Lab.gruppen LAB 300 User Manual

Page 10

Appendix A
Mains voltage selection

LAB 300 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 300 is unplugged from

the mains voltage.

2. Remove the top cover.
3. Locate the terminal block for the mains cable.
4. If the terminal block is three pole, the amplifier

is for 230 volt operation only.

Figure 13. 230 VAC wiring

5. If the terminal block has six poles, 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 T4 A fuse (slow

blow), for 115 volt change to a T8 A fuse
(slow blow).

Replace the amplifier top cover.

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.

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 goes into protect, with power
indicators off.
Check that the AC line voltage is not outside the
amplifier’s operating range (130-260 volts).
Over/under-voltage protection may have occurred.

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.