YORKVILLE K4 YS1045, Руководство по обслуживанию

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w w w . y o r k v i l l e . c o m
REAL Gear.
REAL People.
Yorkville Sound
550 Granite Court
Pickering, Ontario
L1W-3Y8 CANADA
Canada
Voice: (905) 837-8481
Fax: (905) 837-8746
Yorkville Sound Inc.
4625 Witmer Industrial Estate
Niagara Falls, New York
14305 USA
U.S.A.
Voice: (716) 297-2920
Fax: (716) 297-3689
SERVICE BULLETIN
K4 Pre-amp Tube Replacement
The Two 12AX7A/7025A tubes are inside the chassis.
To remove the chassis from the cabinet follow these instructions.
1. Unplug all connections. Make sure the K4 is unplugged from the AC main line and
remove all instrument and other cable connections.
2. Remove K4 Chassis from cabinet. Before removing K4 chassis from speaker
cabinet, make sure to unplug the speaker connectors.
a) Remove the five top bolts and loosen the vent screws holding the k4 chassis to the
cabinet; this will enable you to push the chassis forward approximately 2 inches until the
speaker wire connections at the
rear left will be visible.
b) Disconnect the connecter while
noting the orientation of the
locking fingers for when you re-
connect them after the tubes
have been changed. Continue
pushing the chassis forward until
it is out of the cabinet.
If the chassis snags on the
cabinet vinyl, reverse the process
and push it out the back of the cabinet. You may find it worthwhile to insert thin strips
of plastic as shims between the chassis and cabinet down the sides to reduce the
chance of snagging.
5. Once the chassis is removed, using
a small Phillips screwdriver, remove the
20 screws that are used to mount the
amplifier lid. You will find the tubes near
the front of the chassis on the left side
(looking from the front). They are held in
place with a retaining bracket which needs
to be unscrewed and removed before you
pull the 12AX7/7025s out of their sockets.
Remove the tube-retainer bracket screws,
and pull the bracket upward. Proceed to
replace the two 12AX7A/7025A tubes.
6. Reinstall the tube bracket and chassis lid screws.
7. Slide the chassis carefully back into the cabinet remembering to clear the speaker wires;
don’t forget to reconnect the speaker wires before sliding the unit into its final position.
8. Reinstall the large retaining bolts and tighten-down the vent plate screws.
Amp Cover
Lid Screws (20)
Tube retaining bracket
Tube retaining
bracket screws (2)
K4 Amplifier
Tubes
Speaker Connection
Lid and Tube Retaining Bracket