TECH NOTE SUBJECT: "H" Machine Processor Boards & Wiring Problems

MACHINES AFFECTED: 30022H8J, 30022V5J, 30022T5X, 30022T5J, 30022V6J, 30010G5X, 30015G5X, 30015V5J, 30015V7J, 30015T5X, 36026V5J, 36026V7J, 42026V6J, 30022X8J, 36026x8J, 42026X7J, 42032X7J, 48040F7J

Possible Problems:

1. Output stay on when the control should turn them off, i.e. water valves and chem. pumps that will not shut off.
2. Machine overfilling with water. This could be overfilling even to the point of overflowing from the rear of the machine.
3. Issues with water valves not shutting off. This is normally blamed on pressure transducers that are failed but is probably misdiagnosed because the relay could indeed be off on the processor board. As we check boards that are returned, we find that most transducers work perfectly.

We have diagnosed a few problems with H machine processor boards in the recent past that may prove elusive to the technician in the field.

Overview:
1. Wires may break off inside the connector on the processor board. The damage occurs in shipment as the ferrite beads bounce and fatigue the pins within the connector. Sometimes these are hard to find because the wires appear to be in the connector but the pin is actually broken and making intermittent connection. We have since attempted to support the ferrite beads to prevent damage to the connector pins.
2. Misplaced or missing wires in the harness - M3-12. Some unknown number of machines were shipped without a wire in M3 pin 12 which connects the lower side of some snubbers to the Y-bus of the control voltage. This allows a feedback into the outputs that are connected to this bank of snubbers and may prevent an output from turning off when commanded off.

More Details:

1. On the microprocessor board, our part number 08PH18EPCT (and boards like this), are a number of output relays along with snubbers which help arrest the EMI generated by relay switching. The snubbers are connected in the circuit on the top side of the load and also to the Y-bus of the control circuit. This is done with a couple different wires connected to the board itself. One of these wires - M3- pin12 - was not connected at the factory on a number of machines. We suspect that the wire may have been plugged into pin 14, on some machines. The primary issue with this missing wire in pin 12 is that outputs (valves and pumps) will stay on after being de-energized from their output relay on the board. For example, a hot water valve will stay on even when it should turn off because another output near it on the board is actually feeding back to the water valve via another relay output and snubber set.

2. The feedback is strange in nature because the valve of the feedback is dependent on how many outputs are commanded "on". If the wire in M3-12 is not installed then the feedback is through the snubber resistor of an operating output and will be at a voltage from about 24 volts up to 180 volts. All outputs for water and flush valves, the drain valve(s), optional steam, cooldown, drains, and chemicals are possible affected.

3. Most notably, the water valves will not shut off when expected because the feedback voltage will keep the valve on after the water valve relay turns off. This will cause a higher than desired level in the machine and will most probably cause the technician to diagnose a bad level transducer.

4. If an H board does not have M3-12 connected, connect this wire immediately. You may find the wire needed in pin 14. If there is no wire in pin 13, then it is a safe bet that the wire in 14 is wrongly placed.

5. Order part number 10YMTA01BP which is a wire with pin and butt splice so that you can pin this into the appropriate connector - M3. The other end of the wire must be connected to the Y-bus which can be found on the chemical output page of the schematic. Most control circuits using this board use wire 6 as "Y-bus" or bottom side of the 240 volt control circuit voltage. Check the schematic if unsure for your particular machine.

If any machine has a history of "failing" processor boards, then consider these two issues as the likely root cause.
Related to Broken Wires: This has been a real challenge because the ferrite beads which are attached to these connectors are necessary and at the same time caused damage over the road. We have attempted to strap these ferrite beads to a secure location to stop them from battering the boards and stressing the connectors, but this has proved difficult. If you have broken wires in the field, please report these so that we can know how big the problem is and take corrective action. Please contact Gary Lazarre at [email protected] with this information.


Best regards,

PELLERIN MILNOR CORPORATION
Gary Lazarre
Gary L. Lazarre
Manager
Customer Service

GLL/das