5E3 serious crackling

[wcrankshaw]

I'll have to give that a shot. They're actually all wrapped, with only two places where there's a resistor and cap in parallel having something inserted into the hole.

[Enzo]

It may respond no matter what you touch, but SOMETHING is loose and should be discovereable. Using that chopstick, VERY gently just touch each part. ANd if moving anything disturbs the amp, try using two chopsticks. Use one to push down on the part board in the area you are exploring. Press it down hard against the chassis. Now use the other to gently prod parts. Pushing like this will help prevent pushing on the individual parts from flexing the part board at all.

Isolate the problem. VOlume down, still does it. How about ALL controls to zero. Still?

Start at the end farthest from the power tubes, and pull the first preamp tube. ANy help? yes, I know the amp won;t work that way, but all we care about is the noise right now. Pull the second tube. Anything? GO down the row, eliminating tubes. When you get to just the power tubes, is it still doing it? Or did pulling the PI tube stop it?

Just two power tubes? Pull one. ANy? REplace it and pull the other. ANy? And does it crackle with NO tubes in it? These tests help locate what part of the amp has the problem.

Is your transformer hardware cinched up tight? Loose nut on a mounting bolt can make boocoo noise.

And it may not be on the part board, it may be socket wires.

[wcrankshaw]

Thanks Enzo. I should also add that I just noticed that the entire chassis is sort of acting as a pickup. You can hear the metallic scraping of chopstick on metal, DMM leads on metal, etc.

[wcrankshaw]

It looks like pulling the inside preamp tube, PI unless I'm wrong, stops the noise. Pulling the outside preamp tube does not.

[Enzo]

OK, any tube that stops the noise when pulled either IS the source of the noise or is after the source in the circuit. Sorry, I forgot there are only two small tubes in the 5E3. I made it sound like a long row of tubes.

SInce turning the volume controls down made no difference - right? - then that pretty much localizes the trouble to the PI stage.

Have you tried a different tube in the PI? That 12AY7 input tube is close enough to tell us if the tube is the noise or not, use it.

Make sure none of the female tube socket pins are spread open causing loose grip on the tube pins.

For that matter, make sure none of the pins are broken off. The soler lugs can break off the socket and remain there held by wires. The female part of the pin can break off the part that sticks through the socket body to become the solder lug, but it remains in the hole. That happens, not often, but it does.

Whether it looks like it needs it or not, resolder every pin on the PI socket, and resolder the other end of each wire leaving that socket at the part board end.

Put a good 12AX7 in the PI socket, Remember my two-stick approach? You have the wires trailing off that tube socket. Use one chopstick to pin each wire, one at a time, against the chassis. Now poke the others. Holding a wire down helps prevent it from moving while th eothers are moved. ANy news?

And take a clip wire and ground the center lug of the tone control. Since it is wired to the PI grid, we are grounding that grid. or you can ground that pin of the tube socket it it is accessible. ANy difference? And then ground the other grid. it will make a loud pop, but it won;t hurt anything. ANy effect on the sensitivity? That should help us determine which stage of the PI tube is most involved.

[wcrankshaw]

Problem solved! I feel like sort of a fool, but two of the connecting wires running along the bottom of the turret board had bad solders where they had broken loose after soldering wires to the top side of the board on the same turret. It was the last thing I wanted to mess with since it required unwiring a lot of stuff to get the board flipped over. I guess the low frequencies slowly rattled it loose to the point where it was horrible.

Does anyone have any words of wisdom on securely connected the wires that go from point to point under the board?

Thanks so much to everyone for all the advice and pointers. The amp sounds amazing once again.

[JHow]

Glad it worked out. Just out of curiousity, which part of the circuit were the two wires connected to? Something in the PI?

I think the best advice on turret boards is that your first attempt to solder is your best attempt. Use good wraps, get the bends just right then do the board at one shot. Inspect and check before you install. Do your "mods" as part of the build.

[wcrankshaw]

I'm pretty sure they were part of the PI, although I have to admit by the time I got it taken out and flipped over I was pretty much just hunting for spots on the whole thing. Incidentally it's also a lot quieter idling now than it was before. If the 5F6A is supposed to be the holy grail of tone, I can't imagine how good it sounds if it's better than this thing.

[JHow]

Right on! Time to turn it up.

[JoeM]

Does anyone have any words of wisdom on securely connected the wires that go from point to point under the board?

Do the wires absolutely have to be under the board? On a 5F6A clone I built using turrets, all the wiring is on the top. On an eyelet board, under board wires might have been easier.

[theunrulychef]

For under the board runs on turret boards, I strip the wire enough that it goes all the way through the top of the turret so I can bend it over. That way it doesn't fall out when you solder from the top + you can verify that wire is still in there by sight. I try to make my amps hold themselves together with physical connections before I solder.