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Conference napalm::commusic_v1

Title:* * Computer Music, MIDI, and Related Topics * *
Notice:Conference has been write-locked. Use new version.
Moderator:DYPSS1::SCHAFER
Created:Thu Feb 20 1986
Last Modified:Mon Aug 29 1994
Last Successful Update:Fri Jun 06 1997
Number of topics:2852
Total number of notes:33157

1214.0. "Potentiometers for Mixer (or Pot Dealers Wanted)" by JAWS::COTE (Full Noodle Frontity...) Mon Feb 15 1988 12:15

    ...it's about time to replace some of the scratchy pots on the board.
    Radio Shack has the electrically correct units, but the shaft is
    1.5 inches longer than I need and require a slightly larger mounting
    hole than Peavy provided. This option is my last resort...
    
    Active Electronics had a surprisingly *small* selection of pots
    at surprisingly high prices (2.50 to 10.00). They also didn't indicate
    whether these were linear or audio taper...
    
    The stock pots seem to have smaller than the standard 1/4" shaft.
    
    Does U-Blew-It have a decent selection? Stark? Anyplace else???  
    
    Edd
    
    
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1214.1now your talkingWEFXEM::NETS_EDMon Feb 15 1988 12:311
how many bags do you want me to sell?
1214.2Does this answer the question?JAWS::COTEFull Noodle Frontity...Mon Feb 15 1988 12:516
    
    Well, the input gain requires 100K audio taper, I need six.
    
    I also need 5 10K pan-pots.
    
    Edd
1214.3RUGRAT::POWELLDan Powell/274-6608Mon Feb 15 1988 16:003
Might be a silly question, but have you tried using some spray contact cleaner
on them?
Dan 
1214.4These are sugar coated....JAWS::COTEFull Noodle Frontity...Mon Feb 15 1988 16:108
    Oh yeah, many times. They had Southern Comfort dumped on them before
    I bought the board, then I dumped Dr. Pepper....
    
    They laugh at contact cleaner....
    
    Pot swap city....
    
    Edd
1214.5The day my mouse decided to "Be a Pepper"DREGS::BLICKSTEINDaveMon Feb 15 1988 16:2210
>    then I dumped Dr. Pepper
    
    I once dumped Dr. Pepper on my office MacIntosh's mouse.  That stuff,
    good as it tastes when it's wet, is incredibly sticky when it starts
    to dry.
    
    You might as well just trash those pots if there's Dr. Pepper in
    there.
    
    	db
1214.6It aint broke, it's *special*....JAWS::COTEFull Noodle Frontity...Mon Feb 15 1988 16:3714
    Despite the beating this board has taken (the Southern Comfort
    and Dr. Pepper Stories are true) it continues to function quite
    well, a phenomenon I attribute to Peavy's designers...
    
    What I've done on the stickiest pots is...
    
                    A.  Shoot a shot of cleaner into it
                    2.  When it frees up, move it to the 
                        proper value.
                    C.  Let it harden.
    
    Maybe I should consider this a feature? Pot-lock??
    
    Edd
1214.7RANGLY::BOTTOM_DAVIDThat's my heart in the streetTue Feb 16 1988 06:589
    Edd at the risk of sounding silly have you tried WD-40? It works
    better than any of the cleaners on the market and takes all the
    scratchyness out of pots. I've used it regularly since haveing been
    told about the trick..
    
    dbII
    
    I don't suppose you've called Peavey for the parts? The best bet
    is always the manufacturer.
1214.8Buffer NOTES$EDITJAWS::COTEFull Noodle Frontity...Tue Feb 16 1988 08:028
    Nope, I haven't tried the WD-40 trick... I thought oil was an
    insulator(?); the last thing I want in my pots...
    
    Is Peavey still in Meridian MS??? That's probably the best bet...
    
    Besides, I just *had* to think up a note to go with the title...
    
    Edd
1214.9ganged greenMPGS::DEHAHNTue Feb 16 1988 08:0611
    
    Have you tried Cramolin contact cleaner and restorer? Lots of high
    end hifi shops have the kits. Try Natural Sound in Framingham. It's
    worth the $15 before you dump serious $$$ into new pots. Rat Shack
    pots aren't going to last that long, if you go with good ones they're
    expensive. 
    
    Are the pan-pots ganged? What's the value? I'll look 'em up.
    
    CdH
    
1214.10I've got some Cramolin and WD-40. I'll make soup..JAWS::COTEFull Noodle Frontity...Tue Feb 16 1988 08:3110
    I'm not sure what you mean by "ganged".
    
    The pan-pot values are 10K. 
    
    Is it *really* possible to clean a pot? I'm grateful for all the info
    on Cramola (;^)), WD-40, etc., but are these just band-aids? I'd
    love to avoid swapping out 20-30 pots, but not at the expense of
    performance.
    
    Edd
1214.11Ah Yes, The Log Tapir of South America...DRUMS::FEHSKENSTue Feb 16 1988 09:1811
    "Ganged" means two or more wiper/resistive element assemblies share
    the same shaft.  Depending on the circuit design, the pan pot may
    be a single resistive element with the center tap being the signal
    source and the two extremes the left and right destination (either
    linear taper or a bizarre log-out-from-the-center taper, which I'm
    not sure anybody makes), or two separate assemblies set up like
    normal volume controls, one for the left feed and one for the right,
    (with opposite log tapers).
                                                                        
    len.
    
1214.12Try Stark or Couglin'sPLDVAX::JACQUESTue Feb 16 1988 09:2521
    You might try Stark Electronic, or Couglin Electric, both in 
    Worcester for Pots. Have the manufacturers' parts numbers ready
    before you call Coughlin since they mainly distribute to industry.
    If you plan on changing 20-30 pots with high quality parts (ie
    Switchcraft), plan on spending as much as $5.00 ea. At that rate
    you might consider a buying new Board. I would at least try to 
    isolate the worst pots down to 4 or 5 and just replace them.
                                               
    As was suggested earlier, try cleaning the old ones first. If you
    can pull out the entire module board, pots and all, you might try
    bringing it into a DEC plant with an Ultrasonic cleaning tank full
    of Heated Freon. That usually cleans most any kind of gunk from
    pc boards and components. Most plants that have electronic equipment
    maintainence departments should have a cleaning setup like this. 
    There is one in the building I work in (LM02, Marlboro). 
    
    Good Luck,
    
    Mark Jacques
    
    
1214.13RANGLY::BOTTOM_DAVIDThat's my heart in the streetTue Feb 16 1988 13:378
    the freon trick may backfire, some cleaning agents will make the
    noise permanent.
    
    wd-40....I dunno but I use it on all my pots in all my equipment
    when they begin to get noisy....an old stereo repairman's trick
    as taught to me by an old stereo repairman.....
    
    dbII
1214.14MPGS::DEHAHNTue Feb 16 1988 14:3218
    
    Also, the Freon will wash out any lubrication that's in the shaft
    mechanism, the stuff that gives a rotary pot it's 'feel'.
    
    Edd, looks like about $6 each for the gain trim pots, still have
    to know if the pans are ganged or not. Len described the difference
    and the reason behind them perfectly. Allen-Bradley carbon element.
    
    I'm taking a trip to a vendor tomorrow to pick up some stuff, if
    I can get the details I'll see if they have what you need in stock
    and will pick them up if you want.
    
    Don't knock Cramolin or WD-40 'till you've tried it, they DO work
    if the pot's element isn't trashed. If it's just clogged with gunk
    then they work great!
    
    CdH
    
1214.15JAWS::COTEFull Noodle Frontity...Tue Feb 16 1988 15:1015
    Thanks Chris and len...
    
    I wasn't putting down the WD-40, I"d never heard of it being used
    in this application and it just didn't seem right.
    
    The gain trim pots are not standard 1/4 inch shaft, but do mount
    in ~1/4 inch holes (so hard to measure a whole when the pot is still
    in it), the shaft extends ~3/8 inch above the threaded sleeve. The
    shaft is blue, split and has ridges.
    
    As to the pans, I guess I'll have to open the board up to see.
    
    Thanks again...
    
    Edd