update tommy chong jcm 800 2210 howling

Discussion in 'The Workbench' started by Exotic, Dec 5, 2019.

  1. Exotic

    Exotic Active Member

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    so i just heard from the 2nd tech after i requested a progress report ,gittin antsy ,can't help it ,and he agreed it was actin wierd so he ordered a new set of tubes ,can it be as simple as all that?
    here are the symptoms i took it in for
    1:it was howling with the gain and volume on 10 and the master on 0.
    2:the reverb knob was affecting the volume
    3:no matter the settings of the knobs the amp just didn't sound right, it sounded off .
     
  2. Matthews Guitars

    Matthews Guitars Well-Known Member

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    Tubes are the first thing to check. Of course.
     
  3. Exotic

    Exotic Active Member

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    well in a way i hope that's it because it would be over with and i would get my amp back .
    but in a way i'm hoping it's not it because i recently had 9 brand new jj's put in .
    i'm hoping he ordered groove tubes because at this point i prefer them over jj's ,so we'll see .
     
  4. scott-colorado2016

    scott-colorado2016 Active Member

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    You should post this in the previous thread instead of starting a new thread.
    Humm... So the second tech says tubes as well?
    Any fault that can be duplicated can be repaired. Give him some time to work on it. I'm thinking there is something that is causing the oscillation (what you are calling howling), bad component, improper wire dress, broken down insulation, etc. A problem like that is best troubleshot using an oscilloscope, or at the very least, a whole lot of electronics engineering specializing in electron tube theory.
     
    ricksdisconnected likes this.
  5. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    The only way I can help you is if the tech follows directions.
    Get the tech into the forum and work directly from here.
    You don't want to work on the amp yourself and relaying information isn't working at all...
    Soooooooo..........
    You gotta do this a different way because the way you are doing this doesn't work and isn't solving anything.
     
  6. Exotic

    Exotic Active Member

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    yes he said he would be in touch and ima email him right now ,not in as much of a hurry cuz my jcm 900 came today .
     
  7. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    You either need to get this tech to come into the forum and test the amp step by step...or find a better technician who knows how to work on it.
     
    ricksdisconnected likes this.
  8. pedecamp

    pedecamp Well-Known Member

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    What amp tech doesnt have a spare set of tubes to test it with? Sounds like hes taking a stab in the dark buying new tubes at your expense when you have new tubes of your own in there already. Did you try your old tubes in it?
     
    Lance Chambers likes this.
  9. Lance Chambers

    Lance Chambers Well-Known Member

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    I agree! Hell, I am a techi type and have spares. Who owns a tube amp and doesn't keep spares? :coffee:
     
    pedecamp likes this.
  10. Gunner64

    Gunner64 Well-Known Member Premium Member

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    My 2205 did some weird shit when it had broken solder joints where the pots mount to the pcb. The way the board needs to be wrestled out in these amps involves flexing these connections.

    I have had certain amps where tubes just didn't work together, and squealed when the master and pre where both cranked. (But I really don't see why thats necessary with the 2210/05 but to each his own)So imo a tube issue is possible, but I wouldn't buy a whole new set to find out. Swapping a single tube one by one should find the culprit.
     
  11. JM5010

    JM5010 Member

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    Didn’t read the old thread, but is the amp modded? Some marshall circuits can squeal like crazy if they are modded for high gain and the gain/volume is cranked.

    You can also try plugging into the return of the fx loop to see if it’s a power amp issue.
     
  12. RLW59

    RLW59 Well-Known Member

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    I get that techs may have personal preferences, or that they might like dealing with specific tube vendors, or may get bulk discounts or something.

    But if a tech expects me to pay for a set of tubes, I expect to choose what brand I want.

    If the tech has had bad experiences with the brand I want, or can get some other brand cheaper, I'd appreciate being told that. Might change my mind.

    But unless it's a warranty repair, I should have the final say on how I want to spend my money.
     
    Jethro Rocker and Adieu like this.
  13. Exotic

    Exotic Active Member

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    it's not modded .
    i agree about the tubes ,i don't know what he is thinking .
    it was working fine with 9 new jj's
    did not try my old dead tubes .
     
  14. pedecamp

    pedecamp Well-Known Member

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    A tube issue is possible but sadly i have a low expectation of this tech figuring out the problem.
     
  15. pedecamp

    pedecamp Well-Known Member

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    How long was it working fine with the new tubes before it started howling? Did it work fine with the old tubes (no howling)? It could be just 1 tube thats causing the problem, very easy to troubleshoot.
     
  16. Gunner64

    Gunner64 Well-Known Member Premium Member

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    Exactly. Seems the "tech" is chasing his tail..I have been playing tube amps since the mid to late 70s and I have never seen all the tubes in an amplifier go bad at the same time. Red flag number one..replacing all the tubes.
     
  17. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    If your tech won't come into the forum:
    It's time to gather all the old parts and tubes up.
    It's time to separate from this person and get your amp up and working.
    Too much messing around, time to act.
     
  18. Exotic

    Exotic Active Member

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    it was working fine with new tubes for like 3 or 4 months .
    it was working fine with 2 old tubes and 2 new tubes for around 10 months.

    i don't think he is going to put all 4 tubes in and say ok come pick it up ,he probably ran out of spare tubes and is going to try one by one .


    i would love to go grab my amp but he said he is going to work on it on tuesday . and i told him the previous tech had it 4 weeks ,he said he's not going to take 4 weeks and if he can't figure it out he would say so and give it back to me .
    tomorrow is only 2 weeks so i gotta give him a chance .
     
    Last edited: Dec 8, 2019
  19. Exotic

    Exotic Active Member

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    ok i have news from the tech ,i need your advice .what would u do if u were me?

    the tubes all seem to be ok to me, i replaced all and no change, so I put yours back in. reverb tank and replaced master volume pot are ok too.

    All operating voltages are fine. R31 is correct and is fine. moving wires around makes no change.

    Besides the funny behavior of the reverb pot and volume increase, there is a static that lasts for a few seconds every time I take the amp off standby, I am suspicious of the filter capacitors, there are 3 multisection capacitors cans, all original dated to 48th week of 1989...30 years old. I recommend replacing these, because of their age, but they could be contributing to or be the the cause of the problem. If the noise and weird behavior persists after the cap swap, then I'll move on to the next suspect.

    There is no charge so far, if you'd like to pick up the amp as it is. The cap job will run $100, be prepared to spend up to another $100 if I have to continue to hunt down (and replace) possible bad components. Let me know if you want me to proceed.
     
  20. pedecamp

    pedecamp Well-Known Member

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    I'm no tech so its really hard for me to say, but I would think a tech should be able to isolate the problem and be able to tell good parts from bad parts in an amp and none of this guess work at your cost. Lets keep our fingers crossed and hope you get some answers from the techy guys here. My gut says find another tech that does real work and not guess work. Good luck.
     
    ricksdisconnected likes this.

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