Is it ok to remove one power tube from a 5E3 Deluxe for troubleshooting purposes?

[ctcpete]

Hello guys been a while. I have been trying to troubleshoot my 5E3 Deluxe build, (built by a famous builder but now probably 10 years old) it makes a pretty loud popping noise on an intermittant basis.

Occurs with no guitar plugged in and with each of the pre amp tubes removed. I have chopsticked around and thought I found it with a loose solder connection to the 12ax7 but the problem persists. I have done a lot of searches and have not found this answer.

My basic question is: is it ok to remove one power tube at a time and let the amp idle powered up with one power tube to see if the problem goes away? I assume it is but like to err on the side of caution.

I'll use some de oxit on the contacts of the tubes first. I also have a new rectifier tube on it's way and have tried different pre amp tubes. From what I have read it can be a ground issue so I'll check grounds down the road..trying some simple stuff first.

Thanks.

[pdf64]

The cathode bias resistor is intended to be shared by both 6V6.
If only one 6V6 is in place, that tube will tend to run very hot as the cathode resistor value required for one tube will be about twice that required by two tubes sharing the same resistor.
It probably wouldn't cause a problem if just for a few seconds but I suggest to avoid doing it for more than a minute at a time.

[ctcpete]

OK pdf64 thanks so much ^^^ glad I asked now. I have searched that specific question and I'll be darned if there is anything out there. I'll pull the pair out of my Deluxe Reverb and go that route. I'll be ordering some spares as well. Trying to make up my mind if it is worth it to go NOS with the power tubes or not..not to go off topic ha ha. The ones in there are old USA power tubes, I forget the brand. I've seen some NOS Sylvanias at a not too high of a price. Would get a matched pair just so I know they have been tested at least.

The noise is a quick pop..and occurs after the amp has been powered up a few minutes. Otherwise the amp works great.

[Justin Thomas]

Huh, another good reason to not bias your tubes to run as hot as possible just because you can... I think the main reason we don't get an answer to that question is because most of the time the question of leaving power tubes pulled is in 100W amps, which I have never seen cathode biased... Also a good reason to include separate bias resistors per tube if you have room?

As for NOS, in a 5E3 you should be fine. I think most of the 6V6s people want are the GTA, because they're safer in the BF/SF amps. When you are talking true NOS tubes and NOT reissues, those G/GT/GTA/GB/GC/etc. suffixes actually mean something. NOS 6V6GTs shouldn't be too bad. And, it's wattage that kills tubes a lot more than voltage- don't bias your tubes too hot! But I haven't had any problems with JJ.

Justin

[Pdavis68]

Unfortunately, lots of possible causes:
- Bad tube (preamp or power) with internal arcing.
- Arcing at a tube socket (or switch or elsewhere in the amp). Look for possible burns on components.
- Broken resistor or cap lead. Chopstick everything. Broken leads are sometimes hard to see.
- Failed coupling cap
- A component getting so hot that the solder melts while operating (power supply dropping resistors, power tube cathode resistors, etc).
- Failing choke or OT (if they're vintage, you might pop the bell ends to make sure the wires are still well insulated).

Hope that helps.

[mozz]

My question is, is it ok to use Deoxit on tube sockets? I read somewhere no to do that. Secondly, when it comes to 6v6's, all suffix's are the same rating, even the old metal ones.

[Leo_Gnardo]

My question is, is it ok to use Deoxit on tube sockets?

I use a bristly type pipe cleaner on octal sockets, soak the end with Deoxit, apply & wait a couple minutes. Meanwhile clip off the end of the pipe cleaner, soak the new end with a non residue spray cleaner or ethyl alcohol, scrub those socket electrodes again. One more time especially if the pipe cleaner picks up a lot of grey/black looking oxide.

Same technique for smaller sockets, 9 & 7 pin generally but use a dental brush intended for use between teeth, you can find these at a well stocked grocery store or pharmacy. No point in soaking the whole socket with a big splash of deoxit, just a dab where it will do the most good, and followed up with a little mechanical cleaning action & solvent wash. I havent' ruined any sockets this way, but there have been a few that were beyond cleaning and really did need replacement.

There have been some other so called metal cleaners or contact enhancers that didn't work well on tube sockets. There was one in particular "Tweek" in the late 70's-early 80's that was notorious for leaving behind a layer of non conductive goop that did wreck a number of tube sockets. I'd beware of anything except the authentic item and DO follow up with a solvent cleanup.

[Justin Thomas]

Huh, never noticed that - why bother with the G/GT/GTA then? Still not sure I'd put 420V on a metal 6V6, though - mostly because I can't see if there's a problem! I do know the 6L6 suffixes differ...

I think just about anything would be okay in a tweed Deluxe/Champ. Or just use JJs & be done with it, at least for initial testing!

Justin

[ctcpete]

I had meant to say spray the pins of the tubes with the deoxit, not the sockets, sorry for the confusion. I have also considered using some plumbers metal oxide sand paper or a fine file to rough up the pins as well but would not do that without you guys agreeing.

[pdf64]

I think it may be a bad idea to spray a layer of lube between terminals with a lots of voltage across them.
Best to limit lubricating cleaner to dabbing it on to the actual pins / socket contacts, eg with a cotton bud etc.

[TimmyP1955]

I use CRC QD Electronic Cleaner. Anytime I use DeOxIt on something, I then wash it off with QD. I've seen D... turn to goo on tube pins.

[Leo_Gnardo]

Best to limit lubricating cleaner to dabbing it on to the actual pins / socket contacts, eg with a cotton bud etc.

If tube pins look corroded I clean them first with a strip of 600 or 800 grit super fine sandpaper, then follow up with a Q-tip (cotton bud in proper English) soaked with a drop of deoxit. Some may object to my method, carry on if you must, it works fine for me & thousands of crustomers, so far so good. Finish up with dry cotton or solvent clean then dry. Yes it is a good idea to NOT soak the tube socket with cleaner of any sort. Concentrate on the pins, that's where the contact is made, that's what counts.

[ctcpete]

I installed a set of 6v6s from my Deluxe Reverb and the problem is gone. I'll try the above methods to try and clean the pins on the two old Sylvania 6V6s. If the problem persists it dawned on me that I have a 5Watt Swart amp that uses one 6V6 so the perfect platform to find out which one of the two is the culprit. Unless my thinking is skewed again haha. Wouldn't want to damage the Swart with the bad tube..no chance of that I assume?

Thanks again for the kind assistance. This is a great forum and resource. When I have more time if I ever retire I'd love to do some real tinkering and building. Again, thanks so much.

[ctcpete]

Update: After installing both known good tubes from the other amp and not having the problem, I pulled one out and I swapped in the two suspect tubes one at a time and narrowed it down to one tube. Three times I had that tube installed and the noise returned each time so a safe bet that was the culprit. Thanks again

[mozz]

I never use sandpaper or oxide paper on tube pins, brass brush only. You don't want to remove any type of plating on the pins. New tubes might not follow these rules and use steel pins or a chinese version of steel. I also use that CRC QD brand of cleaner, seems safe.