Brush connection blowing main fuse

XS1961

XS addict!
Messages
740
Reaction score
66
Points
28
Location
England
I hate electrics...I'm just swapping over from TCi system to a Boyer.
When I plug in the stator the main fuse pops . The only happens when the top brush terminal (ringed) is connected.
The lower brush terminal has no effect on the fuse.
Ive fitted an earlier points rotor but same thing occurs with the late rotor.

Somewhere deep in the recesses of my brain I can vaguely remember something about grounded & ungrounded bushes..
 

Attachments

  • brush.jpg
    brush.jpg
    36.2 KB · Views: 262
Last edited:
Not sure if this is your problem, but when I changed my brushes I had that little wire with the hole on the end in the wrong place. It kept blowing the fuse until I had it mounted correctly. Hope that helps.
 
That brush configuration is for 70-79 models, with reg supplying power to the outside brush, and inner brush grounded.

80-up TCI models supplied power to the inner brush, reg would ground the outside brush.

If you have 80-up alternator wiring and regulator, then you have ground-shorted the power there...
 
Yep, the wiring harness is from an '81 with an aftermarket/pattern reg/rec fitted...
Anyways around this?
 
The proper way is to have matched set of alternator housing, brush holder block, brushes, rec/reg and wiring.

If you want to finagle, search on "nylon screw"...
 
mm..Not just a case of swapping over my brush holders then?They do look to be wired basically the same though...
 

Attachments

  • IMG_1202.JPG
    IMG_1202.JPG
    37.7 KB · Views: 246
  • brush.jpg
    brush.jpg
    36.2 KB · Views: 223
Good, you have pics of the two different brush configurations. For more details, you could look up the charging systems on MikesXS. Compare the brushes and brush blocks. I recall that there's a subtle difference in the brush block mount zone of the housings. The main idea is to avoid grounding the innermost brush...
 
Thanks all, good info,I didnt realize others had posted this query too.

Looking at mine I can see the differences, I have half a dozen stators here so Im sure I can cobble something together..
Or go the 'nylon screw' route (not sure I understand the next bit about using a wire to 'live' or 'earth' the brush )..
Maybe its just time for me to invest in the PMA kit Ive been promising myself..
 

Attachments

  • IMG_1204.JPG
    IMG_1204.JPG
    121.3 KB · Views: 202
  • IMG_1205.JPG
    IMG_1205.JPG
    107.8 KB · Views: 190
Last edited:
Those are good pics.
Here they are, annotated to show the different brush-block layouts:
 

Attachments

  • BrushBlock-70-79.jpg
    BrushBlock-70-79.jpg
    24 KB · Views: 198
  • BrushBlock-80-up.jpg
    BrushBlock-80-up.jpg
    23.1 KB · Views: 189
  • BrushBlocks-Outside.jpg
    BrushBlocks-Outside.jpg
    62.5 KB · Views: 926
  • BrushBlocks-Inside.jpg
    BrushBlocks-Inside.jpg
    73.1 KB · Views: 905
If you have an 80 up stator use it. That would be a free fix. A PMA will not be. The PMA's only pro on a pro/con list is that it can run with out a battery. Others will try to tell you different but that's all hype.
Leo
 
Its running the 80+ setup at the moment but Im plagued with minor electrical and/or charging problems and Ive lost confidence in the TCi system (too many parts to go wrong)so Im installing a spare Boyer system which is why I wanted to fit one of my older stators..
I may just end up selling the tci box ,diconnecting the pickup and using the late stator with the Boyer
 
Back
Top