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Technical Service Manual 68 Revision Dat e: August 2004 EXCESS BELT/CHAIN UNDER OVEN IS BOUNCING The ex cess belt or chain under the oven is bounc ing and causing a “j erk y” convey or m otion. POSSIBLE CAUSES If the con…

Technical Service Manual 67 Revision Date: August 2004

PROBLEM WITH THE ENCODER

There is a problem with the encoder causing the conveyor speed to be unstable or causing the

conveyor measured speed to be different from the displayed speed.

POSSIBLE CAUSES

The encoder is mounted next to the conveyor drive motor inside the outer sheet metal.

Check the following items for problems:

1) Encoder assembly. If it seems to be turning, check the output at the controller with a oscilloscope.

Refer to the oven schematics for pin numbers and locations.

2) Encoder data cable. Check for kinks, cuts etc, in wiring

3) Encoder drive assembly (pulley & belt or coupling).

4) Controller power supply. See schematics.

5) Encoder mounting hardware and brackets. Check alignment and tightness.

DRIVE CHAIN TENSION IS INCORRECT

The conveyor motor drive chain tension is incorrect causing the conveyor speed to be unstable.

POSSIBLE CAUSES

If tensioning of this chain is too tight, the motor will be side-loaded excessively and the motor will fail prematurely. If

tension is too loose, the conveyor could "jerk" or vary its speed.

The chain should be adjusted with approximately 1/4" of deflection in the chain when it is pressed down from above.

(This adjustment is not an easy to see or make)

Checking and adjustment of this chain can only be done from under the off-load end of the oven.

VOLTAGE TO THE ENCODER IS INCORRECT OR MISSING

The voltage to the encoder is incorrect or missing causing the conveyor speed to be unstable.

POSSIBLE CAUSES

If you suspect the voltage to the encoder, check in the following places.

1) Power supply for the controller (+5V). See schematics

2) Encoder cables/connections.

3) Encoder voltage (No voltage will cause the conveyor to stop)

3) Controller.

The controller could be over-loading the signal from the encoder. The cables could also be distorting or reducing the

encoder signal. If the power supply has failed, the encoder may not work at all. Refer to the schematics for the oven.

Technical Service Manual 68 Revision Date: August 2004

EXCESS BELT/CHAIN UNDER OVEN IS BOUNCING

The excess belt or chain under the oven is bouncing and causing a “jerky” conveyor motion.

POSSIBLE CAUSES

If the conveyor has a "jerky" motion, look under the oven at the excess belt or chain. Sometimes, the excess belt can

start to bounce underneath. A "standing wave" can be seen on the conveyor. This can be caused by the under oven

idlers and followers sticking. Clean the "bearing surfaces" of the idlers to allow a smooth rotation and linear movement.

Another possibility is that the drive sprockets are holding the conveyor belt/chain too long on the off-load, causing the

conveyor to wrap around the sprocket and then drop quickly, instead of rolling off the sprocket smoothly. This can be

caused by excessive wear between the teeth.

1 Sticky chain/belt idlers under the oven.

2 Chain/belt drive sprockets holding conveyor too long.

3 The Chain may “catch” on the Belt at the ends of the Oven.

THE CHAINS ARE DIRTY (EDGE RAIL CONVEYOR ONLY)

The chains are dirty and/or dry (edge rail conveyor system only) causing the conveyor to “jerk”

as it goes around.

POSSIBLE CAUSES

If the chains are dirty, they will not flow smoothly around the sprockets and the idlers. The links can stick and kink up

holding an angled position instead of laying flat. Clean the chain links if they appear to have an excessive amount of build

up residue. The chains may need to be removed and soaked in a cleaning solvent to completely clean them.

If they look "dry", oil the chains, however, refer to the Preventive Maintenance Manual for lubrication recommendations.

Do not over-oil the chain. Too much oil will cause smoke when the oven heats up.

Also since the opening in the rails is very small, any chain links with any dirt could get stuck in the rails and cause a

"jerky" motion of the conveyor.

RUN “CONVEYOR SPEED CALIBRATION” PROCEDURE

The conveyor is in need of calibration if the measured speed of the conveyor to be different from

the displayed speed of the conveyor.

POSSIBLE CAUSES

Perform the conveyor calibration. Refer to the Oven Operations Manual for details on this procedure.

If after calibration, the conveyor measured speed is not equal to the displayed speed, then the electrical wiring and

components should be checked, especially the encoder output.

Technical Service Manual 69 Revision Date: August 2004

CONVEYOR BELT, CHAIN & RAIL SERVICE

REMOVE AND REPLACE CONVEYOR BELT

DISCONNECTING THE CONVEYOR BELT

1. Locate the master link in the belt. The master link can be identified by the double size 'holes' in the belt. There will be

two double size holes located at the fourth link in from each end. There are five master links in the belt. The single lane

master link is the center link on the belt. The conveyor will have a belt with five single master links. (instead of two triples

and one single master link).

2. At the right side of the belt, locate the master link. Using screwdriver or chain nose pliers, unhook the left hook of this

master link from the belt. Then, using the same tool, unhook the right hook of the master link from the belt.

3. Using a screwdriver, lift the left side of the master link out of its position in the fourth link from the end on the oven side

of the belt. Using a screwdriver, unhook the right side of the master link from the belt.

4. Locate the triple master link on the left side of the belt. Using screwdriver or chain nose pliers, unhook the right hook

of this master link from the belt. Now using the same tool, unhook the left hook of the master link from belt.

5. Using a screwdriver, lift the right side of the master link out. Using a screwdriver, unhook the left side of the master

link from belt.

6. Squeeze the ends of the triple master link together and slide the master link ends out of the oven side of the second

link in from the end.

7. At the right side of the belt, squeeze the ends of the triple master link together and slide the master link ends out of the

oven side of the second link in from the end.

8. The triple master links will stay in this position to reassemble the conveyor belt. Carefully lower the bottom end of the

conveyor belt taking care not to let it get caught anywhere

9. At the center of the belt, using a screwdriver, unhook the right side of the single link. Lift the unhooked side up and

remove the single master link from the belt. The belt will now separate. Unhook the bottom edge of the belt from the

driven shaft and lay it on the floor under the oven.

NOTE: Use only single links for replacement.