Olympic 50 - Page 11

2. Ifthe walking dashes do not appear, and the On/Off
switch is ineffective: Listen for the reed relay clicking (to
turn on the DC power). If clicking cannot be heard then
check the fuses on the back. One fuse is for batteries and
the other is for AC.
Ifthe relay clicks, then the appropriate fuse is functioning.
Then check to determine that the Scale stays on. This can
best be verified by observing the LED, DS1, on the right
front of the Main Board (Fig. 4-11).
The main platform assembly must be removed. DS1
indicates that +5Vd is present.
If DS1 does not come on (even momentarily) then check
connectors from the membrane panel to the Display Card
to the Main Board.
Pressing the On/Off switch should make TP12 on the Main
Board go low. Ifthereis no voltage ofany kind at TP12 then
check that connector P1 from the transformer is connected
to J1 on back of the Main Board.
Also verify that connector P2 is connected to J2 when on
batteries. The aluminum sub-platform must be removed
to inspect these connectors. Also verify voltage at TP7. Try
on both AC and batteries.
If DS1 comes on but no walking dashes appear, it
indicates that the uC is not working. Verify that the
jumpers near the pC (U12) are correct. JP2 should have
a jumper at A and JP3 should have one at B. Also verify
that the EPROM, U13, is properly seated in its socket. The
I/O expander, U15, is also suspect at this point.
If the On/Off switch signal is at TP12 and DS] lights but
‘does not remain lit when On/Off is released, check relay
KI. The pC, EPROM, I/O expander and jumpers are
suspect again (previous paragraph).
IfDS1
won't illuminate, verify voltage at TP7. It should be
about +11.25 V ifon AC and 6 to 8 volts if on batteries.
If proper voltage is present at TP7 and a low (below 0.5V)
voltage reading comes in on TP12 when On/Off switch is
activated, but DS1 still won’t come on, then the On/Off
latching circuit is bad and the Main Board must be
replaced.
If the voltage is not at TP7, check the AC input through F1,
filter FL1 to primary of Tl. T1 secondary voltage coming
into J1 (pins 1 and 3) should be about 19.9 Vac (with Scale
off; no load). Voltage across the large electrolytic capacitor,
C43 should be about 26 Vdc (no load).
Scale will not lock:
Pressing Lock/Unlock should provide a low to pin 16 of
U15 on the Main Board. Ifnot, check membrane switch on
front panel and connectors down to the Main Board. If pin
16 of U15 is receiving the signal but the Lock/Unlock |
function is still inoperative, replace the Main Board.
Scale will not change units:
Pressing the Kg/Lb switch should provide a low to pin 23
of U15 on Main Board. If not, check membrane switch on
Page 4-5
front panel and connectors on the Display Card down to
the Main Board. If pin 23 of U15 is receiving t the signal,
replace Main Board.
Scale will not zero with Zero button:
Pressing Zero should provide a low on pin 1 of U15 on Main
Board. If not, check membrane switch and connectors on
the Display Card to the Main Board. If signal is OK, but
Scale
still shows no response to the Zero button, replace
Main Board.
Recall switch will not turn on the Scale:
Pressing Recall should provide alow at TP13. Ifit does not,
then check the connectors from the membrane front panel
to the connectors on the Display Card and to the Main
Board.
Ifa lowis seen at TP13 when the Recall switch is activated,
but the Scale will still not turn on and show last locked
weight for 10 seconds, then the On/off latch circuit is
suspect. Replace Main Board.
Recall switch activates the display but the Scale shows
the incorrect weight (e.g. 0.00 Kg):
Check that the non-volatile ram, U16, is plugged in. U16
has a small internal battery which may go dead after many
years. Olympic Medical guarantees the battery for 10
years.
Some segments or annunciator lights do not come on:
Turn on the Scale with the On/Off switch while holding
either the Lock/Unlock, Zero or Kg/Lb switch. This turns
on all segments and lights. If all LEDs do not light, either
replace the Display Card or purchase new displays from
Olympic Medical. Replace all six whenever one fails. This
will ensure digits have the same brightness.
Scale will not weigh accurately:
The load cells are suspect. Slight linearity errors (exceed-
ing specifications) or off-center load errors can be caused
by a defective load cell. However, other factors could cause
errors. Check-that nothing (cables, etc.) is touching or
rubbing on platform. All weight must go through the load
cells. Also check that the ends are not binding on the right
load cell.
If the percent error is constant throughout the range,
recalibrate. If errors are random or there is a linearity
problem, calibration will not work.
Check power supply voltages. If voltages are correct,
weighing inaccuracy or drift can be caused by a defective
load cell or the analog circuitry on the Main Board. The
load cell connectors are also suspect. Return Scale to
Olympic Medical for analysis.
Scale drifts;
Drift can be caused by moisture, contamination, a bad
connection or a bad lead cell. Return the Scale to Olympic
Medical for repair.
SS50-N1-220V(B09)