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Odds are that a tube arced over inside and zapped the low-voltage components in the bias circuit with a few hundred Volts or more.

Once they have shorted, the excess current available from the transformer's 12-Volt heater winding will turn a foil trace on a pc board into an auxiliary fuse.

Have seen this sequence play out more than once. Especially if the amplifier was either tuned wrong, driven too hard or keyed too long.

Radiated heat from the nearest final tubes are what melt the meters as a rule.

73

[QUOTE="nomadradio, post: 753112, member: 22"] Odds are that a tube arced over inside and zapped the low-voltage components in the bias circuit with a few hundred Volts or more. Once they have shorted, the excess current available from the transformer's 12-Volt heater winding will turn a foil trace on a pc board into an auxiliary fuse. Have seen this sequence play out more than once. Especially if the amplifier was either tuned wrong, driven too hard or keyed too long. Radiated heat from the nearest final tubes are what melt the meters as a rule. 73 [/QUOTE]

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