Chopstick Diagnostics.......

[Bassman2277]

Hey Guys,

Finished building a 5E3 a few weeks ago and the bright channel sounds good. Toe normal channel on the other hand has a few issues. Firstly, the volume is a little lower than I thought it would be. Secondly, every time I use my guitar's volume pot or the five way switch I get white noise from the pot and incredibly loud popping noises from the switch.

I switched the four leads on the input jacks and the sound followed to the bright channel, put them back. I switched the signal leads on the 12AY7 no difference. I bypassed the normal channel inputs and used a jumper directly to the 12AY7 tube. Louder (no resistors) but still noisy.

Then I took a chopstick and started prodding the various solder joints. Everything is solid, but I noticed that the filter cap/resistor joints for both channels make noise when I poke them. Is this normal? It's definitely louder on the last coupling cap (normal channel). I desoldered the joint and redid the connection. Still noisy, still makes noise when I touch the joint with the chopstick.

So far I've ruled out the input jacks, the volume and tone controls, the tube and the tube socket. I guess the components are probably the next thing to look at.

Anything I might have missed?

Thanks,

David

[stokes]

I would check for dc voltage on the grid.Or possibly a problem with the 1meg/68k resistors.

[Bassman2277]

Hi Stokes,

Could you elaborate about the grid? I'm new to all this and don't quite understand the lingo.

Thanks,

Dave

I would check for dc voltage on the grid.Or possibly a problem with the 1meg/68k resistors.

[Enzo]

Is there any DC voltage coming out the input jack? Noisy controls and switches often is caused by DC voltage on the thing. If there is some DC on the inout jack, it would then get into the guitar and make noisy.

[Bassman2277]

Problem fixed, BIG DUHHHHH.

You know the old saying "there are no stupid computers, only stupid people"? Well, that saying is true!

I miswired two connections at the 12AY7 socket. All is well and the amp works perfectly now.

I think I'll pick up Tino Zottola's books before I build anything else. A little theory will definately go a long way.....

Dave

[Bruce / Mission Amps]

You know the old saying "there are no stupid computers, only stupid people"? Well, that saying is true!

I miswired two connections at the 12AY7 socket. All is well and the amp works perfectly now.

I think I'll pick up Tino Zottola's books before I build anything else. A little theory will definately go a long way.....

Dave

HA ha ha... I wish I had a dollar for every time I've miswired something, sat there and stared at it, scratched my head and said "what the FANKUS is going on here!" only to find a blatant wiring goof the makes me smack my forehead in disgust...
For that matter I wish I had a dollar for every novice-pro builder that called me freaking out about something not working right but swearing up and down they built it EXACTLY like shown, should be built and or totally correct after reviewing it a dozen times, yet it doesn't work right so it must be defective parts somewhere! ha ha....

[Bassman2277]

Sheepish Reply

HA ha ha... I wish I had a dollar for every time I've miswired something, sat there and stared at it, scratched my head and said "what the FANKUS is going on here!" only to find a blatant wiring goof the makes me smack my forehead in disgust...
For that matter I wish I had a dollar for every novice-pro builder that called me freaking out about something not working right but swearing up and down they built it EXACTLY like shown, should be built and or totally correct after reviewing it a dozen times, yet it doesn't work right so it must be defective parts somewhere! ha ha....

I guess I deserved that Bruce! Well, I think for my next build I'll have to check the wiring more carefully. As far as building's concerned, this was my first but definitely not my last.

Just out of curiosity, any damage done by wiring lugs 2 and 3 on the 12AY7 tube socket backwards? That's where my problem was and the reason the bright channel worked but the normal did not. It's also the reason I had DC voltage in the inputs and ,consequently, running into my guitar causing all kinds of noise from the controls. The jumper was on the right lug (8), but the 820 1W resistor/22uF-50v capacitor to lug 3 was actually on lug 2 and the signal lead was on lug 3.

I definitely learned a lot during this build and the troubleshooting afterward.
Thanks to you Bruce, Enzo, Stokes and everyone else who replied to my posts. I couldn't have done it without any of you.

All the best,

Dave

P.S. Rock ON!

[Bruce / Mission Amps]

Just out of curiosity, any damage done by wiring lugs 2 and 3 on the 12AY7 tube socket backwards? That's where my problem was and the reason the bright channel worked but the normal did not. It's also the reason I had DC voltage in the inputs and ,consequently, running into my guitar causing all kinds of noise from the controls. The jumper was on the right lug (8), but the 820 1W resistor/22uF-50v capacitor to lug 3 was actually on lug 2 and the signal lead was on lug 3.

Dave

P.S. Rock ON!

No I don't think it would hurt anything.... a cathode of many 12AX7 tubes can run at 200v with no damage and the grid can be accidentally biased pretty high with no damage.
The pots can be noisy with DC on them but I doubt you draw much current there so I think you are OK.

[Enzo]

Not long ago I was helping a local guy build his own amp from scratch. One of the preamp tubes for some reason he skipped over pin 2 and the next few pins were wired one off. Right in front of me. Had to look for a minute or two to answer his question about the wire for pin 8. "But there is already something on pin 8." Ah. move all these things over one pin now... SOme supervisor I was, I didn't notice while he was doing it.