REAR PANEL (Continued)
SPEAKER OUTPUTS: (Continued) NOTE: If you opt to use only one channel of the 2:100 with speakers connected to that channelÕs output only, you must turn the unused channel’s level control to zero! Otherwise the channel will be operating without a load, and damage to the tubes and/or the transformer will result.
TUBE BAY: The power tubes used in the 2:100 are MESA/Boogie
troublesome power tubes.
Often, you can spot the tube at fault and replace it alone, at considerable savings over replacing all the output tubes. A tube that arcs or Òflashes overÓ inside should be replaced immediately. (In an emergency, you can just remove the bad tube and go on with the show...Órunning on 3 cylin-
ders.Ó) Sometimes a tube will Òshort outÓ intermittently, turn- ing
proper operation. Should this happen repeatedly, careful observation will usually reveal which tube is shorting, even though one or two others may also turn
By viewing the tubes, try to verify which one is reddest or turns red first - that is the bad one and the others are most likely unharmed. Internal circuitry is built to withstand tube failure as much as possible; even if damage were to occur, it would be minor and easily repairable.
When replacing tubes, please use only the MESA/Boogie types specified. Using other tube brands and/or types will invalidate your amplifierÕs warranty! To remove tubes, you must first push back the spring retainers clamped against the tube base. When
DRIVER TUBES: 3 x 12AX7A The three small tubes are type 12AX7A, also known as 7025 or ECC83. These tubes are very long lasting and trouble free in the 2:100; should they ever need replacement due to a specific malfunction, genuine MESA replace- ments are recommended for best performance.
MESA | MESA | MESA |
12AX7 | 12AX7 | 12AX7 |
GENTLY ROCK TUBE BACK AND FORTH WHILE
PULLING UPWARD CAREFULLY
NOTE: You must remove the top cover of the chassis in order to gain access to the driver tubes. These tubes can become quite warm. Allow them to cool down before changing and its always a good idea to power down the unit when changing any of the tubes.
Also, be aware that some of the circuitry components (namely the large round capaci- tors running parallel to the three driver tubes) will store a substantial amount of elec- trical charge even after the amplifier is powered down. For safety reasons be sure
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