I'm a newbie, and I built a standard 5E3 circuit. It sounded glorious through the P12R in my original 5E3. But then I decided to switch out the wire to pin 2 of V2 with a shielded wire, just to try and make it a little quieter, and the amp has been dead ever since. I looked under the board to make sure I didn't accidentally pull out a jumper. All components measure correctly. I put the original wire back to pin 2. I am getting crazy voltages to both 12ax7s.
V1:
pin 1=293V
pin 3=20.3
pin 6=292
pin 7=0
pin 8=19.9
V2:
pin 1-292
pin 3=0
pin 6=240
pin 7=23.4
pin 8=56.3
I have no idea what to do, other than rip it up and start over. I've changed tubes, I've re-flowed solder joints. Not sure how I blew this thing up so badly.
Any insight would be appreciated.
Thanks,
Slim
I just had to mess with it....
Moderators: pompeiisneaks, Colossal
Re: I just had to mess with it....
Sounds like you may have lost some ground connections.
Are you using a standard fender layout? Some pictures of the circuit might help.
Are you using a standard fender layout? Some pictures of the circuit might help.
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Stevem
- Posts: 5604
- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: I just had to mess with it....
You did not blow anything up as when that takes place there smoke and sometimes fire, so remove that from your mind.
What you have found out that most novice do is that it’s easy to build a simple amp, but you need more knowledge then that to troubleshoot it, but this is how we all learn .
Problems make your knowledge grow faster than even 4 builds that all goes well with!
Your issue lies with V2.
Pin 3 which is a cathode has no voltage on it which means the tubes pin 1, 2 and 3 triode section is not idling .
Look at all the other pins 3 and 8 on V1 and V2 from your voltage list and they all have voltage on them so those 3 triode sections are working.
As posted in the reply above mine here I think your issue is simply that the cap and resistor off of pin 3 on V2 has simply lost it ground back to the chassis.
A simple ohm meter test will confirm that .
Also note that when using a shielded cable that only one end should be put to ground otherwise you may get a ground loop taking place.
I need to also ask here what type of noise where you looking to eliminate by swapping in a shielded cable .
Was this a straight hum, a buzz, or a hiss?
What you have found out that most novice do is that it’s easy to build a simple amp, but you need more knowledge then that to troubleshoot it, but this is how we all learn .
Problems make your knowledge grow faster than even 4 builds that all goes well with!
Your issue lies with V2.
Pin 3 which is a cathode has no voltage on it which means the tubes pin 1, 2 and 3 triode section is not idling .
Look at all the other pins 3 and 8 on V1 and V2 from your voltage list and they all have voltage on them so those 3 triode sections are working.
As posted in the reply above mine here I think your issue is simply that the cap and resistor off of pin 3 on V2 has simply lost it ground back to the chassis.
A simple ohm meter test will confirm that .
Also note that when using a shielded cable that only one end should be put to ground otherwise you may get a ground loop taking place.
I need to also ask here what type of noise where you looking to eliminate by swapping in a shielded cable .
Was this a straight hum, a buzz, or a hiss?
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: I just had to mess with it....
How about a nice clear photo of what you're working on?
Someone will probably point it out pretty quick.
Someone will probably point it out pretty quick.
Re: I just had to mess with it....
Thanks, everyone.
After staring at the chassis for a couple of days, and re-measuring all components, re-flowing solder connections, etc., I realized I removed the jumper from the center lug of the bright pot and moved it to the normal pot when I was adding the shielded wire. Rookie mistake, I guess, but this is how you learn.....
Thanks for the help.
Slim
After staring at the chassis for a couple of days, and re-measuring all components, re-flowing solder connections, etc., I realized I removed the jumper from the center lug of the bright pot and moved it to the normal pot when I was adding the shielded wire. Rookie mistake, I guess, but this is how you learn.....
Thanks for the help.
Slim
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Stevem
- Posts: 5604
- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
Re: I just had to mess with it....
That's good news to hear, so now let's get back to this issue that you have in the first place of making the amp less noisy .
What is this noise you have ?
A hum?
A buzz?
A hiss?
A hum issue can be AC at 60 hz, or D.C. At 120 hz.
120 hz is a low B on a guitar.
What is this noise you have ?
A hum?
A buzz?
A hiss?
A hum issue can be AC at 60 hz, or D.C. At 120 hz.
120 hz is a low B on a guitar.
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!