Owner`s manual

10
REPLACING a FUSE or a TUBE:
Yes there are user-servicable parts inside! (Contrary to what The Safety Regulatory People tell us to
declare on the rear of the chassis.) But, as with other vacuum tube based products, there is also high
voltage present. Therefore caution must be used when covers are removed; otherwise there could be
shock hazard. Probably not enough to kill you, only enough to severely annoy you should you
inadvertently grab onto the B+ volts. As with all mains-powered gear make sure the mains power is
off and mains cord is unplugged. If the amp has been powered up within the last 15 minutes stop! and
let the large electrolytic capacitors discharge otherwise you could still get a shock even though the
unit is unplugged. Really! You will need a #1 Philips screwdriver to remove the bottom cover screws.
MAINS FUSE: See page 3.
B+ FUSE: If all of the sardine none of the tubes show any bias reading at all, and the lights are on,
and no tunes will play, you might have popped a B+ fuse. This fuse is here to protect the output
transformer from a rougue tube or some other strange event. Before replacing it, stop and think a
minute if you noticed anything, like a bang or crack noise coming from the speaker. Or maybe you
notice one of the tubes looks cracked or sick. Or maybe you smelled something funny? And saw a
tube take off and glow bright red or orange? Any of these events could be a tube "running away". If
you are aware of what went down and can clearly see the offending tube, then yes, do replace it and
then replace this B+ fuse. Always check the bias on a new tube as the amplifier warms up and watch
him closely like a new puppy to make sure he behaves for the next little while. The fuse is a1/2 Amp,
250v MDA SLO-BLO (time delay). The size is 1/4" x 1 1/4". Only use a ceramic fuse here as the
glass ones sometimes flame out or crack. Do not use a Fast Blow fuse or you will be replacing them
on every downbeat. And remember those 575 volts we mentioned? They are living here on this fuse,
so you had better MAKE SURE THE AMPLIFIER IS OFF AND UNPLUGGED AND
DISCHARGED before you dig in here! Use one hand only when reaching into the enclosure or
touching any components inside. Keep the other hand away from the amplifier, preferably in your
pocket. For real!
SWAPPING TUBES: Three tube types that are electrically and plug-socket compatible with the
12AT7A dual triode include the 6021, 6679, and the ECC81. There is no direct replacement for the
7044 dual triode, although the 6900 or 5687 are pin-compatible substitues. We have no experience
with either of those two types and thus cannot vouch for their worthiness in the Snappers. The 7044 is
really the best choice here, trust us. Actually think long and hard before just trying to score some
golden lovely tubes on ebay for $125 each. Are they really what they claim to be? (Paint can be
scraped off or applied at will.) Are they really new? (Hard to tell sometimes.) Are they tested? Were
they tested for optimum performance in a Snapper? We didn't think so. By virtue of our experience,
testing, and selection we do recommend you obtain replacement tubes from the factory. We will
indeed be looking after the best interests of you and your Snapper in our tube selection travails.
Please direct any other more involved questions regarding the guts of the Snapper to
MANLEY LABS Tech Support for further assistance.
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