11
EvoLution Series
Fuse Protection
Warning! Fuses are safety valves. They should always be replaced with the exact same value and type.
Never attempt to check or replace a fuse while the amp is plugged in. Turn it off and unplug the AC cord
before continuing. Wait 10 minutes to let tubes cool down and the circuit to fully discharge.
Mains Fuse: The mains fuse is located on the rear of the amplifier, just
below the power cord socket (see picture on the left). The fuse rating is 1 x
Littelfuse 213 Series 3.15A Slow Blow 5 x 20mm fuse for 100-125VAC and
Littelfuse 213 Series 1.6A Slow Blow 5 x 20mm fuse for 200-250VAC.
Always replace with the same type and value fuse! Littelfuse 213 is a
special time-delayed slow blow fuse! Not a standard slow blowe fuse!
The fuse holder can be opened using a small slotted flat blade screwdriver.
The IEC connector is mounted with 2 different color screws. One silver, one black. The silver screw
indicates the Live AC in the IEC connector. It helps with the "correct" connection to AC. Nevertheless
always check the AC cable by measuring as not every AC cable is constructed the same way.
The Adaptive Auto Bias Board is protected with an easily accessible Littelfuse
213 315mA fuse located next to the on / off power switch.
Electronic Protection
The PrimaLuna EVO Tube Poweramplifiers are equipped with Soft Start™ and come with an extensive
output stage protection circuitry with +B relay to protect output transformers, resistors and high voltage
power supply in case a tube fails.
The board also comes with a BTI™ circuit. BTI™ stands for Bad Tube Indication (by the change of front
LED to red), making tube-life again a bit easier. The BTI™ circuit is totally inactive during normal
operation. However when one (or more) output tube(s) draw(s) significantly more current than normal for
a couple of seconds, such as when a loudspeaker terminal short-circuits with volume turned up, or in the
case of an output tube failure, the BTI™ circuit “reads” the changes as a potential threat and as a
protective measure, interrupts the power supply. It indicates, by the led in front of the power tube, which
tube might be bad. To reset, simply turn the power off and after two minutes, turn back on. However,
you do not want to repower the unit until the cause of the failure has been identified and resolved.
Switching the power back on too early also can fool the BTI circuit into acting as though the problem has
not been totally resolved and it may put the amp back into protection mode again. So be sure to give it
enough time to reset! At power on and power off, one or more of the LEDs may light up for a second.
This does not indicate anything at all. Tubes can often “burp” during this time.
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