No Heater Glow

[Jana]

Good luck getting help with that attitude.

+1

[Cygnus X1]

Well, I know I can go through my various posts of really stupid questions-many of which I simply shot myself in the foot in the learning process...

Even got told to "hit the books".

It reminds me of the apprentice days where I learned Tool and Die under true masters-they may seem to be haughty and insulting, but they offer a free hand of help-to those who will help themselves.

I am flying under the radar in a way, a realative beginner trying to help someone who may have shot himself in the foot.

The largest part of the experience is often not the lesson in itself, but the humility to show when you find you have messed up. I have been in the machinist's trade for decades, and still have the ability to do something completely bass-ackwards. The trick is to be human when it happens, and not blame anyone but yourself for the decisions made.

It's all good, in my eyes, and to the OP-take that as a lesson.

[ryanburton]

the power inlet/fuse i'm using is http://www.mouser.com/Search/ProductDet ... 252byLc%3d

one terminal from this "switch" (#7 in attached pic) goes to one end of light, other end of light connected to one black lead from PT (mojo bf princeton), other black lead to other "switch" terminal (#5 in attached pic)

[M Fowler]

Yellow wires from PT to pins 2 and 8 rectifier tube, what is the voltage? 405 DC


Red wires from PT to pins 4 and 6 rectifier tube, what is the voltage? 340 AC

Twisted pair wires from PT 6.3 tap to heater string what is the voltage on the heater pins? 4/5 and 9 on all 12ax7 and pins 2 and 7 on 6V6 sockets.

Heaters are AC and will read as 3.15 AC with respect to ground.

Mark

[Phil_S]

Ryan: I've been scratching my head a bit.... You have connected the lamp to pin 7 of the switch and one primary lead on the PT. Pin 7 is the neutral. Typically, the lamp is on the hot or line leg. But that is neither here nor there. (Look on the IEC; it is marked L for line and N for neutral. The third/middle terminal is marked E for earth or ground.)

I believe the problem is putting the lamp in series with the a/c power supply. The bulb is acting as a limiter and you will never achieve full power with an incandescent in series. I suspect this lamp only gives you a dim glimmer, not full brightness. Is that the case?

Try putting the lamp in parallel to the PT primary. The switch controls both the line and neutral, so when you turn it on, it will connect the lamp and the PT at the same time. Like the sketch I made below.

[ryanburton]

Phil_S - thanks, your lamp suggestion seemed to be the solution i was overlooking.

i took the lamp completely and rewired the PT from scratch paying very very close attention to solder joints etc. i powered up and measured ~6.3VAC on the heaters. popped in tubes, saw glow from all tubes, although the rectifier looked more red than i recall from similar amps. flipped to standby, waited a minute or so, biased tubes to ~19mvdc. plugged in guitar, sounds ok, some hum. played for 10min at halfway. really loud with volume on 9. powered down. rectifier and 6V6s felt hot, but not scalding shortly after.

thanks to everyone for all the help and suggestions, and even the critics to keep the post near the top

[ryanburton]

Phil_S - thanks, your lamp suggestion seemed to be the solution i was overlooking.

i took the lamp completely and rewired the PT from scratch paying very very close attention to solder joints etc. i powered up and measured ~6.3VAC on the heaters. popped in tubes, saw glow from all tubes, although the rectifier looked more red than i recall from similar amps. flipped to standby, waited a minute or so, biased tubes to ~19mvdc. plugged in guitar, sounds ok, some hum. played for 10min at halfway. really loud with volume on 9. powered down. rectifier and 6V6s felt hot, but not scalding shortly after.

thanks to everyone for all the help and suggestions, and even the critics to keep the post near the top

[Phil_S]

Ryan: good job on fixing it. Google for "dim bulb tester". That is what you had in the circuit. I was unable to understand from your earlier descriptions that you had the lamp in series. As you can imagine, this sort of diagnostic is hard to do without the equipment in front of you. I am glad we could both rise above the earlier stuff about whether you were up to it. I hope you understand there were only good intentions.

BTW, power and rectifier tubes will get way too hot to touch. Your typical 12AX7 may be cool enough at operating temperature to touch, but will make you uncomfortable and even burn you slowly.

Enjoy the amp.

Phil

[Tubetwang]

Ryan: good job on fixing it. I am glad we could both rise above the earlier stuff about whether you were up to it. I hope you understand there were only good intentions.



Enjoy the amp.

Phil

Good intentions and intelligent folks is what makes this place fun to hang around...

[M Fowler]

Maybe I am being too forward here but if that was all the probem was then you should have looked at the TW layouts as they clearly show how to wire up an AC circuit and would have solved the problem from the get go without all the grumbling back and forth.

Just my 2cents worth

[Structo]

Yeah but we got three pages worth out of it.

[Tubetwang]

and i do get 5 cents per word...