DIAGNOSING
Let us begin by saying; It is a Òvery goodÓ idea to keep at least a couple of spare
The best way to approach a
If you cannot narrow down the trouble to a specific mode or channel, the problem may be the small tube that drives the power tubes which is operational in all modes and channels. Though rare, a problem with the driver tube would show up in all aspects of perfor- mance - so if you canÕt narrow the problem down to being mode or channel specific, you may want to try replacing the driver tube. Driver problems generally show themselves in the form of crackling or hum in all modes of performance and/or weak overall output from the amplifier. Occasionally an anemic driver tube will cause the amplifier to sound flat and lifeless, but this is somewhat uncom- mon, as worn power tubes are a more likely suspect for this type of problem.
Sometimes making the diagnosis is more trouble than itÕs worth and itÕs faster and easier to merely replace the small
Remember, take your time, be patient and chances are real good that you can fix your amp yourself by finding and replacing the bad tube. It kills us to see someone who has shipped their amp back to us...and all it needed was a simple tube replacement! If you must send back your amp, unplug the power cord, speaker and reverb cables then remove the chassis from the cabinet by unscrewing the four mounting bolts on top. The chassis then slides back like a drawer and comes out. Remove the big power tubes and mark them according to their location from left to right 1, 2 etc. They need to be wrapped separately with plenty of wadded up newspaper around them and put in a smaller box within the larger carton.
To wrap the chassis, use plenty of tightly wadded up newspaper so there is at least six inches of Òcrush spaceÓ between the chassis and the cardboard box. Bubble wrap also works well, but please DONÕT use styrene peanuts - they will shift during transit and get lodged inside your electronics as well as allowing your amp to end up at the bottom of the box unprotected and possibly damaged.
Therefore, it is not a good idea to change them just for the sake of changing them. If there isnÕt a problem - donÕt fix it. If there is no result from your substitutions, it may be possible that you have more than one problematic tube. Though rare, this does happen and though it makes the troubleshooting process a little more intimidating, it is still possible to cure the problem yourself.
NOTE: It is normal to hear a slight metallic ringing sound when tapping on the preamp tubes. As long as the tube does not break into oscillation or start crackling or any other form of bizzare noise, it is considered normal and functional.
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