I60 Owner’s Manual Ver 1.2
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voltmeter (like the RadioShack pictured) don’t worry if you can’t get to
exactly 2.00V. Plus or minus 0.05V is more than accurate enough!
Once you have adjusted the bias of one tube, move the red probe to the
other hole labeled (+) to adjust the bias of the other tube before moving to
the other side of the amplifier to adjust the bias of the other channel.
Replacing Tubes
When replacement parts are required, make sure that the service technician
uses parts that are as specified, or have the same characteristics as the
original part. Unauthorized substitutions may result in fire, electric shock, or
other hazards.
The only valves that may need replacement are the power output valves –
these should be replaced with matched pairs of KT88’s. As the I60 has
individual bias controls for each tube, matched pairs need not be used.
However, if matched pairs are used, the matches should be placed on both
the left output pair, and the right output pair.
When you replace the power output valves, you will have to rebias the
amplifier as described above. In normal usage of approximately 500 hours
per year, the power output valves will last you 6 to 8 years.
The vacuum valves used on the I60 are high quality, reliable, low gas valves.
It is highly recommended that you replace these valves with equivalent
valves from reliable, quality suppliers.