First disconnect the red (red/wht on C72/77), brown & yellow from the rectifier, as it's not possible to successfully test components whilst in circuit.
With a multimeter, self-powered test lamp or self-powered piezo buzzer, carry out the following tests:
Ready? phasers on stun...sorry multimeter on diode test (or 'beep')
1: probe AC1 (brn) with neg lead and + with pos lead, result should be a short beep
2: reversing probes should result in silence
3: probe AC2 (yel) with neg lead and + with pos lead, result should be a short beep
4: reversing probes should result in silence
5: probe - (gnd) with neg lead and AC1 with pos lead, result should be a short beep
6: reversing probes should result in silence
7: probe - (gnd) with neg lead and AC2 with pos lead, result should be a short beep
8: reversing probes should result in silence
All a diode really is is an electrical non-return valve; positive flow is from anode to cathode (as with all DC circuits), or in the direction of the 'arrow' - this is known as forward current; conversely, negative can be understood to 'flow' in the opposite direction - this is known as reverse current. So think of your multimeter probes (meter on beep) as pos (r) & neg (bk). A good diode will allow forward current (hence the short beep), but will block DC in reverse. A duff diode will either block in both directions or allow flow in both directions. It only takes one diode in a rectifier to mess up the flow sufficiently to reduce the charge dramatically or negate it completely.
I'm open to Qs.
Steve Edwards
Let's test a rectifier (celenium diode [pack])
Let's test a rectifier (celenium diode [pack])
Hey joewier1, essentially no. The rectifier just straightens out the curvy bits, turning ACV into DCV in order to charge the battery. There appears to be no regulator on these systems, which is odd, so I can only assume, at this point, that there is some form of regulation within the rectifier itself. The CB wiring shows 2 diodes per leg, but they are just that - diodes, not zener diodes (which DO offer a crude form of regulation called 'shunting', whereby excess voltage above the zener's threshold is wasted by being turned into heat). I'm looking into it to see how we might improve the charging efficiency.
Incidentally, selenium rectifiers (Honda's technical writer wrote them in as 'celenium', so I've continued that spelling to offset confusion - we should start spelling in English really, instead of Japlish) are notoriously unreliable owing to the heat they produce causing the selenium film to break down and short out. This leads me to believe that back in the early 60s this crude method of 'regulation' was considered sufficient, as opposed to efficient! I suspect that the heat loss is the regulation on these otherwise-brilliant bikes. The headlight, BTW, appears to be powered by ACV direct from the alternator. I gotta get my hands on a C-series combo keyswitch to prove this. On CB77 models. The headlight bulb is 12v DC power. The headlight switch does have AC going to it from the dynamo supplied by the pink wire. When the headlight switch is in the middle position or in the on position it feeds the yellow wire (going to the rectifier) additional voltage. This is supposed to compensate for the additional draw from the headlight.
Ah, now I've got it! But it doesn't add up; unless the alternator coils are wound and placed in exactly the same orientation on the stator. Yes, of course, that's making sense now. The coils are concentric & side by side on the stator and not 180º removed from each other. This means the alternator IS a dynamo. And I thought it was just the Japlish translation-loss! The additional AC voltage gets added to the rectifier input, increasing the current available at the battery terminals and compensating the system for the extra load. I don't have a working HL or combo switch to hand, so this info is invaluable. Thanks again for all input here.
I'm still unsure why, on the wiring diagrams, the rectifiers differ. Regards guys, Steve PS: If anyone has a clear C77 diag, can you tell me if the lower connections on the 'A.C. Dynamo' coils are actually shown to be common please? My copy is a bit fuzzy even on A3 paper, but it looks like they are. This would make sense, as the Dream has a 2Ah-greater capacity battery and a slightly higher load factor (winkers).
E3steve how much do you know about electrical circuits? I known just about enough to get me in trouble, but I feel with enough brain power we can come up with a way to improve the charging system. Let me start the brainstorming: The dynamo (I will call it alt.) supplies three legs of A/C voltage at approximately 4 to 6 a/c volts a leg. These wires are the pink, yellow, and brown. In theory the pink and yellow combine (with light switch on) and gives approx. 12v a/c to one leg of the rectifier. The brown wire feeds approx. 6v a/c to the other leg of rectifier. And as such, the rectifier is supplied with 18v a/c. Through diodes it will convert this a/c to d/c output feeding the battery and the reverse wave will dissipate to ground. This is my understanding of how it works. My thoughts are that instead of using a full wave bridge rectifier (that only has two hookups for a/c input, would be to use a diode trio which I believe has 3 legs to hook a/c input. It would require rerouting the pink wire away from the light switch and not letting it combine with the yellow wire but give it its own hookup to the rectifier (diode trio). Thoughts? Comments?
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