Tiger cub rectifier .

[john11668]

Cub is not charging and we believe that the rectifier is the problem .   9.5 volts easily out of the alternator cables.  Nothing beyond the rectifier.
Got a replacement But while I am generally  ok with electrics this one has got be beaten. We were recommended one by the local auto electrician.
Pics of old and new attached  but there are so many options for connections on the new one, and I just cant get my head around the directions of the diodes

Any advice would be welcome 

[L.A.B.]

Pics of old and new attached  but there are so many options for connections on the new one, and I just cant get my head around the directions of the diodes

As standard, your Tiger Cub's electrical system would be positive earth/ground.

That rectifier is not only a nine-diode type for a three-phase excited field (slip-ring) alternator as it appears to be a rectifier for a Lucas "ACR" alternator but it is almost certainly negative earth polarity. 

http://freerollguide.net/probably-fantastic-free-automotive-alternator-wiring-diagram-pictures/images-of-wiring-diagram-lucas-18-acr-alternator-wiring-diagram-image138-that-great/


https://www.ebay.ie/itm/REPLACEMENT-12-VOLT-ALTERNATOR-RECTIFIER-LUCAS-ACR-LRA100-UBB109-83166-130643-/281815311556

A 4-diode rectifier like this is all that's required as it can be used for either positive or negative earth.
http://www.rexs-speedshop.com/Single-Phase-Bridge-Rectifier 

Or:
http://www.classicmotorcyclespares.com/index.php/default/electrical/charging-system/classic-bike-rectifiers-regulators-bsa-triumph-norton/rectifier-replica-lucas-positive-earth.html#Charging_System

The old selenium rectifier needs throwing in the bin, regardless.

[iansoady]

What he said.

The problem is that most auto electricians will know nothing about this type of system hence why they've sold you the wrong thing. Easy to connect - there are 2 connectors (diagonally opposite each other) for ac from the alternator - the other 2 are the + and - connections.

You'll probably find that there's a double wire going to one of the ac connectors - this connects extra coils of the alternator into circuit if the lights are switched on. Crude but quite effective.

[john11668]

Is it reasonable to assune these are the same kit ??
https://www.ebay.co.uk/itm/British-motorcycle-solid-state-rectifier/223116553410?hash=item33f2c86cc2:g:SGgAAOSwInxXOPCG
Postage seems a bit steep from Rex speedshop

[L.A.B.]

Yes.

[john11668]

or this even , If you are not in a hurry
https://www.ebay.co.uk/itm/KBPC5010-1000-Volt-Bridge-Rectifier-50-Amp-50A-Metal-Case-1000V-Diode-Bridge/291862837146?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20131017132637%26meid%3D5ca3b54b4b66480bb0cfb182320b7463%26pid%3D100033%26rk%3D3%26rkt%3D8%26sd%3D223116553410%26itm%3D291862837146&_trksid=p2045573.c100033.m2042

[L.A.B.]

or this even , If you are not in a hurry
https://www.ebay.co.uk/itm/KBPC5010-1000-Volt-Bridge-Rectifier-50-Amp-50A-Metal-Case-1000V-Diode-Bridge/291862837146?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20131017132637%26meid%3D5ca3b54b4b66480bb0cfb182320b7463%26pid%3D100033%26rk%3D3%26rkt%3D8%26sd%3D223116553410%26itm%3D291862837146&_trksid=p2045573.c100033.m2042

https://www.ebay.co.uk/itm/British-motorcycle-solid-state-rectifier/223116553410?hash=item33f2c86cc2:g:SGgAAOSwInxXOPCG

"I can buy in the KBPC 50-10 rectifier at 56 pence .I could start selling that type,however,they do not work in the same manner as the correct KBPC 35-04 that i supply.Sharp practice to be selling the wrong rectifiers as suitable on classic bikes."

[iansoady]

When you say "do not work in the same manner" could you expand? From my limited electronic experience one bridge rectifier is much like another provided the operating parameters are the same.

Interestingly I seem to able to buy 2 35-04 for £2.50 with free postage.....

https://www.ebay.co.uk/itm/2-x-KBPC3504-Metal-Bridge-Rectifier-DIODE-35A-400V-W1O5/282785569446?epid=15011616854&hash=item41d7555aa6:g:ozQAAOSwEEBaQctS

[L.A.B.]

When you say "do not work in the same manner" could you expand? From my limited electronic experience one bridge rectifier is much like another provided the operating parameters are the same.

I didn't say. It's a "quote" from the ebay ad.

[iansoady]

Ah, sorry I misinterpreted.

[john11668]

Thanks for help so far guys but I am stuck again. Got the correct rectifier 35-04 and fitted it
Wiring on this cub however doesnt seem to fit any wiring diagram I have yet found.
See pics

Alternator wires seem to be a pair of green and white , and a single green
Rectifier had white/green,  brown/purple , and green black . I connected positive direct to battery positive (earth) terminal and toog a guess that the Br/pu would be the one to connect to negative on the rectifier .

On firing up there was no real rise in voltage at the battery and the rectifier heated up quite significantly so killed it before it did damage. Can anyone advise if the connections I have made at the rectifier are correct , and if so what should be my next step?

[L.A.B.]

Judging by the condition of that wiring the best thing to do would be to rip it out and replace it.

[john11668]

You may well be right , but maybe it would be better if we had the correct wiring diagram, and had resolved the charging problem first.  Then we can go for the cosmetics

[R]

Having decent wiring is not entirely just a 'cosmetic' issue..... ?

[john11668]

Fine ! I can go with that but I would like to resolve the issue first .   Then we can test out the functions of everything and if all is looking good we can deal with the duff wiring.
Can anyone add something constructive here