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Thread: Took my amp to a tech today...

  1. #1
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    Default Took my amp to a tech today...

    and after I explained the symptoms to him he said it sounds like the transformer has gone. Something about a break in the secondary coil? The problems are completely my own fault, I kept switching the rectifier knob when the amp was powered on.

    Sorry that I can't give any more information on it but I was hoping someone might be able to explain some of the basics about this secondary coil to me. He's gonig to ring in a few days to tell me what he thinks I should do and I'd like to be in a position where I've got some clue what he's talking about. I had a read of Aspen Pitman's Tube Amp Book regarding the matter but I couldn't find much that I could understand.

    Thanks,
    -Benja
    Guitars:
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    Danelectro U2 '56 Reissue
    Yamaha APX5LA
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    Marshall JTM60 combo

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    Ultimate Tone Slacker tone?'s Avatar
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    Default Re: Took my amp to a tech today...

    Dude is this in the new prosonic amp you got??

    that sucks.
    hopefully it isnt the transformer and hopefully it is something they can fix. i wouldnt worry too much if it is the prosonic cause fender should have replacement parts for it.


    how was that amp sounding for ya?

    sorry to hear that again
    Ibanez Roadstar II
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    Jack Nicholson: It's not true. Some have great stories, pretty stories that take place at lakes with boats and friends and noodle salad. Just no one in this car. But, a lot of people, that's their story. Good times, noodle salad. What makes it so hard is not that you had it bad, but that you're that pissed that so many others had it good.

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    Default Re: Took my amp to a tech today...

    Thanks tone? I bought if from Ebay and I'm pretty sure the fault is my doing.

    HA HA
    I also took my Marshall JTM60 to him so hopefully he can fit a fan and the over-heating problems will go away for good this time. I know how uch you love that amp! LOL. Seriously though, I quite like it (except for the reliability issues, obviously) but I'm only fixing it up to sell. Got to pay for the Fender somehow, my Dad lent me the money and he's going to want to get back sometime.

    Did you ever try doing anything about the JTM's reliability?
    Guitars:
    Epi LP (SH-11b + SH-55n)
    Danelectro U2 '56 Reissue
    Yamaha APX5LA
    Pedals:
    MXR Super Comp, HBE Power Screamer, Toadworks Death Rattle, Carl Martin Crunch Drive, Boss CE-2, Marshall Ed The Compressor, Marshall Drivemaster, Arion EQ, Bespeco Volume Pedal
    Amps:
    Fender Prosonic combo
    Marshall JTM60 combo

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    Default Re: Took my amp to a tech today...

    Sorry about my typo's. It's late over here, honestly!
    Guitars:
    Epi LP (SH-11b + SH-55n)
    Danelectro U2 '56 Reissue
    Yamaha APX5LA
    Pedals:
    MXR Super Comp, HBE Power Screamer, Toadworks Death Rattle, Carl Martin Crunch Drive, Boss CE-2, Marshall Ed The Compressor, Marshall Drivemaster, Arion EQ, Bespeco Volume Pedal
    Amps:
    Fender Prosonic combo
    Marshall JTM60 combo

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    Default Re: Took my amp to a tech today...

    how was that amp sounding for ya?
    To be honest, I don't know. I broke the thing about 10 from turning it on. The active EQ's really threw me as I've no experience with them what-so-ever. I think I've got a bit to learn (and a lot of fiddling) about them before I really feel like I'm on top of them.
    Guitars:
    Epi LP (SH-11b + SH-55n)
    Danelectro U2 '56 Reissue
    Yamaha APX5LA
    Pedals:
    MXR Super Comp, HBE Power Screamer, Toadworks Death Rattle, Carl Martin Crunch Drive, Boss CE-2, Marshall Ed The Compressor, Marshall Drivemaster, Arion EQ, Bespeco Volume Pedal
    Amps:
    Fender Prosonic combo
    Marshall JTM60 combo

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    Default Re: Took my amp to a tech today...

    See thats the problem with the JTM

    i e-mailed MArshall england and they replied and they got in touch with marshall greece ( where i live) . this all took alot of time mind you cause the guy in marshall england that does this sort of work is always away on business trips. Makes me wonder why he does that sort of work when he cant meet up to it. Anyway Marshall greece just shrugged their shoulders kinda at me about the whole thing.

    they said "sorry dude but marshall made a crap product back then and why do you think that they discontinued it?" and the guy kinda was looking at me like i was an idiot for buying it and too bad. im so serious that is how it went. And im no pushover so i said to the guy " well talk to your techs and ask them if there is a workaround technically cause i have heard different stuff on forums on the net. but nothing happend. he said " the best we can do is give you a real 'friendly price' on the next marshall you buy."

    i was dumbfounded. it was like thanks alot. no one wanted to create a workaround.

    im sure that this isnt the first time marshall had this problem with this model amp. and they couldnt find a workaround????!!!!!!
    so what is all the workarounds that techs on the net always talk about with these amps?

    so anyway i just sold the sucker for 650euros and danced when it left my hands.

    so their is the story of why that amp pissed me off so much.

    dude that prosonic has waaaaay better tone of what i remember hearing. and it is custom shop built. real good work from what i remember hearing.

    how do you like the amp compared to the JTM? the JTM must sound like a toy compared to that.
    Ibanez Roadstar II
    EBMM AXIS HoneyBurst
    VHT 50/12 Pitbull

    Jack Nicholson: It's not true. Some have great stories, pretty stories that take place at lakes with boats and friends and noodle salad. Just no one in this car. But, a lot of people, that's their story. Good times, noodle salad. What makes it so hard is not that you had it bad, but that you're that pissed that so many others had it good.

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    Default Re: Took my amp to a tech today...

    how do you like the amp compared to the JTM? the JTM must sound like a toy compared to that.
    Yeah, I hope so. But like I said, I don't know yet. LOL. When I took the amp to the tech he just stared at me like I was a complete idiot, I don't blame him though. He was like, 'You had the amp on for 10 minutes and you broke it?' Erm... Yeah.

    That's really ****ty about Marshall. I have to say that every time I've contacted them they've been very helpful. I guess it depends on who picks up the phone.
    Guitars:
    Epi LP (SH-11b + SH-55n)
    Danelectro U2 '56 Reissue
    Yamaha APX5LA
    Pedals:
    MXR Super Comp, HBE Power Screamer, Toadworks Death Rattle, Carl Martin Crunch Drive, Boss CE-2, Marshall Ed The Compressor, Marshall Drivemaster, Arion EQ, Bespeco Volume Pedal
    Amps:
    Fender Prosonic combo
    Marshall JTM60 combo

  8. #8
    Ultimate Tone Slacker Chaos's Avatar
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    Default Re: Took my amp to a tech today...

    Quote Originally Posted by benjaturner
    Sorry that I can't give any more information on it but I was hoping someone might be able to explain some of the basics about this secondary coil to me. He's gonig to ring in a few days to tell me what he thinks I should do and I'd like to be in a position where I've got some clue what he's talking about. I had a read of Aspen Pitman's Tube Amp Book regarding the matter but I couldn't find much that I could understand.
    1.) A wire passing through a magnetic field creates current flow in that wire. Or conversely, a magnetic field moving past a wire will induce current flow in that wire (either the wire or the magnetic field has to move).

    2.) Current flowing through a wire will create a magnetic field around that wire.

    In a typical transformer, the primary coil (windings of wire) is connected to an AC power source. Current flowing through the coil creates a magnetic field around the coil. Since the power source is AC (alternating current) the direction of the current flow and the magnetic field alternates back and forth.

    The secondary coil(s) are not physically connected to the primary coil (isolating the input of the transformer from its output) but instead placed close enough to the primary coil that the primary coil’s magnetic field surrounds the secondary coil(s).

    Since a moving magnetic field induces current in a wire (see #1), the alternating magnetic field from the primary coil creates current flow in the secondary coil(s) (again without any physical contact).

    Voltage is directly proportional to the ratio of windings between the primary and secondary coils. If a primary coil had 10 windings and a secondary coil had 1000 windings, the voltage produced in the secondary coil would be 100 times greater than the voltage applied to the primary (and of course current would be 100 times less – you can’t get something for nothing) This would be an example of a “step-up” transformer. If you reversed the ratios you would have a “step-down” transformer.

    In it’s basic form a transformer is about as simple as it gets… Two or more coils of wire (not connected to each other) in close proximity, usually wrapped around a ferrous core (for magnetic field strength).

    Now that being said, it gets a bit more complicated in actual use – in addition to the previously mentioned variables - voltage and current there is a third variable I haven’t mentioned yet called resistance. A very simple equation (Ohm’s law): current (I) = voltage (V) divided by resistance® makes up the ‘backbone of electronics. If you know any two variables you can calculate the third.

    Resistance and reactance (damn another term) impede the flow of current. The term impedance refers to the relationship between these two variables. ..

    At this point it is getting way too complicated for a layman’s discussion of transformers. The only reason I started down this path is to illustrate how complex the selection of a couple of pieces of wire can get.

    An amplifier designer needs to match the voltage and current requirements of the amplifier with the impedance requirements of the speakers. Choosing the wrong impedance selection or disconnecting your speakers with power applied creates a power mismatch in the coils of a transformer. This in turn causes reflected energy / heat to build up which can damage / open up a coil.

    <--just for the fun of it.
    THE LOST ART OF BEING STOIC
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    2. Quit your crying.
    3. Suck it up.
    If in doubt, ask yourself: What would Clint do?

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    Default Re: Took my amp to a tech today...

    Thanks for the help Chaos, I think I'm a bit better informed now although I'm going to read that through a few more times to digest it properly. I remember some of this stuff from GCSE Electronics now.

    In your experience whats the cost of getting this sort of stuff sorted? I borrowed £680 to buy the amp just a few weeks ago so I'm not exactly made of money right now.

    Thanks again,
    Benja
    Last edited by benjaturner; 09-02-2005 at 06:02 PM. Reason: I pressed enter too soon
    Guitars:
    Epi LP (SH-11b + SH-55n)
    Danelectro U2 '56 Reissue
    Yamaha APX5LA
    Pedals:
    MXR Super Comp, HBE Power Screamer, Toadworks Death Rattle, Carl Martin Crunch Drive, Boss CE-2, Marshall Ed The Compressor, Marshall Drivemaster, Arion EQ, Bespeco Volume Pedal
    Amps:
    Fender Prosonic combo
    Marshall JTM60 combo

  10. #10
    Ultimate Tone Slacker Chaos's Avatar
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    Default Re: Took my amp to a tech today...

    Check out: Tubes & More for part prices. I'm guessing an hour or two in labor if your transformer needs replacement.
    THE LOST ART OF BEING STOIC
    1. Quit your whining.
    2. Quit your crying.
    3. Suck it up.
    If in doubt, ask yourself: What would Clint do?

  11. #11
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    Default Re: Took my amp to a tech today...

    Quote Originally Posted by Chaos
    Check out: Tubes & More for part prices. I'm guessing an hour or two in labor if your transformer needs replacement.
    Listen to the dude, he knows his stuff.

    and it's good to see you around here again Choas, you've been gone for a while, haven't you?

  12. #12
    Ultimate Tone Slacker Chaos's Avatar
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    Default Re: Took my amp to a tech today...

    Quote Originally Posted by Naps
    and it's good to see you around here again Choas, you've been gone for a while, haven't you?
    Thanks Naps,
    I come and go on a whim… Try to keep my post count low (so no one takes me too seriously)

    BTW, Saw the pics of your rig the other day!
    THE LOST ART OF BEING STOIC
    1. Quit your whining.
    2. Quit your crying.
    3. Suck it up.
    If in doubt, ask yourself: What would Clint do?

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