5E3 volume problem

I've been having trouble with my 5E3 clone for a while now. I found the problem to be in the grounding and lead dress. The hum and a couple of other issues have been resolved.

Now....Plugged into channel 1 there is no volume control, to speak of. There is pretty much full volume with the volume control off. Turn up the volume control gets a bit more sound. Channel 2 works as it should.

I've checked all solder joints and traced all wires. Any ideas would be appreciated.

Thanks

It's broken man. I'll take it off your hands for ya.


But seriously. Open it up and check the pots and input jacks.

LOL..........:lol:

Already did that. Since I have slept and dreamt, (is that a word?), I think the problem may still be in the lead dress. There are two wires coming from the inputs section then under the board and onto the pre amp tube. Tapping on those wires generates significant noise. I rearranged them last night in addition to a couple other things and that is when the volume problem started.

The strange thing is the amp worked great for a good while then started having occasional problems. The first being static noise upon startup. Some crackling developed later but would always go away shortly after it warmed up. Then it would lose volume after a few minutes of playing time. I thought I had those problems fixed when finding a NOS 5Y3 tube and adding some Zeners to bring down the voltages. Again it worked good for a while then the static upon startup started again.

Gonna have some breakfast and fiddle with the wires some more.

LOL..........:lol:

Already did that. Since I have slept and dreamt, (is that a word?), I think the problem may still be in the lead dress. There are two wires coming from the inputs section then under the board and onto the pre amp tube. Tapping on those wires generates significant noise. I rearranged them last night in addition to a couple other things and that is when the volume problem started.

The strange thing is the amp worked great for a good while then started having occasional problems. The first being static noise upon startup. Some crackling developed later but would always go away shortly after it warmed up. Then it would lose volume after a few minutes of playing time. I thought I had those problems fixed when finding a NOS 5Y3 tube and adding some Zeners to bring down the voltages. Again it worked good for a while then the static upon startup started again.

Gonna have some breakfast and fiddle with the wires some more.


9 times out of 10 that is a tube heading south.
I have had several EH12AY7's do that recently(suspected bad batch)

After a good heatup they were tolerable, but the just got worse and worse.

LOL..........:lol:

Already did that. Since I have slept and dreamt, (is that a word?), I think the problem may still be in the lead dress. There are two wires coming from the inputs section then under the board and onto the pre amp tube. Tapping on those wires generates significant noise. I rearranged them last night in addition to a couple other things and that is when the volume problem started.

The strange thing is the amp worked great for a good while then started having occasional problems. The first being static noise upon startup. Some crackling developed later but would always go away shortly after it warmed up. Then it would lose volume after a few minutes of playing time. I thought I had those problems fixed when finding a NOS 5Y3 tube and adding some Zeners to bring down the voltages. Again it worked good for a while then the static upon startup started again.

Gonna have some breakfast and fiddle with the wires some more.



Sounds like you found it. If it worked fine before messing with the wires, and now it doesn't...

Is it stranded or solid core wire? Solid core can be bent only a few times before it actually breaks/snaps. Also, do the wires go under the board AND solder in from underneath? You might want to check to see if they didn't fall out - which is why I always wire above board now.

I have given up :sad:

I fixed the schnizzle sound upon startup only to have the tone control act like a volume control. I've got something wired up wrong and my dumb butt can't see it or..........a resistor or capacitor has gone south.

It may even be a volume pot. DVM readings on the pots reveal the tone and channel 1 to be operational. The 2nd channel pot gives me a reading of zero when off then 6 in the middle position then 0 again at full volume.

I've spent half my Saturday working on this thing and now I'm taking it to the shop on Monday.

It's fun to troubleshoot amps when I can actually fix them. Much to frustrating when I can't.

I'll pay someone else to pull their hair out. :lol:

I have given up :sad:

I fixed the schnizzle sound upon startup only to have the tone control act like a volume control. I've got something wired up wrong and my dumb butt can't see it or..........a resistor or capacitor has gone south.

It may even be a volume pot. DVM readings on the pots reveal the tone and channel 1 to be operational. The 2nd channel pot gives me a reading of zero when off then 6 in the middle position then 0 again at full volume.

I've spent half my Saturday working on this thing and now I'm taking it to the shop on Monday.

It's fun to troubleshoot amps when I can actually fix them. Much to frustrating when I can't.

I'll pay someone else to pull their hair out. :lol:

Just a thought here based on something I had to fix last week for a guy.

The Silver Mica 500pf cap on the tone pot, is it one of the newer dipped styles?
http://www.progressive-concepts.com/images/products/capsm.jpg

Try changing it.

You can measure the voltages till the cows come home and everything will look perfect, but if that cap poops out, it does a lot of what you are saying.

Update on the volume issue.

I never took the amp to the tech dude. I let it sit for a couple days then went back to troubleshoot some more.

Turns out one of the volume pots had a loose connection. Something broken on the ground lug that caused intermittent operation. I could push on it with a pencil and it would work then vibrations would cause it to go bad again.

I ordered new parts including the 500pf cap. I changed the grounding layout which isolated the preamp section from the amp section.

Now for the weird part. I have it working now, but................

The Tone pot is not grounded. It sorta works that way. Channel 1 tone reveals very little difference from one extreme to the other. Channel 2 tone works backwards but still little difference in extremes. The amp sounds really good and the volume controls are interactive.

If I ground the tone pot it turns into a volume control. Doesn't matter if it is grounded to itself via the ground lug or a wire grounded to anywhere from the ground lug. The tone also works properly when grounded.

The volume pots are grounded to the input grounds which then goto a post on the preamp side of the chassis.

The tone control problem may have existed since building the amp. I don't recall ever turning the tone control to the 1 position. I always left it around 6 so I can't say it ever worked correctly.

Just for more info which may be related, but I doubt it. In an effort to reduce B+ voltage I found and installed a NOS 5Y3 and installed 3 Zener diodes from the center tap, (red/yellow wire on a MOJO tranny), to ground. This made a huge difference in the amps sound and performance. Those changes reduced B+ voltage by 30 volts.

I would appreciate discussion about this stuff.

Randy

The tone control grounds through a 0.005 uf capacitor. If you are wiring the "ground lug" to ground without the cap, it would act like a volume control.

The 500 pf cap is wired from far right lug of tone control to the center lug, of the first volume control. This is per the layout diagram for the 5E3. The layout also shows the ground lug of tone control going to ground with a .047 cap.

I have a suspiction.. but I'll need some photos of the entire amps circuit and one close up of the Volumes and tone controls.