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Peavey Combo 300 cracks & pops !?...

Discussion in 'Amps and Cabs [BG]' started by nuno1959, Mar 8, 2013.

  1. Hi Guys

    sorry if this has been answered already, i looked around but couldn't find anything so...

    when i switch on my Peavey Combo 300 ( 30 years old ?.. ) i get these loud cracks & pops, regardless of plugged bass or not, Pre or Post Gain up or not, EQ or no EQ -
    i recorded it on my iPhone, check it out here :

    https://soundcloud.com/nuno1959-1/cracks-pops - lovely isn't it ? :-b

    i already opened the amp looking for a bad connection, cracked wire or PCB or something, unplugged every plug, checked them for tightness, sprayed them, made sure everything was nice & tight, sprayed it all, etc.... BUT, since i know NOTHING about electronics, i didn't want to mess with it too much & end up making it worse

    this doesn't always happen, somedays it does, some it doesn't & some days after i switch it on & off a few times it stops !?

    before i lug it to my friendly local Peavey dealer a gazillion miles away, i hoped maybe someone here has come across similar behaviour & could point me in the right direction or just tell me to forget it & take it to a dealer for a repair ?

    any help will be VERY appreciated since until this is sorted only way i can play my bass is.....unplugged :bawl:
  2. 30 years old could be arcing in the power supply caps? Take it to the doctor before they short and kill the power transformer if that is the cause. Caps are cheap, power transformers are not and can be hard to find.
  3. imdkoz


    Nov 16, 2006
    Mine wasn't making the exact noise but was making a loud hum. Took it in and they had to replace a resistor on the board. When I opened mine up it didn't look there was anything wrong. Wish I was more help. Good luck.
  4. Don't try using it by the way until properly looked at! That is some serious noise.
  5. thanks guys for your input !

    B-string : can you tell me what are caps ? are they those big blue cylindrical ''whatchamacallits'' by the transformer ? P.S.: yes, i know - it's appalling & when you hear it ''in loco'' it's WAY WORSE !!

    imdkoz : no worries my friend, just trying makes me feel a bit better if that makes sense !
  6. Yes and there may be others under the chassis you can't see. :)
  7. hi guys

    tonight after somebody else told me AGAIN it could be the capacitors, i decided to get the amp out & take some photos to post

    as soon as i pulled out all the screws securing the board & pulled the board i noticed a rattling sound not dissimilar to that of a failed lightbulb when shaken coming from the big, blue capacitors !?
    i may not know much but this doesn't strike me as being how it should, right ? other than that as far as the eye can see everything looks hunky-dory ! :-b

    what do you think ? : http://www.flickr.com/photos/13706825@N03/8546590875/in/photostream/lightbox/

    to view all the photos click on the arrow at the top centre of window after the video...

    thanks for taking the time to check this...
  8. Steve Dallman

    Steve Dallman Supporting Member

    The caps need to be replaced. They are not very expensive (at least they shouldn't be). Modern caps are smaller in size, so you can up the capacitance if you wish, which will improve headroom.
  9. Hi Steve

    thanks for your input !! ;-)

    that sounds like good news : cheap & more headroom ? gosh, if only i knew about it sooner, i would've busted them myself !!...LOL...

    a couple of doubts though :

    1 - these original capacitors are roughly 3.149'' tall ( 8cm..) X 1.377'' diameter (3.5cm..) & have 6 ''prongs'' at their bottom going into the board which don't seem neither too long or too flexible so, if i get modern/smaller replacements can i bend the prongs gently until they align with the holes in the PCB so i can solder them ?

    2 - what brand would you say are REAL good quality - since i'm at it & they're cheap, i figure i might as well get the best possible, you know ?..

    3 - last but not least, what sort of spec would you recommend i use to get that extra headroom ?

    the originals have the following written on them :


    70320039 85ºC

    > 5000 MFD 55 WVDC


    8714 460 F

    FIB1938 37783G

    white fonts printed on some sort of blue shrink wrap material - & i tried to reproduce as exactly as possible the spacings between each nº/symbol & word

    again thank you so much for your help - very appreciated

  10. ooops , me again :-b

    last question : suggesting a nice, reliable online supplier would be the cherry on top of the cake AND definitely elevate you to HERO status !! little privilege or perks come with it but...LOL...

  11. Hi J

    & thanks, i have already contacted a couple of suppliers & as soon as they answer back, i most certainly will contact Peavey !
    at this point i'm VERY curious about the possibility of ''upgrading the caps'' in order to obtain more headroom so, let's see how that pans out

    i'll post as soon as i hear from any of them, thanks for your input ;-)

  12. jastacey


    Feb 8, 2009
    I'd contact Peavey, they will have the correct part, I don't know any part suppliers in Europe, but here is the Peavey contact info: http://www.peavey.com/support/contactinfo/ , I don't know if they do ship internationally and they may have a source in the EU ...wouldn't hurt to send an E-mail and ask ... is it a USA unit or an export model?
  13. thanks , i will ;-)
  14. jastacey


    Feb 8, 2009
    Ok ... just out of curiosity I called Peavey, and here is what I found out .... the Peavey crossover part # is 30320146, and it is a 4700 MFD-63 volts, the original part 70320039 is NLA, they don't ship internationally anymore .... I only did this because I have a Combo 300 and was curious about parts availability, they did say it is NOT a physical match, you'll have to make it fit, and the cost was $10.00US each .... as a side note this was for a USA model
  15. hI J

    that's pretty much what the guys at the Peavey Service Centre here in Portugal told me & why i contacted other suppliers - to see if they had as close to an exact replacement as possible..

    if all else fails, it will be easy to modify the Combo to get a nice, compact 15'' cab out of it ( it's a BW speaker in there..) & will buy a 2nd hand amp head for it like a nice 200 or 300W Trace Elliot or small Ampeg & then later a 2X10'' cab

    if all else fails of course... ;-)
  16. jastacey


    Feb 8, 2009
    In my experience in repairing older amps, it is not a big deal in fitting new caps, if you have the space to work with, if you glue them, use a thermal, non-conductive RTV, to keep them from working loose ... also you can go 10/20% up or down on the MFD value, but it will change the sound somewhat, higher will give a tighter sound, lower will be looser, sometimes you can hear the difference, sometimes not ... never go lower on the voltage (55 volts ), you can always go higher
  17. Hi guys

    i'm back.....with a vengeance !!! ;-)

    FINALLY ! my Peavey Combo is sorted - a friend gave me the contact of this guy near where i live, he does mainly repair work on mixers, power amps/ PA maintenance & such so i sent him an email, we made an appointment & today i took just the Peavey's amp section leaving the cab at home....

    got to his place, he had already sourced a schematic for it & started immediately working on it - right there in front of me !?

    after checking & re-checking, measuring & re-measuring FINALLY he found what was causing havoc : one contact of a teeny weeny zener diode was badly oxidised so it ''de-soldered'' itself loose-ish & developed an intermittent contact with the board & a badly regulated current ( 23V instead of 15 i think he told me.. )

    check the photo here :

    http://www.flickr.com/photos/13706825@N03/8577468167/in/photostream/lightbox/ - the faulty ''wire'' is the one facing down, towards those condensers

    when i asked him how much i owed him, he turned & charged me 50€ for 3 hours labour, 2 extra 4A fuses & a cleaning spray - how cool is that ?
    as i was leaving, since he's worked w/ all sorts of Peavey gear over the years & knows most inside out, he guaranteed me my combo is ready for another 20 or 30 years !!...LOL...

    plop, plop, fizz, fizz.....aahhhhh.....instant relief !! yes , life is good again ;-)

    only one big problem now : since i had psyched myself up that the repair would be terribly expensive, i kindda decided to get this simple yet very sexy little Hartke LH500 head & build a couple of 12/6 fEARful cabs to go with it !

    so let me ask you : what am i supposed to do now with this ''acute case of unreleased GAS'' ??

    talk about coitus interruptus, jeez !!......

    anyway i want to take the opportunity to thank all for your input/suggestions - it 's been VERY appreciated !!

    cheers guys !...
  18. Glad you got it fixed.
    At the very least you now have an amp that's got a long life ahead, even if it's only as a spare/practice.

    You might consider getting another cab to add to it.
    The old Peavey 8-ohm 210TX and 410TX cabs are really good sounding for their low price, and last year I did a show using a similar PV combo (different year and preamp bells/whistles, same power amp and a BW 15") with my 410TX on top, and it was like night and day better than the combo alone.
    I know--mixing drivers blahblah--but in fact these 2 cabs were designed in part to be used with the 15" combos and the division of power as well as dispersion absolutely works.
    Having some 10"s closer to my head was a 100% improvement in itself.

    Just a suggestion...if you feel like spending a little money instead of a lot.

    I noticed that the cabs had nearly identical dimensions and stacked like they were meant to be together.
    When I used the combo alone at rehearsal (belongs to our singer--I was head-shopping) the Black Widow held up okay if I kept the volume down around halfway, but with the 410 added I could open it up a lot more and the amp still ran cool. It was much louder, yet also cleaner.
    I only needed to use this setup for one show before finding my MKIII Bass head (and later a MAX tube preamp) but I was perfectly satisfied and so was the rest of the band + soundman. Could have kept using it for a long time and been quite happy.
  19. Hi Keith

    & thanks for your suggestions, much appreciated ! i HAVE heard a combo such as mine with a 4X10'' as you say & yes, it sounded surprisingly nice

    at some point i was considering a Peavey 2X10'' extra cab since in the band i jam with there's REALLY no need for a 4X10'' - what am i talking about ? even the PV Combo alone is MORE than enough to drown most anything there except for the 100W valve Marshall head & it's 4X10'' if at full blast.. ;-)

    thing is now that my PV combo is working, i can ''manage'' my upgrade strategy/expenditure & don't have to spend all in one go to replace it IMMEDIATELY - i admit that was p*****g me off a bit !!

    this way i can follow the DIY route for a couple of 12/6 fEARful cabs : slightly cheaper + being a silversmith by trade AND a very good DIY'er, quality finish IS MY THING ( if i may say so.. ) so they WILL end up VERY nice..

    later i may even get the Hartke LH1000 instead of the 500 AND save the PV as a great back-up, just in case. & then i'll be set for life - or so goes the theory ;-) !!...LOL...

  20. My version of Heaven would be old Peavey headed fEarfuls.
    But us Texans are hard-headed and a little drunk.

    No matter what, hook another cab to that combo just so you know what's possible.

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