Topic: need help building a rectifier.

[maliveline]

Well I have a honda cb750a that is having charging problems. I've basically narrowed it down the the rectifier. I was going to buy a new one but realized they cost more than I want to spend.
I've seen a couple posts on here that talk about building a rectifier from buying stuff at radio shack. I really want to do this and save some cash but most of the posts on building rectifiers are written on other bikes and I dont have a schematic for the rectifier for my bike and I basically need some because I really have know Idea what I'm doing. I saw some posts where people talk about the regulator like its part of the rectifier but im pretty sure thats not the case on my bike because I looked in the shop book I have and the rectifier and the regulator are on opposite sides of the bike and they are not the same part. I know they connect somehow through wiring but like I said I'm a little lost. I have some experience with this kind of stuff and all and all I would say I am pretty good with electrical systems but I could really use a push in the right direction. if someone could help me I would greatly appreciate it.

[Alan F.]

These should help:

http://forums.sohc4.net/index.php?topic=12465.0

http://forums.sohc4.net/index.php?topic=19155.0

http://forums.sohc4.net/index.php?topic=70478.0

http://forums.sohc4.net/index.php?topic=29111.0

And in case you're looking for a manual, or a different manual: http://forums.sohc4.net/index.php?topic=17788.0

Just find the right wiring diagram, figure out the color codes of the wires you want to identify and zoom in on the rectifier in the wiring diagram.

check this out too, a color wiring diagram for your 750A, just scroll down to the bottom and it's on the right.
http://oldmanhonda.com/MC/WiringDiagrams/MCwiring.php

When connecting to the bridge rectifiers, I'd suggest a good solder connection followed by a layer or two of heat dhrinkable tubing, a little corrosion inside a crimped connector will cause reliability issues in a fairly short time. Be sure to use some sort of a heat sink, and spread some of that white, heat conducting grease between your rectifiers and the heatsink.
Alan

[ZoomyZen]

I build custom guitar amplifiers and effects, and have lots of experience building rectification circuits.  Unfortunately, I know nothing about bike circuits hah!.  
If you have already found the info cool.  
If you can find a particular circuit for your bike, I can help you decipher the schematic, the "layout" (a term used to describe the physical arrangement of the parts in the circuit as it sits in whatever will contain the total sum on the bike) and locate the right parts.  If you need to build a custom rectifier for a special build I can help with that as well!

EDIT:  I guess it would be more applicable for me to extend an offer of help if you need it with any problems you think I might be able to solve.  Just let me know!

[Really?]

Have you looked here?  Might be cheap enough for you so you do not have to sweat building one.

http://www.oregonmotorcycleparts.com/rectifiers3p.html

[TwoTired]

Green wires are all the connected together, if they are stock Honda.

So you have 5 connections points  3 Yellow are AC, like a symbol ~
(+) goes to red, and (-) goes to green wires.

[maliveline]

ok I think i am figuring this stuff out slowly. so I can buy 2 rectifiers from radioshack that are like 25A and 50v. each rectifier has a total of 4 connections. So I hook up my red wires on the 2 postive connections on the rectifier and I hook up the black wires on the 2 negative connections on the rectifier. but that leaves 4 A/C connections left to hook up to and I only have 3 A/c wires on my wire harness. how do I wire those up? also does it matter how I wire up my A/c wires? Can I do it in any order as long as they are hooked up to the a/c connections on the rectifier?
and of course, I will need a heat sink probably.

[ZoomyZen]

ok I think i am figuring this stuff out slowly. so I can buy 2 rectifiers from radioshack that are like 25A and 50v. each rectifier has a total of 4 connections. So I hook up my red wires on the 2 postive connections on the rectifier and I hook up the black wires on the 2 negative connections on the rectifier. but that leaves 4 A/C connections left to hook up to and I only have 3 A/c wires on my wire harness. how do I wire those up? also does it matter how I wire up my A/c wires? Can I do it in any order as long as they are hooked up to the a/c connections on the rectifier?
and of course, I will need a heat sink probably.

The rectifier should have 4 nodes:  One with a positive sign (+) one with a negative sign (-) and two with something to indicate AC, like a ~ or something.  What you are attempting to use appear to both be what are called full wave rectifiers,  which require two separate ac inputs per individual unit.  Forgive my ignorance about bike and car AC but does an alternator have three power wires emanating from it? If so, it''s probably a 3 phase device.  You can still use the two full wave units I believe but you have to hook the rectifiers up a special way.

Check this out a little. 

http://www.allaboutcircuits.com/vol_3/chpt_3/4.html

I have to work on something, I can help more later.  Sorry!!!!

[maliveline]

yes there are 3 power wires comming from my alternator. everything you just said is pretty much true. basically I was wondering if I had to hook up my ac wires in a special order for this to work. but now im pretty sure it will work in any order as long as I hook up my negative wires to the negative terminals on the rectifier and my positive wires to the positive terminal on the rectifier and of course the ac wires to the ac terminals on the rectifier. basically im going to end up having 1 ac terminal that will be unused. i feel like a noob for having such a hard time figuring this out but its all commnig back to me now. i think :p

[TwoTired]

ok I think i am figuring this stuff out slowly. so I can buy 2 rectifiers from radioshack that are like 25A and 50v. each rectifier has a total of 4 connections. So I hook up my red wires on the 2 postive connections on the rectifier and I hook up the black wires on the 2 negative connections on the rectifier.

Black wires in Honda bikes are +12V.   You want green to the Neg (-) terminals of the rectifiers.

but that leaves 4 A/C connections left to hook up to and I only have 3 A/c wires on my wire harness. how do I wire those up? also does it matter how I wire up my A/c wires? Can I do it in any order as long as they are hooked up to the a/c connections on the rectifier?

You will leave one of the 4 ~ AC connection unconnected.  Doesn't matter which.

[Clutch Cargo]

If you really want to "roll your own", get a three phase bridge rectifier like this - http://www.vishay.com/docs/93565/93565.pdf

Vishay Part number   36MT20-ND

I have one of these in my 76CB750 - still running fine after three years.

PS - you will need to find a nice heatsink - I used one from an older Pentium based computer.

Clutch