Lt coil replacement.
Posted: Wed Nov 16, 2016 4:24 pm
I'm replacing the LT coil on a lambretta electronic ignition and converting it to DC.
This is the second one I have repaired, both showing the same symptoms of a burnt out LT coil and the pad that sits under that copper/aluminium washer has gone brittle and disintegrated and I'm trying to work out why they overheated?
When looking for a replacement coils I noticed that The vespa set up and the BGM set up all have a sandwich of
Coil-fibre pad-copper washer-heatsink , I can't work out what the heat sink is for as its insulated from the coil by what looks like a big fibre pad? The coil is further insulated as its in a plastic former, none of which are great for heat transfer.
From my days working with electronics we never fitted a heatisink without using heatsink compound to ensure that there was a good heat transfer path from the components to the heatsink.
I was considering doing away with the fibre pad and fitting the washer to the coil using thermally conductive glue to aid heat transfer and help reduce vibration.
Use the same glue when bending laminates in place for the same reasons and a few dots of epoxy to ensure it all stays in place with little or no vibration.
Does Anyone have any better ideas? Are my assumptions wrong?
This is the second one I have repaired, both showing the same symptoms of a burnt out LT coil and the pad that sits under that copper/aluminium washer has gone brittle and disintegrated and I'm trying to work out why they overheated?
When looking for a replacement coils I noticed that The vespa set up and the BGM set up all have a sandwich of
Coil-fibre pad-copper washer-heatsink , I can't work out what the heat sink is for as its insulated from the coil by what looks like a big fibre pad? The coil is further insulated as its in a plastic former, none of which are great for heat transfer.
From my days working with electronics we never fitted a heatisink without using heatsink compound to ensure that there was a good heat transfer path from the components to the heatsink.
I was considering doing away with the fibre pad and fitting the washer to the coil using thermally conductive glue to aid heat transfer and help reduce vibration.
Use the same glue when bending laminates in place for the same reasons and a few dots of epoxy to ensure it all stays in place with little or no vibration.
Does Anyone have any better ideas? Are my assumptions wrong?