5F1 Champ No Sound

[dujuarez]

 I hope someone can help me. I have twice printed out the layout and gone over it with highlighter. I did find one problem with speaker output wiring and have corrected it. I'm not getting any sound and noticed that the 6V6 tube is not warm to touch, as are the 5V4C and 12AX7. Here are the voltage readings I am getting:


12AX7


Pin 1 at lug where 100K resistor connected - 193V
Pin 3 at lug where 1.5K resistor connected - 1.68V
Pin 6 at lug where 0.022uf capacitor connected - 192V


6V6EH
Pin 3 - 452V
Pin 4 - 355V


5V4C
Pins 2 and 8 - 452V
Pins 4 and 6 - 333V


Reading where 16uf capacitor and 10K resistor meet - 451V
Reading between 10K and 22K resistor - 357V
Reading where 8uf capacitor and 22k resistor meet - 307V


Please let me know if I left out anything important.


Thank you.

[eleventeen]

Those voltages look right, maybe a bit high. (Indicating that the amp is not doing any work and if your 6V6 is dark, it's not!)

"6V6 tube is not warm to touch"

Can you see the 6V6 heater lit up? You can see orange glow of some kind in all the other tubes. You would have to: You would not have your DC if the 5V4 wasn't lit up and you would not have tube current thru the 12AX7 (indicated by the 1-2 volts on 12AX7 cathode, pin 8 or 3.) No heater lit up in that 6V6 tube and you'll have an exceptionally quiet amp! It should be easy to see *unless* you are using an older grey-inside-coated 6V6 where you can't see the insides of the tube very well. But you are right to suspect it: It SHOULD be warm, even hot.


So the 6V6 could be bad. (VERY unlikely) but if it is lit up and yet cold, your cathode-to-ground connection is missing. Make sure the 470 0hm resistor in the 6V6 cathode is not a 47K or something like that. Or open.

[Reason #317 why we like tubes]

[Paul1453]

Unless the 6V6 heater filament is open.   

Swap in a different 6V6 and make sure the heater lights.   

[Willabe]

Unless the 6V6 heater filament is open.   

Or, could be bad/cold solder joint, broken heater wire, loose socket pin(s).

[Colas LeGrippa]

check the speaker out jack, or the sseaker itself

Colas

[Willabe]

How many speaker jacks do you have, 1 or 2?

[labb]

Check voltage at pins 2 and 7. Will be AC not DC. Check voltage (DC) at pin 8 to ground.

[dujuarez]

Don't have extra 6V6, just order a couple. I'm not seeing any glow at all from the tube. I turned off the lights just to make sure. I'm getting glow from the other two tubes.
Just using 1 speaker jack. Only connected the 4 ohm side of the output transformer.
I believe the speaker works, when I checked the voltage of pin 3 on the 6V6, I could hear static from the speaker.
I'll have to wait till I get the new tubes in to check it against the one I have.


Thanks for all quick responses.

[Willabe]

I'm not seeing any glow at all from the tube. I turned off the lights just to make sure.

That's the best way to see if the heater is lighting up or not. 

[ratgon]

I can't tell from your image if you've done this but I gotta admit that after pulling the board members through the ringer with a no sound issue for two days I finally noticed the little note on the layout telling me to ground the 470/3w resistor where it connects to a filter cap. Viola! It worked perfectly from then on

[PRR]

Take-out the 6V6.  What is the Ohms from pin 2 to pin 7?

Few-Ohms is good. Infinite Ohms (anything over 10) is a dud tube.

While there, examine the solder in the end of these pins. Occasionally the tube worker gets a bad joint; good-enough to pass inspection but works loose on the long boat-ride to you. Touch-up solder may work.

Also HBP's power-on cathode voltage check (below).

One or the other must be wrong for a 6V6 to be "cold". Just-heater will be warm. Heater plus cathode current is typically HOT (red skin in 5 seconds).

[HotBluePlates]

... I'm not getting any sound and noticed that the 6V6 tube is not warm to touch
...
6V6EH
Pin 3 - 452V
Pin 4 - 355V
...

What is the voltage across the 470Ω cathode resistor for the 6V6?

[Colas LeGrippa]

if the tube is not warm, it is the heater that's defective. swap the tube put a el34, 6L6 whatever you got and see if they lit.

[Colas LeGrippa]

you don't have to put HT at this moment you only want to check for the heaters ..........there is no standby switch on the original version I think.........anyway HT or not, it doesn't matter as long as you don't put your tongue on pin3 or 4....( while having a feet bath )
 

[dujuarez]

Checked the ground from 470 ohm resistor, it's good. Removed the 6V6 and got 0.4 ohms across pins 2 and 7 of 6v6 socket. Put in 6L6 and got 25 volts across 470 ohm resistor. But the best news is when in put the 6L6 in and turned the volume up, I could hear that rush of sound that I know too well. Strummed the guitar and viola, it's working. I guess I had a bad 6V6 after all.

Thanks to you guys, I got my amp working. This is my first build and it feels great.
Again thanks to everyone!


David

[Paul1453]

Yup, if the heater doesn't light there will be no electrons rushing about making sound for us.   

It always feels good to find the problem and fix your own amp.   

[Colas LeGrippa]

great, you did it once, you'll want to repeat the experience !!!