Hi
I am new to building amps and decided to give it a shot. So I just finished building the amp which is based on the Fender 5e3 with a few mods.
I followed the first startup guide linked below: Amp Startup
So after powering up the amp, there was no audio. I noticed the rectifier tube seemed to be dead so I replaced it and it was working fine. However, I still have no audio from the amp.
This is the schematic I followed
OP FINAL.pdf - Google Drive
Here are a few photos of my build
Untitled folder - Google Drive
Would appreciate any pointers as to where the problem may lie
Thank you
I am new to building amps and decided to give it a shot. So I just finished building the amp which is based on the Fender 5e3 with a few mods.
I followed the first startup guide linked below: Amp Startup
So after powering up the amp, there was no audio. I noticed the rectifier tube seemed to be dead so I replaced it and it was working fine. However, I still have no audio from the amp.
This is the schematic I followed
OP FINAL.pdf - Google Drive
Here are a few photos of my build
Untitled folder - Google Drive
Would appreciate any pointers as to where the problem may lie
Thank you
I’ve tried all the above to no avail. The voltages seem to check out as well. The tubes are glowing. At first there was no glow in the 5Y3GT so I popped in a new one and it began to glow. So all the tubes are glowing but no sound at all. The speaker wiring is correct and the speaker is working.
Sorry for the delayed response
Sorry for the delayed response
Start tracing the signal from input to output. That'll find your missing connection or dry joint.
That is, plug an mp3 player (or tone generator or similar) into the input socket (turn it waaay down). Use an audio monitor (aux in into the stereo or spare amp) and probe (with earth clamped to the chassis and a 600V rated decoupling cap in the "hot" line) and follow the sound through the amp. Input socket, first gate, after first decoupling cap (go directly to the plate and you'll get a THUMP), etc etc etc
Be warned it gets LOUDER as you move through the amp!
That is, plug an mp3 player (or tone generator or similar) into the input socket (turn it waaay down). Use an audio monitor (aux in into the stereo or spare amp) and probe (with earth clamped to the chassis and a 600V rated decoupling cap in the "hot" line) and follow the sound through the amp. Input socket, first gate, after first decoupling cap (go directly to the plate and you'll get a THUMP), etc etc etc
Be warned it gets LOUDER as you move through the amp!
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So while probing I should use a stereo system or any monitors and they should be plugged into the aux output of the amp if I understand correctly ?
I did not understand the probe setup either. What is the capacitance of the capictor to be used for the decoupling cap in the hot line. ? Is the hot line the one I am probing with or something completely different.
Sorry pretty new to this stuff
I did not understand the probe setup either. What is the capacitance of the capictor to be used for the decoupling cap in the hot line. ? Is the hot line the one I am probing with or something completely different.
Sorry pretty new to this stuff
An amp can be used to troubleshoot itself. There should be some noise coming out the tail end, especially if you touch one of the output tube grids with a voltage probe. But just to eliminate a lot of guessing how about a tube pin list and their voltages?
Touching the grid will cause a pop or tick in the speaker. If you do not get that it does not matter what is going on before this. With no sound the output jack could be shorted. With sound, work your way back to the input touching each grid.
Touching the grid will cause a pop or tick in the speaker. If you do not get that it does not matter what is going on before this. With no sound the output jack could be shorted. With sound, work your way back to the input touching each grid.
If you're not happy playing inside a live amp there is another alternative (which I use regularly), particularly once you're convinced the DC voltages are correct.
Turn the amp off; disconnect the mains; drain the caps and pull the tubes.
Then you can safely inject and trace a signal within each stage of the amp:
that is; from input jack to the grid of the first tube; then from the plate of the first tube to the next grid, etc etc etc.
Finally, feeding a signal into the primary of the OPT (via the final plates) should provide an audible (if very quiet) signal at the speaker.
Turn the amp off; disconnect the mains; drain the caps and pull the tubes.
Then you can safely inject and trace a signal within each stage of the amp:
that is; from input jack to the grid of the first tube; then from the plate of the first tube to the next grid, etc etc etc.
Finally, feeding a signal into the primary of the OPT (via the final plates) should provide an audible (if very quiet) signal at the speaker.
I should start out by saying that working on tube amps in the attempt to fault-find them can be DANGEROUS. The only way to find the fault is to make various tests and measurements with the power turned on. Making a mistake here can injure or kill you.
So, unless you're confident that you know how to keep yourself safe, the wisest thing to do is to take the amp to someone who does know how to work on it safely - either an amp tech, or someone with plenty of experience working safely on tube amps.
Okay, that's out of the way. What to do if you decide to proceed on your own?
If you have a link to the schematic from which that layout was constructed, please post it, as it might help with troubleshooting.
You've done the quick and obvious checks, and that didn't locate the problem. So now you have to get very methodical and systematic. The key to trouble-shooting a circuit like this one is to narrow down the scope of the problem, and keep narrowing it down, until you are able pinpoint exactly what is wrong, and fix it.
Imagine you live in Southern California, and a friend got lost on the way to your house. If the only thing you know is that he is lost somewhere in Los Angeles, you can't really help him. But if he looks at a couple of sign-posts and tells you he's driving on N. Soto St, and just crossed Valley Blvd, now you can help him (you still need to figure out if he's headed north or south on Soto.)
Both Thoglette and Printer2 were giving you ways to find some sign-posts. Your amplifier is a chain of signal-processing stages; if you inject an audio signal at the input and follow it through the amp (with an audio probe, such as Thoglette described), one stage at a time, it will eventually disappear. You have now narrowed down the trouble to somewhere between the last two points you tested.
While Thoglette suggested injecting audio into the input and tracing its path until you get to the speaker, Printer2 suggested doing the opposite; start out injecting a signal directly at the loudspeaker, work backwards one stage at a time, until the signal disappears.
Both those approaches are time-honoured ways to troubleshoot a circuit like the one you built.
Measuring DC voltages on every tube electrode is another very useful check (and one Enzo suggested). Do you have a voltmeter? If not, one should be the first piece of test equipment you get. It doesn't need to be expensive, as long as it is rated to handle at least 1000 volts DC, to keep you safe when measuring high voltages in your amp.
So, that's where I'd start: (a) Post a link to the schematic (not the layout), (b) Measure DC voltage on every pin of every tube, and list them, along with enough information to identify that tube on the schematic. (For example, "pin 1 of tube V1, 250V DC".
-Gnobuddy
So, unless you're confident that you know how to keep yourself safe, the wisest thing to do is to take the amp to someone who does know how to work on it safely - either an amp tech, or someone with plenty of experience working safely on tube amps.
Okay, that's out of the way. What to do if you decide to proceed on your own?
That is a layout diagram, which shows the physical appearance and placement of wires and components. An electronic schematic (aka circuit diagram) is more like an architectural blueprint - it doesn't look like a photo of the finished building, but once you know how to read it, it tells you a lot more than a layout diagram (or photo of a building) does.
If you have a link to the schematic from which that layout was constructed, please post it, as it might help with troubleshooting.
Right now, there are hundreds of possible reasons why your amp doesn't work - all we know is, somewhere in that maze of components and wires, there is at least one mistake or defective part.
You've done the quick and obvious checks, and that didn't locate the problem. So now you have to get very methodical and systematic. The key to trouble-shooting a circuit like this one is to narrow down the scope of the problem, and keep narrowing it down, until you are able pinpoint exactly what is wrong, and fix it.
Imagine you live in Southern California, and a friend got lost on the way to your house. If the only thing you know is that he is lost somewhere in Los Angeles, you can't really help him. But if he looks at a couple of sign-posts and tells you he's driving on N. Soto St, and just crossed Valley Blvd, now you can help him (you still need to figure out if he's headed north or south on Soto.)
Both Thoglette and Printer2 were giving you ways to find some sign-posts. Your amplifier is a chain of signal-processing stages; if you inject an audio signal at the input and follow it through the amp (with an audio probe, such as Thoglette described), one stage at a time, it will eventually disappear. You have now narrowed down the trouble to somewhere between the last two points you tested.
While Thoglette suggested injecting audio into the input and tracing its path until you get to the speaker, Printer2 suggested doing the opposite; start out injecting a signal directly at the loudspeaker, work backwards one stage at a time, until the signal disappears.
Both those approaches are time-honoured ways to troubleshoot a circuit like the one you built.
Measuring DC voltages on every tube electrode is another very useful check (and one Enzo suggested). Do you have a voltmeter? If not, one should be the first piece of test equipment you get. It doesn't need to be expensive, as long as it is rated to handle at least 1000 volts DC, to keep you safe when measuring high voltages in your amp.
So, that's where I'd start: (a) Post a link to the schematic (not the layout), (b) Measure DC voltage on every pin of every tube, and list them, along with enough information to identify that tube on the schematic. (For example, "pin 1 of tube V1, 250V DC".
-Gnobuddy
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