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AVP342
United Kingdom
22 Posts |
 Posted - 17/05/2016 : 20:59:03
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Can any of you electrical wizards offer any advice with the following:
The ignition warning light on my PA lights normaly when the engine is started but as the revs build up the charge rate increases to approx. 4 amps then drops back to zero.
I suspect the cut out is the cause because there are signs of burning
under the cover (melted solder).
If it is the cut out at fault, can they be rebuilt or can any one help with another?
AVP 342 |
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bloodysalmon
Spain
1482 Posts |
Posted - 17/05/2016 : 22:18:26
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isnt that what a cutout is suppose to do Derek, cutout if the amp's are to high?
Chris Blood (D0407 & F0753) |
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dade
United Kingdom
513 Posts |
Posted - 18/05/2016 : 08:52:28
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Hi Derek
Get hold of Nick Feakes "Triple-M Electrics" this will give you the basics of the Charging System.
I think that it is available from this forum if not from Nick himself.
Classic Dynamo and Regulator Conversions Ltd will also help should you decide to convert the "innards" to modern electronics.
Regards
Russ
PB0333 |
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sam christie
United Kingdom
3104 Posts |
Posted - 18/05/2016 : 09:37:03
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There is of course the diode alternative which Nick has described.
By the use of a simple reliable diode a cut out is no longer needed. I have the conversion to a diode on my M-type to Nick's specification which works fine and cost under £3. The original Rotax cut out remains in a purely decorative rôle.
The diode (fixed unseen behind the dash) has the advantage, if it ever fails, of 'failing safe' and it is unlikely to set the car on fire.
Sam |
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BobH
United Kingdom
250 Posts |
Posted - 18/05/2016 : 10:03:09
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quote:
Originally posted by bloodysalmon
isnt that what a cutout is suppose to do Derek, cutout if the amp's are to high?
Chris Blood (D0407 & F0753)
Not quite Chris - the cut-out is to disconnect the dynamo from the battery when the dynamo isn't producing enough voltage at low revs. Without the cut-out and with the battery voltage higher than the dynamo output, there would be a high reverse current back into the dynamo.
Derek - overheating in the cut-out may be due to a bad contact connection as that takes all the charging current - you could try cleaning the contacts with fine glasspaper (disconnect the battery first - if you close the contacts by hand there will be a very high current flow which could damage something). Also have you checked that the dynamo brushes are good and are free to move in the holders?
In Nick's information I think there should be details about replacing the cut-out with a diode, which is pretty simple to do. It would be a reasonable alternative to getting a faulty cut-out fixed, if that really is the cause of your problem.
(sorry Sam - I took so long in my repy that your post got there first!) |
Edited by - BobH on 18/05/2016 10:07:14 |
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AVP342
United Kingdom
22 Posts |
Posted - 18/05/2016 : 11:14:16
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Thank you everyone for your help. I was quite overwhelmed by the number of helpful comments and advice.
My local auto electrician assures me that the dynamo is producing 8 amps at source, so, I think I will go for the diode system which sounds safer.
Derek |
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Nick Feakes
USA
3377 Posts |
Posted - 18/05/2016 : 13:25:29
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Derek
I have sent you my Electrics Book
Nick |
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AVP342
United Kingdom
22 Posts |
Posted - 21/05/2016 : 16:27:03
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Hi Nick,
Thank you so much for sending a copy of your very comprehensive book on how to understand electrics, a subject which I have always
found difficult to understand. So, as I'm now In my eighty sixth year I have decided to take the easy way out and go for fitting a diode!
Derek
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Nick Feakes
USA
3377 Posts |
Posted - 22/05/2016 : 12:46:58
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Derek
Excellent! Please do not hesitate to contact me if you need any further help
Nick |
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AVP342
United Kingdom
22 Posts |
Posted - 22/05/2016 : 18:03:47
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Hello again Nick,
Could you please give me the reference number or part number of a diode to enable me to buy one, and is it
a simple job to wire in myself?
Regards Derek PA1997 |
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Peter Scott
United Kingdom
1240 Posts |
Posted - 22/05/2016 : 19:57:10
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Derek
Two components which i have used, following Nick's advice, are:
Bridge rectifier - Maplins - Stock no AR85G - Pt no KBPC2504
Schottky diode- RS Components - Stock no 766-0328 - Pt no NTSJ30U100CTG
The Maplins rectifier is the easier to install as it does not require any soldering. The RS Components Schottky diode has the advantage that has a lower voltage drop and so generates less heat but it does involve soldering the leads to the diode.
So you takes your pick. I have used both at various times and they both worked fine.
Peter |
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AVP342
United Kingdom
22 Posts |
Posted - 23/05/2016 : 14:19:50
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Thank you Peter, that's just what I needed to know.
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