Troubleshooting FET

[philbard]

Phil, the NTE 452 can take up to 30v at the drain. Even if your B+(5) goes up 100v from 300v to 390v the voltage at the divider would only go from 20v to 25v. The catch is what the voltage is when you first hit the stand by switch.
CW

Interesting, my gut would have been that it was more sensitive. Luckily not, although I have a back up handy and could have swapped it out. Thanks for the info, my amp sounds fabulous and I'm appreciative of all the support from the TAG community.