Technical_reference - 第66页

Technical Service Manual 66 Revision Dat e: August 2004 PROBLEM WIT H SPROCKET A LIGNM ENT O N DRIVE/DRIVEN SHA FTS There is a condition with the sprock et alignm ent on either the dr ive or the driven shaf ts caus ing t…

Technical Service Manual 65 Revision Date: August 2004

THE CONTROLLER HAS HAD A FAILURE

The controller has had a failure causing one or more of the following symptoms.

1) The conveyor stops running

2) The conveyor speed is unstable

3) The conveyor measured speed is not same as actual speed

POSSIBLE CAUSES

If the controller fails, there are other symptoms to help isolate the problem.

It is possible to isolate a controller failure by monitoring the signals from the controller at the I/O board

HINT: There is an Amber LED indicator on the front of the controller that which flashes on and off at a regular interval

while the controller is functioning properly. There also is a Green LED which is on steady when the unit is powered.

The items to check in the event of a suspected controller failure:

1) Controller.

2) Controller cables and connectors.

3) Power supply for the controller (see Oven Schematics).

PROBLEM WITH OPERATION OF TRANSFER GEAR ASSEMBLY

There is a problem with the transfer gear assembly causing either unstable conveyor speed or a

jerky motion of the conveyor.

This applies only to a combination conveyor system.

POSSIBLE CAUSES

Unstable conveyor speed and/or jerky motion of the conveyor can usually be attributed an improperly lubricated or

improperly adjusted chains or rails.

Check the following for tightness and adjustment:

1) Transfer gear assembly (sprocket and shaft).

2) Transfer gear chains.

3) Sprockets for transfer gear chains on the conveyor shafts.

THERE IS A BOARD JAMMED SOMEWHERE ON THE CONVEYOR

There is a board jammed somewhere on the conveyor and this is causing the conveyor to stop running

POSSIBLE CAUSES

There is a printed circuit board assembly somewhere in the oven that is keeping the conveyor from running. Some

places to look are:

1) The chain guards on the ends of the chains on rail and combination ovens

2) The small gap between rails and chains on combination ovens

3) Between belt and rails on combination ovens.

4) Improper boards placement onto conveyor.

If this type of problem is a regular occurrence in the oven and it happens in approximately the same place or with the

same product, then perhaps the areas in question should be realigned/readjusted. This could be a warning sign for other

problems in the mechanics of the conveyor system such as improper leveling or lack of rail parallelism.

Technical Service Manual 66 Revision Date: August 2004

PROBLEM WITH SPROCKET ALIGNMENT ON DRIVE/DRIVEN SHAFTS

There is a condition with the sprocket alignment on either the drive or the driven shafts causing

the conveyor speed to be unstable.

POSSIBLE CAUSES

When the sprockets on a belt conveyor are not lined up properly, the belt can sometimes jump, jerk or "pop" as it goes

around the shaft producing a jerky belt movement and can affect belt tracking. The side of a belt loop catching on the

sprocket teeth as the belt goes around the sprocket causes the “pop”. The proper way to align the belt sprockets is to

center the belt on the shafts and line up the sprockets with the belt.

1) Adjust the outer sprockets to less 1/8" from the sides of the belt.

2) Center the belt on the shafts by lining up the belt with the wear rod carriers.

3) Align every sprocket within 1/8" of the outside edge of its belt loop. This means that half of

the sprockets must be aligned on the left side of the belt and the other half on the right side of the belt.

If the oven has a rail or combination conveyor, the problem could be with the chain idler followers. (They are located

below the surface of the belt where the chains go down to/come up from the under side of the oven). The sprockets are

adjusted with precision shims to locate them in reference to the drive sprockets. Confirm that the extension arm that

holds the idlers is straight, and that the chains track correctly. Too much bend in the extension arm can cause the chain

to jump or bind.

The assemblies to check are:

1) Sprockets/idlers

2) Drive/driven shafts

3) Belt/chains

4) Idler brackets/shims

PROBLEM WITH THE ENCODER DRIVE LINKAGE

There is a problem with the encoder drive linkage causing the conveyor speed to be unstable.

POSSIBLE CAUSES

On ALL conveyors, there are a couple of pulleys and a toothed belt driving the encoder from the conveyor assembly.

If the encoder drive is loose, then check the clamps for tightness. Check the belt for proper tension (1/4" to 1/2" full

deflection when squeezed) and missing or damaged teeth. Check the pulleys for wear and tightness of the setscrews on

the shafts.

Areas to check are:

1) Encoder pulleys and belt.

2) Encoder alignment.

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.