Dirty Pots? Old AMP BH 260 question

Discussion in 'Amps and Cabs [BG]' started by conebeckham, Jul 8, 2008.


  1. conebeckham

    conebeckham

    Jun 27, 2008
    Bay Area CA
    So, I've got an AMP BH-260, I know the company went belly-up years ago.

    I've been using it as a power amp, and running either a Demeter Pre or a TC Electronics Paramatric (or both) through the "power amp in" for years now.

    But carrying around the rack, to smaller gigs, was getting bothersome. And I wanted to see how the ol' AMP preamp sounded after several years of my Demeter-TC tweaked tone.

    So I disconnected, and used the AMP head alone..and lo and behold (or behear, I suppose!) turning the volume knob, and also the "tone balance" knob, is giving me all kinds of noise....and the signal cuts in and out, loud and soft, with crackling and popping noise.

    Do I need new pots? Any ideas on how to fix this puppy? Or do I just buckle down and take it to a repair shop?
     
  2. SubXero

    SubXero

    Apr 27, 2008
    Philadelphia
    If it's seriously damaged, then yeah you might need a new pot. However more often than not it's repairable with any electronic contact cleaner. You usually have to spray it in from electronics-side of things (not from the top side with the knob) since it's generally impossible to get any of it into the inside of the pot's cavity from the top. Once you spray it in there, make sure you twist the knob around and such to spread it around.

    in a pinch, you can usually spray some wd40 in it and that'll fix it.That's actually closer to WD40's real purpose than what most people use it for (it's not a substitute for grease/oil!!!)..I'd recommend actual electrical contact cleaner if you can get it, it's generally quite similar. I've used wd40 to clean a pot before and I haven't had any trouble with it since. The only thing you risk versus regular contact cleaner is perhaps some residue, though I've used wd40 for this on multiple occasions and have never had a problem.
     
  3. conebeckham

    conebeckham

    Jun 27, 2008
    Bay Area CA
    Thanks! I've got the cover off, at home, already...wanted to see if it was visible dust.

    Will try the contact cleaner idea, and let you know how it turns out.

    Could my problem be caused by any other reason, do you think?
     
  4. SubXero

    SubXero

    Apr 27, 2008
    Philadelphia
    from what you described it sounds like a pretty typical dirty pot. Scratchy noises and popping when you turn the knob and etc.

    I've actually come across a dirty pot on a brand new bass before! No joke...right out of a sealed box with a dirty pot. I guess it's not super-surprising, moisture and what not on top of not being used sitting in storage at some warehouse...That's the same one I used wd40 on and it's been silent ever since. Just make sure you actually get the contact cleaner into the pot, it can be tricky and some pots are more sealed off than others. Generally you can't do that much damage with the contact cleaner, but I put some paper towels and etc around where I was spraying so it didn't make a mess all over and it cleaned up much easier as well. I'd definitely make sure you do that if the bass is oil/natural finish since you wouldn't want to stain it...
     
  5. Lowbrow

    Lowbrow Supporting Member

    Apr 22, 2008
    Pittsburgh PA!
    Most times I've been able the put a dirty amp pot right just by flicking it back and forth a bunch till the scratching cleared up. I find that sometimes a pot will develop a dirt scratch when it's been left in one position for an extended period.

    I had a Yamaha B100 ss amp head on which I left the mid knob at 12 o'clock for 10 years (no joke). Then I guess I moved the knob, because the rig (I was running it into 2 Sunn 2x15s loaded with JBL D140s) started to sound like every speaker was blown!

    It took me a week of switching out every patch cord and gluing my ear to each speaker till I accidentally discovered the pot "scratch" when I quite naturally moved the knob back to 12 o'clock! This was easily fixed by the "flick" method, but man, I sweated that one out good because the dirty pot sounded nearly identical to a blown speaker -- or in this case maybe 4 of them!
     
  6. eff-clef

    eff-clef Supporting Member

    May 6, 2007
    Baltimore,Md.
    I bought that same amp about 10 years ago. I had just read about them in Bassplayer mag., and saw one for $250. in a local store. I new it's history and thought it was a very good price. So I auditioned it in the store and the same thing happened to me.Scratchy sound and some of the controls would make it cut out all together. At the time most people (including the store) didn't know it's value. They were eager to sell it, so I told them if they could get it running well I would buy it. This store hapens to have a very good repair dept. ,and they are very honest. So 2 days later they called me and said it was fixed so I bought it. The repair guy(Ron) told me that the pots just needed to be cleaned with tuner spray. He told me if that happened to any of my other amps that you could sub WD-40 for the pricey tuner spray. He said just mop up the over spray with a paper towel. That amp is the direct cousin to the Funkbass amps. It sounded great, real punchy. Hope this helps. I wish I never sold it!
     
  7. conebeckham

    conebeckham

    Jun 27, 2008
    Bay Area CA
    Well, it worked! There's a bit of noise on a few of the EQ knobs, though I sprayed them all...but overall the thing sounds great. I forgot how clean and responsive this thing sounded.....I'm gonna use it alone for a while, without my other preamps.....

    Thanks all!
     
  8. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
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