HENNESSY INDUSTRIES Coats IBS 2000, Service Manual And Troubleshooting Manual

24 • Service Manual — COATS Model IBS 2000

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Piezo Crystal Checking Procedure

This procedure details how to check for an “upside

down” piezo assembly (the crystal has been assem-
bled upside down inside the piezo assembly). This can
result in various problems; primarily high weight read-
ings, or the position may read 180 degrees out. The
piezos may be checked in or out of the balancer. The
procedure below details checking them in the balancer.

1.

Using a Digital Volt Meter select the DC setting.

2.

Connect the red (positive) lead to the piezo tap.

3.

Connect the black (negative) lead to ground (the

bottom of the piezo assembly).

4.

The meter may indicate a fluctuating or negative

reading, ignore the reading at this time.

5.

Apply firm downward pressure to the front of the

motor (if out of the balancer apply pressure directly to
the piezo) and note the signal.

6.

If the piezo is good, the signal should read positive

(+) at the instant pressure is applied for *

right

piezos.

7.

If the piezo assembly is “upside down” the signal

will read negative (-) at the instant pressure is applied
for *

right

piezos.

*Note: When checking the 

left

piezo the

readings in step 6 and 7 will be opposite.

Balancer Display Diagnostics

This is a diagnostic menu that should only be

accessed by authorized Hennessy service personnel. It
allows you to perform tests on the components within
the POD. To access this menu you press the PLANE 2
key on the WEIGHT LOCATOR display and turn the
power on simultaneously. You may use the RS232 cable
or a spare “test” cable. The menu will display several
tests. Each test will display step by step instructions.

Tests on this Menu Include:

• KEY PAD TEST

• LCD TEST

• LED TEST

• RAM TEST

Note: This is not the same RAM test on the
main diagnostic menu. This RAM test is for
the LCD board.

• SOFTWARE REVISION

• SERIAL LOOPBACK TEST

Serial Loopback Test

This is a Display Board software communication test.

It checks the transmitted and received data. Follow the
instructions on the screen.

1

. Connect a cable between the CPU1 (P3) and TEST

(P2) connections on the top of the display board. Refer
to the wiring diagram #112368 on Press CONTINUE.

2.

The screen will not display the 

Transmit

data and

the 

Received

data.

3.

You will then receive a PASSED or FAILED mes-

sage.

Note: If the test FAILED, check and replace
the cable or the display board. If the test
PASSED, but you still get a communication
error, check the CPU board RS232 cable or
the CPU board itself.