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LH1000 Channel Busted?

Discussion in 'Amps and Cabs [BG]' started by phnord, Nov 21, 2020 at 5:25 AM.

  1. phnord


    Oct 26, 2010
    Brooklyn, NY
    I've been having an issue with my Hartke LH1000 that I'm wondering if someone could shed some light on

    The amp has two modes – Bridge mode, wherein there is a single Speakon output for the whole 1000 watts, and the normal unbridged mode, wherein there are two seperate speaker channels (A & B) that each have two jacks to connect speakers with. When unbridged, there is a balance control to pan between the two speaker channels

    The amp used to work fine; recently, however, whatever is plugged into Channel A gets no power at all. This is regardless of whether it is in unbridged mode or bridged mode, and regardless of where the balance pan is set

    I'm wondering if this seems like something that could be a quick DIY repair. I'm comfortable repairing / installing / customizing electronics in my basses, guitars, cabs, computers, etc. I'm skilled enough with a soldering iron and a multimeter. I'm *not* experienced at making my way around amplifier motherboards, and the internals on this one seem... rather daunting

    Does anyone have any thoughts?
  2. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Does the unit work in bridge mode?

  3. Redbrangus

    Redbrangus Supporting Member

    Nov 19, 2018
    Under The X In Texas
    I'm going to respectfully suggest that unless you also have a 'scope and know how to use IT, this is job for an actual, knowledgeable technician, not a "hunt-and-peck"-er. No offense intended. :) It's fairly easy for a person with a limited amount of understanding of what's happening to cause even more damage in the process of trying to repair what might be a relatively simple fix for a experienced tech.
    Zooberwerx likes this.
  4. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    It’s possible that there is a failure with channel A, or the signal path involved with channel A.

    Look over the manual to be sure you are not making a mistake with the configuration of the way the amp is supposed to work in both modes (including the wiring of the speaker cables) first. Then, it’s time for a QUALIFIED service tech.
    Gearhead17, mikewalker and Aqualung60 like this.
  5. dbase

    dbase Gold Supporting Member

    Jan 3, 2008
    South Jersey, USA..
    All I know is that there are two separate 500 watt power sections... my 2 cents ;)
  6. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    "Dual Parallel mode 2 x 225 watts @ 8 ohms , 2 x 320 watts @ 4 ohms, 2 x 545 watts @ 2 ohms

    Bridge mode 1 x 750 watts @ 8 ohms , 1 x 1100 watts @ 4 ohm"

    Kinda sorta. Every amp designation known to man (...or so it seems) is based on bridge mode @ 4 ohm.

  7. Redbrangus

    Redbrangus Supporting Member

    Nov 19, 2018
    Under The X In Texas
    Or do they just add up the theoretical maximum total output power at the lowest possible impedance of the two channels regardless of whether they can be bridged or not? E.g., Peavey's CS-800. I guess it depends on which manufacturer one is referring to -- for instance, a lot of amps won't drive a 4-ohm load in bridged mode, which implies a 2-ohm per-channel capability.
    Zooberwerx likes this.
  8. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Yep. My Epifani is a "1000" dual-channel. Each channel does 500 @ 4 ohm, 300 @ 8 ohm. In bridge mode, it will do 1000 into an 8 ohm load but won't do 4 ohm like a conventional "1000" power amp.

  9. AdamR

    AdamR Supporting Member

    Sep 24, 2007
    Bethel CT
    I had a Kilo that had the same issue. one power amp died.
  10. mikewalker

    mikewalker Supporting Member

    Jul 30, 2017
    Canada, Eh!
    Last edited: Nov 21, 2020 at 6:35 PM
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