Bridgeport Traverse Potentiometer replacement
Close
Login to Your Account
Results 1 to 6 of 6
  1. #1
    Join Date
    May 2019
    Country
    UNITED KINGDOM
    Posts
    2
    Post Thanks / Like
    Likes (Given)
    3
    Likes (Received)
    0

    Question Bridgeport Traverse Potentiometer replacement

    Hello All!

    I'm looking to replace the potentiometer in the traverse panel of our Bridgeport.

    Really hoping that everyone can assure me I'm correct and maybe point me to a reputable supplier in the UK.

    As you may be able to see from thge pictures the pot has had a bit of a bodge job to repair it a few years ago.
    Currently the pot doesn't affect the speed of the traverse at all and it's always WAY too quick!

    I'm pressuming it's just a 50k pot that it needs replacing with.

    Cheers!

    img_3022.jpg
    img_3951.jpg

  2. #2
    Join Date
    Aug 2008
    Location
    Sussex, England
    Posts
    3,329
    Post Thanks / Like
    Likes (Given)
    12
    Likes (Received)
    710

    Default

    OEM was fully enclosed wirewound so thats probably the best to go for although in practice pretty much anything will work for "a while". Right down to bottom end, open carbon track, thingies usually chosen for low fi applications. One such in mine when I got it which lasted 3 years for me and dunno how long before.

    Sorted UK seem to list the ABW 1, AVX, watt wire-wound as OEM replacement for £22 near enough. Pretty much half the price on Farnell CPC £11.58 + VAT and post of course.

    Doesn't seem worth faffing around for a bargain elsewhere. You can find "looks as if it ought to do" around the £5 or £6 mark but nothing out there I'd bet the farm on. Especially as many of the less costly ones are 6 mm rather than 1/4" shaft so the knob won't fit. If you do go hunting look for cermet, wirewound or hybrid cermet over wire types.

    Mine wears a military grade uber linear Plessey hybrid 'cos I had one in stock. Which pretty much defines overkill in this context. You don't want to know what that cost Her Maj back in 1978!

    Clive

  3. Likes CliveWr liked this post
  4. #3
    Join Date
    Dec 2013
    Location
    Fort Wayne, IN
    Posts
    615
    Post Thanks / Like
    Likes (Given)
    682
    Likes (Received)
    225

    Default

    Just cause the pot doesnt change the speed of the motor doesnt mean its the pot. Pots rarely go bad. Also, that is not an OEM pot.

    I would go ahead and clean your motor first and change the brushes, 95% of the time that fixes the issue. Mostly the brushes have VERY condensed springs and arent making good contact on the armature that is covered in carbon and gunk, esp if you are using a thinner oil that seeps into the motor.

    If it is running fast, almost at rapid speed all the time, there is a chance that your board is toast.

    If you are set on changing the pot, we need to know what circuit board you have in it, as the 6F board and 8F board use different resistance pots.

    Jon
    H&W Machine Repair.

  5. Likes CliveWr liked this post
  6. #4
    Join Date
    Dec 2008
    Location
    IL/WI border
    Posts
    3,085
    Post Thanks / Like
    Likes (Given)
    974
    Likes (Received)
    892

    Default

    Before you replace it, use your tester to measure resistance and its changing across the legs to make sure the potentiometer is, indeed, faulty. Do it with wires disconnected from the pot.
    Last edited by MichaelP; 05-17-2019 at 10:50 PM.

  7. Likes HWElecRepair, CliveWr liked this post
  8. #5
    Join Date
    Aug 2008
    Location
    Sussex, England
    Posts
    3,329
    Post Thanks / Like
    Likes (Given)
    12
    Likes (Received)
    710

    Default

    Quote Originally Posted by HWElecRepair View Post
    Just cause the pot doesnt change the speed of the motor doesnt mean its the pot. Pots rarely go bad. Also, that is not an OEM pot.

    I would go ahead and clean your motor first and change the brushes, 95% of the time that fixes the issue. Mostly the brushes have VERY condensed springs and arent making good contact on the armature that is covered in carbon and gunk, esp if you are using a thinner oil that seeps into the motor.

    If it is running fast, almost at rapid speed all the time, there is a chance that your board is toast.

    If you are set on changing the pot, we need to know what circuit board you have in it, as the 6F board and 8F board use different resistance pots.

    Jon
    H&W Machine Repair.
    I'd agree that cleaning out the motor is essential regular maintenance. Insides of mine looked like a lump of coal with the mill in as-delivered with several faults (but what did you expect for that money) condition. Certainly cleaning got it turning but things still weren't properly playing ball.

    CliveWR is UK based so his set-up will be a 6F or 8F with almost certainly a Nelco or Framco motor and Erskine or Quantum controller. Quantum being a lightly modernised version of the Erskine. Interchangeable. I have schematics for a typical Erskine. Probably better kit than what came out of the American factory. Fairly sure that the official OEM pot would have been an industrial quality Colvern wire wound one. No longer available unfortunately. If you are lucky New old Stock or lightly used military grade ones of the right value sometimes appear on E-Bay. But nowt in that rating this week. The one in there looks to be a low to mid range industrial sealed one installed as a field repair. I'd guess 10 to 15 years on it which is the sort of life I'd expect.

    Pots are mechanical devices and they do go bad. How long it takes depending on quality. Military grade Colverns were, if I recall correctly from my MoD days rated for 25 years in static ground environments. A bit less on vehicles. Cheap'n nasty sometimes barely last until the solder has set. I've changed fair few too cheapies in my time on electronics stuff that "someone" has allegedly fixed. The one I linked to should be good for at least a decade.

    Obviously disconnect the wires and do the resistance change with movement test as MichaelP suggests. But if there is the slightest doubt as to smoothness and linearity of change bin it. Hafta say that these days I've given up on fiddling. Generally if its over 10 years old and even slightly suspect it gets binned. Life is too short to mess around with fixes that may only last a year or three. especially as modern, adequate quality components are so relatively cheap.

    Clive

  9. #6
    Join Date
    May 2019
    Country
    UNITED KINGDOM
    Posts
    2
    Post Thanks / Like
    Likes (Given)
    3
    Likes (Received)
    0

    Default

    Hi All,

    Thanks for the quick replies and all the info.
    I'll try all the solutions you have suggested and see what happens!

    Cheers,
    Clive


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •