Lab.gruppen LAB 500 - Manual (Page 11)

11
Appendix A
Mains voltage selection
LAB 500 is normally shipped for 230 volt AC
operation only. For export there is a 115/230 volt
AC option available. To check if the amplifier is
equipped with this option, please follow these
steps:
1. Make sure that the LAB 500 is unplugged from
the mains voltage.
2. Remove the top cover.
3. Locate the terminal block for the mains cable.
4. If the transformer’s primary side has two wires
only, the amplifier is for 230 volt operation
only.
Figure 13. 230 VAC wiring
5. If the transformer’s primary side has four
wires, the amplifier has the 115/230 volt
option.
6. To select the desired mains voltage, wire the
terminal block as shown in Figure 13 or 14.
7. For 230 volt operation; use a T6.3 A fuse (slow
blow), for 115 volt change to a T10 A fuse
(slow blow).
8. Replace the amplifier top cover.
9. For 115 volt operation; stick a ”115 VAC”
label on top of the 230 VAC label on rear
panel.
Figure 14. 115 VAC wiring
Warning: This modification should only
be made of an experienced service
technician.
Maintenance
Under normal use the amplifier should give years
of trouble free service. The only user maintenance
required from the user is to vacuum the front grill
periodically.
In some extreme cases it may be necessary for
your supplier to clean the inside of the amplifier.
These conditions usually occur after prolonged use
in environments using "cracked- oil" smoke
machines.
If you are using your amplifier for heavy duty use
i.e. concert touring or industrial music it is
recommended that you have your amplifier
serviced every 3 years, purely as a preventative
measure
Troubleshooting
These are typical things to check if you think your
amplifier is faulty:
Fault: No output.
If the output bargraph is functioning there is
nothing wrong with the amplifier, and the likely
cause is an unsecured Speakon.
Check that the VHF protection is not activated. If
it is, remove possible high frequency oscillations
from the relevant input.
Fault: The amplifier goes into thermal protection
when driven at low level.
Check that your loudspeaker has not got a short
circuit in its windings, (this can occur when the
speaker coil gets warm).
Fault: The amplifier does not respond even after
checking above items.
In the unlikely event, that there is a non-user
rectifiable fault, return the amplifier to your
supplier or an approved service centre.
Lab Gruppen cannot be held responsible for
damage or injury, as a result of the top cover
being removed.