Debugging New 5E3 Quirks

[crunchman]

Just finished a Triode 5E3. It fired right up and sounds pretty good.I am getting alot of static
through the speaker, moreso at loud volumes.Twice so far the amp cut out completely, I was able to
bring it back by pushing down on the Tone knob ?? Could this be a bad pot ?? Not sure, Thanks

[JHow]

I'd be looking for loose connections, especially if this is something you just put together.

[crunchman]

I tried a little "chopsticking to no avail, I'm gonna go around and tighten
any ground lugs.How do people feel about grounding to the "chrome"
chassis stuff ? I have a few grounds at the tube socket screws,etc.


I just noticed one of the PT nuts was left off, I've heard some say
those need to be tight tight ! I really need a good set of nut-drivers !!
I hope thats it !

[Chuck H]

If the problem gets worse at higher gain setting I might suspect parasitic oscillations. Lead dress and ground scheme are the primary causes.

[crunchman]

It (static) increases with temperature, thats all I can really say for sure. I'm gonna re-do the heater supply, I used an old section of 22g
solid core that just seems kinda, the voltages were fine though.I'll reflow all the turret joints, I think this is the last time I use turrets, seems to me
a terminal strip layout would be more effective and easier to troubleshoot (sourgrapes, I know).I was wary of the turrets, made sure all underboard
wires came up through the turrets to contact the other components were possible, but still got issues.I have a few days to ponder as were off to
California for a family wknd......Thanks so close but yet so far !

[crunchman]

Ok, what are some ideas in detecting a bad/cold solder joint.My guess would be using a heavy chopstick
And/or needle nose to press/wiggle connectors and the joints while the amp is on.Will this method work with V1 removed? Just some ideas so I can ponder till I get back to the amp.I suppose there is still an outside chance a tube may be bad, the new ones are on the way?Other than that my plan was to reflow the turret joints first with sufficient heat and add some new solder where appropriate.Thanks

[JHow]

The main thing on the chopstick is to use something non-conductive. I would avoid the metal needle nose - too easy to short something, including yourself. I would also try just looking at each joint - they should be shiny and clear, if they are hazy or grainy that is suspicious. Also just look at how the components are wrapped. If wrapped well mechanically, then solder is almost an after-thought. I have seen 60 year-old joints in radios where they missed applying solder in assembly but it still made a connection and worked because they wrapped the lug so well.

[crunchman]

With many of the board component caps/resistors I simply dropped them in and bent them, I did wrap some of the wires

[crunchman]

well, I'm gonna try and find the problem here, first thing is to install the new tubes (I don't think thats the issue, we'll see)
I'm gonna first look for a definite problem with a chopstick, if I can't find a "smoking gun" I will re-solder all the turrets then the wires
going to the tubes.I will try pulling tubes to see if I can determine what stage the problem is in.Looking for advice moving forward so feel
free to chime in ! .................Thanks.

[Chuck H]

FWIW I think solid core wire SUCKS for amp building. Too stiff (more prone to age related failures) and a greater likelyhood of a cold joint.

Flux, or even solder, can bleed into tube socket contacts and cause problems.

Many "new" tubes come out of their boxes hummy, staticy or otherwise noisy. It frustrates the crap out of me. When I plug NEW tubes into a new build and the first thing off standby is HUMMMM, the first thing I used to think is that "I" must have screwed up the wiring!?! But as often as not it's a hummy preamp tube that I just removed from a box!!!

If you can get access to a scope any noises will be much easier to locate. Other than that you can pull tubes (starting with the first preamp tube in the signal chain and moving forward). When the noise stops you'll have isolated the noise to a specific area.

[crunchman]

Well, I put in a new pair of Tung sol reissue 6V6 tubes and everything has cleared up, amp sounds Fantastic btw ! I had some old 6L6'S
that I wasn't sure about, but now the amp is quiet with no static or anything major.Did I say this amp sounds awesome !

There is one issue, when its cold, it will drop out (no volume) then if I press down on the Tone knob it comes right back, a ground issue
I assume ?? There is also a low freq hum when cranked to 6 or above, nothing that would bother me but I will address it after I play
a little more.Thanks for the help !

[lowell]

Sounds like a bad tone pot. If it were a ground for the tone circuit or volume control u would not lose volume. The source of the hum must be before the volume. That means It's between the input jack and the volume knob. Is the hum there with nothing plugged into the input? If it is then try shorting the jack tip to ground. Sometimes shorting jacks are faulty and it sounds like when u have a cord plugged in with the other end unterminated. If that's not it then could you describe what quality hum it is?