Hartke HA3500 - Passive input and XLR amp output seem dead

Discussion in 'Amps and Cabs [BG]' started by Glazenn, Jan 8, 2016.


  1. Glazenn

    Glazenn

    May 16, 2011
    France
    Yesterday night, I and the guy at the mixing console tried some DI box and XLR combinations to get the signal of my bass through the recording and sound system.

    1) the XLR direct output at the back of the amp never worked when linked to the console (this is what we tried first). I had never used that output before.

    2) and then the amp passive input died suddenly after testing some connections, whilst the active input remained OK, so I used the active input for the rest of the gig, with the DI box (a Behringer DI100) receiving the bass signal (INPUT jack) and sending it to the console (XLR output) and to the amp active input (from the LINK socket). The DI box was powered with the 9V inside battery. We also tested a BSS Audio AR-133 that worked fine too with the same connections and a 9V battery.

    3) the input into the mixer in all cases was through a jack (linking the XLR output of the DI box to the TRS jack input of track 14 on the console, not to the XLR input).

    I think any phantom 48V voltage entering the bass amp out of the console was unlikely...

    What can I do to have the amp XLR output and the passive input working again?
    Is there anything that I can check visually or with a multimeter?

    I have some experience in electronics/circuitry, last were modding significantly a Fender Super Twin valve amp (now used as a bass head) and replacing burst caps in a Samsung TV...

    My bass rig yesterday: HA3500 + AK115 cabinet.
    I believe the recording console was a digital Presonus Studiolive 16.4.2.

    Thank you
     
    Last edited: Jan 9, 2016
  2. B-string

    B-string Supporting Member

    I would try cleaning cable connections make and break on the interconnect cables inside the amp first using DEoxIT D5. There is a chance the first opamp had one section die (usually both go). but they are protected at the inputs by caps from phantom power.
     

    Attached Files:

  3. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    I would suggest troubleshooting again step by step.

    First try the bass into the amp's passive input, no DI or box.

    Then with the on-board DI set to pre eq, check the DI out into a known good channel with a known good XLR cable. If not working, be sure to check mixer channel with a dynamic mic. If you are really using one of the 1/4" inputs on the console, it's entirely possible that there is a level mismatch of 30dB which you didn't realize. Also, what kind of adapter did you use?

    Doing this step by stem allows you to systematically eliminate causes one by one rather than guessing.
     
  4. Glazenn

    Glazenn

    May 16, 2011
    France
    Thank you, I will test everything again today at home using my Yamaha MG10 mini-console.
    I did not use an adapter, it was a cable that has an XLR at one end and a 1/4" mono jack at the other end (we were just short of XLR-XLR cables yesterday as all that we had were used for the drums).
    What worries me most is the dead passive input. I will have a visual inspection of the surrounding components first.

    Thanks, but that one does not work any longer...
     
  5. Glazenn

    Glazenn

    May 16, 2011
    France
    Update...

    I opened the amp chassis top and scrutinized the input jacks PCB. There are only the two jacks and two small 100 pF caps on it. I did not see anything blatantly wrong (except one of the caps has a small black dot on the top, is that right?)

    Now, the active input (the bottom jack) is not working, while the passive input is OK.
    So I think I likely made a mistake and wrongly identified from memory the two inputs in my narrative above.

    Probably one a least of the two caps C101 and C103 was blown or so is anything else across the active channel (schematics below). I don't mind much as I mainly use the passive input.

    HA3500 Input stage.JPG

    The chip datasheet is here : NJM072 pdf, NJM072 description, NJM072 datasheets, NJM072 view ::: ALLDATASHEET :::
    If one half of the chip is blown, would it affect or risk to affect the other half?
     
    Last edited: Jan 9, 2016
  6. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    Almost certainly not the caps you mention.

    The only way to troubleshoot this is with a scope and DMM. Could be a bad solder joint, cracking the PCB. Wire harness between PCBs, IC, 1uF cap,.

    Unless you know what you are doing, you may be better off leaving things alone. More damage from a messed up repair is more expensive to fix.

    I do not think your two problems are related. I suspect you had a bad cable or console configuration issue.
     
    B-string and Glazenn like this.
  7. Glazenn

    Glazenn

    May 16, 2011
    France
    Many thanks @agedhorse. I will bring the amp to a tech.
     
    agedhorse likes this.
  8. Chris Cooney

    Chris Cooney

    Apr 11, 2022
    N/A I'm an amateur musician with old equipment I need to fix.
    <BR><BR>
    Chip? Where is this chip? I don't see chips on my input jacks. My passive input wore out. My active is fine. I removed the passive and I need to replace it. I've been looking for this schematic and am still looking for the wiring diagram (for the physical wiring so I can use a generic jack), Can someone please explain how the active and passive inputs are different? From what I see, these are electronically identical, with only one discrete component for each, the capacitors (C101 & C102), but these are both 100p. Yet the diagram shows JK101 at -20db and JK102 at -10db. Are these the afore mentioned 'chip's? And are they integrated on the circuit board?
    While I'm at it... Can those black plastic housings be removed without destroying them? This would be a great help, as I could just see the actual connections.
     
  9. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    No, they have nothing to do with chips.

    Just order the factory replacement jack and fix the problem rather than create new problems. Be careful not to damage the PCB...
     
  10. Glazenn

    Glazenn

    May 16, 2011
    France
    I thought this might be the culprit in my case:
    upload_2022-4-14_3-29-5.png
    I have not done anything to correct the default since my post, and I am happy with the passive input that is working well.
    The problem arose when one of my bandmates who was at the mixer 'injected' a 48V phantom voltage into the active input, never knew why and how... possibly blowing the chip (circled in red).
     
  11. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    If the switch inside the jack is damage, specifically from a cheap plug that may have hung up and bent the tip contact, the results could be exactly the same.

    You are better off identifying the cause before changing out parts. I see more damage from guessing than from proper troubleshooting.
     
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