Looking for a little help regarding my princeton build. Being pretty new to the whole game, I figure I've done something stupid rather than some never before seen issue.
The problem I'm having is - When I power my princeton clone on, everything but the preamp tube lights up. After about 5-7 minutes of the amp burning (rectifier and power tubes are all lit) the preamp tube finally gets heated and working like nothing was ever wrong in the first place. Is there something I'm missing that would cause the heater to delay on the 12ax7?
I HAVE replaced the preamp tube with known good tubes, same result.
newbie question delayed preamp heater
Moderators: pompeiisneaks, Colossal
Re: newbie question delayed preamp heater
There's nothing in the Fender Princeton circuit that could cause this behavior. It's a bug, not a feature. If you have ruled out the tube as the issue, then it's an intermittent connection, possibly heat related. Anyway, reflow the heater connections to the pins and retension the pins.
Oh, failed to mention the obvious thing: hook your multimeter to the heater pins on the bad tube socket and observe what's happening.
Oh, failed to mention the obvious thing: hook your multimeter to the heater pins on the bad tube socket and observe what's happening.
I build and repair tube amps. http://amps.monkeymatic.com
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standardofken
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Re: newbie question delayed preamp heater
will do, thanks for the response!
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Stevem
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Re: newbie question delayed preamp heater
You have a poor connection either in regards to the socket to tube pins, or the heater wiring to the socket, as in bad solder joint or very little wire strands making the connection!
If the tube can not pull the current it needs it will not power up and this goes for the DC side of things also not just the AC heater wiring!
It takes very little current flow to make a voltmeter read so you may be going going nuts seing good voltage readings take place but having no heater glow!
If you reflow the wire connections on the tube socket be sure to do so without the tube in so that the connection gets fully hot fast and the solder flows as it should!
If the tube can not pull the current it needs it will not power up and this goes for the DC side of things also not just the AC heater wiring!
It takes very little current flow to make a voltmeter read so you may be going going nuts seing good voltage readings take place but having no heater glow!
If you reflow the wire connections on the tube socket be sure to do so without the tube in so that the connection gets fully hot fast and the solder flows as it should!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: newbie question delayed preamp heater
Yep, high resistance in series with the heater. It's low enough to let the heater (barely) heat up, but it takes a long time.
Heaters have a variable resistance, like other filament heated bulbs. When they're cold, they are low resistance, and with another resistance in series, they take a long time to get up to the resistance that lets them take over most of the power available.
Heaters have a variable resistance, like other filament heated bulbs. When they're cold, they are low resistance, and with another resistance in series, they take a long time to get up to the resistance that lets them take over most of the power available.