5e3 runs on very low volume

[Meshugana]

My recently built 5e3 kit worked great until last week. The volume went up and down extremly when I turned up the volume pot. But now the volume is about 2% from what it should be.

I replaced all tubes (exept the rectifier) and speaker, but that didn't solve the problem.

What could be the cause of this problem?

[d95err]

You're going to have to provide more debugging info. How are the voltages? Stock circuit or modded? Etc.

[loudthud]

Turn the amp and guitar all the way up. Is the sound that comes out of the amp distorted? Distorted sound could be a short at the speaker jack. Clean sound could be a problem on the input jacks. Check all solder joints.

[Meshugana]

Turn the amp and guitar all the way up. Is the sound that comes out of the amp distorted? Distorted sound could be a short at the speaker jack. Clean sound could be a problem on the input jacks. Check all solder joints.

Thanks for your reply. The sound is distorted when the volume is all the way up. I will check the speaker wires later today. Thanks.

[Meshugana]

Thanks for your reply. The sound is distorted when the volume is all the way up. I will check the speaker wires later today. Thanks.

Checked the speaker wires but that isn't the problem.. Could it be the output transformeren?

[Meshugana]

You're going to have to provide more debugging info. How are the voltages? Stock circuit or modded? Etc.

Stock circuit with tone/volume mod. Which volumes schould I measure? Please let me know so I can check the voltages.

[d95err]

Stock circuit with tone/volume mod. Which volumes schould I measure? Please let me know so I can check the voltages.

NOTE: Take all appropriate safety measures when working in inside the amp while it is plugged in! Keep one hand in your pocket, etc...

Start by checking that B+ to all tubes look reasonable, just to make sure the powersupply looks OK. I'm not sure what the exact voltages should be in this amp, but one schematic I have lists 340V at the first filter cap, 307V at the second and 224V at the third. To do it completely, check the voltages on all pins of all tubes and post them here (check some other debugging threads and you'll get the picture).

Another thing to try is the chopstick test - use a wooden or plastic chopstick to poke around in the amp and see if anything appears to be glitchy.

[loudthud]

Thanks for your reply. The sound is distorted when the volume is all the way up. I will check the speaker wires later today. Thanks.

The signal is probably making it from the input jacks thru the volume/tone controls (atleast as far as) to the second 12AX7. It could be the OT but that is rare so continue looking at the tube sockets and eyelet board.

Use your meter's ohm function to verify any of the wires that are soldered on the backside of the eyelet board from the component side of the board. Many novice builders connect the wires to the wrong eyelets.

Measure the resistance between the speaker terminals at the speaker. You should measure about 6 ohms when the speaker is disconnected from the amp and almost a dead short when it is plugged into the amp. It's hard to tell the difference between the low resistance of the output transformer and a short at the jack. Unsolder one wire from the OT (not the black one) at the speaker jack and check the resistance at the speaker again to verify that resistance is now 6 ohms.

[Meshugana]

Turn the amp and guitar all the way up. Is the sound that comes out of the amp distorted? Distorted sound could be a short at the speaker jack. Clean sound could be a problem on the input jacks. Check all solder joints.

The speaker output jack had a short. Too much solder.. After replacing the output jack everything worked fine again. Thanks for your input.

[tubeswell]

If the amp was working fine until 'last week', then the first thing I'd suspect is one of the tubes. Have you tried swapping tubes out to see if that fixes it?