SOHC.co.uk Forums > CB750

Field Coil/Charging problem...

(1/4) > >>

JimJam:
Hello,
I am hoping someone can help please…
Bike is a CB750 F1 SOHC 1977
Following a 2 year restoration, I finally took the bike out for a first test. Largely all went well, apart from the distinct lack of charge to the battery.
Checking the stator wires with the bike running at varying rpms (2000- 4000) showed 0 Ac voltage across all three.
Stator resistance is consistent 0.8ohms with no continuity to ground
Field coil resistance is 7.2ohms with no continuity to ground.
The replacement solid state R/R gave correct results on the diode test.
I believe the issue is the field coil is not receiving 12+v from the R/R. As I understand it, with the ignition on the Regulator should supply 12+vdc to the field coil which will then magnetise. This is clearly not happening.
Could someone please confirm my wiring is correct?
  [ Guests cannot view attachments ]
3 Yellow R/R wires to 3 Yellow Stator wires
Green = direct to ground
Red to Battery +
Black to ignition
White to White Field coil wire (being 12+v supply)
The green wire from Field Coil is direct to ground.
With everything connected and ignition on, I expected to see 12+vdc at the white field coil wire, but I am currently seeing 0v. What has gone wrong?
The wiring guide from the R/R manufacturer is:
RED: Positive      YELLOW: Phase input from stator      WHITE: Field Output for Alt.
GREEN: Ground      BLACK: Original sense input for Regulator
Any help greatly appreciated!
James

AshimotoK0:
I can't comment on the regulator/rectfier as no experience with them. However, why not temporarily feed 12 to the field coil and see if you get any charge? (disconnect from RR unit when doing this !) Did you check for infinite (open circuit) resistance between each of the 3  yellow stator wires and the mag-frame of the stator?

Welcome to the forum BTW  :)  cheers Ash

JimJam:
Cheers Ash,

Yes, good idea on the direct feed. will give that a go.

I checked each of the stator wires for continuity to ground against the Alt. engine case.  There was no continuity. Is that sufficient? 

BigAl (Alan):
You would require a 12 volt + supply from the regulator to the field coil to start the charging process. A higher voltage insulation tester (as image) would also confirm that the windings within the stator & field coils have not shorted to the frame/ground, as the low voltage multimeters may not provide the correct reading.

JimJam:
Thanks Al.

Could you please clarify that with the ignition on (only) the white Regulator wire leading to the Field coil should be reading 12+v and that the green Field coil wire is sent directly to ground?  Y/N


Thank you.

Navigation

[0] Message Index

[#] Next page