Morris Minor Owners Club

Lost charging on my Series MM this week, did usual tests and finally removed the regulator which revealed a 63 ohm resistor mounted behind.
This has gone high in value and unable to energise the dynamo field coils and needs replacing.
It's a physically large component but could probably be replaced which something a lot smaller which would still be rated at a similar wattage.
My question is does anyone know the wattage rating of the original?

Alan

What voltage is it fed with? If 12 Volts maximum, it is easy to apply Watts = Volts x Amps, or other variations of the formula for Electrical power. Ohms Law is useful to sort it outif you don’t know the other formulae.

If 12 V, 2 1/2 Watts is not a particularly high value. Temperature rise may be needed to be kept sufficiently low to avoid an increase in resistance as the temperature rises, hence its relatively large physical dimensions.

Yes, that's the theory I used. I found a 68 ohm 10w wirewound resistor which is still smaller than the original!
Should do the job.

Alan

63 and 68 Ohm resistors could be the same value (if + or - 5%). If smaller tolerance it may not be quite OK.

Adding a 1k resistor in parallel will give close to 63. A much lower powered resistor would be adequate for that.

Inverse law applies to resistors in parallel.

RAB