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Audio and Video Talk
Valves / Vacuum Tubes
Quad II trouble
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<blockquote data-quote="fdlsys" data-source="post: 405552" data-attributes="member: 2310"><p>6.7Vac on the heater would be lethal to the cathode over period of time, no question. That is pretty much what you are experiencing, right? From the schematic, it seems that heaters are powered directly from the secondary which leaves you with only one possible cause, the transformer. Either the 220-230-240-... primary VAC selector is set wrong, or the secondary itself is out of spec. (no idea if it's possible for transformer to drift over time?)</p><p></p><p>Remedies </p><p>- you could drop voltage using a large power resistor? </p><p>- rectification and regulation would be even better - and safer in long term. 6.3v regulators are commonly available.</p></blockquote><p></p>
[QUOTE="fdlsys, post: 405552, member: 2310"] 6.7Vac on the heater would be lethal to the cathode over period of time, no question. That is pretty much what you are experiencing, right? From the schematic, it seems that heaters are powered directly from the secondary which leaves you with only one possible cause, the transformer. Either the 220-230-240-... primary VAC selector is set wrong, or the secondary itself is out of spec. (no idea if it's possible for transformer to drift over time?) Remedies - you could drop voltage using a large power resistor? - rectification and regulation would be even better - and safer in long term. 6.3v regulators are commonly available. [/QUOTE]
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Audio and Video Talk
Valves / Vacuum Tubes
Quad II trouble
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