ECC88 heater overvoltage damage? - diyAudio
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Old 9th November 2008, 08:30 AM   #1
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Join Date: Jan 2005
Location: Zagreb
Default ECC88 heater overvoltage damage?

Hi all,
just did something stupid, hooking 12VDC instead of 6.3V to a pair of ECC88. It didn't last longer than a minute.
Tubes glow normally now, heaters draw ~300mA which is close to spec.
Since my project is in construction phase, I have no way of checking if they're OK or not.
Did I damage the heater/tube?
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Old 9th November 2008, 10:54 AM   #2
ilimzn is offline ilimzn  Croatia
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Join Date: Feb 2005
Location: Zagreb
Probably not. In fact, if there was anode voltage, this sort of technique is sometimes used to 'rejuvenate' old tubes. In the end you will have to try and see, but you have good chances that all is well.
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Old 9th November 2008, 10:55 AM   #3
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Location: Melbourne, Victoria
If the heaters are still continuous and the heater isn't continuous with the cathode (as in, the heater-cathode insulation is still working), I wouldn't worry about it. Valves are quite robust devices, unlike the three legged fuses often used nowadays.
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Old 9th November 2008, 02:35 PM   #4
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thanks, there was no anode supply during the situation and there is no connection between heaters and other pins.
one more reason to love them
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