nuno1959 Posted March 10, 2013 Share Posted March 10, 2013 Hi guys being new here, i just posted my introduction & left there a link to this post instead of posting it in there, it didn't feel right ! basically my problem is that after bringing back my old Peavey Combo300 into active duty ( opened it, dusted it all nicely, sprayed it all to clean it, checked every wire & plug to make sure all was nice, tight AND properly connected, no cracks on solder, PCB, etc.. ) & have been playing with it for a few months now WITHOUT any troubles, a couple of days ago when i switched it on it started making these obnoxiously loud crack & pop sounds as if some pop corn from hell being cooked on Mount Vesuvius !!??.. i immediately switched it off & tried turning it on again just to record the noises also hoping they'd be caused by some bad contact inside & that it would miraculously stop ? it didn't but i recorded it on my phone, check it out here : [url="https://soundcloud.com/stream"]https://soundcloud.com/stream[/url] again i opened it, re-checked everything best i could BUT...i have no clue when it comes to electronics & if it isn't down to something you can see like a loose plug/wire or so, i'm stuck ! :-b does anyone ever experienced this, or any idea what could be causing it ? being a 30 year old amp i'd like to get a feel of how much it could cost to repair BEFORE shipping it to the Peavey Service Centre a gazillion miles away & spend a fortune doing so given it's weight - this thing wieghs a TON !! specially since these days one can get a nice enough 200 to 300W combo for reasonable money any help/suggestions would be VERY appreciated, thanks for reading Nuno Quote Link to comment Share on other sites More sharing options...
BassTractor Posted March 10, 2013 Share Posted March 10, 2013 Hey Nuno, The link is a generic one. You might be able to edit it. best, bert Quote Link to comment Share on other sites More sharing options...
3below Posted March 10, 2013 Share Posted March 10, 2013 Since I do not use fb I was unable to access sound clip. Several possible causes. First thing to try would be rotating the controls a lot when switched off. Rotate each control back and forward several times. If this helps then spraying contact cleaning spray (e.g. Servisol) into the pots may fix the issue. Next areas I would explore - [size=4]If you can de solder / solder it is diy and not expensive - [/size][size=4] [/size][size=4]replace the smoothing capacitors, they are 20? years old. If that does not remedy, then replace diodes in bridge rectifier. All of these can be done for small expense and worth a try unless you have access to an oscilloscope. With a scope and the circuit diagram (easily available on web) you should readily find the problem.[/size] Quote Link to comment Share on other sites More sharing options...
nuno1959 Posted March 10, 2013 Author Share Posted March 10, 2013 OOOPS !!....sorry guys, my bad : i don't know what i did there w/ the 1st link i posted but thank goodness it had nothing to do with red buttons & ICBM's......LOL... Bert, i think this now IS the correct link : https://soundcloud.com/nuno1959-1/cracks-pops - but do lower the volume, it does sound toxic ! 3below - thanks for your input ! i think if you click on this new link it WILL get you there ( i also DON'T use fb.. ) now, the amp is in reality 30 years old & NEVER got any thing replaced/repaired, etc...so most definitely considering how hard it has worked most it's life, it might be time to do so.. when i brought it back to action i did open it & thoroughly sprayed it, rotate all pots to get rid of any gunk/oxydation, etc...didn't use Servisol but another a local electronic components shop owner recommended me - he's a nice guy, has ENDLESS patience for my ignorant questions & comes across as very knowledgeable about his thing so...i'm sure the spray was appropriate for the job now, if soldering for me is peanuts - i wouldn't be much of a silversmith if i couldn't pull THAT off.. - the problem is that although familiar with such words as capacitors, diodes, etc...& knowing VAGUELY each one's role, when i open the amp & look at it i feel as we say in my country : " like an ox looking at a palace" - CLUELESS !! what is what, you know ? but what if i posted a series of nice, sharp high res photos of the insides of the beast ? would you be so kind as to point out which components to go for ? THAT would be something on another forum i subscribe to, someone also suggested : ''...30 years old, it could be arcing in the power supply caps..." keep those suggestions coming cause it might not be the best amp in the world but i kind of have a soft spot for it , cheers !! Quote Link to comment Share on other sites More sharing options...
icastle Posted March 11, 2013 Share Posted March 11, 2013 Does it make that noise with the volume turned down? Quote Link to comment Share on other sites More sharing options...
nuno1959 Posted March 11, 2013 Author Share Posted March 11, 2013 this amp has a ''Pre Gain'' pot & a ''Post Gain'' pot & regardless how you set them : yes absolutely ! Quote Link to comment Share on other sites More sharing options...
icastle Posted March 11, 2013 Share Posted March 11, 2013 Right in that case it sounds like a power supply issue to me. I'd suspect the smoothing caps. I can't find a picture of the board to give you precise details of where these are located, but they will be two of them, they will be the largest capacitors in the amp and they will be somewhere near the power socket. Before you try changing them, take a look at the underside of the board and make sure they are soldered firmly to the circuit board - they have been known to fracture the solder joint over a long period of time because the components are large and the connections are small. Quote Link to comment Share on other sites More sharing options...
nuno1959 Posted March 11, 2013 Author Share Posted March 11, 2013 ok, i took the amp section out of the combo & took some photos which i think are good enough to identify the components ! as i was taking the PCB out i noticed a very slight but discernible rattling sound coming from inside the large blue cylindrical things which i suppose ARE capacitors - the sound reminds me as when you shake a blown lightbulb kind of thing, slightly ''glassy'' as we speak, i'm uploading them to Flickr & i will get back to you as soon as it's done, OK ? i shot a short video too.... thanks Quote Link to comment Share on other sites More sharing options...
nuno1959 Posted March 11, 2013 Author Share Posted March 11, 2013 (edited) OK, i FINALLY got it going - damn Flickr today was in reverse & just WOULDN'T budge, no matter what ! here are the photos i took of the insides of the beast + the video of the rattling sound : there shouldn't be any sound like this right ? [url="http://www.flickr.com/photos/13706825@N03/8546590875/in/photostream/lightbox/"]http://www.flickr.co...tream/lightbox/[/url] - to view all the pics, click on ''Older'' at the top centre of the window after viewing the video.. other than that sound every thing seems in order as far as solder joints, spigots broken or as far as any other visible physical damages of parts are concerned, what do you think ? if these big blue capacitors are not supposed to make this sound, then they are to be replaced - are these components i can get from most any electronics supplier ( as long as they are of the same ''standard''.. ) or should i get originals from Peavey themselves ? or could i even upgrade them ? thanks for taking your time with this , it really helps ! ;-) Edited March 11, 2013 by nuno1959 Quote Link to comment Share on other sites More sharing options...
icastle Posted March 11, 2013 Share Posted March 11, 2013 Yep, it's those big blue things They certainly shouldn't be making a noise like that! There's not really an upgrade for them, a capacitor is just a capacitor as far as power supplies are concerned. As long as the replacements are the same voltage and value, they'll work just fine - they don't need to be Peavey ones. You need to be aware though, those caps are definitely blown, but there might be other things wrong as well, so don't get too excited yet... Quote Link to comment Share on other sites More sharing options...
brensabre79 Posted March 11, 2013 Share Posted March 11, 2013 I'd say the caps are blown! But like iCastle says, might not be all... Another thing the Combo 300 is rather prone to that makes a crackle is the soldering of the inductor coil. Its easy to spot this, its a coil of copper wrapped in cardboard. These can work a bit loose with the internal vibrations and very small cracks can appear in the solder - which supports the entire weight of the coil! It should just need resoldering - it happened to mine and it took me ages to figure it out. Simple test is to turn the thing on with the amp open and, with something non-conductive (plastic pen), you can give the coil a light tap. Quote Link to comment Share on other sites More sharing options...
3below Posted March 11, 2013 Share Posted March 11, 2013 (edited) [quote name='brensabre79' timestamp='1363020853' post='2007041'] I'd say the caps are blown! But like iCastle says, might not be all... Another thing the Combo 300 is rather prone to that makes a crackle is the soldering of the inductor coil. Its easy to spot this, its a coil of copper wrapped in cardboard. These can work a bit loose with the internal vibrations and very small cracks can appear in the solder - which supports the entire weight of the coil! It should just need resoldering - it happened to mine and it took me ages to figure it out. Simple test is to turn the thing on with the amp open and, with something non-conductive (plastic pen), you can give the coil a light tap. [/quote] A good point, I had forgotten that little issue that they develop. I have just looked at the photos. Looking at the photo with the transformer (real iron lol) you will see to the right and front of the blue capacitors another pair of capacitors - black and grey with polarity arrows. These are also electrolytic and if I had the soldering iron to hand I would replace these as well. They will be cheap and available from any good electronics supplier. Edited March 11, 2013 by 3below Quote Link to comment Share on other sites More sharing options...
icastle Posted March 11, 2013 Share Posted March 11, 2013 Another thing that just occurred to me that I should have mentioned. If you're replacing these capacitors then they have a '+' wire and a '-' wire (it's marked on the side of the casing). Make sure you put them back in the right way round. Quote Link to comment Share on other sites More sharing options...
nuno1959 Posted March 11, 2013 Author Share Posted March 11, 2013 Hi guys 1st of all : thanks for your patience & input ! ;-) i have contacted the Peavey Service Centre in Lisbon & a couple of online suppliers for these caps or equivalent ... at this point either changing them works ( + maybe re-do all the soldering on this board, that would be easy for me.. ) or i'll just get a nice second hand, newer amp if fixing it becomes a big thing !? i've found an Ampeg B2R for 350€ right near me in VERY good nick which i might get for say...280€, 290€ ?.. & an Ashdown ABM500 Evo III from a fellow Forum member here for £330 + postage to Portugal ( postage costs MIGHT be a killer though..) if i went down this route & since this combo has a bulletproof 15'' BW speaker, i could modify it into a nice compact cab ( easy, peasy..) then later maybe get a 2X10'' ? & PRESTO : instant El Cheapo Mongrel bass rig w/ a decent sound/power for little $$ to be honest i'd rather fix the old boy, i've had from new, other bass rigs have come & gone but despite not being exceptional, since it was my first REAL BASS AMP, i always kept it - i just might have a soft spot for it after all ! ;-) + it looks like crap & kicks bass butt & i like that sort of thing !!...LOL... regardless, i'll certainly keep you posted on the developments - again MANY thanks to you all for your kind assistance ;-) cheers Quote Link to comment Share on other sites More sharing options...
3below Posted March 11, 2013 Share Posted March 11, 2013 My advice would be fix it. The construction makes this easy - large components, widely spaced and big wide pcb tracks. You can keep this amp going forever. It is also a relatively simple amp in terms of design so fault finding is straightforward. I had one, extremely loud and no annoying fan is a big plus. As Icastle states, do make sure you get the capacitors wired with correct polarity. The results of getting it wrong are quite spectacular. The BW in mine failed in a surprising way - like yours it was about 30 years old. A buzzing noise started on some low notes. The glue holding the cone to the frame had given up. If you catch this early before too much damage it should be an easy repair. Quote Link to comment Share on other sites More sharing options...
nuno1959 Posted March 11, 2013 Author Share Posted March 11, 2013 Hi 3below if the repair job is too big or complicated ( measuring component values, etc...) i'm a bit stuck because where i live the electronic repair guys i know of are useless : the kind that gets stuff going just enough so.....you go back soon after to repair something else he MIGHT have screwed up, you know what i'm saying ? being totally ignorant on the subject one CAN'T state this much less prove it BUT when this happens to too many people !?... don't get me wrong i DO like the Peavey, a LOT actually : when i'm out jamming with my friends despite the guitar players run a Marshall 100W tube head & the other a 100W Valvestate pushed LOUD + the drummer is banging it away with some serious OOOMPH, i've never been found lacking, having trouble hearing myself or making myself be heard - quite on the contrary !! it IS a LOUD puppy w/ surprisingly decent tone & flexibility !...LOL... & that's one more reason why i've never gotten around selling it & other, theoretically better ''BRAND'' amps/cabs HAVE come & gone during the years ! ;-) Quote Link to comment Share on other sites More sharing options...
nuno1959 Posted March 21, 2013 Author Share Posted March 21, 2013 [color=#000000][font=verdana, geneva, lucida,] 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 : [url="http://www.flickr.com/photos/13706825@N03/8577468167/in/photostream/lightbox/"]http://www.flickr.com/photos/1370682...ream/lightbox/[/url] - 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 !...[/font][/color] Quote Link to comment Share on other sites More sharing options...
3below Posted March 21, 2013 Share Posted March 21, 2013 Resist GAS [size=4] [/size] Quote Link to comment Share on other sites More sharing options...
nuno1959 Posted March 21, 2013 Author Share Posted March 21, 2013 ohhh....... you're BAD !!!!! ;-) giving in is SO SWEET !...LOL... Quote Link to comment Share on other sites More sharing options...
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