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#718355 12/10/17 7:46 pm
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Hooked battery wrong accidentally and wire to rectifier got really hot, not melted. Did I just fry the rectifier?

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Did the fuse blow? That's your only hope. Solid state one's aren't too costly though. Loads of test rectifier posts abounding.

koan58 #718395 12/11/17 7:19 am
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Hi Dave,

Originally Posted by koan58
Did the fuse blow?

No fuse on standard '55 electrics; Lucas must've thought there wasn't enough power to do any damage ... facepalm

Originally Posted by koan58
Loads of test rectifier posts

Regards,

koan58 #718447 12/11/17 8:28 pm
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I will just test it later today, Christmas party for car club ate up the time yesterday. Thanks for responding.

Stuart #718449 12/11/17 8:33 pm
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True no fuse, installed a new wire harness last year and didn't think to install one. My favorite shop for old Triumph parts is closed on Monday. I will test old rectifier, but deep down I think a new one should be installed.
Thanks for responding.

scott garland #718470 12/11/17 11:28 pm
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Hi Scott, I've never worked on a '55, so I may be blowing smoke. Take it for what it may be. But I'm curious.

At work I found generally if the capacity of the diode in rectifier was greater than the load, damage is not usually done. I don't know the capacity of Triumph rectifier.

If the diode was burned open, the wire would have cooled on it's own. Did that happen or did you catch it in time?

What happens now with all hooked up correctly motor not running? If that's ok...

What if you start motor & test output voltage at battery? If that is normal, I think you'd be ok. Again, take my thoughts for what they're worth.

Curious as to what Stuarts thoughts are about my thoughts.
Don


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scott garland #718588 12/13/17 12:53 am
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Side show to the Big show, perhaps.

We burned up so many of the three-tier rectifiers that I went with the tympanium units on my OIFs. Haven't had a burnout since. Original? Nope. And I hate that. But I've ridden much further than with a rectifier.

Just my two pence.

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I don't wish to be argumentative but merely present a different view; I've never burnt a rectifier and only one Zener since I started out in 75. The burnt diode was my own fault as I "temporarily" fixed it to a steel bracket. And yes I've owned and worked on a great number of British bikes.
I suppose our cooler climate may have something to do with it...? The South in summer is murder!

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Originally Posted by scott garland
Hooked battery wrong accidentally and wire to rectifier got really hot, not melted. Did I just fry the rectifier?



Maybe.

Test it.


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Why doesn't someone tell him how to test it? I asked too and no one came forth with the answer. What is with this cat and mouse?

Scott. I can't remember exactly how to do it. But the rect consists of tiny diodes in between those plate. A diode will conduct one way and not the other. That is what it is supposed to do. Cut off half the wave of the AC the alternator puts out, so it effectively converts to the DC that will charge your battery.

So you put your multimeter probe on one lead of the diode confirm that it conducts one way but not when you reverse the probes.

If they all test OK. You can do a simplified version of the correct test, which should be done with two batteries. Start the bike. Put one probe on one battery terminal and the other on the other. Set the meter first to DC. Confirm that charging rate with DC increases with increased RPM. Then set your multimeter to AC and do the same. The AC rate should be very small, if it is not than the rectifier is not doing its job, and you need another.

That is the best I can do from memory. The proper way to do it is to have two batteries. One to run the bike and the other to be tested. But I think my method might be good enough. I had a bad rectifier. It was partially working and would charge the battery, but it let through too many AC spikes which kept blowing my head light bulb. The zener will not cut off the spike of AC, only DC, as I remember. It was an ongoing problem for me to blow headlight bulbs, and took a long time to consider that the rectifier was the problem, because the battery was charging. It was John Healy who suggested the check. None else here even considered it.

Maybe one of geniuses here can give you a better description of the test. When they are a mind to do so, after someone has tried and they can prove how smart they are by dissing him.

Then of course there are those that will say just ditch the rectifier/zener and put in a POD. And while you are at it replace all your wiring, add a fuse to the ground side, clean the kill switch, put in a better headlight.

Last edited by btour; 12/14/17 7:32 pm.

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A multimeter on "ohms" doesn't always work on diodes, but a battery and bulb across the DC output, whether that's two terminals or one terminal and the centre stud, should conduct and light up in one direction and not the other.

Or start the bike and see if it charges.


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Only if there is something seriously wrong with the meter, or it's battery, would you not see the obvious difference between huge Ohms and small Ohms.

But the time old test of TT will do.

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Originally Posted by koan58
Only if there is something seriously wrong with the meter, or it's battery, would you not see the obvious difference between huge Ohms and small Ohms.



No. Some old rectifiers, in working condition, will not conduct at the voltage applied by common or garden multimeters set to ohms.


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I suppose if the meter applies less than the voltage drop across the diode, then it will appear non-conducting, even though healthy.
I've not had this situation, all meters I've had use 9V batteries, they would only have to apply 1V to identify the difference between one way and the other.
If it won't conduct with that, imagine the heat and wasted power when current is forced through at say 7V?

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I'm no expert, but that's what I've found.

Anyway, fire it up. Does the headlight get brighter when you rev up off idle?


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btour #718821 12/15/17 8:45 am
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Hi Bob,

Originally Posted by btour
Why doesn't someone tell him how to test it?

confused

Originally Posted by TR7RVMan
start motor & test output voltage at battery? If that is normal, I think you'd be ok.

Or this is a mature site with a working Search and:-

Originally Posted by Stuart
Originally Posted by koan58
Loads of test rectifier posts

Originally Posted by btour
Then of course there are those that will say just ditch the rectifier/zener and put in a POD. And while you are at it replace all your wiring, add a fuse to the ground side, clean the kill switch, put in a better headlight.

Then of course there are those who'll lengthen the thread unnecessarily by waffling without reading and understanding what's been posted already ...

Previous posts confirm: standard 6V electrics, which therefore don't have a Zener as standard, so "ditch the rectifier/zener and put in a POD" is pointless; a new wiring harness was installed last year; "a fuse to the ground side" would have avoided precisely the problem Scott The O.P. has posted about; standard 6V electrics, which therefore don't have a "kill switch" to "clean"; standard 6V electrics, from which "a better headlight" isn't likely to benefit.

As I've posted before, electrics on these old heaps are simple, unless you set out to make it difficult. smile

Hth.

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Originally Posted by triton thrasher
Originally Posted by koan58
Only if there is something seriously wrong with the meter, or it's battery, would you not see the obvious difference between huge Ohms and small Ohms.



No. Some old rectifiers, in working condition, will not conduct at the voltage applied by common or garden multimeters set to ohms.


Too lazy to walk all the way over to the Bonnie Castle on this frigid morning, but I tried my ohmeter on several non-Brit Iron selenium rectifiers I have lying around the house. They read in high megohms range both ways and I'm pretty sure they're good. A quick search on the Internet confirms that the high voltage drop across selenium rectifiers makes checking them with an ohmeter problematic.

I remember constructing projects using them as a kid and always had to mount them where they had good ventilation or drill lots of holes if they were on the interior of a chassis.

Big, hot, inefficient. Pretty good reasons why they were replaced by silicon diodes.


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Stuart,

I am pretty good at searches and I have done it many times. I have yet to find any posts which detail how to do to test the rectifier. Many many many posts mentioning rectifier.

If you know how to do it, why don't you post how? If you can do the search which finds the answer, then why don't you link it?

Do you know what happens on a playground with bullies? Even the good kids want to be like the bullies. Did that happen to you? I see they pick on you here frequently.


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This is a Norton manual. Page 60 has rectifier tests.

http://www.classicbike.biz/Norton/Repair/1960s/NortonRepair1960-1968.pdf

Don't know if it's any help to Mr Garland, but it might stop Bob moaning at Stuart.


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John RGS posted this, but no links.

Scott,

Start here for info: http://www.britcycle.com/help.htm on just about anything.

Here is a link on how to test a rectifier. test rectifier. testing a rectifier . Now maybe it will turn up in a search. I did not read it yet

http://www.britcycle.com/manuals/rectifier.pdf

You could also start here and read on:

http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=82833

Here:

http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=322354#Post322354

Here is a simple one by Pete R. One of the Titans. Wish they would return to earth.

http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=495704#Post495704



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Originally Posted by triton thrasher
This is a Norton manual. Page 60 has rectifier tests.

http://www.classicbike.biz/Norton/Repair/1960s/NortonRepair1960-1968.pdf

Don't know if it's any help to Mr Garland, but it might stop Bob moaning at Stuart.


I don't moan! Someone has to put you P's in your place. Might as well be me. Get a helpful attitude without the kicks in the groin. Ankle biters!


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Quote
I don't moan! Someone has to put you P's in your place.


Is it safe to ask what "P" stands for?



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VOM meters vary on voltage used to measure resistance. One of my meters has a high and low voltage switch for Ohm measuring. The high voltage is used for diodes because, depending upon the material (silicon or germanium) they have different voltage drops but are all less than 0.8 volts. The low output is 0.6 volts and the high is 3 volts. Reversing the meters (the other does not have a switch for voltage output on the Ohm scale), the non-selectable meter outputs 3 volts on the 200 Ohm range and 0.3 volts on the higher ranges.
The 0.6 volt output will read resistance (with a silicon or germanium diode but not a selenium) in the forward direction and infinite in the opposite. The 0.3 volt output will read infinite resistance both ways.
If the meter has a diode capability, use that.
Lucas plate rectifiers are selenium or silicon. I do not know when the change came but probably all the '60s-on bikes are silicon.
You can test the rectifier using the Lucas Service manual found here:
https://www.britishonly.com/pdf/Lucas/LucasServicemanual_noSB519_part6.pdf

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Originally Posted by triton thrasher


not.

it's on page 68.

just sayin, though, norton books seem better written than the triumph variety.


i'm old enough to remember when patriotism meant not trying to overthrow the government.
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Originally Posted by kevin roberts
Originally Posted by triton thrasher


not.

it's on page 68.



Seems to be on 60 as well. Anyway, between the two pages it should be enough to stop Bob moaning at Stuart, which he doesn't do.

Last edited by triton thrasher; 12/15/17 9:00 pm.

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