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Patrick Francis
Prolific User
Username: jackpot

Post Number: 236
Registered: 11-2016
Posted on Sunday, 08 July, 2018 - 03:31 am:   Edit PostDelete PostView Post/Check IP

Hi Guys
I took my Shadow 1 into the paint shop to touch up some nicks and scratches. When I picked it up, the gen light would not extinguish, and as I was travelling back home, it was misfiring, and getting worse.
I know they did some welding without disconnecting the battery. I presumed that this had fried my regulator, and hoped that changing it might fix the misfire.
I have replaced the regulator, but the generator light has not extinguished, so I presume the problem lies deeper.
Also the misfire is still there, so I am sure that the Powerspark is also fried.
I have not started digging yet, but before I do, does anyone know what else could have blown, apart from the regulator which I have replaced. I know modern alternators have the regulator as an integral part with some big diodes that can blow. Does the Rolls also have those, or is everything controlled through the regulator?
I am waiting for an answer from Powerspark as to whether their units can misfire when damaged, or that they either work or not. Any suggestions on what I should check in the meanwhile would be welcome and appreciated.
Thanks as always....
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 1988
Registered: 5-2012
Posted on Sunday, 08 July, 2018 - 04:11 am:   Edit PostDelete PostView Post/Check IP

Hi Patrick

The alternator does contain diodes. Section M5 of the manual is very comprehensive and gives procedures for testing the alternator.

I had a quick google of welding cars and disconnecting the battery. As often happens on the net, opinion is divided. Some people say they have welded many cars with no problems, others who say they always disconnect the battery. One person mentioned that exhaust shops never disconnect car batteries and often carry out welding - I suspect most would be using oxy-acetylene however.
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 1989
Registered: 5-2012
Posted on Sunday, 08 July, 2018 - 04:17 am:   Edit PostDelete PostView Post/Check IP

BTW - when my Powerspark failed it did so gradually with misfiring. This was confusing as I thought it would either be on or off. I therefore replaced the other ignition parts (coil, rotor, leads) before reverting back to points, when the engine ran ok again.

Could you let us know Powerspark's response - it would be interesting to know.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1916
Registered: 9-2004
Posted on Sunday, 08 July, 2018 - 05:56 am:   Edit PostDelete PostView Post/Check IP

Have used arc and mig tig etc and for the last 20+ years have never disconnected the battey,
have always used one of these to stop spikes etc.

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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 1990
Registered: 5-2012
Posted on Sunday, 08 July, 2018 - 06:07 am:   Edit PostDelete PostView Post/Check IP

Hi Patrick (L) - I assume the Sykes Pickavant device is a large smoothing capacitor. So, logically, we can assume that car electrics are prone to spikes from MIG/TIG welders, else there would be no need for such devices.
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Vladimir Ivanovich Kirillov
Grand Master
Username: soviet

Post Number: 1017
Registered: 2-2013
Posted on Sunday, 08 July, 2018 - 06:35 am:   Edit PostDelete PostView Post/Check IP

Apart from oxy welding I always disconnect the battery. I mean really how much effort does it take to disconnect the battery?

I have heard mig welding will not blow diodes in alternators. I do not care. I always disconnect the battery.

This thread is another reminder to me why I simply will not let any workshop near my cars.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1917
Registered: 9-2004
Posted on Sunday, 08 July, 2018 - 06:48 am:   Edit PostDelete PostView Post/Check IP

Cripes Vladimir, hope you never disconnect some moderns can be a costly time consuming job to re programme with lost codes etc.
Battery disconnect went out years ago.

How is the super Camargue engine coming along.
I need one to put an engine in, if you need to sell at any time give me a bell.
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richard george yeaman
Grand Master
Username: richyrich

Post Number: 983
Registered: 4-2012
Posted on Sunday, 08 July, 2018 - 08:25 am:   Edit PostDelete PostView Post/Check IP

Patrick F I would start with the alternator, a half charged battery isn't helping your chance of a good sparking plug, order up a new power spark and also a spare one.

Kind Regards.

Richard.
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1918
Registered: 9-2004
Posted on Sunday, 08 July, 2018 - 05:33 pm:   Edit PostDelete PostView Post/Check IP

May be beneficial to know what parts have been welded. Could be burnt loom etc.
Maybe a nothing more than a fuse blown during the operation if fitted.
Connection left off if removed.
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ross kowalski
Grand Master
Username: cdfpw

Post Number: 842
Registered: 11-2015
Posted on Monday, 09 July, 2018 - 11:32 am:   Edit PostDelete PostView Post/Check IP

Patrick F,

As to the welding thing, I've welded a lot of metal on a lot of vintages of cars. If it's someone else's I disconnect the battery, on mine it's cables on. Never had a problem. Of course I ground correctly so there's less chance of electrons going where they shouldn't. In both cases, never a problem. And in all the car welding I have direct knowledge of, no mig / tig induced problems.

Could you get massive current flow somewhere you don't want it or induce current in something electromagnetically or create some high voltage spikes,.. sure.

Even with the "running fine before shop" / "running badly after shop" clue, I would still diagnose this the same way I would any misfire.

If you are more comfortable with replacing stuff, testing the Pertronix would seem easy enough, put the points back in, time them and see if the goes away.

Three days ago I welded front clip back on my new mini, 1.5 hours straight welding.



Battery on, no problems.

Two days ago I welded in metal to fix rusted out drivers and passengers door sills on Ford truck. 1 hour welding time ( job time four hours)



Battery on no problems.

No pictures, but today I welded an exhaust on a Ford Festiva battery on, no problems except I cannot get the dignity back I lost working a Ford Festiva.

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