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Lookin for guidance with troublesome lighting...

Discussion in 'The Garage' started by Scrappy608, Apr 17, 2019.

  1. Scrappy608

    Scrappy608 Roll Those Dice!

    Hey there, so i am new the forum, and its been a long time coming...and i am in need of suggestions.

    I have a '79 that i have chopped into a fun little bobber and have toyed with for some years and have ripped around on and had a blast on.

    Last summer, i fried the Pamco, which i attributed to the ground on the Capacitor vibrating loose.

    So... new Pamco, solid grounds (checked all grounds and freshen'd em all up) PMA seems fine...
    however... when i put a bench battery on, all's well...but when i remove it start the bike, as soon as i twist the stick, the tail light gets bright, and pops...should this not happen, the 10a fuse for the light circuit will blow.

    Am I lookin at a reg/rectifier gone bad? fallout still from the loose cap. ground? and help would surely be appreciated.
     
    gggGary likes this.
  2. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    Get a voltmeter on it, check in several places both plus 12 and grounds, frame, engine, headlight shell, etc.Careful you don't take out another pamco with excessive voltage. Yeah VR is a suspect.
     
    Scrappy608 likes this.
  3. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    Hugh and (some) others have found the folly :doh: in reselling the cheapest Chinese knock off voltage regulators. Plenty of them on fleabay yet, :mad:
     
  4. Scrappy608

    Scrappy608 Roll Those Dice!

    Right on gggGary, all went through and off to the reg/rec store . So i shot an email to Hugh regarding the difference between his mosfet and standard reg/rec, as its stated on his site about too small of load go with the mosfet...how does one sort out if the load is too small?
     
  5. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    You can start comparing watts, what does the PMA put out, what are your (always on after starting) loads?
    biggest draws are the ignition coil and headlight, after that other lighting.
    hint you can select a headlight bulb to help balance the system. H4 type bulbs are available in watts from ~35 to 80+
    riffing:
    The PMA is advertised as 200 watts so you want to have, idunno, a minimum of 130 watts of load? That leaves 70 watts for the regulator to dissipate. You can see why regulators have fins and must get some air flow. A stock charging system is more sophisticated and varies the alternator output like a car charging system. PMA and many other stock MC systems go for simple, full power all the time, alternators and dump the excess watts through the regulator, why dead regulators are so common on many bikes. Sorry if this sours the taste of the kool-ade.
    Easy way to add steady load is with incandescent bulbs.
    For my money it's hard to beat a battery in the system for best, easiest operation. It doesn't need to be huge.
     
    Last edited: Apr 20, 2019
    Scrappy608 likes this.
  6. Scrappy608

    Scrappy608 Roll Those Dice!

    thanks man! i appreciate the break down

    cheers!
     
    gggGary likes this.
  7. Superjet

    Superjet XS650 Junkie Top Contributor

    Fit a battery and small voltmeter if you can on your bike. You can keep and eye out for what is going on and the battery will keep constant power to the pamco ignition which it needs.
     
    Scrappy608 and gggGary like this.
  8. Grimly

    Grimly XS650 Addict

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    If you want to keep the PMA and avoid more trouble, fit a series reg-rec, such as the Shindengen SH-775.
    All the others are shit. Total shit in the case of the cheapies and just ordinary shit in the case of the standard reg-recs from the manufacturers.
    With a series RR you can be guaranteed stator health, charging system reliability and a heavier wallet, as you're not forking out for more replacement RRs and stators. Oh yeah, the current isn't dumped to earth, it's shunted back down through the stator wiring, heating it up even more on top of the heat from extracting the power in the first place and the engine heat that's already there. PMAs have a lot of shit to cope with.
     
    Scrappy608 likes this.

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