Maintenance and Trouble-Shooting
In general, the LD90 system will require very little maintenance. However,
the following is a list of routine tests that should be carried out as often as
local regulations require, but at least annually. RCD's should be te sted
monthly.
Routine Tests
Fault finding
1. Load wiring should be tested in accordance with local regulations.
2. Check all terminals for tightness.
3. Ensure vents are always kept clear and not obstructed.
4. Test optional RCD's.
Fault finding is relatively easy with LD90 systems because the racks
include diagnostic software (tests are run each time the rack is powered
up) and include status LED's and the LCD display.
Experience shows that common faults are connected with the control signal
wiring. The following will help you to identify any faults that occur:
System Problems
Problem
Answer
Problem
Answer
The following problems are those that are generally found to affect a whole
lighting system, rather than a particular rack.
None of the lights will come on throughout the system.
Having checked the obvious things such as power to the dimmers, the most
likely cause is failure of the MUX connection. This can be verified by
observing the MUX OK LED on each rack. Assuming that the MUX
protocol has been selected correctly and the MUX start number or patch
are as required (see earlier), if none of the MUX OK lights on any rack is
on, then the cable is probably at fault. Check the connectors at each end,
and, using a ohmmeter, check that the signal(s) and shield are not shorted.
If they are not shorted, then the most likely cause is an open circuit
somewhere along the line.
Some lights can't be turned off.
There are many ways to control lights with an LD90. Some common
problems are: Presets being called up unexpectedly from a handheld control
or wall station, or the NoMUX preset is being called up because the racks
have not detected MUX (wiring fault etc.). Note that it is also possible to
leave a PRESET on via the PRESET VIEW facility.
Maintenance and Trouble-Shooting 1
Also MIN LEVEL may be set for a particular dimmer. There is no way of
turning off a dimmer with a min level set.
Problem
Answer
Problem
Answer
The lights flash or become erratic. The MUX OK LED goes on and off
erratically.
This problem may be caused by one MUX sig nal wire being loose or
disconnected. It is most often seen with DMX512 installations. Both
DMX512 signal connections and ground (screen) must be connected to all
dimmers and the control desk. A common installation fault with DMX512 is
the reversal of the two signal connections, or a signal connection and
screen. This causes havoc! Check that all cables have the correct wiring.
A further problem can be caused by either over terminating the line, or not
terminating the line at all. Make sure that only the rack farthest away from
the console has its line terminated (see line termination earlier)
The lights very occasionally flash or misbehave.
This may be caused by interaction with other systems. Try to isolate the
occurrence of the problem and tie it in with activity in other parts of the
building. Arc welding or unsuppressed motors (lifts etc.) can cause mains
disturbances or corruption of control signals. LD90 is highly immune to
such problems, but in extreme cases interference can occur.
If time is available, set ALL dimmers to a given (low) level from the rack
keypad. This isolates the control signals and allows observation of the
dimmers alone. If the problem still occurs, then it is a mains -borne
interference. The solution will be to re-route the feeder cables to another
supply (if at all possible), or suppress the offending equipment. If, however,
the problem goes away, then it may be in the signal wiring (see above), the
routing of the wiring (make sure it is not near noisy equipment), or a fault in
the control desk.
If your control desk signal can use the SMX protocol, then this will provide
a far greater immunity to interference than DMX512 or D54. Changing the
protocol on both the dimmer(s) and control system to SMX is a cheap
alternative!
Problem
Answer
2
The handheld control or wall station operates erratically.
The wiring between the dimmers and control system is similar to the
handheld or wall station wiring. The same rules as above apply.
in each power block
L1 L2 L3
Rack type problems
Problem
Answer
Problem
Answer
Problem
The following problems are those that are generally found to affect a single
dimmer rack, while other parts of the system are work. correctly.
One rack doesn't work properly, the others do.
This can be caused by the wiring faults as described above. It may also be
caused by incorrect programming. It is quite easy to set a dimmer to a
LEVEL from the keypad, and in so doing disable MUX control. The
dimmer reverts to normal control at power up, thus power cycling is a quick
way to check. Equally, setting the level from the keypad verifies electrical
operation of the dimmer regardless of control system.
An extreme example of a wiring fault is a loose power connection to the
rack. Loose neutral connections in particular cause havoc!
Some dimmers don't appear to work.
Use the LEVEL key to check dimmer operation. If the dimmer fails to
work, and all load wiring and connected load has been tested, then the
dimmer will require service. If the dimmer works from the keypad, but not
from the control desk, check tha t the START NUMBER or PATCH are
set correctly. Check also the dimmer patch in the control desk if applicable.
One power block isn't working
Answer
Problem
Answer
Check that the POWER LED is on for the relevant phase. The ordering of
the LED's is the same as the power blocks. If power is OK, then check
that the RCD unit (if fitted) hasn't tripped. If power is definitely present,
turn the dimmer off and back on, and observe the "sign-on" message:
LD90 V. XX 888
Software Version No. of dimmers
The number of dimmers in each power block should be consistent with the
number of circuit breakers. If a figure is 0, then the power block may not
be connected correctly.
Lights don't appear to track each other in fades.
This can be caused by using different DIMMER LAWS on each dimmer
or setting dimmers to different max. output voltages. The keypad can be
used to set ALL dimmers in a rack to the same law and voltage (see
above) to rectify the problem.
Maintenance and Trouble-Shooting 3
Processor Unit
Removethesetwoscrews,an
d
First Line
Maintenance
Replacement
The following procedures are designed for a semi-skilled technician to
follow in the event of minor failures. They do not involve the use of
complex tools or equipment.
Hazardous voltages are contained within the rack. All maintenance
operations must be carried out with power to the rack properly
isolated.
The processor unit contains many complex circuits, most of which are
surface mounted on a multi-layer PCB. This is an expensive item, and no
attempt should be made to repair it, under any circumstances.
It is, however, feasible to replace the module with an exchange unit. The
following procedure should be adopted.:
1. Switch power off.
2. Remove the front cover of the rack.
3. Remove the two fixing screws shown arrowed in the diagram below.
4. Remove the earth strap from the earth bus-bar to the Processor Unit.
5. Slide the unit out approx. 75mm, giving enough space to disconnect all control
signal cables, the 3-phase power cable, and the Power Block cables as shown
below. Note the positions of all connectors as several of them are similar.
6. Slide the unit forward and out of the rack.
7. Replacement is the reverse of the above procedure. Make sure that the
connections to the Power Modules are made to the correct plugs on the PCB.
They are clearly marked "DIMMERS - PHASE L1", "DIMMERS-PHASE L2",
and "DIMMERS-PHASE L3".
8. Ensure that the rack cover is replaced before applying power again.
slide Processor Unit forward
Remove 3-phase
power connection
and separate earth
Processor Unit Fuses
(05 004 17)
Remove control signal
and Power Block
connections
4
Processor Unit
Reconfiguration
Processor Unit Fuse
All user configurations are held in a non-volatile memory device
(EEPROM), IC 12, on the Processor Unit PCB. This device is socketed,
and it is therefore possible to "transplant" it into an exchange unit, so
avoiding the necessity to re-configure the unit manually.
The memory device is Static Sensitive. Do not attempt removal and
replacement without using proven anti-static precautions, such as an
earthed wrist strap and earthed anti-static working surface. If you are
in any doubt, do not proceed.
Front of Processor Unit
LK3
IC12
EEPROM
Replacement
ProgramStorage
EPROM
1. Remove the Processor Unit from the rack
2. Remove the Processor Module cover (two screws)
3. Ensure anti -static precautions have been taken.
4. Gently lever out EEPROM, IC12
5. Repeat above two steps with exchange unit.
6. Swap devices over. Make sure that the device is oriented correctly, see left.
7. Replace the covers on both units.
The replacement unit will now have the "personality" of the previo us one,
and will require no setting up.
Test the unit as if you were applying Power for the first time (see Testing
After Power On, in the Installation Section).
Note that the Operating Program is stored in the EPROM, IC16 next to the
EEPROM, IC12. Software upgrade is a simple matter of swapping this
device. Refer to the Issue Notes supplied for any compatibility issues.
The Processor Unit power is supplied via three fuses mounted directly
above the Unit. In the event of a major Processor Unit fault, one or more
of these may be blown. This is very unlikely, and will almost certainly mean
that the Processor Unit will need to be exchanged.
Maintenance and Trouble-Shooting 5
Once the Processor Unit has been removed, the fuses may be examined.
A fuse is removed by gently pulling the "cap", which contains it. Spare
parts numbers are given later in this section.
The fuses must only be replaced with ones of the correct value and
similar specifi cation. Failure to use the correct values could have
serious safety implications.
Power Device
Replacement
PowerDevice
LV1
LV1
NEU1
NEU1
Power devices on all 2.5kW dimmers are identical, as are all devices on
5kW dimmers. Replacement on 2.5kW dimmers is very easy because each
device is individually connected with screw terminal blocks on the Power
PCB.
Power Devices typically fail "short circuit", and the classic indication of
this, is the inability to turn a dimmer off. To verify that a device has failed,
attempt to control the load using the LEVEL facility, this ensures the
problem is not with the control wiring. If it is impossible either to turn the
dimmer on, or off, and MCB has been checked, then the power device is
most likely to be at fault.
Power Devices can be damaged by a fault condition on the load wiring,
and it is important to check that any wiring fault has been repaired
before repairing the dimmer.
If the dimmer is a 5kW type, the whole Power Block will need to be
replaced. This is done as a reversal of the Installation Procedure, see
earlier. Repair must be done only by qualified Strand Service agents.
If the dimmer is a 2.5kW type, use the following procedure:
1. Identify which physical dimmer is at fault, by reference to the fascia panel
labelling.
2. Isolate the rack and remove the front cover.
3. Remove all the fascia covers from the Power Block is question, by gently
pressing the "legs" inwards to release them from the extrusion.
4. Unscrew and remove the Power Device.
5. Replace the device with one of the pair supplied in the spare part kit 05 004 18.
6. Ensure that the screws are done up tightly to avoid a "hotspot" on the device
in service.
7. Replace the mounting screw with the one supplied in the spare part kit above.
This is essential to guarantee adequate thermal contact with the heatsink.
Do not attempt to operate the dimmer without fitting a new Power
Device of the correct type. It would cause considerable damage to the
firing circuit.
6
Spare Parts
The following are branded spare parts to be used with LD90. Do not use
any other parts, as these may compromise safety and reliability.
05 004 14
05 004 16
05 004 17
05 004 18
08 680 28
LD90 Processor Unit.
LD90 Spare Fascia Panel, complete with all label types.
LD90 Processor Module Fuse (3 off).
2.5kW Power Device (2 off).
5kW Power Device.
Maintenance and Trouble-Shooting 7
8
Loading...