Fender Hot Rod Deluxe pooping out again...please help!

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by dmc777, Jan 22, 2012.

  1. dmc777

    dmc777 Member

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    Hi guys, maybe someone can help me.

    Amp-US made fender hrd never even gigged

    Problem-When turned on the amp distorts, pops, crackles, etc..with or without guitar plugged in. Sounds kinda similar to unplugging your guitar or an effect repeatedly when everything is turned on for reference. Kinda like a ground issue.

    I just had the a tech work on it almost 2 years ago because the sound was cutting out and getting crossover distortion. Replaced all plastic jacks and a few other things per my request. Also put in a set of SED 6L6 power tubes and replaced preamp tubes.

    Could this be a tube problem or worse? Anything I can look for? Any suggestions?

    In the meantime could I use my Egnater Tweaker 15w to power the deluxe? If so would just plug it into the power in on the deluxe? Any help would be appreciated.
     
  2. LPMark

    LPMark Member

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    Theses things are notorious for broken or cracked solder joints on the PC boards.
    Especially the tube sockets. Does it do it when you gently rock the tubes, use a rag on the hot power tubes and "gently" wiggle.
    You can pull the first 2 preamp tubes to isolate the problem to the preamp or power sec.
    Could just be a bad preamp tube.
    If you can make it do it by wiggling and tapping on things it's probably a solder joint.

    If your'e comfortable pulling it out of the cab a visual inspection with a mag glass once you determine the area is sometimes all you need.

    Mark
     
  3. dmc777

    dmc777 Member

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    Thanks for the reply. I haven't tried moving the power tubes with the amp on yet but I will try that. I had a funny feeling that it may be the socket cause it doesn't really sound like what "I think a bad tube" would sound like. I don't have to wiggle or anything I just turn it on and it's just the horrible noise. I did try tapping on the tubes to see if they were microphonic and one of the preamp tubes did sound a little hollow. I will try you suggestion tonight.

    Can anyone give me some info on if I can power the deluxe using my egnater tweaker head? They're both 8 ohm. I don't really care for the tweaker cab too much...plus it doesn't have reverb.
     
  4. dmc777

    dmc777 Member

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    Well I tried wiggling all the tubes but none proved to be the culprit. However it isn't making the intermediate noises anymore. Instead, when I plug my guitar in and strum it just sounds real fizzy/distorted sounding and hardly any volume. Sounds the same plugged into the power in also. I exchanged all preamps but no luck. Guess it's the power tubes...or something worse. Could a power tube failure cause this kind of problem?
     
  5. Jerry Glass

    Jerry Glass Member

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    It sounds like the main filter cap failed. It's a common and fairly easy fix that I'd suggest you leave to your tech.

    I have one on my bench right now with this issue. Volume is significantly reduced, very distorted with a very out-of-tune quality to it. The main filter (47uF @ 450v) is completely open.
     
  6. BONGKARMA

    BONGKARMA Member

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    it could be a cheap input jack. i had the same kind of problem with mine a while back.
    the next time you hear it turn the amp volume down low and give the amp a tap on the top side near the jack and see if it changes anything.
     
  7. dmc777

    dmc777 Member

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    I've had all the plastic jacks replaced with switchcraft or neutrek I can't remember. I had it worked on a little over a wear ago and had the tech do some improvements. Guess not enough.

    I guess I'll have to take it back to the tech. Any suggestions or improvements I can have done while he's already in there? I already have a cannabis rex I guess I'll have him put in. This amp doesn't even move yet still seems to screw up.
     
  8. LPMark

    LPMark Member

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    Did you recently unplug the speaker and perhaps plug it in the wrong jack?
     
  9. dmc777

    dmc777 Member

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    Unfortunately not. I was curious about the speaker connection though until it started doing what it is now.

    I just moved away from Memphis where the tube depot is which actually have techs that know their ****. I'M in Greenville, Ms now in the heart of the delta blues and I don't know of anyone. I've built a few pedals and actually studied up on tube amps but Ive gotten a little rusty now.
     
  10. Moddjobbs

    Moddjobbs Member

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    The cap is definitely suspect. Also, if the amp is more than 5 years old, and your tech hasn't already, have him check and possibly replace the phase inverter plate load resistors. (82K and 100K) I've seen probably 10 of the dozens I've repaired come through with open or out of spec resistors in this area, and it wreaks havoc on the clean headroom and gain structure of the amp. I usually replace all the preamp plate loads also (R4, R11, R16, R22, R57, R58) 5 100K and an 82K; All 1/2W min

    Good luck getting it back up and running! :)
     
  11. dmc777

    dmc777 Member

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    Thanks a lot for the info guys. I may try to tackle this on my own since I have experience solderin, circuits and have wanted to learn what I can about tube amps. I have a bias tool but haven't used it yet. I do know I need to drain the filter capacitors first. My main concerns are getting the chassis out and back in since Ive heard this can be a pain, and cold solder joints since they seem to be more problematic than in pedals. Any specific kind of filter capacitors i should put in and resistors? Sprague, mustard. Allen Bradley or metal film for example? Also, if i were to take it to my tech should i replace the sockets? Maybe I should just look at the available mod kits that are around.
     
  12. bsuite

    bsuite Supporting Member

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    These are a pain in the arse to work on.
    You can cause even more problems than what you already have just by removing the circuit board to work on them.
    Junk IMO.
     
  13. LPMark

    LPMark Member

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    Are you sure the power tubes are good?

    You can check DC voltage and resistor values without taking the chassis out of the cab, but to replace any components it's a lot easier if it's out.

    As Moddjobbs said check the plate load resistors, theyr'e physically bigger than the rest. Go through and measure the resistance of all the large resistors, ignore the little ones.

    Check the Screen resistors on the tube socket PC board, and inspect the solder joints of those components and the large ceramic 470 ohm resistors, those like to burn up.

    If you have low voltage on any of the main filter caps then those are bad.

    Those checks will probably reveal the problem.

    Good luck,

    Mark
     
  14. gldtp99

    gldtp99 Member

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    :agree--- people who bring me amps like this get directed to the local pro tech----- they work on cheaply made, modern PCB amps like this all the time over there
     
  15. mageerc

    mageerc Member

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    dmc777,

    I'm in Leland, MS... I'm not a professional tech, but I can probably help you out...
     
  16. LarryN

    LarryN Member

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    Ditto on burned resistors common on that type amp.
     
  17. Hwoltage

    Hwoltage Member

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    I would check the plate resistors on the PI.
     
  18. cap47

    cap47 Member

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    Did you try a jumper cable between the EFX loop? Could just need jacks cleaned!
     
  19. dmc777

    dmc777 Member

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    I
    What do you mean exactly? Just connect the pre in to the power out with a standard cable?

    Also how would I know if I have a blown fuse or bad transformer?
     
  20. cap47

    cap47 Member

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