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Blues Deville 212 problem - help diagnose

Discussion in 'Glowing Bottle Tube Amp Forum' started by 98muted, Oct 3, 2017.

  1. 98muted

    98muted TDPRI Member

    16
    Jul 9, 2014
    Orange County, CA
    Have a '95 blues deville 212 that has been played pretty hard for 20 years. Started having a problem 4 years ago where it would cut out to about 1/4 or less volume after playing loudly. I shelved it as I was using my orange ad30 for gigging anyway. About a year ago I decided to take it to a tech who replaced the tubes, cleaned some joints and gave it a clean bill of health....I had been playing it in an apartment at low volumes and it worked perfectly for the last year.

    Last night I decided to take it to rehearsal and crank it....about a couple minutes in I hit my OCD pedal and 30 seconds later the problem occurred again, little volume and some distortion, even when turned up to 10. I checked the tubes and one of the power tubes was out, cold and lifeless. Would this cause this problem, or are these problems separate? The amp sounded great at full power for a couple of minutes. I need to know if I can just replace the power tubes or if i need to take it to a tech....any help is appreciated.
     

  2. brogh

    brogh Super Moderator Staff Member

    Jun 26, 2010
    italy
    Hi,

    The tech guys will chime in for sure, one of the things you can do is swap the tubes and understand if it's a socket or tube problem, but i'd say probably you just have a blown tube and you'll be needing to replace it anyway, the operation is quite simple and safe.

    If you want to be safe and 100 % sure bring it to your tech.

    DIY way: what can happen if something bad is going on ... is that eventually you'll blow another tube, then i would say it is tech time. bad tubes happen, i don't know if tubes played at a certain volume for a long period when cranked could cause problems .. doesn't make sense to me...

    Cheers
     

  3. -Hawk-

    -Hawk- Friend of Leo's

    Oct 14, 2015
    IL, USA
    Sorry that I can't help, but I am compelled to ask how the hell you managed to crank that beast! I play in a six person band and can't get past 2 without my ears ringing. More power to ya!

    Hope you can get it fixed.
     

  4. 98muted

    98muted TDPRI Member

    16
    Jul 9, 2014
    Orange County, CA
    Hahaha we rehearse in a very large 30x40 room with a large stage so I'm able to push it...the volume gains after like 4/5 on the dial aren't much, it really just saturates and sounds great.

    Hoping that this problem sounds consistent with just a bad tube!
     

  5. tubejockey

    tubejockey Tele-Meister

    198
    Nov 25, 2015
    the bozone
    It is very possible that you just have a bad solder joint on that power tube socket. These are quite common especially on board mounted sockets. If you can see that the heater is not lit, I would look for a broken solder at pin 2 or 7, or something connected to it.
     
    Bill Moore likes this.

  6. brokenbones

    brokenbones Tele-Meister

    220
    Mar 15, 2012
    Indy
    Have you tried switching the power tubes around to see if the problem persists? It could be as simple as a 'cruddy' tube socket or, like tubejockey suggested, a broken solder connection. At worse it could be a faulty screen resistor.
     

  7. teletimetx

    teletimetx Poster Extraordinaire Gold Supporter

    Jul 25, 2011
    Houston, TX
    Here's a link to the schematic - I think - just for reference, but since your amp is 20 years old, definitely sounds like time to go back to the tech - might need to have the electrolytic capacitors replaced.

    http://www.thetubestore.com/lib/thetubestore/schematics/Fender/Fender-Blues-Deville-Schematic.pdf

    on page 2, the layout, you can see the large caps next to the reverb and presence pots, C34, C35, C41, C42, C45, C46. It's not the only indication, but sometimes, on the ends of the caps, you can see it leaking, trying to blow its brains out. But this is all for a real tech to check out.

    You replaced a tube and it immediately burned out?

    Hopefully some of the real amp gurus on TDPRI will check in.
     

  8. 98muted

    98muted TDPRI Member

    16
    Jul 9, 2014
    Orange County, CA
    Tech replaced the tubes, I never checked them after that, so I'm not sure if it was bad the whole time. I have been playing it at low volumes for about a year with no issues. It wasn't until I turned it up at rehearsal last night that I had issues. I will swap the power tubes tonight to see if it is the socket....hoping it's not something more. Just not sure if the problem sounds like it could be arising from a tube/socket issue or something else.
     

  9. Bill Moore

    Bill Moore Tele-Holic

    Aren't these like the early HR Deluxe circuits with a problem of power resistors too close to the circuit board?
     

  10. Silverface

    Silverface Poster Extraordinaire Platinum Supporter

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    I agree that the electrolytic capacitors should be replaced - even if another problem is found. At 22 years they're past the normal useful service life. If they aren't causing this problem they may cause others before long, and if one blows it can cause a very expensive power transformer replacement.

    It should be done regardless of a "clean bill of health".
     

  11. 98muted

    98muted TDPRI Member

    16
    Jul 9, 2014
    Orange County, CA
    So I switched the tubes...and one tube is definitely dead, as the working one works in both sockets. The problem is I can’t test it at volumes where the problem occurs until I take it to rehearsal which I don’t have for two weeks.

    Would a bad tube be causing this problem? Or should I take it to a tech anyway?
     

  12. Silverface

    Silverface Poster Extraordinaire Platinum Supporter

    Age:
    65
    Mar 2, 2003
    Lawndale CA
    Possibly, but not likely. And it may well be on of the overdue filter capacitors beginning to fail. And if you replace the power tubes the amp needs to have the bias checked and probably adjusted anyway. You don't replace one power tube.

    As noted previously it should have the electrolytic filter caps replaced whether they're a problem or not - they're past end-of-service life. And that may fix it or it will eliminated them as a cause of the problem.

    It should go to a tech.
     

  13. Dacious

    Dacious Friend of Leo's

    Mar 16, 2003
    Godzone
    The bad tube is a bad tube - but given the problem pre-existed it may be just that's the first tube to 'give'. A problem with this series was as someone said the big bias resistors on the board (white blocks) would unsolder themselves. That will give you a tube bias issue which can cause the volume to drop out.

    Secondly the tube sockets themselves - my bandmate's Blues Deluxe (diff amp, similar construction) had the issue of the tube sockets were very badly soldered - strings of elephant snot on the PCB. His amp would work for twenty minutes then fade out. Retouching those joins with fresh solder fixed that five years ago.

    But yes, if you've given it a belting, often letting the amp sit will be worse that continuous full blooded usage, the filter and small signal caps do dry out and can, maybe cause volume drops or futzing out.

    It can also be the preamp out/power amp in jack sockets need a clean/retension. Had an Ampeg doing that, was the effects loop jacks dirty.
     

  14. blues bondsman

    blues bondsman Tele-Holic

    648
    Feb 12, 2012
    Indiana
    These amps and many other hot rod ish amps all have two big sandbox resistors on the board that over time due to vibration end up having solder joint issues and heat issues.
    I do also agree that the electrolytic caps are beyond there life span.
     

  15. blues bondsman

    blues bondsman Tele-Holic

    648
    Feb 12, 2012
    Indiana
    That and most of these I've had on my bench had ribbon cable issues , where I had to remove the ribbon cables and solder in individual wires (huge pain !!!)

    Willing to bet this is your issue
     

  16. 98muted

    98muted TDPRI Member

    16
    Jul 9, 2014
    Orange County, CA
    Well, I dropped it off at a new amp tech today. Hoping he can fix this thing once and for all, and hoping it's not too expensive of a fix. Really love this amp as a pedal platform compared to my orange ad30 that I like more on its own
     

  17. 98muted

    98muted TDPRI Member

    16
    Jul 9, 2014
    Orange County, CA
    So it looks like I need a power tube socket replaced. He is going to replace filter caps and reflow solder in some suspect areas. Hopefully this addresses all of the problems and I get it up and running soon!
     

  18. Dickey01

    Dickey01 TDPRI Member

    Age:
    63
    73
    Jul 19, 2017
    Florida
    Look at the silver label on the back of your amp. If it says "Made in Mexico"...that's your problem right there. They used cheap circuit boards that expanded to quickly with heat, breaking solder joints, especially the tube socket joints. Hadda re-solder mine every 3 or 4 gigs. Only way to fix is to buy "Made in USA" amps.
    If your amp is made in USA, my guess is prolly the same thing, but happened over a longer time. If you're handy with an iron, try re-soldering the tube sockets joints.
     

  19. T Prior

    T Prior Poster Extraordinaire

    Mar 17, 2003
    Charlotte NC
    The tech probably should have replaced the E Caps the last time around. They are the primary FILTERS for clean High DC Voltage, which the power tubes require for full out circuit operation. Loss of volume, dirty bottom end when it should be clean , are symptoms of aged E caps. they are not there just for good looks. The Power Supply is the heart of the engine. Even if you read the proper +DC voltage with a meter that is not the final say, a Scope may be required to literally LOOK at the DC voltage . E Caps live in the +/- 15 year window. Quality ones maybe a tad longer, lessor quality maybe a tad less.

    Bringing it back to the tech is a good thing. Replacing those OLD Filters creates a whole new reference.
     

  20. 98muted

    98muted TDPRI Member

    16
    Jul 9, 2014
    Orange County, CA
    New filters, new tube socket and new solder and cleanup, and now we find that one of the speakers is shot....so it looks like I'll be getting a new speaker as well
     

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