Issue: Tele tone control only affects volume of bridge pickup, NOT tone...

scarry67scarry67 Frets: 143
I'm sure I read something similar here last month but any advice welcome. The tone knob on my my oldish MIJ JD Tele only works as a volume control - if I turn it right down there's barely any amplified sound and then it just adds volume when rolled up. Does this mean a new pickup or is this fixable by a tech?
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Comments

  • m_cm_c Frets: 1211
    If it was working ok previously, then it's probably something shorted out (might even be the capacitor gone short circuit), so the tone pot is now just acting as a drain on the signal.
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  • ICBMICBM Frets: 71960
    The pickup coil will be open circuit at the ground end - usually the inner end of the coil. This may be fixable by resoldering the eyelet if it's a cold joint there, but if it's the coil itself which has broken - fairly common, they corrode through where the wire is wrapped onto the magnets - then a rewind or a replacement is the only option.

    If it was a shorted tone cap it would affect the neck pickup as well.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • FunkfingersFunkfingers Frets: 14323
    m_c said:
    it's probably something shorted out (might even be the capacitor gone short circuit), so the tone pot is now just acting as a drain on the signal.
    Does the tone control issue occur in all five selector switch positions?

    On stock JD wiring, when the five-way selector switch is over towards the neck, the tone control should be out of circuit. 

    Be seeing you.
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  • scarry67scarry67 Frets: 143
    The tone works well on the neck pickup (position 4) but I suspect I’m not getting best range of tones on bridge/neck combinations due to issue. It’s the 3rd one of these I’ve had over the years and not, I’m sure, as Strat-like in position 2 as the others. It’s a lovely guitar and warrants a nice pickup - could be time to invest...
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  • ICBMICBM Frets: 71960
    If the bridge pickup is open circuit you will get almost pure neck pickup in the combined positions, so it will sound much less Strat-like in position 2 since that relies on the pickups being roughly the same volume as each other.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • scarry67scarry67 Frets: 143
    That sounds likely. Thanks for all input. 
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  • FunkfingersFunkfingers Frets: 14323
    scarry67 said:
    The tone works well on the neck pickup (position 4) 
    With respect, it was position 5 that I asked about. The idea was to eliminate some of the possible causes of your problem from enquiries.
    Be seeing you.
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  • scarry67scarry67 Frets: 143
    Yes, the 5th position - neck pickup “open” without tone control is as it should be and the tone pot works fine in 4th position which is conventional. 
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  • FunkfingersFunkfingers Frets: 14323
    Thank you. 

    Removing the strings and bridge to inspect the condition of the bridge/Treble pickup and its solder joints will be a drag.

    If your guitar still has the original OTAX four-pole PCB selector switch, I would begin by inspecting the connections and cleaning the moving contact parts.
    Be seeing you.
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  • scarry67scarry67 Frets: 143
    Looks like original switch so I’ll give it a clean this week. 
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  • peteripeteri Frets: 1283
    This was my thread a few months back with the neck pickup. 

    It was on a vintage tele I’d just bought. ICBM called it. Broken wire in the pickup shorting 
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  • ICBMICBM Frets: 71960
    edited November 2017
    In my experience this symptom - tone control acting as a volume - is always a broken coil. If it's the switch you get intermittent loss of volume or silence, but not this thin, weak sound which the tone control will roll away almost completely. You will also hear very little difference between the both-pickups position and the other pickup alone. I have seen this many times and it's always the same cause.

    If the coil is broken at the ground end, some signal will still leak through via the capacitance between the coil and ground (the pickup baseplate and the bridgeplate, on a Tele - which makes the result slightly stronger than the same thing on a Strat). It usually breaks at the ground end because moisture gets into the inside of the coil bobbin via the small hole in the flatwork, then condenses where the coil wire touches the magnets and corrodes through the wire.

    If you're very lucky it can sometimes be a cold joint at the pickup eyelet, so it's always worth trying resoldering this first, or very carefully scraping the enamel off the coil wire - be *very* careful not to cut it - and metering to the other end of the coil to see if there's any hope…  but there usually isn't.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • scarry67scarry67 Frets: 143
    My soldering skills have let me down in the past so if it needs care I think it might be a job for someone more capable. 
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  • FunkfingersFunkfingers Frets: 14323
    How are your skills with a multi-meter? It might be worth attempting to get a D.C. resistance reading between the two soldering eyelets of the pickup.

    On the other hand, the stock MIJ pickup is no great shakes. Give it a decent burial and invest in a superior replacement pickup. :)
    Be seeing you.
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  • scarry67scarry67 Frets: 143
    Yep. I feel an investment coming! 
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  • AlegreeAlegree Frets: 665
    tFB Trader
    You might get lucky and have the ground end on the outside of the coil too, which makes it a 5 minute repair job.
    Alegree pickups & guitar supplies - www.alegree.co.uk
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  • m_cm_c Frets: 1211
    I should really learn to pay attention to thread titles, and not just read the content.

    A faulty pickup does sound more likely.
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  • FunkfingersFunkfingers Frets: 14323
    Alegree said:
    You might get lucky and have the ground end on the outside of the coil too, which makes it a 5 minute repair job.
    IIRC, the MIJ Telecaster pickup in the JD sig model is of normal magnetic polarity and coil winding direction.

    The neck position Strat pickup gets to do all of the partial phase reversal business. I can not recall whether it is RPRW or not.

    There is an argument for replacing both pickups at the same time. ;)
    Be seeing you.
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  • scarry67scarry67 Frets: 143
    Funkfingers - does this mean that the neck pickup is a regular Strat pickup or something out of the ordinary? I presumed that the wiring/capacitor did all the clever stuff imitating the Strat in-between "quack" (which, as I said, is rather missing at present from my JD.) 
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  • FunkfingersFunkfingers Frets: 14323
    On the USA JD signature model, both pickups were supplied by Seymour Duncan. The bridge position unit is to Jerry's specifications (the STL-3JD) and the neck position unit is a production line SSL-2 Vintage Flat. The critical detail is whether the Strat pickup needs to be RPRW.

    In the JD circuit, by definition, only one of the two bridge + neck PU combinations can be made noise-cancelling. Given Donahue's regular use of vintage style Fender guitars, it is difficult to imagine him being overly concerned about whether selector switch position 2 or position 3 is the one with the partial noise cancelling.

    The position 2 "quack" is achieved by a combination of frequency filtering and electrical phase reversal. It is a refinement of an idea first devised by Bill Lawrence.
    Be seeing you.
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