# Do I have a dead power tube?



## Guncho (Jun 16, 2015)

Fender Bassbreaker 15

I think I know the answer to this question but....
I just bought this amp a week ago and it started making a static sound even with the mute switch on, so I opened it up and one of the EL84s was lit up orange on the inside and the other was dark and cold.

Dead tube? Any recommendations for replacements?

I'm assuming I should not turn the amp on until I get new tubes?


----------



## Alan Small (Dec 30, 2019)

clean those sockets with a high quality cleaner that leaves no residue: poor contacts can cause both your observations: all amps should have this service done regularly, then;
and new pair o tubes


----------



## Latole (Aug 11, 2020)

Tube is red plating.
Something wrong with amp *or with this tube
Don't use amp until is fixed.

* Bad contacts ; socket, circuit , solder or issue with bias 240 ohms 5 W resistor or grid stopper resistor : 270 ohms 2 watts

You can safely do a test; Reverse both EL84 tubes
If the same tubes red plating on other socket, it is a tube issue
If it is the other tube is red plating , it is a amp issue.
Don't let the amp ON more time you need to see.

Tubes replacement ; buy a matched pair, replace both
You can buy any brand, best choice is the same brand and keep the good tube as spair

Fender Bassbreaker 15 output tubes don't need ( most of the time) a bias adjustment


----------



## Guncho (Jun 16, 2015)

Latole said:


> Tube is red plating.
> Something wrong with amp *or with this tube
> Don't use amp until is fixed.
> 
> ...


My concern was not really the tube that is on on the left, it's the one that looks off on the right. Are you sure the tube on the left is red plating and not just working harder to compensate for the tube on the right not working?

My plan right now is to pick up a matched pair and replace them.


----------



## Verne (Dec 29, 2018)

Have you tried swapping the tubes in their sockets? If the same thing happens, then definitely amp. If the one is still dark and the other is bright again, wait for new tubes. Do you not have other EL84s to pop in to see as well? Takes nothing to swap them around as a quick check.


----------



## Paul Running (Apr 12, 2020)

I can't tell if the filament is lit on the RH tube...glare from the LH tube. Does it feel cold? You may wish to check the continuity of the filaments.


----------



## Latole (Aug 11, 2020)

Guncho said:


> Are you sure the tube on the left is red plating and not just working harder to compensate for the tube on the right not working?


No, a pair of tubes don't work like this.
One tube is red plating.


----------



## Guncho (Jun 16, 2015)

Latole said:


> No, a pair of tubes don't work like this.
> One tube is red plating.


I don't think the picture is giving an accurate representation of what's happening. The tube on the right has light reflected on it from the right tube but I assure you it is not on at all. 0 light and dead cold. I am absolutely not an expert but I've looking up red plating and the right tube doesn't look that at all. It looks like it's running pretty hot but it's not burning a large hole in the side of the tube.

Regardless, hopefully a new set of tubes solves the problem.


----------



## Latole (Aug 11, 2020)

It is not easy to ( help to ) fix a amp than by photos and especially without having the amp in front of me.


----------



## Guncho (Jun 16, 2015)

Latole said:


> It is not easy to ( help to ) fix a amp than by photos and especially without having the amp in front of you


Totally. I appreciate the help. Picking up some tubes today and will report back.


----------



## Latole (Aug 11, 2020)

Try reverse tubes


----------



## Guncho (Jun 16, 2015)

Latole said:


> Try reverse tubes


----------



## Paul Running (Apr 12, 2020)

Guncho said:


> red plating and the right tube doesn't look that at all.


No but the left tube is beginning to red-plate. I'm positive that the green-circle is not a reflection...that tube is in an initial thermal-runaway state. You start strumming some heavy-ass chords and that tube will be toast.


----------



## Paul Running (Apr 12, 2020)




----------



## Guncho (Jun 16, 2015)

Ok things are not going well.

I bought a matched quad of lightly used tubes off Kijiji. I plugged them in and the tube on the right started to red plate.

Time to take amp to a tech, try the other two tubes or do I try and get a refund? I bought the amp on reverb 12 days ago. I really do like the amp and got it for $500. If it's tech you say, any recommendations on the Oakville area?


----------



## Latole (Aug 11, 2020)

I would never buy, nor advise, to buy used or advertised power tubes on sites like kijiji, Marketplace. There is too much chance of having problems with defective tubes as these ones seem to be.
Had I known that was your intention, I would have dissuaded you.


----------



## Latole (Aug 11, 2020)

Guncho said:


> View attachment 384596



The tube we talk about since the beginning is bad. On right socket is red plating too.
1+1 = 2
You only need a know good pair of tubes, amp look ok


----------



## Guncho (Jun 16, 2015)

Latole said:


> The tube we talk about since the beginning is bad. On right socket is red plating too.
> 1+1 = 2
> You only need a know good pair of tubes, amp look ok


So after having problems with two sets of tubes your suggestion is to spend $60 on a new pair of tubes? That's how much it would cost to have a pair of JJ's shipped.

What are the odds of having three bad tubes in two sets and not having a problem with the amp? I would think at this point I would take it to a tech or try and get a refund. The seller mentioned changing tubes at some point.


----------



## Latole (Aug 11, 2020)

Reading what you say about amp / tube issue and your pictures. IMO it is the tube.

You have to take chance to buy a $60 tubes set or pay a amp tench ( $50 or more ? ) plus a $60 tubes set.


----------



## Latole (Aug 11, 2020)

The same tube is red plating in the left and right socket,
Not the other tube 
It can't be the amp.


----------



## Guncho (Jun 16, 2015)

Latole said:


> The same tube is red plating in the left and right socket,
> Not the other tube
> It can't be the amp.


Neither of the tubes in the last picture are the same tubes we started with. Does that make a difference to you?


----------



## Paul Running (Apr 12, 2020)

It may be time to measure some voltages on the output tubes.


----------



## Latole (Aug 11, 2020)

Guncho said:


> Neither of the tubes in the last picture are the same tubes we started with. Does that make a difference to you?


The last picture show ( another ) bad tubes you bought on kijiji


----------



## Guncho (Jun 16, 2015)

Paul Running said:


> It may be time to measure some voltages on the output tubes.


I don't know how to do that.


----------



## greco (Jul 15, 2007)

I am so confused!

Good Luck with getting it sorted out.


----------



## Latole (Aug 11, 2020)

There are lethal voltage there. 

A bias reading will tell everything. It need some knowkedge


----------



## Guncho (Jun 16, 2015)

Latole said:


> The last picture show ( another ) bad tubes you bought on kijiji


Or there's something wrong with the amp.

Do I:
A) Try to return it to the Reverb seller. It worked when I got it so not sure that's an option.
B) Spend $60 on new tubes which might solve the problem.
C) Spend $200 (I'm guessing) at an amp tech for a guaranteed fix.


----------



## Latole (Aug 11, 2020)

A or B

I'll go for B


----------



## Latole (Aug 11, 2020)

Don't forget answer #9 
" It is not easy to ( help to ) fix a amp than by photos and especially without having the amp in front of me "


----------



## Paul Running (Apr 12, 2020)

Guncho said:


> I don't know how to do that.


I always remember my dad's words to me when I said that to him: "son, you'll never learn any younger". He never explained it to me but I caught on later in life.


----------



## dtsaudio (Apr 15, 2009)

See the first post here.


New model Fender Bassbreaker 15 repair - Music Electronics Forum


I suspect this is what is happening. You have a shorted bypass cap, and the tube(s) are drawing way to much current.

On two other posts
Never by tubes off kijiji (or eBay for that matter).
Never clean tube sockets with contact cleaner, especially any that leave a residue. Some cleaners will eventually eat the plating, and then you're f**d.


----------



## Guncho (Jun 16, 2015)

dtsaudio said:


> See the first post here.
> 
> 
> New model Fender Bassbreaker 15 repair -  Music Electronics Forum
> ...


Any recommendations for a tech in the Halton/Hamilton area?


----------



## Budda (May 29, 2007)

Guncho said:


> Any recommendations for a tech in the Halton/Hamilton area?


Chris Church in Hamilton.


----------



## Guncho (Jun 16, 2015)

Budda said:


> Chris Church in Hamilton.


I swnt him an email he asked me to give him a call tomorrow which I will do.


----------



## Latole (Aug 11, 2020)

dtsaudio said:


> Never clean tube sockets with contact cleaner, especially any that leave a residue. Some cleaners will eventually eat the plating, and then you're f**d.


You can do safely with a good contact cleaner.


----------



## Paul Running (Apr 12, 2020)

Latole said:


> You can do safely with a good contact cleaner.


As long as you clean-up the residue. I recommend a rolled-up piece of Kim-wipe (great for electronic work), placed between the jaws of a fine pair of forceps (medical suppliers have the best selection) and rub-away...get all that residue off...that stuff is electrically conductive at high-voltages...I've witnessed a few arc-overs in my time...the socket is toast after that.


----------



## Guncho (Jun 16, 2015)

dtsaudio said:


> See the first post here.
> 
> 
> New model Fender Bassbreaker 15 repair - Music Electronics Forum
> ...


Found this:


----------



## Alan Small (Dec 30, 2019)

Paul Running said:


> I always remember my dad's words to me when I said that to him: "son, you'll never learn any younger". He never explained it to me but I caught on later in life.


with age comes wisdom


----------



## jb welder (Sep 14, 2010)

Guncho said:


> Any recommendations for a tech in the Halton/Hamilton area?


You didn't notice from his sig. line that the poster you were replying to is a tech in Hamilton? 






Instrument Amp Repairs


DTS Audio has extensive experience with most Fender, Gibson, and Ampeg amps (among many others)




www.dtsaudioelectronics.com


----------



## Guncho (Jun 16, 2015)

jb welder said:


> You didn't notice from his sig. line that the poster you were replying to is a tech in Hamilton?
> 
> 
> 
> ...


I did not as it's not visible unless you expand his signature. That is funny though.


----------



## Latole (Aug 11, 2020)

Guncho said:


> Any recommendations for a tech in the Halton/Hamilton area?


It's a good idea to have this amp repaired and serviced.
A competent technician will put it in order and you won't have any problems for many, many years.

And, not least, you will have had a good technician


----------



## Alan Small (Dec 30, 2019)

dtsaudio said:


> See the first post here.
> 
> 
> New model Fender Bassbreaker 15 repair - Music Electronics Forum
> ...


----------



## RBlakeney (Mar 12, 2017)

Alan Small said:


> View attachment 384813


Tube Pins vs tube sockets.


----------



## Alan Small (Dec 30, 2019)

RBlakeney said:


> Tube Pins vs tube sockets.


understood and thank you; plus clean pins clean the socket somewhat while inserting and hopefully better contact on all pins improves the operation


----------



## Guncho (Jun 16, 2015)

So I have an appointment with Chris and he said 3-4 weeks. No idea of the price.

My wife thinks I should go after a refund from the reverb seller but I'm not sure I have a leg to stand on. It was working when I got it two weeks ago but I never checked the tubes. I was getting normal sound so I assumed they were both working. He did mention that he changed the tubes a while back and in his feedback he either sold another exact same amp a while ago or he did and someone returned it. He's just some guy not a pro seller of gear so that all seems a little sketchy. Did he know this was a lemon? I think maybe he did but can that be proven is another story.

That being said I really like the amp and think it would it be better keep this amp and repair it. I paid $500, and I am guessing the repair will be $200 but I really have no idea. Or would it be better to get a refund and buy a brand new one for $1000 with a two year warranty. This seems like a common issue with these amps. Who's to say I wouldn't be looking at the same repair three years from now?

I have an appointment to drop the amp off for repair tomorrow so I guess that's what I'm doing.


----------



## RBlakeney (Mar 12, 2017)

Guncho said:


> So I have an appointment with Chris and he said 3-4 weeks. No idea of the price.
> 
> My wife thinks I should go after a refund from the reverb seller but I'm not sure I have a leg to stand on. It was working when I got it two weeks ago but I never checked the tubes. I was getting normal sound so I assumed they were both working. He did mention that he changed the tubes a while back and in his feedback he either sold another exact same amp a while ago or he did and someone returned it. He's just some guy not a pro seller of gear so that all seems a little sketchy. Did he know this was a lemon? I think maybe he did but can that be proven is another story.
> 
> ...


I feel like getting a refund will be tough since you say it worked fine when you got it. 
I feel like it’s kind of the game you okay when buying used gear, sometimes It needs maintain an extra sooner than later. 🤷


----------



## Budda (May 29, 2007)

Guncho said:


> So I have an appointment with Chris and he said 3-4 weeks. No idea of the price.
> 
> My wife thinks I should go after a refund from the reverb seller but I'm not sure I have a leg to stand on. It was working when I got it two weeks ago but I never checked the tubes. I was getting normal sound so I assumed they were both working. He did mention that he changed the tubes a while back and in his feedback he either sold another exact same amp a while ago or he did and someone returned it. He's just some guy not a pro seller of gear so that all seems a little sketchy. Did he know this was a lemon? I think maybe he did but can that be proven is another story.
> 
> ...


Is Chris giving you a quote before he does the work, or a bill?


----------



## Guncho (Jun 16, 2015)

Budda said:


> Is Chris giving you a quote before he does the work, or a bill?


A quote but that may not be for weeks.


----------



## jb welder (Sep 14, 2010)

Guncho said:


> That being said I really like the amp and think it would it be better keep this amp and repair it. I paid $500, and I am guessing the repair will be $200 but I really have no idea. Or would it be better to get a refund and buy a brand new one for $1000 with a two year warranty. This seems like a common issue with these amps. Who's to say I wouldn't be looking at the same repair three years from now?


The zener issue seems to be a bug with this model. So I don't think this particular amp was a lemon, it's more a design issue.
If you get the bug dealt with (removal), you should be good. As you say, you could buy a new one and have it do the same thing after the warranty is up, you never know.
If it is the zeners, I would not recommend replacing them, especially in a model like this where they are so tough to get at. You could put in new ones and they might do the same thing in time. 
But see what Chris thinks is the best course of action, he may have dealt with the issue before.


----------



## Guncho (Jun 16, 2015)

jb welder said:


> The zener issue seems to be a bug with this model. So I don't think this particular amp was a lemon, it's more a design issue.
> If you get the bug dealt with (removal), you should be good. As you say, you could buy a new one and have it do the same thing after the warranty is up, you never know.
> If it is the zeners, I would not recommend replacing them, especially in a model like this where they are so tough to get at. You could put in new ones and they might do the same thing in time.
> But see what Chris thinks is the best course of action, he may have dealt with the issue before.


Yeah for sure. When I say lemon I mean I suspect the seller was aware of the problem this amp is currently having and chose not to mention it. He's a private seller yet happened to sell the exact same model of amp a while ago and he also mentioned he changed the tubes a while ago. Nothing I can prove of course.

If you had to ballpark the repair cost including two new EL84s, what would you guess? I'm guessing $200 but I have very little knowledge to base that on so could be completely out to lunch. I really hope I don't end up paying the cost of a new amp.


----------



## Frenchy99 (Oct 15, 2016)

dtsaudio said:


> Never clean tube sockets with contact cleaner, especially any that leave a residue. Some cleaners will eventually eat the plating, and then you're f**d.


Hey Dan, which contact cleaner would you recommend ? I use a generic brand and you now have me worried.


----------



## jb welder (Sep 14, 2010)

Guncho said:


> If you had to ballpark the repair cost including two new EL84s, what would you guess? I'm guessing $200


I think that is a reasonable guess. With a more normal 'serviceable' style amp, I would think an hour shop time, but this one will probably take double that. Not sure what the shop rates are in your area though.


----------



## dtsaudio (Apr 15, 2009)

Frenchy99 said:


> Hey Dan, which contact cleaner would you recommend ? I use a generic brand and you now have me worried.


I use this








409B - Electrosolve Contact Cleaner


Suitable for use in food facilities as a Non-Food Chemical—Canadian and NFS recognition letters available on request Safe on many plastics Zero residue Fast evaporation rate Dissolves oils and residues RoHS compliant




www.mgchemicals.com




Inexpensive and doesn't leave crap behind.


----------



## Paul Running (Apr 12, 2020)

The circuit on the left is the original bias arrangement. The circuit on the right is how they used to cathode-bias P-P amps...5 extra components that are potential failures...why do you require 39V clamping diodes? Ask Chris those questions.


----------



## Guncho (Jun 16, 2015)

Paul Running said:


> The circuit on the left is the original bias arrangement. The circuit on the right is how they used to cathode-bias P-P amps...5 extra components that are potential failures...why do you require 39V clamping diodes? Ask Chris those questions.
> 
> View attachment 384929
> View attachment 384930


Yeah i wonder what Fender was trying to achieve with those diodes.


----------



## dtsaudio (Apr 15, 2009)

Guncho said:


> Yeah i wonder what Fender was trying to achieve with those diodes.


They are there supposedly to protect the tube from runaway. However at 39V, by the time you reach this point the tubes are already toast. Take them out.


Paul Running said:


> The circuit on the left is the original bias arrangement. The circuit on the right is how they used to cathode-bias P-P amps...5 extra components that are potential failures...why do you require 39V clamping diodes? Ask Chris those questions.
> 
> View attachment 384929
> View attachment 384930


Paul, you should still bypass the resistor (and should be 120 ohms), but I agree the old way has some advantages besides cost.
Matching becomes less critical as the tubes will tend to share current. With Fender's new way, matching is critical. You could end up with one tube doing all the work, while the other just coasts along.
I would also ask Chris if he thinks those tubes are running too hot. I suspect they are.


----------



## Paul Running (Apr 12, 2020)

dtsaudio said:


> and should be 120 ohms


Yeah, it runs hotter with the 110Ω. I used to series a 100Ω resistor with a 25Ω pot and experiment with the tone. I seem to like the EL84s on the hot side...pushing the tubes for that trade-off.
As for the by-pass cap, I consider it a matter of choice. In this particular case, with a balanced output, it shouldn't loose much power or shift much in bias...best to experiment.


----------



## dtsaudio (Apr 15, 2009)

Paul Running said:


> Yeah, it runs hotter with the 110Ω. I used to series a 100Ω resistor with a 25Ω pot and experiment with the tone. I seem to like the EL84s on the hot side...pushing the tubes for that trade-off.
> As for the by-pass cap, I consider it a matter of choice. In this particular case, with a balanced output, it shouldn't loose much power or shift much in bias...best to experiment.


I prefer to bypass that resistor as it tends to lesson subsonics and limit bass a bit. Power difference is minimal. 


I agree that EL84's sound better run on the hot side (think Vox AC30), but reliability is an issue with these amps so cooler may be safer.


----------



## jb welder (Sep 14, 2010)

Guncho said:


> Yeah i wonder what Fender was trying to achieve with those diodes.


He talks about it in the excellent video you posted earlier. Around the 13:23 mark, I'll try to cue it up below.
It's a variation of what is sometimes called the 'Chuck H mod' which sort of creates a hybrid of cathode and fixed bias to avoid bias shifting and excess 'fizzy' crossover distortion. It does seem though that Fender chose the wrong value for the zener, I think in the 15 to 20V range is usually used for the mod.


----------



## Paul Running (Apr 12, 2020)

I believe that constant-current sources are the most under rated configuration in audio electronics. LM317s are ideal to use as a CCS for EL84s.
The circuit below is reliable and the addition of a T-cap, allows the use of un-matched tubes:


----------



## Guncho (Jun 16, 2015)

Well my guess of $200 for the repair was pretty close. $240. Chris removed the Zener diodes.


----------

