Testing And Troubleshooting On Opened Unit; Testing Power Supplies; Testing Triac; Testing Battery Charge Current - Bosch BSL 2470 Repair Instructions

4 Testing and troubleshooting on opened
unit
When testing, check for signs of intermittent contacts, contami-
nated and corrosive plug contacts, as well as any kinking and
crimping of the cables!
4.1

Testing power supplies

Make sure that the battery charger is not connected to
any voltage source!
1. Check the power cord for continuity
2. Check the mains switch (fig. 2, pos. 16)
3. Check the change-over switch for 12/24V (fig. 2, pos. 16)
4. Check the safety switch (fig. 2, pos. 21) for continuity
i Two temperature fuses are integrated into the mains
transformer's primary winding (fig. 5).
S01-150.05:
This temperature fuse opens, when the temperature of
the mains transformer exceeds 150 °C and closes again
after the mains transformer has cooled down. For this
reason the mains transformer must be cooled down
when testing the temperature fuses.
S3M.184.05:
This temperature fuse opens, when the temperature of
the mains transformer exceeds 180 °C; but does not
close again once the mains transformer has cooled
down.
If the temperature fuse is faulty the mains transformer
has to be replaced; it is not possible to exchange the
temperature fuse.
5. Check the temperature fuses in the mains transformer in
the following manner:
- remove X12 (fig. 6) on the printed circuit board
- check for continuity between X12/1 to X12/3
6. Check mains transformer's primary winding
- unplug X2 and X7 on the printed circuit board (fig. 6)
- The following resistance values are general values:
Change-over switch for 12/24V in position 12V
resistance value between X2/X7 approx. 1.2 W
Change-over switch for 12/24V in position 24V
resistance value between X2/X7 approx. 0.9 W
If the resistance value lies significantly above this
general value, the mains transformer should be re-
placed.
7.
Check power supply on printed circuit board
- check F1 fuse on printed circuit board
- connect battery charger through isolating transformer to
mains supply
- test voltage on printed circuit board from P3 to P4 (fig. 6)
Target value approx. 17.4 V= ±10%
If this voltage lies significantly below the target value the
printed circuit board is to be replaced.
8. Checking the red LED
- the voltage on the printed circuit board between X9/1
and X9/2 must be at least approx. 1.9 V.
If the voltage lies significantly below this value then
the printed circuit board is to be replaced. If the voltage
is correct the LED is either incorrectly connected or
faulty.
10
4.2

Testing Triac

1. Checking the Triac control on the printed circuit board
A clocked D.C. voltage must be applied to the printed
circuit board between P3 and P7.
This voltage can be measured using, e.g. a PMS 100 and
amounts to approx. 15 V - 17 V
If the measured voltage lies significantly below this general
value then the printed circuit board is to be replaced.
2. Disconnect all triac connecting lines and use a multimeter
to test between connection "G" and "A1" in the diode
measuring range in both directions.
In each case a diode section must be measured.
An on-state voltage should not be recorded when measur-
ing from „G" to "A2" and "A1" to "A2".
3. Measure the secondary no-load voltage on the mains trans-
former.
Between the mains transformer's mid connection
at each end of the winding (fig. 5) an alternating voltage of
approx. 6.9 V should be measured.
If the voltage lies significantly below this value then the
printed circuit board is to be replaced.
4. Connect the test battery to the battery charger.
Set the potentiometer to the left-hand limit stop.
! If a very high current flows once the battery charger has
been switched on, then the charger should be switched off
immediately!
In this case the triac is defective and has to be replaced.
4.3

Testing battery charge current

1. Checking the power relay
Connect the test battery to the battery charger.
Set the potentiometer to the left-hand limit stop.
Switch on the battery charger.
- power relay can be audibly heard to switch.
Use a multimeter to measure the potential drop
across the power relay's switching contact.
The potential drop should not be greater than 100 mV.
If the potential drop is greater, then the relay is to be
replaced.
- power relay does not switch on
Use a multimeter to measure the voltage between
connection 31 and 50 on the power relay.
Target values should be approx. 24.5 V= ±10%
If this value lies significantly below this target value then
the printed circuit board is to be replaced.
If the target value is reached then the relay is to be
replaced.
2. Battery charge current cannot be regulated
Check the potentiometer (10 kΩ) and replace if necessary.
If the potentiometer is ok replace the printed circuit board.
3. If the ammeter fails to display a value despite battery current
flowing then it should be changed as follows:
The rectifier's connecting cable to the power relay is not
properly connected to the ammeter, but rather only looped
through.
To change the ammeter disconnect this cable from the
rectifier.
! Note in which direction the connecting cable has to be routed
through the ammeter.