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Lucas CS switch cutout points issue
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jp928



Joined: 07 Jun 2016
Posts: 249
Location: Australia

PostPosted: Sun Jul 30, 2017 8:13 am    Post subject: Lucas CS switch cutout points issue Reply with quote

26 Rover 9 - when I first got it running I was not getting any charge, and a DVM saw wildly fluctuating volts. After trying other things I gave the cutout points some attention with wet&dry paper, and got proper charge back. Now after around 1 hours running the charge has gone again, and some arcing is going on - putting the leads of the dvm anywhere near the engine shows wild readings even with nothing in contact. Based on earlier fix I think its the cutout points again, but its difficult to get at them, can only get one thickness of wet&dry in there, but only short length, difficult to apply much pressure to clean up the faces of the points.
Does anybody have any experience of these switch boxes, or know if the cutout comes out readily, before I dismantle it back out of the dash please?
thanks
jp
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47Jag



Joined: 26 Jun 2008
Posts: 1480
Location: Bothwell, Scotland

PostPosted: Sun Jul 30, 2017 5:00 pm    Post subject: Reply with quote

JP,

It sounds like the cut-in voltage needs adjusting. Here are some adjustments that can be checked/done. This is for a MCR2 but the basics are there.
http://www.voc.uk.com/net/docs/8.4/8.4-163-5.pdf

Art
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jp928



Joined: 07 Jun 2016
Posts: 249
Location: Australia

PostPosted: Sun Jul 30, 2017 11:25 pm    Post subject: Reply with quote

The problem with the document is that the cutout is INSIDE the CS6 switch body, and access to the points is difficult, so seeing the state of them is impossible, as would be getting a feeler in there. The top of the cut out body is marked 'Do Not Attempt to Adjust'......
Has any had one of these apart and can offer any advice please? There is one of these (marked Armstrong Siddeley) on ebay, at GBP250, but its in poor condition apparently - not inclined to take a chance on that.
thanks
jp 26 Rover 9
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47Jag



Joined: 26 Jun 2008
Posts: 1480
Location: Bothwell, Scotland

PostPosted: Mon Jul 31, 2017 11:22 pm    Post subject: Reply with quote

JP,

You have my sympathy with this problem. I found the switch you mentioned. I would say you're screwed trying to resurrect something like that. I would suggest trying to find a stand alone cut-out and utilise that unless originality is an issue.

If you are interested https://www.ebay.co.uk/itm/112496357807 is on at just a fiver plus postage.

You are in OZ aren't you? If you want it and the vendor won't post to you get it shipped to me and I will send it on. I have a mate in Melbourne who does this all the time.

Art
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jp928



Joined: 07 Jun 2016
Posts: 249
Location: Australia

PostPosted: Tue Aug 01, 2017 1:59 am    Post subject: Reply with quote

Thats a thought, thanks, but if I am going to modify much I am almost thinking of going to a modern cut-out & regulator that I could hide somewhere. Problem with this is that the dynamo has only one lead - output charge, and is internally grounded (-ve earth), which case is not well explained anywhere if going modern.
The car did come with a separate Lucas cutout unit - marked as 339260 and 6V ER 1145 - has 4 terminals labelled A2,D,E,A. This is not shown on the wiring diagram, so maybe the previous restorer planned to fit it to replace the built in cutout in the CS6 switch block?
I will watch the ebay item and come back to you if I think to acquire it.
Will persevere with trying to clean points and see if I can get clean charge back again.
Update - now getting charge -~4A at idle (3rd brush as low as I can get it), goes up well with revs. BUT still seeing lots of movement on DVM volt scale when its anywhere near the engine - dirty voltage coming off dynamo?

thanks
john.
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peter scott



Joined: 18 Dec 2007
Posts: 7113
Location: Edinburgh

PostPosted: Tue Aug 01, 2017 9:02 am    Post subject: Reply with quote

Hi John,

Looking at the Armstrong Siddeley photos it looks like it's not too difficult to remove the assembly from the surrounding metal box. Does that not give you sufficient access to clean and adjust the points?

DVMs can be pretty useless for car electrics because of their susceptibility to radiated interference from sparking.

Peter
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1939 SS Jaguar 2 1/2 litre saloon
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jp928



Joined: 07 Jun 2016
Posts: 249
Location: Australia

PostPosted: Tue Aug 01, 2017 9:40 am    Post subject: Reply with quote

Sort of - from looking at pics of mine there is a bolt into the coil core from the back, but a couple of wires come from the front through holes in the main plate, which may mean disturbing unrelated stuff to gain access. I will remove the whole thing from the dash to get better access to the points if I must....but make a good drawing of connections before I disturb them. Dont want to go backwards from everything electrical working .
thanks
jp
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47Jag



Joined: 26 Jun 2008
Posts: 1480
Location: Bothwell, Scotland

PostPosted: Wed Aug 02, 2017 10:16 am    Post subject: Reply with quote

JP,

The markings you mentioned are as follows A2 - Fused battery, D - Dynamo,
E - Earth and A - Battery. As you say it looks like a PO has utilised an external cut-out. You can't really use a 'modern' regulator/cut-out with you 3 brush Dynamo.

Art
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