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Electricaly challenged

Discussion in 'Norton Commando Motorcycles (Classic)' started by Richard Tool, Nov 5, 2019.

  1. batrider

    batrider

    Joined:
    Aug 9, 2008
    Dyno Dave has a nice graph of the Zener curve on his Atlantic Green website. With 21V in through 1K and measuring around 14V the Zener current is only about 7 milliamps or in the mud at the bottom part of Dave's graph. So looking at the first rise where the Zener starts to conduct, your voltage readings look like they are in the ballpark to me. You are testing at a very low current but the diodes are likely to be fine.

    http://atlanticgreen.com/images/zener.gif
     
  2. maylar

    maylar VIP MEMBER

    Joined:
    May 13, 2007
    As batrider said, that is very low current and doesn't represent what the zener will be in actual operation. The factory test (bike running) specs the voltage at 2 amps, a reasonable level in actual service. You'd need more than 15 volts and much less than 1K ohms to do that. Factory spec is 13.5 - 15.5 volts at 2 amps.

    I would add your 0-15 volt power supply in series with a 12 v battery and use a headlamp as the current limiter. As I mentioned, the zener will need to be on a heatsink else it'll get mighty hot.

    That said... The low current test will tell you if the zener is toast or not, so it's not worthless. And the 1K resistor only needs to be about 1/2 watt. You still need more than 15 volts though.
     
  3. Richard Tool

    Richard Tool

    Joined:
    Aug 3, 2019
    Next question - I have run a test of the rectifier with a multimeter on diode setting. Getting readings of baseline in one direction and values of .480 , .884 , .476 in the other direction. Do the different values mean it needs replacing ? The high number was the center pole. Thanks- RT
     
  4. maylar

    maylar VIP MEMBER

    Joined:
    May 13, 2007
    If baseline means infinity (open circuit) then that's OK.
    I would expect .6 - .75, but I don't know your meter.
     
  5. gtiller

    gtiller VIP MEMBER

    Joined:
    Nov 5, 2012
    @Richard Tool here are the steps involved with testing your rectifier.


    ORIGINAL RECTIFIER
    1.jpg

    AFTERMARKET RECTIFIER
    2.jpeg

    AFTERMARKET REGULATOR/RECTIFIER (replaces zener and rectifier)
    3.jpg

    You cannot test the new MOSFET regulator/rectifiers in this way, as they don't use standard diodes.
    If you have a factory original rectifier, make sure you have a new battery in your multimeter - the diodes are chunkier than on the modern equivalents.


    You should have 8 numbers - follow the process below, and write the numbers down as you go, so you don't lose track.

    In the tests below - the STOP sign on tests 1, 2, 5 and 6 shows no voltage is flowing.

    For the remaining tests 3, 4, 7 and 8 you should see a value on your multimeter. This will vary per unit but importantly the value from all four readings should be the same (within a few ohms)


    TEST 1
    rectifier test 1a.png

    TEST 2
    rectifier test 1b.png

    TEST 3
    rectifier test 2a.png

    TEST 4
    rectifier test 2b.png

    TEST 5
    rectifier test 3a.png

    TEST 6
    rectifier test 3b.png

    TEST 7
    rectifier test 4a.png

    TEST 8
    rectifier test 4b.png

    If you are not seeing the desired values on just one of these tests, it means that you have a malfunctioning component (diode) within the rectifier.
    Unfortunately, these are not user serviceable or repairable, so you need to replace it.
    Make sure you throw the defective part away, rather than put it in a drawer in your workshop. This will make sure it doesn't find it's way back on to a bike in the future!!!


    Hope this helps!
     
    texasSlick likes this.
  6. Richard Tool

    Richard Tool

    Joined:
    Aug 3, 2019
    Thanks all for the help -
    maylar - baseline is 1. - the number on display at start up for every function- don’t know why it isn’t zero but it indeed means no current.
    gtiller- Thanks - VERY helpful - tests 1,2,5 & 6 show no current
    Values for others are:
    3 - .468
    4 - .463
    7 - .454
    8 - .452
    I will repeat test this evening with new batteries.
    Thanks again- RT
     
  7. gtiller

    gtiller VIP MEMBER

    Joined:
    Nov 5, 2012
    @Richard Tool your values are close enough together to say the rectifier is absolutely fine!
     
  8. brokeneagle

    brokeneagle VIP MEMBER

    Joined:
    Oct 30, 2014
    In testing a suspect podtronics 200W with ohm setting @ 200 my numbers are as follows:
    1. stop 2. 176.3 3. stop 4. 176.4 5. stop 6. 12.0 7. stop 8. 11.4
    @gtiller I guess this is ready for the trash can. From your knowledge can you tell from these #s what it was doing? Sending A/C to battery, not charging at all? It will be replaced, just curious.
     
  9. kommando

    kommando

    Joined:
    May 7, 2005
    I would suspect it's just about working as you have all the stops in place and all the reverse flows are open with 2 lower resistance, however it's too risky to continue as those low resistance diodes are going to fail.
     
  10. Richard Tool

    Richard Tool

    Joined:
    Aug 3, 2019
    so I have bench tested original Zener diode by doing the following :

    mounted diode on z plate - placed two new 6 v drycell batteries in series - voltage measured 13+ v.

    connected dry cells in series with variable power supply which can produce 15 v so total capability 28 v ?

    connected all to diode with ground to positive and placed 65w automotive headlamp bulb in circuit as resistor between negative side of diode and power.

    lamp lit immediately upon connection without even turning on variable power supply .

    took all apart and used variable power supply alone across diode and had current at very low voltage-

    I take this to mean that diode is shorted and therefore no good - am I correct ?

    Thanks all for any input and babysitting me electrically - RT
     
  11. maylar

    maylar VIP MEMBER

    Joined:
    May 13, 2007
    Be sure the polarity of your test is correct. Positive ground for that old zener. If reversed, it'll conduct at much lower voltage (under 1 volt usually).
     
  12. Richard Tool

    Richard Tool

    Joined:
    Aug 3, 2019
    Ran test again with variable power supply and multimeter- red leads connected to mounting stud of diode @ Z plate & black leads connected to spade terminal on diode . Both power supply & multimeter showing conduction @ .1 v - so is diode bad ?
     
  13. maylar

    maylar VIP MEMBER

    Joined:
    May 13, 2007
    Yep. Toast.
     
  14. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    I’d fit the original equipment and test the Zener by revving up and seeing what the voltage reaches.
     
  15. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    I’m no expert, but I don’t believe that story.
     
    MexicoMike likes this.
  16. Richard Tool

    Richard Tool

    Joined:
    Aug 3, 2019
    I’m a long way from running the engine - just read through threads on Podtronics/ alternator and even the original poster says there are many thousands of Podtronics in use and relatively few alternator failures - I have had a Podtronics in my ES2 for many years with no issues- sealed battery as well . 6V dynamo so perhaps that makes a difference vs alternator - once again I am handicapped by my lack of electrical knowledge.
     
  17. Richard Tool

    Richard Tool

    Joined:
    Aug 3, 2019
    Thanks Maylar for your help in confirming what I suspected.
     
  18. Tornado

    Tornado VIP MEMBER

    Joined:
    Dec 5, 2017
    I think the standard shunting type reg/rec units like the podtronics and used on nearly all modern bikes are fine with standard norton setup. Issues more likely as you make other changes like LEDs and LiPo batts. With LEDs etc you're lowering power loading and once batt is fully charged that excess alt output is shunted back to alt coils and makes heat. Like many things in life there needs to be a certain amount of balance to output vs consumption.
     
  19. gtiller

    gtiller VIP MEMBER

    Joined:
    Nov 5, 2012
    @Richard Tool the DC regulator for a 6 volt dynamo based charging system is a very different can of worms to an AC regulator/rectifier for a 12 volt alternator based charging system.

    Your 6 volt unit is all about producing a stable supply rather than any conversion from AC.


    I am just speculating here, but do bear in mind that Podtronics was bought by Coventry Spares, and manufacturing was outsourced to Taiwan a few years ago.

    The product line was rationalised, and I would suggest they are not built with the same care and attention as they were when Bob Kizer was at the helm.

    I do wonder if this is why Tri-Spark have seen issues with interference and I question whether it is a good thing that the single phase unit is now just a three phase with one of the yellow AC input wires cut off.
     
  20. Richard Tool

    Richard Tool

    Joined:
    Aug 3, 2019
    So run incandescent bulbs with lights on all the time ( which one should do regardless) and standard battery and I will decrease the chances of a damaged alternator if I understand correctly, yes ?
     

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