Mk III lost its volume! What is the problem?

Discussion in 'Amps and Cabs' started by teddy boy, Sep 13, 2008.

  1. teddy boy

    teddy boy Member

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    Gents,

    I have an '86 "black stripe" Boogie Mk III that I really dig. However, now it seems I have encountered a problem with it. I turned it on today and discovered that I'm lackig a lot of volume. With the input volume at 7, lead channel volume at 10 and master at 1.5 I was hardly getting any sound out at all. Usually this would be very loud. I had to turn the volume up to 3.5 until I was getting a good volume. Normally 3.5 would create vomit inducing sound pressure levels.... something is wrong. What?

    I also plugged my delay into the loop. When I switched the dealy on I lost all volume again. Weird!

    Can anybody help?
     
  2. Pickmaster

    Pickmaster Member

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    First of all check all valves - preamp and power.
    Also clean (with spray) loop in - out's.
     
  3. Blue Strat

    Blue Strat Member

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    Remove all effects and get down to cable, guitar amp. Try it again.

    Still low? Be sure your speaker cab is plugged into the right speaker jack.

    Still low? Swap in your spare set of tubes and see what happens.
     
  4. teddy boy

    teddy boy Member

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    Cheers guys!

    Got as far as checking the valves for starters. V1 had blown and back came the volume, all the top end and oomph. I'm still not sure if it is as loud as it used to be. I tried putting back the old power tubes but they made no difference except sounding a little more dull.


    I haven't got my delay at home now so I can't try the loop. Anybody know which tube drives the loop?

    Cheers!
     
  5. Blue Strat

    Blue Strat Member

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    No, but it's likely the tube closest to the loop send jack.
     
  6. teddy boy

    teddy boy Member

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    I think the reverb tube is before the loop and output driver is after the loop... Perhaps one of those?
     
  7. GTRJoe

    GTRJoe Supporting Member

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    I believe V2 runs the loop. V 1 is first stage, V 3 is the lead stage, V 4 is for reverb. That's looking at the back of the amp from right to left. V 5 is the driver. V 5 sits back by itself.
     
  8. fusionbear

    fusionbear exquirentibus veritatem Gold Supporting Member

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    I own a Green Stripe MKIII. I have noticed that many of the MKIII's suffer from a problem of corrosion on the send and return jacks of the effect loop. To test your amp and confirm this problem, insert a short patch cable in the loop's send to return. If the volume returns, you have confirmed the problem. The best way to clean the jacks is to take the chassis out of the head or combo and very carefully clean the jacks with de-oxit and lots of cue-tips. Hope this helps.....
     
  9. teddy boy

    teddy boy Member

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    Thanks GTRJoe and fusionbear! I'll give them a good clean. The problem may have not been the loop though, I think my Memory Lane is bust. It didn't work with my Bad Cat either. It's weird that two things broke simultaneously...V1 and the Memory Lane...
     

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