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Gswitz

Tubes for a Fender Devillle 4x10

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Posted (edited)

I bought the amp in 1995 new. I love it but it's a little heavy. Sounds great.

A while back I got a Rivera Rock Crusher and I started really driving it. So much fun!! But now, as the tubes warm up the volume drops precipitously.

So I'm thinking I need to replace tubes. I had a couple of AX7s laying around for mics and I switched them in. I replaced 2 of the 3, but didn't fix things.

So then, what do I need to buy??

From the pdf for the amp

  • Three Fender Groove Tube GT12AX7 (099-4005-000)
  • Two Fender Groove Tube GT6L6B (099-4401-*02)
  • Tube label color: Red=1, White=2, Blue=3

So, I'm looking for where to buy my first set of tubes and any advice on replacing them...

I found this... What do you think?

https://www.stewmac.com/Pickups_and_Electronics/Amp_Kits_and_Parts/Tubes/Replacement_Tube_Sets/Fender_Amp_Tube_Sets/Fender_Hot_Rod_DeVille_Tube_Set_with_Matched_Power_Tubes.html?utm_source=google&utm_medium=shopping&utm_campaign=2019-06-gp&gclid=Cj0KCQjwo7foBRD8ARIsAHTy2wko8pW2nZ08sFkB1dgHVuUiAuppDAQdsMw9M51s4HcuLrUzIIDOEM4aArHaEALw_wcB

Can I touch the tubes? I have always put my fingers on the ax7s b/c I never figured they got hot enough to matter.

Thanks for any help!

Edited by Gswitz

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I would handle tubes with tight-fitting gloves or plastic ones, like they use in hospitals. I may be overly careful, but don't like to put prints or body oil on the tubes. Outside of that, can't hurt to try those stewmacs

 

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If you think pushing the amp caused the problem I would look at the output tubes not the preamp tubes. Try replacing the 6L6s. I use attenuators on all my amps and haven't had any problems. I buy tubes from a number of places - https://www.tubesandmore.com/ comes to mind.

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Handling hot tubes can damage the internal wires and grids! It's always a good idea to let the amp and tubes cool for a little bit before grabbing and snatching them around.

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The amp is at least 15 years old now.  It would be a good idea to have an electronics technician check out the resistors and capacitors.  It's not that unusual for passive components to change value as they deteriorate over time.  Capacitors are known to dry out or leak dielectric, resistors absorb moisture and transformers overheat from an overload or dust bunnies.

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If the amp is that old, it will probably need a dedust of the circuit board, just a general clean and then just replace all the tubes at once and be done with it.  I would replace both the ax7 and 6l6 tubes, do them all.

If you have a local established guitar/amp repair shop, give them a ring and see what they recommend, they might do the whole thing for you and give it a service for a reasonable cost. They can clean it, install the tubes and then test it, apart from using electrical equipment, they can tell from the noise it makes whether it is on spec or if anything else is wrong with it and what that will be. I don't touch tubes at all, always use tissues or a clean tea towel or something when I replace them. Habit I guess.

If it were me, I would dismantle the whole thing, including the amp head section, the speakers and the handles....everything,  give everything a good clean, then tighten everything back up again, put those new tubes in and then call it a day. If it's still behaving strangely after that, I would take it to the shop as it will be beyond my knowledge.

Stuff can get loose with age which can lead to rattles and buzzes etc which sometimes you only hear when you record.

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There's no harm in touching the tubes. They are pretty robust. 

 

They should generally all be changed at the same time. Some amps are exceptions, but you also should have the bias checked/ adjusted.

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Thanks for the manual link. I have that already. I've replaced all the tubes. I'm starting to think the problem is with the rock crusher.

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I'd swear I tested with and without the rock crusher in the chain, but right now, there is evidence pointing that way.

So, when I turn the amp up to around 5 or 6 and play with bypass on for the rock crusher, it works fine.

I turn off bypass and at first the volume attenuates as expected by then after a few moments playing it almost disappears.

When I reduce the attenuation, the problem goes away.

I'm going to call Guitar Center where I got it and see if there's any hope. I can just use it with less attenuation.

Thanks to everyone for all the help!!

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Sounds like the "Crusher" is maybe shorting the signal to ground; this would not be good.
IF the "load" is suddenly a "dead short" you're going to damage the output tranny, 6L6's and accompanying circuitry.

As to handling the "tubes" (these are electron valves, just so you know).
They are not "fragile", BUT best practice; let them cool before handling.
If the "valves" are cool then the B+ voltage will most likely have "bled" off.
Best not to insert or pull tubes with the B+ at 400 volts.

T

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Posted (edited)

So, I'm now thinking i damaged the tubes with the rock crusher because the rock crusher wasn't working properly on the studio setting. That would explain the problem existing with the rock crusher in and out of the chain.

New tubes up to the minus 20db setting is working fine.

I've sent a note to support for the rock crusher to see what they say.

Thanks again everyone.

Edited by Gswitz

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Turns out i bought the Rock crusher used. Oops. 😃

So i think i will just avoid the studio setting.

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You said you had replaced 2 of the 3 preamp tubes.  Did you do the power tubes as well?  Those tubes are right next to the speakers and take a beating at high volume.

Fender, unfortunately, took some cost cutting measures on those amps.  If you are getting it serviced, make sure to have the big power resistors on the +/- 15 volt supply for channel switching checked out and re-soldered as necessary.  They used solder as the means of mechanically securing two big power resistors.  I've seen those solder joint crack, and when they do they get hot and can also arc, causing HUGE heat loads that can burn the board.

If you are in there, you might as well swap out the electrolytic filter caps as well.  Good ones (sprague atoms) will last 20+ years.  I've seen the caps in the hot rods/deville fail after only a few years.

Also, if you are in there, replace the plastic input jacks.  Not only do the pin's solder joint to the board fail due to high stresses on insertion, the input bezel is supported by a little metal ring.  These pop off and then the jack breaks.

The solder joints on the power tube board should be re-flowed.  These are under stress as well. 

I hope that helps.

 

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Spent a few minutes looking for a schematic for this bad boy (to no avail).

My guess is the attenuator (the load) is just fine.
Something must be "wonky" in the tap, or the level pot, for the "Studio" setting.
I'd tear it apart, they are pricey; but hey, you bought it used, hence no warranty; whadda ya got to loose?

Just my nickel98's worth....

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Posted (edited)
3 hours ago, DeeringAmps said:

Spent a few minutes looking for a schematic for this bad boy (to no avail).

My guess is the attenuator (the load) is just fine.
Something must be "wonky" in the tap, or the level pot, for the "Studio" setting.
I'd tear it apart, they are pricey; but hey, you bought it used, hence no warranty; whadda ya got to loose?

Just my nickel98's worth....

The service manual pdf file linked in my prior post includes the schematic I sent it to you via personal message in case you want to add it to your collection.

Edited by fogle622
Noted personal message.
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(Don't want to be a party pooper, but shouldn't this be in the Coffee House or something?)

I'm a pro amp tech and designer, and have lost count of the  number of  Hot Rod/Blues DeLuxe/Villes I've had through my shop in the past 15 years.

Basically yes to most or all of what @Tubeydude says, but I find that with good jack hygiene, which on those amps means looping your cable through the handle on top to act as a strain relief, the nylon input jacks are just fine.

At this age, and with those symptoms, the power tubes are suspect and should be swapped out by a tech who can properly set the bias for you.

As for the power supply caps, in the mid 2000's, China's manufacturers had a massive problem that affected many brands of electrolytic capacitors, including Illinois, the supplier of the caps for Fender's tube amps (The common failure mode of LCD TV's and monitors where they come on for 10 seconds and then go back off is due to the cap cootie problem, and most of those TV's and monitors can be repaired with $10 worth of caps. Yes, all those 52" TV's that are sitting in landfills....). That's why Tubeydude has seen those poor Illinois fail after only a few years, and I'll bet they had that crud that looks like Gorilla Glue oozing out of them.

Any current manufacture electrolytic capacitor, even generic, will likely last at least 30 years in that application. I see 40 year old caps in Fender Twins that are still holding on, and electrolytic caps, China crisis aside, are not in the category of things that used to be made better than they are now, quite the contrary. Materials science and manufacturing have advanced greatly in the past several decades.

And yes, the power resistors for the 15V rails should be checked, as they do melt their own solder joints. I think they're 470 ohms standard and I started stocking 500 ohms to swap them out with, which cools things down and still provides plenty of current.

I'm not familiar with the Rock Crusher, but aren't attenuators supposed to attenuate? I kid, but this one sounds like something's gone wrong and I hope the manufacturer of the device can set you up with a manual and expected behavior and all that. They do put a strain on your power tubes.

Oh, and whatever you put in there, I suggest you make sure that whatever the labeling, it's made by Sovtek/EH/New Sensor. Sound great and last a long time. They make the tubes for Fender/Groove Tubes.

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Posted (edited)

From rivera support...

There's a protection mechanism in the studio setting so just be sure that you're not plugging it in backwards . Just pay very special attention to the labeling. If it is plugged in correctly that means at one time it was plugged in backwards and it blew out that protection mechanism.

Unfortunately it's not something you can do your self. It's very small and it's in a network of capacitors and it needs to be taken apart and replaced. It's easy for our tech but not if you aren't familiar with it.

We can fix it here too if you want and it's just around $50.

From Geoff

I'm fairly confident I've never plugged it in backwards. I think the unit I bought may have come with this fault. I don't use the studio setting often and at low enough gain it works. I don't like to be able to hear pick noise over the guitar, so I usually use the louder settings.

Edited by Gswitz
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I'd get it fixed for the $50. If it's part of your sound, two years from now company (and tech) may no longer exist.

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