No Heater Glow

[Cygnus X1]

Careful Jana.
Studies reveal 9V's are a "gateway" to car batteries.

Friends don't let friends "just say no"...or something like that.

[Tubetwang]

Tubetwang,
You think that the warning about hazards of getting shocked is overblown?

Did you know that if you get a shock from one hand to the other the current will pass through your heart?

Did you know it takes less than 300ma to stop your heart if you happen to get the right mix of voltage and current?

So no, the dangers are not exaggerated at all.

It would be very tragic if we helped somebody do something inside their amp without mentioning the hazards and dangers and that person electrocuted himself while probing inside the amp.

I understand and agree that a warning is welcome...

But a warning and an answer is better than a warning alone...

Cuz...you see... a warning alone, does'nt do much to fix dude's amp...

As far as yar heart stopping...here's my advise...

If you find yourself with a stopped heart due to an electric shock...here's what i do...get another electric shock...that is usually sufficent to kickstart the mother...

If not... repent...



And yes...like Mark says...l jumped ship at 18watt for it got old pretty fast...can't do this, can't do that...too serious... i moved on when they close the Lounge...

Now let's repent, shall we?

http://www.youtube.com/watch?v=y_uuxFqFNN4

[Structo]

I stick my tongue on 9 volt batteries to test them.

Really, I do!

Me Too!

Tubetwang, the dangers present in tube amps is probably why just about every site that deals with tubes has a big disclaimer bold faced about the dangers lurking inside tube amps.

In reality, if you do not educate yourself to the dangers of high voltages present inside a tube amp, you probably deserve to make the annual Darwin Awards list.

[ryanburton]

thanks to Cygnus X1 for being the only person to actually attempt to answer the questions rather than give me the safety lecture.

if any of you drink alcohol, drive a car, ride in planes, have sex, or smoke cigarettes, you should stop immediately cause those things kill too, everyday. also since i'm ranting i'll also point out that the Tom Mitchell book is available for quick shipping on amazon, because i got it there along with Dan Torres' book, and 2 books by morgan jones, plus the old mullard and rca manuals. i can read, and like to read, but sometimes i prefer good ole human confirmation of fact.

i mistyped pin 1 instead of pin 9 for a heater and everyone freaks out rather than looking at the attached photos to check my work for themselves. i have seen threads on this site about DC heaters, so i wanted to make sure that wasn't part of my problems. i WAS reading the schematics correctly, but suspected i was misinterpreting or that the schematic was WRONG. i forget that everyone else is perfect and i'm the only one that messes up.

this forum isn't to remind everyone how knowledgeable they are about safety, this is about technical discussion of amps.

[Structo]

i've just finished a tweaked princeton build and i don't seem to be getting any reaction from the filaments from any of the tubes.

what is the proper way to check the voltage on the heaters?

Well, you have to admit, your first post did not reassure us that you had enough knowledge to be inside an amp safely.

We don't want anyone to die!

You say you don't get any reaction from the filaments. What does that mean?

Does it mean that the heaters are not glowing?
Does it mean you are not getting electron flow from the cathode to the plate?

Then to ask how do you measure the voltage on the heaters also does not build confidence in your abilities.
Because normally you don't measure ac voltage with one lead clipped to the chassis. You measure across the two wires with your meter set to ac volts.

This thread was not about us espousing our collective knowledge to the world to make us feel better.
It was about making sure that you weren't going to electrocute yourself when you stuck your hands inside a live amp.

[Cygnus X1]

Yup-it may seem backwards, but I check the heaters from the farthest point, then work in.
So get what you have with one lead on 4/5, the other on 9. On to the other preamp tubes/phase inverter, etc.

Then to the power tubes.
Where you will clip your leads to 2 and 7 on a 6V6.

Of course if there is zero glow, then check the green leads out of the power transformer, check the lamp, on to the first tubes it runs the filament on-usually the power tube(s).

Another little note-I recently had a flickering lamp killing my heaters! It drove me nuts for a little bit-it even managed to fry some seemingly unassociated components along the way. Because the tubes were trying to "run" without any heater voltage, and the current draw was frying resistors hooked up to the tubes.
Some things you just don't see in the books.



Yes, these guys are far more experienced than I am, don't kick back for the safety talk. It does count.

[ryanburton]

You say you don't get any reaction from the filaments. What does that mean?

it meant that i could not detect any evidence they were functioning. i could not see red nor was there an increase in temperature to the tube. what else could that possibly mean? could they actually be functioning with those observations?

[Cygnus X1]

Dumb question, then.
Is the pilot light working?

If it is, then there is some sort of filament current coming out of the power transformer.
After that, who knows.

Clip a lead to pin 2 and and the other on pin 7 of the 6V6.
Set your meter to AC, then turn the amp on.

It should show around 6 volts whether or not standby is on or off. If not, and the lamp is glowing...then there is a wiring problem in between the lamp and the tube.

I would advise having the tubes out of the sockets for this test.
And yes, there is still high AC and worse-DC voltage available when you test. Be careful.

[ryanburton]

Is the pilot light working?

Clip a lead to pin 2 and and the other on pin 7 of the 6V6.
Set your meter to AC, then turn the amp on.

It should show around 6 volts whether or not standby is on or off.

I would advise having the tubes out of the sockets for this test.

the light is AC. AC goes from wall through integrated switch/intl-voltage selector/fuse. one terminal from this "switch" 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. pic attached, hopefully that helps clarify my description.

this PT is from another amp i disassembled. it worked great in the other amp. the heater wires were too short to reach the 1st power tube so i spliced in another pair. i used a similar sized wire as the PT heater. i twisted both wires together, soldered, & shrinkwrapped. this is where the "how to correctly measure heater voltage?" post originated.

neither my power tubes or the rectifier tube are showing red on the heaters.

[Cygnus X1]

OK, so your lamp is 120V.

I prefer using a 6.3V lamp there, so I know right away if the filament circuit is working before hitting the standby
switch for full power-up.

Is there a center tap on the heater wires coming out of the tranny (by any chance)?

[ryanburton]

there is not a center-tap for the heaters

[Phil_S]

Ryan: It is very normal for an amp group to vet the level of expertise of a first-time poster. No one wants to have it on their conscience that they sent someone to do what amounts to a fools errand or worse. I suggest you should not fault us for our concern for safety. The brevity of your first post told us very little, almost nothing, suggesting a lack of experience. We don't mean to lecture...maybe we/I did...take it with a grain of salt. It did no harm. You will see we are not such a bad lot.

It is always better to state your observation than your conclusion. This gives us facts rather than opinion. The "tubes are cold and I see no glow" is much better than "tubes are not working." You did put this in your thread title, and it is so noted. What I'm saying is that you'll get more participation if you state your observations. There is nothing wrong with stating your thoughts on the problem, and doing both will stimulate comments. I see that you've moved in this direction and now you are getting some action on your issue(s).

As for Amazon and the Mitchell book, your experience is more recent than mine. Several years ago, I waited about 8 weeks. I'm very glad they have improved on delivery and thanks for the update.

neither my power tubes or the rectifier tube are showing red on the heaters.

This is telling us something very important. I think you've got 3 secondaries on the power transformer and you just told us, after several days, of this important observation. There is no flow on either filament secondary according to what you say. I would not be surprised if the high voltage secondary is also not supplying voltage. Have you checked that out? With no tubes in the amp. put your meter across pins 4 and 6 of the rectifier tube (the red wires) and tell us if there is voltage present.

If all three secondaries are not supplying voltage, the problem is likely to be on the primary side. I am unable to make out the primary wiring in your pictures, as all that black on black is obscuring it. So, some simple questions:
1) Have you checked your fuse to see if it's blown? If it is blown, chances are you have a mis-wire on the primary. Stop here and correct it. If you are unclear about the appropriate wiring, I've posted a diagram that I lifted from Miles O'Neal's website about Kalamazoo amps.
2) It looks like you are using an IEC connector with integrated switch. It that what I see? Is there 120VAC across the hot and neutral terminals of the IEC inlet on the inside of the amp?
3) When you turn the power switch on, is there 120VAC across the switch terminals?
4) Can you describe exactly where the black primary wires of the power transformer are connected?

This appears to be your description of the primary wiring and I think it is not complete.

the light is AC. AC goes from wall through integrated switch/intl-voltage selector/fuse. one terminal from this "switch" 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.

I think what you say is this. Between terminal 1 of the switch and the power transformer, you have the light in series. Like this: T1-----bulb-----PT black primary. Is this correct?
Then, you have the other black primary wire from the PT going to terminal 2 of the switch.

If this is what you did, you are not supplying power to your transformer.

Follow the diagram: IEC neutral goes directly to one black PT wire. IEC hot goes like this: IEC+ ----- Fuse -----T1 Switch T2-----other black PT wire. The lamp connects to the neutral (at the IEC inlet is a good spot) and to T2 of the switch. This way the lamp and the PT are in parallel, so when you close the switch (turn it on) the lamp will light and the PT will receive power.

[ryanburton]

Phil- enough with the lectures. amp info or nothing please.

1) Have you checked your fuse to see if it's blown?

my lamp works, fuses are ok.

2) It looks like you are using an IEC connector with integrated switch. It that what I see? Is there 120VAC across the hot and neutral terminals of the IEC inlet on the inside of the amp?

Yes approx 120VAC, i mentioned this power inlet in a previous post.

3) When you turn the power switch on, is there 120VAC across the switch terminals?

Yes

4) Can you describe exactly where the black primary wires of the power transformer are connected?

the light is AC. AC goes from wall through integrated switch/intl-voltage selector/fuse. one terminal from this "switch" 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.

[Phil_S]

See my edit. I think your wiring is wrong. I do not think you have completed the PT feed to the neutral.

[Structo]

Good luck getting help with that attitude.