Why did the original use no heat sink, but the new improved need a heat sink?
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Stella - 1977D survivor, back on the road.
Probably because these new ones are sealed units. The original was an "open air" design. That, and the 2 tin plates that sandwiched the exposed diodes together provided adequate cooling I guess .....
Here's another rectifier from the same era, one off an XS500. It's a sealed unit and as you can see, it's housing is a finned heat sink type .....
I've acquired a couple of these over the years and would like to try one out on my 650. It looks to be a nice little unit.
Here's another rectifier from the same era, one off an XS500. It's a sealed unit and as you can see, it's housing is a finned heat sink type .....
I've acquired a couple of these over the years and would like to try one out on my 650. It looks to be a nice little unit.
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DanielBlack
XS650 Junkie
Further info on my rectifier(s).
I retested my spare new one. This and the failed one on the bike had both measured the same on the bench.
With my usual meter:
I'm going to call those good.
I don't think it's going to be a problem with the rectifiers themselves. Something has to be cooking them. Either a wiring fault or some other weak component. More testing to follow.
Test #1, battery:
Last night I unplugged the rectifier on my way home thinking the first rectifier had failed to the point of creating a crippling short to ground. With 12.7v at the start, I kicked her over and rode the four miles home. 12.4v when I got there. Then I left the switch on with the headlight on for 25min. The headlight stayed bright and the battery only lost another .5v.
Battery is good, ready to start with Curly's.
Edit: As part of my lighting redesign, I added Pamcopete's neutral switch to the headlight. I'm happy I did. Usually I sit at red lights in 1st, with the headlight on, but it was nice to have the option to save the battery last night. My LED constant-on stalks kept me visible to others while drawing a minimum of current.
I retested my spare new one. This and the failed one on the bike had both measured the same on the bench.
With my usual meter:
- Red lead on +, Black lead on the AC terminals. ---, ---, ---
- Black lead on +, Red lead on the AC terminals. ~.480, ~.480, ~.480
- Red lead on -, Black lead on the AC terminals. ~.480, ~.480, ~.480
- Black lead on -, Red lead on the AC terminals. .000, .000, .000
I'm going to call those good.
I don't think it's going to be a problem with the rectifiers themselves. Something has to be cooking them. Either a wiring fault or some other weak component. More testing to follow.
Test #1, battery:
Last night I unplugged the rectifier on my way home thinking the first rectifier had failed to the point of creating a crippling short to ground. With 12.7v at the start, I kicked her over and rode the four miles home. 12.4v when I got there. Then I left the switch on with the headlight on for 25min. The headlight stayed bright and the battery only lost another .5v.
Battery is good, ready to start with Curly's.
Edit: As part of my lighting redesign, I added Pamcopete's neutral switch to the headlight. I'm happy I did. Usually I sit at red lights in 1st, with the headlight on, but it was nice to have the option to save the battery last night. My LED constant-on stalks kept me visible to others while drawing a minimum of current.
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Meters that can do diode Vf tests will have a diode symbol on it somewhere.
Meters that don't have that diode symbol, or don't specifically state diode test feature in the instructions, can still be used with the selector in the 200 ohm (or lowest) setting. The displayed number may not have significant meaning...
TimeMachine
SeventyEighte
DB , you all have provided great data and info.. Im gonna pass on data which is "good" or "wrong" from my stock electrically 78e that runs well enough it's really gaining my trust.. Yesterdays test results : Engine off, battery 12.62 v , 1thou rpm 12.5 v, 2thou 13.0 v, 3thou 13.5 v, 4thou way up 14.65 v, all stock bulbs,points, &charging system. I expect some variation due to conditions. So there is an example to refer too.. hope that is interesting to you all.. -RT
DanielBlack
XS650 Junkie
Both meters have diode settings and that's what I used. I too felt the specific number isn't too critical given the inaccurate consumer models I'm using. But the fact that all the Vf numbers are fairly close to each other and there is non-continuity where there should be tells me I have a good rectifier.
DanielBlack
XS650 Junkie
Tested the ol' original.
5twins, you're right, these take a beating but keep on ticking. Crusty, green, and ugly, but reads ~.450 (my usual meter) where it should and --- where it shouldn't.
Still, I doubt the problem is the new rectifiers. I'm not sure about the first, but the second bench tested OK. Both new ones worked fine at first installation. They only failed after a few miles of riding.
5twins, you're right, these take a beating but keep on ticking. Crusty, green, and ugly, but reads ~.450 (my usual meter) where it should and --- where it shouldn't.
Still, I doubt the problem is the new rectifiers. I'm not sure about the first, but the second bench tested OK. Both new ones worked fine at first installation. They only failed after a few miles of riding.
Have you checked the alternator/brushes as suggested by Retiregentleman? Issues with brushes making poor connections and other loose connections on the ignition/alternator system can generate spikes to the detriment of the rectifier diodes.
I was viewing Ebay today and International Rectifier diodes are available at good prices - something to consider as an alternative to Chinese made.
I was viewing Ebay today and International Rectifier diodes are available at good prices - something to consider as an alternative to Chinese made.
DanielBlack
XS650 Junkie
I have not yet started the full step-by-step testing of the whole charging system. Maybe Tuesday before I get the chance. Stella's parked and I'm back on my wife's twist-and-go 170.
I really don't think it's a problem with the rectifiers. Each of them worked before taking a ride. And if I can fit it, I'll likely use the original after I clean it up.
I really don't think it's a problem with the rectifiers. Each of them worked before taking a ride. And if I can fit it, I'll likely use the original after I clean it up.
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I agree with you in that there is probably another issue going on and the rectifier fault is a consequence. I meant also to say that those older style rectifiers can still be easily replicated using axial diodes or the type that bolts on at one end, but I cannot remember their name. But again I suggest buying quality.
Best of luck with the project.
Best of luck with the project.
DanielBlack
XS650 Junkie
Ah, one step deeper into DIY. Very cool.
I believe that would be illegal in Canada. Anytime the engine is running, in Canada, we have to have the headlight on. That started around 1978, using the Safety Relay to turn on the headlight, as soon as the alternator produces power. In 1979 Yamaha removed the Headlight Switch from the handlebars.
Your voltages look normal, except for the 14.65. I suspect you are still using the old original regulator. The 14.65 is too high, and will cause your battery to lose electrolyte. A good regulator will only charge as high as 14.4 volts. 14.1 volts is the preferred maximum.
DanielBlack
XS650 Junkie
Yes, that's probably the case here as well. Like I said, I usually sit in 1st so it's not an issue the majority of the time. It usually only comes into play when idling at warmup. Also, my replacement headlight has a parking light in it which I will wire up on Br keeping the headlight lit even with the big incandescent turned off. That little guy will go LED, too.
Edit: The best info I can find, which is a guide for motorcyclists published by the state motor vehicle division, shows that here in Arizona headlights are highly recommended, but not actually required. It does mention that post-78 headlights automatically turn on.
"The best way to help others see your motorcycle is to keep the headlight on — at all times (new motorcycles sold in the USA since 1978 automatically have the headlights on when running). Studies show that, during the day, a motorcycle with its light on is twice as likely to be noticed. Use low beam at night and in fog."
https://www.azdot.gov/docs/default-source/mvd-forms-pubs/99-0129.pdf?sfvrsn=6
I AM NOT RECOMMENDING RIDING WITHOUT A HEADLIGHT. IN NORMAL USAGE, MY HEADLIGHT IS ON AT ALL TIMES WHEN ON THE ROAD.
My recommendation on the matter:
Make yourself as visible as possible, pretend you're not at all, get home safe.
Edit: The best info I can find, which is a guide for motorcyclists published by the state motor vehicle division, shows that here in Arizona headlights are highly recommended, but not actually required. It does mention that post-78 headlights automatically turn on.
"The best way to help others see your motorcycle is to keep the headlight on — at all times (new motorcycles sold in the USA since 1978 automatically have the headlights on when running). Studies show that, during the day, a motorcycle with its light on is twice as likely to be noticed. Use low beam at night and in fog."
https://www.azdot.gov/docs/default-source/mvd-forms-pubs/99-0129.pdf?sfvrsn=6
I AM NOT RECOMMENDING RIDING WITHOUT A HEADLIGHT. IN NORMAL USAGE, MY HEADLIGHT IS ON AT ALL TIMES WHEN ON THE ROAD.
My recommendation on the matter:
Make yourself as visible as possible, pretend you're not at all, get home safe.
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TimeMachine
SeventyEighte
I think I can turn my voltage regulator down. Should be kinda like tuning a horn.. one of these days, its a rainforest here now. -RT
DanielBlack
XS650 Junkie
More testing. I haven't yet put a new rectifier in, or started the motor to check alternator output or to jumper past the regulator.
Two possibilities I see: low voltage on the green brush, low resistance on the stator. Of course the usual problem of inaccurate meters puts these numbers to doubt. My leads are rather thick gauge, zero out when touched to each other, but likely reads low. For my coil spec'd at .6 ohms I measured .3ohms, Boyer replied that a coil that low wouldn't work. Mine does. So my .2ohm readings on the stator might be fine.
Thoughts?
- Battery voltage, ignition off 12.9v, 12.3v on.
- Strong slap.
- Green brush 11.2v, ignition on, motor off
- OEM brushes, 11mm inner, 12.5mm outer
- Rotor ring to ring 5.0-6.1ohm wandering
- Both rings to ground, no cont.
- Stator white to whites .1-.3 ohms, mostly hovering .2
- With yellow wire unplugged, they'd start at .4ohms and settle to mostly .2
- Whites to black, no cont.
Two possibilities I see: low voltage on the green brush, low resistance on the stator. Of course the usual problem of inaccurate meters puts these numbers to doubt. My leads are rather thick gauge, zero out when touched to each other, but likely reads low. For my coil spec'd at .6 ohms I measured .3ohms, Boyer replied that a coil that low wouldn't work. Mine does. So my .2ohm readings on the stator might be fine.
Thoughts?
OH man , Daniel this stuff makes smoke come out of my ears. I hope some of the resident Gurus can help you.
Hope you can get a handle on this soon.
Hope you can get a handle on this soon.
DanielBlack
XS650 Junkie
Thanks Bob. We'll get there, I'm sure. The electricals are really no more complicated than the mechanics. A lot comes down to knowing how to measure properly. I came into this with troubleshooting skills learned with 120v. The general principles apply but I'm learning a lot about electronics and component testing.
11.2 volts on the green brush is good, no problem there. There is always going to be a voltage drop through the main fuse,
ignition switch, and voltage regulator.
Brushes are OK now, but should be replaced at around 10 mm.
My stator reads 0.5 ohms white to white, and 0.25 ohms white to yellow. As I said before, some meters don't measure reliably when ohms are less than 1.
ignition switch, and voltage regulator.
Brushes are OK now, but should be replaced at around 10 mm.
My stator reads 0.5 ohms white to white, and 0.25 ohms white to yellow. As I said before, some meters don't measure reliably when ohms are less than 1.
DanielBlack
XS650 Junkie
Ok. I'm thinking my stator is probably fine. Before my rectifiers crap out charging goes to 14.2v with no problem. Here's a thought.
What size wire would you recommend for the pos and neg rectifier to battery connections? According to the chart I'm using 18g is suitable for 30A with less than 3' of wire. My rectifier to battery wires are 16g.
What size wire would you recommend for the pos and neg rectifier to battery connections? According to the chart I'm using 18g is suitable for 30A with less than 3' of wire. My rectifier to battery wires are 16g.
