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Warwick Preamp Issue. Any help appreciated!

Discussion in 'Pickups & Electronics [BG]' started by eyeballkid, Aug 10, 2017.

  1. eyeballkid


    Jul 19, 2009
    wes virginny
    So today my Limited Edition Warwick Streamer Rusty got sick. it developed an issue today. While messing around with different tone configurations today I by chance turned the treble knob all the way off. The bass went silent. I thought "wait, there should be tone still of the mids and bass". I just touched the bass knob and the sound came back. Any slight touch of the pot and it comes on and off, but ONLY when the treble is all the way down. Conversely, if you turn the treble all the way up and then touch the bass knob a more fuller tone and volume jump happens. That tone is spectacularly rich, and actually seems like the way the bass sounded at one point, except with obviously more treble.

    there is obviously something going on with the bass pot and its interplay with the treble. I made sure the pot was mounted securely. Ive opened it and looked and all solder joints seem secure. Any wires touching solder leads have been moved away. I tried replacing the battery just to make sure the preamp doesnt do weird stuff when the battery is low.

    This has me REALLY dismayed as this bass has been really babied and given the hours on it and the type of use its had this is NOT something that should happen on a $3.5k bass!

    my questions are:
    Is this just a pot going bad?
    or, is this something with the preamp in general?
    Anybody got any ideas?

    Also... I understand the MEC preamps are >$500 to replace (plus labor) and given its apparent unreliability I doubt I want the same thing. Has anyone ever replaced the preamp in these themselves? What preamps are compatible, given that it is a two pickup bass with added in series/single/parallel switches for each preamp? Any user feedback on different preamps used?

    in the first pic the bundle of wires im touching were laying over the solder joints of the pots. I moved them just to be certain it wasnt making some kind of grounding issue.
    in the second pic the metal wire running under the input jack is nowhere near touching the jack, so thats not an issue. The pot closest to the jack is the bass, the next is the treble.

    if I have time when I get home tonight I will make a demo video to show the behavior.

    thanks in advance guys.
    20638596_1529530363735364_7106737138195109717_n. 20664008_1529532337068500_3315160900974097756_n.
    Last edited: Aug 10, 2017
  2. eyeballkid


    Jul 19, 2009
    wes virginny
  3. 4StringTheorist

    4StringTheorist Supporting Member

    It frankly sounds to me like a wiring issue with one or more of the pots.
  4. DWBass

    DWBass The Funkfather

    $500 for a preamp?
  5. eyeballkid


    Jul 19, 2009
    wes virginny
    That's what I read mec replacements run for the stock preamp... which is ridiculous.
  6. eyeballkid


    Jul 19, 2009
    wes virginny
    But why would it start out of the blue?
  7. 4StringTheorist

    4StringTheorist Supporting Member

    Shorts in pots often show up suddenly.
  8. eyeballkid


    Jul 19, 2009
    wes virginny
    Video coming ..
    So if it is the pot, can you tell what kind it is from the picture and where I can get one?
  9. eyeballkid


    Jul 19, 2009
    wes virginny
  10. 4StringTheorist

    4StringTheorist Supporting Member

    Yeah, I'm convinced that a wire or wires in the bass pot or treble pot (or both) is grounding out and kicking the preamp into a state that it's not normally supposed to function in. Some sort of interaction with ground and the circuit topology of the preamp may be responsible for why the issue is semi-interactive between the bass knob and treble knob. Try using some cleaner on both the bass and treble pots, see what happens.
  11. eyeballkid


    Jul 19, 2009
    wes virginny
    Anyone have any idea what pot this is (bass pot in the pic) and where to get one?
  12. 4StringTheorist

    4StringTheorist Supporting Member

    Are the bass and treble pots the ones that say B100K on the back of them in that picture?

    If so, you're looking for 100 KOhm linear pots I believe.
  13. eyeballkid


    Jul 19, 2009
    wes virginny
    Those are the ones..
    Went to Warwick site.. there's like 100 different pots. I'll figure it out somehow.
  14. somebrains

    somebrains Supporting Member

    Feb 7, 2017
    I've worked on my MEC preamps in both of my $$'s (and my old Thumbs, Fortress, and Streamer).
    Go get a multimeter and get ready to do some continuity checks.
    The really rich spike you get tells me that you want to test to see if voltage is consistent in the circuit. My 5-string had done that thru it previous owner until I fixed it. Nothing with a pair of MM humbuckers should sound as thin as some of the $$'s I've heard, even in dual singlecoil mine sound like I put in big pile hot J's.

    The grey wires from the dip switches are the pickup hots.

    There's a ground from each pickup that should go to the pads on either side that should twin to a ground wire out.

    Bass pot has 3 wires that are soldered to the preamp board, the bridge ground is usually on it, it's one of those stupid hard to loosen up joints. If your bridge ground is drilled more center than low in relation to the jack I've seen those have really messy installs. Mind the bare wire, those are your grounds.

    Treble is the same 3 wires to preamp.

    There will be bare wire from pot to pot, check those.

    I probably should have raised his shrinkwrap box and sleeved everything, but people complained about how the $$ was muddy compared to the FNA and FNA Jazzman that I found those early basses came with SD preamps and sometimes pickups. 5's tend to need more help than 4's, so I was going to swap this preamp out.

    I use my buddy's Hakko soldering station. He is just more experienced than I am. What looks like a good solder joints can be crystallized underneath. You really want to be able to go from 800 degrees to 650, depending on what you are working on. Nothing like being told you are in the burn components zone.

    What looks like an obviously bad solder joints probably is, but if it tests fine then cleaning it and redoing it doesn't get you anything.

    The preamp in the pic works after I fixed it.
    It's out of my red 5-string.
    I don't know why people think any random preamp will sound good installed in a 4, 5, 6 bc bc the bass itself rings differently. 4's are such a problem, they have big spacing and less neck to ring. Extended range basses take some thought about what their real voice is, I digress.

    My 4-string has the MEC still in it.
    I mean I should have 1 Warwick that has that scooped nasally tone.
    Wait, I have an OBP-3 sitting in a box.

    The bad soldering is factory, but they're holding after I tested them so I left them alone.
    The nice shiny ones are from me buying a solder sucker and solder wick to clean up the joints. You want both on hand.

    The little solder joints in the harnesses to boards can be problematic. I tend to drop the temp from 800 to 650 for those and just dab from the tip. Get a feel for it, drop on perfect little 3mm blobs on wood before you do any work. No laying on the soldering iron and ramming on solder.

    Good news, your problems aren't rare and they're easy enough to fix if you are patient and use a multimeter to confirm diagram conformity.

    Bad news, the $$'s sound a lot better with Aguilar, Nordstand, SD, Haz clone, Smith clone, EMG for passive, Darkglass, or Glockenklang preamps.....preferably a 3-band. I think that MEC preamps aren't the best thing in perfect working order. Think of them as catalytic converters with 100k+ miles on them that rattle when you knock them with a screwdriver. That rich sound is probably the way your bass actually sounds, when the preamp decides to not be a restrictor. You just found a spot, test it after you've resolved the other issues and take voltage readings.

    What you find may make you go shopping for something you can tidy the install up and cram a 2nd battery to go 18v.

    The headroom is glorious on these basses.
    Last edited: Aug 14, 2017
    kulit17 likes this.
  15. eyeballkid


    Jul 19, 2009
    wes virginny
    So Warwick put me in touch with the bass place, who got me in touch with warwicks parts people in Nashville. Got a new bass pot. Soldered it in and problem solved!

    Btw... I really need to give a lot of credit to the Bass Place. I called them and within two minutes they knew whether or not the part was in stock and gave me the number to call. I ordered it and it was shipped out the same day. Had the part in two days. Those guys have it down!
    Last edited: Aug 25, 2017
    Crater likes this.