Auto-Diagnosis Menu; Msr (Samples) - Bosch WBE 4200 Instructions De Réparation

7.

Auto-diagnosis menu

On every Bosch balancing machine, you can find an
auto-diagnosis menu that you can use during the
assistance in order to check the machine very carefully.
1. Keep the <MENU> key pressed.
2. As soon as TST, appears on the display
release the <MENU> key.
3. EPress the <USER>key within 1.5 seconds.
 The left display shows...
i
Press the <OPERATOR> key to switch from one
function to another.
"
The following information is displayed:
R
Indication of the pick-up voltage
$
MSR is shown on the display
R
Indication of the shaft angle position
$
EN is shown on the display
R
Check of shaft speed
$
SP is shown on the display
R
Analogical signals reading
R
Meter starts
$
CNT is shown on the display
R
Test display
$
LED is shown on the display
R
Indication of calibration data
$
TAR is shown on the display
R
Reading of the digital inputs
$
I_0 is shown on the display
R
Current balancing of a wheel
$
REL is shown on the display
R
Illuminator functions test
$
ILL is shown on the display
7.1

MSR (Samples)

"
Access the TST menu;
"
Access the submenu MSR ;
i
To scroll the submenu, press the <RIM
DISTANCE>key.
The first step in the test menu is checking the pick-ups;
this procedure, that will be analysed in details later on,
is fundamental to identify any sensor problem.
BALANCING SYSTEM
The tool that is used to measure the wheel unbalance
has a mechanic system based on a lever at 1°degree.
The piezoelectric sensors which are in the lower part of
the shaft, at its sides, detect vibrations by converting
the strength into electric tension.
Robert Bosch GmbH
Auto-diagnosis menu | WBE 4200 | 45
Fig. 4: Position of the piezoelectric sensors
TENSIONS
The piezoelectric sensors, according to where they
are, receive a different stress and weight. In fact, the
internal one, in the left side of the shaft, is excited
less than the external one. So we can say that the ratio
between them is 1.6, that is, the tension measured by
the external pick-up is 1.6 times higher than the tension
measured by the internal pick-up.
Fig. 5: Stress spread on the shaft
PHASE ANGLE
In general, we use the word phase to identify a
particular moment during a periodical phenomenon
(in this case it is the electrical signal generated by
the pick-up during the launch of the wheel). When we
consider two signals (generated by the internal and the
external pick-up), we can say that there is a phase angle
between them which means that there is a difference
between the tensions. For instance, in this picture, if
the black signal represents the tension of the external
pick-up and the red signal represents the tension of
the internal pick-up, we can say that the tensions are
opposite, that is, that the difference is 180°. The crests
of a signal are lined up with the troughs of the other
and vice versa.
Fig. 6: Ratio between the tensions measured by the pick-ups
en
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1 695 600 091 2012-11-16