Issues with 5e3 Deluxe build.

I've built a 5e3 Deluxe recently, but I've encountered some gremlins  :

99% of the time it works perfectly and sounds good, however, sometimes is creates a whistling noise and sometimes it continuously cuts out... sounds almost like bad cable loosing contact but it is not.
I only noticed it after hours of using it.

The volume knobs don't have an effect on it, so I suspect the issue lies somewhere after the volume attenuation.
My guess is an oscillation problem, maybe coupled with arching?

You can rarely hear it, and it makes it difficult to pin point the location of the problem.

Does it ring any bells to you?

Its difficult to say what the problem is ,have you kept to the original layout?
Kinda sounds like you maybe have a problem with a tube ,a weak rectifier or output tube might be the cause ,you might have a leaky cap somewhere ,in which case your voltages will drift . You could try pulling the 12ax7, if the noise persists ,you have an issue in the output stage or power supply. Sometimes just moving a wire a few cm's can fix things. You could try substituting in different tubes and see if the problem goes away . Are you using brand new components or did you use new old stock stuff? Sometimes electrolytic caps need time to form and can make strange noises while doing so ,if all your voltages measure correctly ,soak test it by leaving it on for a long time 12-24 hours and see if the problem continues .Maybe post a pic of how it looks

Yes, I used the same layout - but I added a half power switch (virtual triode).

It is difficult to troubleshoot it, because most of the time there is no problem. On rare occasions it starts cutting out or making high pitch whistle noise.
The components are brand new.

I'll do some measurings tomorrow and report back.

> cuts out... sounds almost like bad cable loosing contact but it is not.

2 cents says it IS a bad contact. Get the guts out in the sunlight with a magnifier and criticize all your solder joints. (I'll raise a penny to say that after you get the chassis 100% right, you will find a bad contact in a cable that you didn't know about....)

to see if it is a loose connection, bag on the side of your amp with your hand,

does it have a feedback loop? check polarity of that. but that is probably not th problem as it would oscillate all the time unless the f/b resistor is big.

PRR said:

> cuts out... sounds almost like bad cable loosing contact but it is not.

2 cents says it IS a bad contact. Get the guts out in the sunlight with a magnifier and criticize all your solder joints. (I'll raise a penny to say that after you get the chassis 100% right, you will find a bad contact in a cable that you didn't know about....)

Click to expand...

What I wanted to say it sound like a bad input cable, but it is not. I do suspect a bad solder joint - I inspected all solder joints but they seem okay. Unfortunately can't inspect the back of the turret board.
I also poked them with a chopstick, to see if there is mechanical failure.
One of the tube socket lugs on the power tube was making noises, but then it went away.

I hear cutting off only 1 time, and also oscillation 1 time, before I poked the solder joints.
Now it makes pops from time to time (maybe once 20 minutes) when it is idle.

I would like to pinpoint the problem before doing any re soldering. I was wondering if there is a way to induce these problems, so I can locate where it's coming from.

Here's a picture.

cathode resistors brown green red red= 15200 ohm
your pwr tube grid leaks are red red yellow red= 22400 ohm



best wishes,
andy

andyfromdenver said:

cathode resistors brown green red red= 15200 ohm
baddaboom badda bing. *unless that last band is brown.

best wishes,
andy

Click to expand...

It is a 1.5k resistor.... I double checked it with a multimeter.

Anthon said:

It is a 1.5k resistor.... I double checked it with a multimeter.

Click to expand...

interesting ok, I just updated my post
thought I hit a home run for ya...sigh.

I know you'll find it! stupid gremlins.

andy

andyfromdenver said:

interesting ok, I just updated my post
thought I hit a home run for ya...sigh.

I know you'll find it! stupid gremlins.

Click to expand...

Double checked them also - 221k.
Yes, gremlins gonna die.

Anthon said:

Double checked them also - 221k.
Yes, gremlins gonna die.

Click to expand...

haha!
if it's not trouble, have you checked, or wanna post voltages?
when i troubleshoot, I have a few known good tubes, and chopsticks, and a looping pedal with a strong guit signal.
Intermittent problems are the worst though.

that's my favorite no trem-verb fender amp. I was teaching a little class for my "bucket-list" newb friends a while back and we did the 5f1 and 5e3.
a whistling sound sounds like a tube issue to me, your wiring looks very fender-y and not suspect.

sometimes it's good to remove any mods and see if stock solves it.  some compressed air blasts under the board incase there is crud. and to this, a check with the mm on every turret to make sure an underwire hasn't slipped and is contacting the chassis.

take care!
Andy

Hmmmm JJ tubes ,
Ive had some issues with them before ,brand new Ecc83's very microphonic ,totally unusable in early stages of  high gain amps, just about passable in vintage non master volume amps. E34L's which were supposed to be special quality EL34, absolute garbage ,worked ok at switch on then gradually for no apparent reason the bias voltage on the grids drifted positively until the whole amp was in danger of going into melt down ,red plating on the tubes and mains transformer hot enough to fry an egg on , no experience with their 6V6's or 5Y3's though. Ive heard of a few people who swear by the JJ ,I wont touch em with a barge poll.

I'd consider taking the 6.3 volt wires from the transformer direct to the first 6V6 and not to the bulb as you have done, did you put a standby switch in there too ? maybe post a schematic of the half power mod you spoke of also.

Tubetec said:

Hmmmm JJ tubes ,
Ive had some issues with them before ,brand new Ecc83's very microphonic ,totally unusable in early stages of  high gain amps, just about passable in vintage non master volume amps. E34L's which were supposed to be special quality EL34, absolute garbage ,worked ok at switch on then gradually for no apparent reason the bias voltage on the grids drifted positively until the whole amp was in danger of going into melt down ,red plating on the tubes and mains transformer hot enough to fry an egg on , no experience with their 6V6's or 5Y3's though. Ive heard of a few people who swear by the JJ ,I wont touch em with a barge poll.

I'd consider taking the 6.3 volt wires from the transformer direct to the first 6V6 and not to the bulb as you have done, did you put a standby switch in there too ? maybe post a schematic of the half power mod you spoke of also.

Click to expand...

So far I've had no problems with JJ...
I've done several projects, and from experience if something doesn't work properly, it is always some painfully obvious thing that I did wrong, never a malfunctioning part.
I guess there is first time for everything and I never had an intermittent problem, I'll try swapping tubes.
I suspect solder joints in the power tube sockets - I think I'll just re solder them if changing tubes doesn't solve the problem, and see if it does.

I'm using half power switch from Rob Robinette site. It works fine on my Bassman clone.
Most of the 5e3 builds run heaters thru the pilot light first.
The reason there is a standby switch, is because the chassis has a hole and a silkscreen for it.

So I've been doing more poking around (pun intended).

It seems if I poke the base of the turret (not the joint) of the preamp B+3, it translates the pokes into pretty loud sounds (microphonic), interestingly enough - only the bright channel is affected, even though on Deluxe there is a huge crosstalk between channels.
I guess it shouldn't do that.
Maybe it is bad joint on the back of the turret board, but then why would only Bright channel be affected? The B+3 from this turret feeds both channels. (I would like to understand the problem, because removing the turret board would be a lot of work).
I guess a bad joint could explain nasty artifact I've been hearing.

Layout: https://robrobinette.com/images/Guitar/5E3P_Build/5E3_Layout._Annotated_Signal.gif

Edit: it seems there is no effect if I use a plastic pen, then tapping on the b+3 turret (so not mechanical issue I guess).
But the wire running from volume to second preamp does make sounds if you scratch it with plastic or wood stick.

I notice a wire on the first power tube socket, maybe a lead of the grid stopper, picture attached.  I recall a common problem of solder on a tube socket pin with a wire or component lead going through the solder, but not bonded with the solder. I have seen this more than once on vintage Fender amps that had never been reworked.  It may not be the case with this amp, but that lead dress looks like it could be cleaned up.  You could try poking with the chopstick in a darkroom, arcs will be visible.  Can you connect an o-scope, to determine where the noise originates?

walter said:

I notice a wire on the first power tube socket, maybe a lead of the grid stopper, picture attached.  I recall a common problem of solder on a tube socket pin with a wire or component lead going through the solder, but not bonded with the solder. I have seen this more than once on vintage Fender amps that had never been reworked.  It may not be the case with this amp, but that lead dress looks like it could be cleaned up.  You could try poking with the chopstick in a darkroom, arcs will be visible.  Can you connect an o-scope, to determine where the noise originates?

Click to expand...

Thanks. This is a lead of a pair of 100 ohm resistors for referencing heaters to virtual ground. It's should be there.
I can not induce the problem.
I'm not sure even if there is a problem at this point... it seems that from time to time there are tiny scratch noises.
Haven't heard pops in a while.

Microphonic cable going from volume to second power stage does look suspecios.

A few years ago a buddy of mine managed to pick up a Jcm800 from a music shop that was closing down ,the lead channel never worked properly,so the customer returned it ,it lay in the basement for probably close to 30 years . I took a look and found that one of the preamp tubes only one section heated ,on closer inspection I noticed that one of the heater pins wasnt soldered properly , it had an intermittant physical connection , quick dab of the soldering iron and he had more or less a brand new Marshall for silly money ,Im sure several of the staff at the music shop had looked at the amp over the years ,was a good feeling to be able to return the amp to my buddy for just a nominal fee though .

Yes, it always ends up being something painfully obvious. (maybe in retrospect).

Anyway, at this point I start to doubt there is even something wrong...

When it started to cut off, I used an instrument cable with improvised connectors as a speaker cable just for a quick test... it only happened once, and after I changed the cable to a proper speaker cable, I never heard it again..
Oscillation - happened once, and again, I was using a really bad improvised 'speaker cable'.
Yeah, I'm not sure why I didn't put two and two toughether.  :
Maybe because I tried to repeat the fault, but it didn't work, so I assumed the fault was coming from the amp.  ???

Scratchy noises - well that's just p12r going into saturation. They tend to produce these high pitch scratchy distortion sounds, when they break up. I guess I'm listening to hard to find artifacts in the sound.
Some bad connection noises I heard perhaps came from a bad instrument cable or the pickup switch on my guitar, which malfunctions from time to time. Again, for some reason I automatically assumed it's the amp. Yeah, I should really invest in some proper cables.
About pop sounds - only heard it 2 times ... maybe there was something wrong with the power lines.

Have you ever experienced that you were chasing gremlins, and then it turned out it was all in your head?

Well thats good news then , maybe a ghost in the machine after all .
One small point I might as well add here ,noiseless guitar cables usually have a semi conductive black between the screen and the central core, its easily removed with a finger nail ,thing is if you dont remove it ,and it touches the signal conductor it certainly can cause the signal to drop and sometimes pops or crackles as well. Ive seen many people who soldered up their own leads not knowing to remove this carbon loaded plastic layer . Goes without saying ,but always best to use high gauge speaker cables for speakers ,never for signal , you might get away with a signal lead in place of speaker cable in a pinch ,but definately not good practise.

Anthon said:

Have you ever experienced that you were chasing gremlins, and then it turned out it was all in your head?

Click to expand...

Not yet. But I did have a bur take up most of a day trying to figure things out.