manual switch checks okay, the relay is defective and should be replaced. If there is a constant “low” air pump output, the solid state timer or relay is defective and should be replaced.

3.IF NO AIR ENTERS LINER, check output of pump through outlet fittings on urn front. If okay, then make sure all connections are tight. Check for leaks at gauge glass, at top, bottom and at cleanout cap. May require new o-ring or silicone grease on top cap; upper or lower gauge glass washer; or, if chipped or cracked, new gauge glass. Also, make sure passageways through top cap and gauge base are clear.

4.IF LITTLE OR NO AIR COMES THROUGH FITTINGS ON URN FRONT, open control box and check pump operation. If pump operates, but has weak output, replace it. If air pump is okay, air lines between control box and front fittings are blocked or leak. Blockage usually is caused by overfilling liners. Use stiff thin wire to clear. If air lines leak, coffee liners are removed first, then tighten compression fittings at each end of lines.

5.IF NEITHER AUTOMATIC NOR MANUAL AGITATION OPERATES PUMP, pump is most likely defective and should be replaced.

6.IF AUTOMATIC AGITATION IS OKAY, BUT MANUAL DOES NOT WORK, replace manual agitation switch.

7.IF MANUAL AGITATION WORKS, BUT AUTOMATIC DOES NOT, replace the solid state brew timer or separate solid state agitation relay.

American Metal Ware 87710E Coffee Urn Page 17