Tubes Asylum

Rectifier 280 tube problem ? loud and soft

61.8.254.10

tangotango

Have a yamamoto a08s with 280 rectifier tube. The amp was working fine then the volume start to turn soft for a short period before going back to normal. This happened a few times. I noticed that the filament of the 280 tube dimmed when the volume went down. Does this indicate that my 280 tube is dead or some other problems ?

Follow Ups:

Not necessarily... - Lee of Omaha 13:29:59 03/17/14 (0)
You might be right, but the phenomenon you witnessed can also be an indication of a rather severe brownout. Or something within the amp drawing enough current to overload the power transformer. Clearly, the 80 filament wasn't getting enough voltage. The question is why.

Your 280 is the same as an 80, 180, 380, and 480. In the early days the first digit indicated manufacturer. Generically, you have an 80. They're pretty cheap and readily available.
Not necessarily... - Lee of Omaha 10:24:14 03/17/14 (0)
You might be right, but the phenomenon you witnessed can also be an indication of a rather severe brownout. Or something within the amp drawing enough current to overload the power transformer. Clearly, the 80 filament wasn't getting enough voltage. The question is why.

Your 280 is the same as an 80, 180, 380, and 480. In the early days the first digit indicated manufacturer. Generically, you have an 80. They're pretty cheap and readily available.

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