1. Win a Broadcaster or one of 3 Teles! The annual Supporting Member Giveaway is on. To enter Click Here. To see all the prizes and full details Click Here. To view the thread about the giveaway Click Here.

Tweed Deluxe major volume loss...help?

Discussion in 'Amp Tech Center' started by Duke, May 28, 2013.

  1. Duke

    Duke Tele-Meister

    Age:
    59
    Posts:
    198
    Joined:
    Jan 20, 2007
    Location:
    Hanover, Ontario Canada
    Hi all. I built my 5e3 a few years ago and it's serviced me well. A few months ago I started to get crackle/pop noises when playing at high volumes. I opened it up and poked around with a chopstick and couldn't find any loose connections. I also swapped out tubes with no difference. I haven't played it for a month or so and fired it up today. I tested it at high volume again with the same result and then the volume dropped out to maybe 10% of what it should be. The strange thing is that it seems to keep the same tonal characteristics. For example, plugged into the bright channel I can adjust the normal volume and get the breakup and clean just like always, just at a very low volume. Before I jump in I thought I'd throw it out there to see if other 5e3 owners might have experienced something similar. Thanks for any help.
    -Duke
     
  2. BobbyZ

    BobbyZ Doctor of Teleocity

    Posts:
    13,621
    Joined:
    Jan 12, 2011
    Location:
    Snellman MN
    Check the tube sockets. It could be something simple like a bad solder joint or loose socket so one power tube is cutting out. Good way to burn your fingers but wiggling the tubes a little while playing it might be worth a shot.
     
    jsnwhite619 likes this.
  3. Duke

    Duke Tele-Meister

    Age:
    59
    Posts:
    198
    Joined:
    Jan 20, 2007
    Location:
    Hanover, Ontario Canada
    I resoldered everything. I did a full retune. I still have low volume. It's like my usually super loud 5e3 has turned into a bedroom practice amp. It still sounds good, just not loud. All voltages are good. Perhaps the OT is kaput?
     
  4. muchxs

    muchxs Doctor of Teleocity

    Posts:
    13,171
    Joined:
    Aug 14, 2004
    Location:
    New England
    Homebrew amps and online diagnostics present their own set of challenges. Troubleshooting is a guessing game. Bein' good at it is all about makin' better guesses...

    It's kinda like bein' psychic. :lol:


    Low volume may be a capacitor that's not doing its job. I'd say replace the 500p on your tone control. Maybe that will do it, maybe it won't. If not that one try the .0047 in the tone control circuit.

    Heat sink the leads before you solder them in place. You can use a plain old alligator clip as a heat sink.


    You may want to poke a few resistors with your meter. If you put the heat to the 100k plate resistors maybe they're not 100k anymore.


    You went after your solder joints. How are your grounds?
     
  5. printer2

    printer2 Poster Extraordinaire

    Posts:
    7,274
    Joined:
    May 24, 2010
    Location:
    Canada
    I'll guess also. Same tonal characteristics just lower volume. I'll go with capacitor also for 100 points but I am thinking cathode bypass on the output.


    Actually it could be anything, you just have to check each stage and eliminate sections till you pin it down.
     
  6. BobbyZ

    BobbyZ Doctor of Teleocity

    Posts:
    13,621
    Joined:
    Jan 12, 2011
    Location:
    Snellman MN
    Damm I was hoping I guessed right !
    I did have a new 250pf cap go bad one time after about a half hour. What made that interesting was it was the only new part in the stupid amp. So you can guess what I checked LAST.
     
  7. Duke

    Duke Tele-Meister

    Age:
    59
    Posts:
    198
    Joined:
    Jan 20, 2007
    Location:
    Hanover, Ontario Canada
    BobbyZ, what were the symptoms of that? I posted this hoping that I might get lucky and someone else would have experience the same thing with a 5E3. I thought I might get lucky before I started taking off parts and testing them. In other words, I was being a bit lazy. I do have a spare OT and lots of other parts, so I guess I'll start pulling, testing, replacing, and testing. Like you, I'll probably find it on my last try. More to come.
     
    mojek likes this.
  8. BobbyZ

    BobbyZ Doctor of Teleocity

    Posts:
    13,621
    Joined:
    Jan 12, 2011
    Location:
    Snellman MN
    The symptoms. Well it was a Vibro Champ I found in a junkyard in the 90s I'd done some mods to it from a Weber book so it was more like a tweed Champ with a master volume. It was like that for years then I rewired it back to stock. That's where the 250pf cap came in.
    When the cap went the volume dropped way down and a voltage check was off where the 250pf, ..047 and .01 caps all sort of come together. So I changed the .01 then the .047 and maybe a few other things before I got it through my head that a new part can go bad.

    Oh the point I was trying to make was I think what Muchxs said about the 500pf cap is worth a try. :lol:
     
  9. Wally

    Wally Telefied Ad Free Member

    Posts:
    39,002
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    Start at the plates of the power tubes and do a voltage test on each section. AS you go back toward the input, the POP! that you hear when maing contact with that plate to test that voltage should get louder at each stage...wiht the input stage being the loudest since that signal is amplified through the whole circuit. IF you find a weak spot---lower volume than from the last test point that was closer to the OT, then you have found the area of concern. IF it is weak everywhere but louder at each step going back toward the input, maybe the problems are close to the output????
     
  10. Duke

    Duke Tele-Meister

    Age:
    59
    Posts:
    198
    Joined:
    Jan 20, 2007
    Location:
    Hanover, Ontario Canada
    It was the OT. New one on the way.
     
    mojek likes this.
  11. mojek

    mojek Tele-Meister

    Posts:
    215
    Joined:
    Jul 2, 2014
    Location:
    Praha, CZ
    Hi Duke,
    did the new OT solve the problem? I have the very similar issue with mine. Tonaly it stays all the time the same, but it's very quiet (opposite what say 5e3 owners) and from time to time it makes strange noises, sometimes it' s like a volume sums for a moment up and than back again.. I have changed the tubes and when the harsh sounds occurred I tried to move with tubes, but nothing helped..

    Many thanks!
    Mjk
     
  12. mojek

    mojek Tele-Meister

    Posts:
    215
    Joined:
    Jul 2, 2014
    Location:
    Praha, CZ
    Problem solved. After cleaning all tube sockets, changing tube without an effect. Decided to measure primary/secondary windings DCR. Simply took out the tubes, disconnected the speaker jack and measured opened speaker jack and plate/b+ resistances on both 6V6 sockets.
    Primary is 0.9 ohm (is OK). Blue/red is 325 ohm(seems OK), brown/red 174 ohm(NOT OK), 500 ohm blue/brown(summ of them agrees). The values of each OT secondary wirings should be similar.
    It' s 2007 Mercury Magnetics OT in first Fender 5E3 reissue. The trannies are both Mercury Magnetics.

    If you have similar issue, try to measure the same, then you can be sure, that OT is OK, clean the sockets and in next step try to switch/change the tubes. Typical was decrease of headroom, from time to time it made strange noises a few seconds and sometimes the volume jumped very shortly up.
    Since the amp is AB, but very near A, it' s very hard to judge, because the sound "quality" remains very nearly the same even with amp running with one tube on 50% and the other on 100%..
     
    nathan5782 likes this.
  13. Wally

    Wally Telefied Ad Free Member

    Posts:
    39,002
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    Mojek, ime, the two sides of the primary do not have to be equal. I have never seen a perfectly balanced situation there. A new Peavey replacement OT was once so ‘imbalanced’ that I called Peavey to ask them about it. I gave them the measurements, and they said that is exactly how it was designed. The OT worked perfectly.
    You say that the problem is solved. Did you replace the OT?
     
    mojek likes this.
  14. mojek

    mojek Tele-Meister

    Posts:
    215
    Joined:
    Jul 2, 2014
    Location:
    Praha, CZ
    Hi Wally,
    you are right, the DC resistance difference between two sides of primary is normal. It is caused by different length of the wires. In case of 5E3 it's usually 1400 turns per side, sometimes (old Schumacher trannies) have the second side wired with slightly thicker gauge to compensate the wire length difference. I remember f.e. the DCR's in case of my 5E3/5 clone were 170 and 190 ohms. However, 330 ohm (which I find OK) and 170 ohm is twice the value, and would mean there is twice as much of wire on one side to another.. The amp sounds really really good, but as loud as my 77 Silverface Champ. I have measured all the Voltages, changed all the tubes, cleaned the tube sockets, moved with the tubes when the strange noises occurred and nothing happened.

    The true is that the problem is not solved, it' s not 100% proved :)

    I have ordered new transformer from TAD, which will come next week, will replace it next week and keep you updated.
     
  15. mojek

    mojek Tele-Meister

    Posts:
    215
    Joined:
    Jul 2, 2014
    Location:
    Praha, CZ
    Here is the update...

    Today I have obtained the TAD replacement OT. First measured both primaries, one was 239 and the other 240,5 ohms. 1,5 ohms difference look much better than 160 ohms. This is really small difference and I believe it can be caused by using slightly thicker wire on second primary (the longer wire), otherwise it can be easily 10% of DCR more. The transformer is on paper bobbin, paper interleaved and smells after bees wax :)

    I have soldered the transformer in the amp and tested it... I am totally blown away.. its 2-3 x louder than with the faulty MM tranny. The volume pots work as usual, 0-3 a lot of volume change etc.. But, it distorts later, the sound is somehow more compact and living it was hard to stop playing my Telly with it how inspiring it was
    However, the main reason is IMO that now both 6v6's are working (not just one) and there is not present the distortion connected with class AB (i.e. part of wave is not present or distorted...when only one tube is working)..

    Please, if you have problem with sudden headroom loss, simply take any ohm-meter and measure the DCR of primary and secondary winding of the OT. You don't have t take the amp apart, just take out the power tubes and measure the resistance between brown (on the first), blue (the second) and B+ red wire. If the differ significantly, there is something wrong with your OT.. and you can save the time and money of changing tubes as I did't
     
    Muttlyboy and nathan5782 like this.
  16. mojek

    mojek Tele-Meister

    Posts:
    215
    Joined:
    Jul 2, 2014
    Location:
    Praha, CZ
    Wally, please, what was the Peavey OT type and the DCR ‘imbalance’ of the OT?
     
  17. Muttlyboy

    Muttlyboy TDPRI Member

    Age:
    59
    Posts:
    56
    Joined:
    Feb 22, 2020
    Location:
    Queens, NY
    A friend of mine gave me a 5e3 chassis to check out because I mess with amps as a hobby...

    The symptoms seem to be pretty much as you desribe...very low volume and early distortion. The voltages look good, but it's biased a little bit cool with a 330R cathode resistor.

    I couple guys said to get a 270R resistor in there, but I'm thinking that slightly cooler bias wouldn't result in dirtier tone and less volume

    Just so happens to also have a Mercury Magnetics OT.

    I just read your post and grabbed my meter...

    Red to brown, 551 ohms
    Red to Blue, 916 ohms

    This is interesting. Thank you
     
    mojek likes this.
  18. sudogeek

    sudogeek Tele-Meister

    Posts:
    378
    Joined:
    Sep 9, 2016
    Location:
    Palm Beach FL
    I also had a similar issue in a reissue Fender 57 Deluxe reissue with a blown/failed OT. It was a head from 2014 which developed a loss in volume. I bought it broken. After checking the cathode cap, resistor, and voltages, and finding the output was all of 4W, I found a similar asymmetry in the resistance of the sides of the OT. I replaced the stock MM-manufactured OT with a MM FTDO-59S which, according to MM, was the closest to the Fender part. Fixed the problem and then some!

    At first, I chalked it up to the seller having run the head without a speaker load or some other user error. Subsequently, I tracked down 3 other reports by various posters on other sites which described a similar problem with the Fender reissue 57 Deluxe. OEM parts are often manufactured to the specs of the buyer and, possibly, these were a bit -ahem- under-engineered to meet a certain price point. Anyway, this appeared to be surprisingly common on my brief searching the web. But now, these reports are of 5E3 clones. I hope my replacement MM OT holds up. So far, so good.
     
    Last edited: May 2, 2020
    mojek and Muttlyboy like this.
  19. Muttlyboy

    Muttlyboy TDPRI Member

    Age:
    59
    Posts:
    56
    Joined:
    Feb 22, 2020
    Location:
    Queens, NY
    That's the same part number that I have in front of me FTDO-59S.

    If it would be possible, could you measure the DC resistance of the the primary halves?
     
    mojek likes this.
  20. sudogeek

    sudogeek Tele-Meister

    Posts:
    378
    Joined:
    Sep 9, 2016
    Location:
    Palm Beach FL
    @Muttlyboy: Here are the numbers this afternoon:
    MM FTDO-59S - Resistance red-blue 366 ohms, red-brown 331 ohms, brown-blue 692 ohms
    Output (with JJ 6V6Ss): 14 W RMS
     
    mojek and Muttlyboy like this.
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.