an analog meter if a tube shorts or flashes. We suggest a using a digital voltmeter as most
digital voltmeters have excellent protection.
FUSES
The fuses for your RM200MkI/MkII have been carefully specified.
The output tube fuses are ceramic, 5 X 20 mm, 250 mA, slow blow, high-interrupting
(interrupt rating: 1500A@250VAC). Please note that typical fuses have a much lower
interrupt rating of 35A@250VAC, and are not suitable for your RM200MkII.
The mains fuse is 5 x 20 mm standard slow blow, 5.0 Amp (for 120 volt) or 2.5 Amp (for
240 Volt).
For your protection and safety, always replace with identical or comparable fuses. DO
NOT SUBSTITUTE! Using a different fuse will void your warranty. You may order
additional fuses from RAM Labs/Music Reference (www.tubeaudiostore.com) or your
dealer.
WARNING: Do not use “Tuning Fuses”, “IsoClean”, “Furutech” or any of the high-end
fuses as they have already shown that they are unable to protect the tubes and output
transformers. The people making them know nothing about high-interrupting fuses
(interrupt rating: 1500A@250VAC). Roger A. Modjeski was told by one distributor that their
ceramic fuse was equivalent to our high-interrupting ceramic fuse because they were both
ceramic. This is clearly not factual.
TUBES
The six tubes in your RM-200MkI/MkII have been carefully selected by RAM Labs for best
performance. The operating parameters have also been selected to achieve long life and
reliable operation. We suggest replacing with RAM Labs tubes when that time comes.
You may notice a bright flash from the bases of V1 and V2 on turn-on. This is perfectly
normal and does not shorten the life of the tube in any way. The flash is due to the fact that
the filaments are coated to insulate them from the cathode sleeve. In the process of
connecting the tungsten wires to their pins, the coating has been removed. This uncoated
portion has less thermal mass and thus heats quickly, causing the flash. The input tubes
are rated for 10,000 hours and 10,000 turn-on cycles. Therefore, it is perfectly OK to turn
the amplifier off and on again if you are not listening for an hour or more. Although there is
a common myth that tubes do not like to be cycled, I have found it to be without foundation.
Filament failures in well-made tubes are so rare, I can't remember when I last saw one.
You may notice some hum from your speakers if your hand or an AC cord is placed near
V1 or V2. This is normal as the tube is unshielded. If you notice crackling noises, try
cleaning the pins of V1 and V2 with a small brass wire brush and lightly coat the pins with
DeoxIT, use sparingly.
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