Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: neat street on August 15, 2025, 11:35:27 AM
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Hi All, looking at trying to clean and test this unit from my 500. any ideas on how to do both please? I have tried contact cleaner but did not even touch it. thank you, John.
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Looks like the original lacquer on the board has been 'got at' . Need to get it off with acetone or paint stripper, clean the board and apply some PCB lacquer.
I would do be inclined to test it before cleaning.
The following assumes it's a 3 phase rectifier, 3 yellow wires, green chassis and black +12v.
To do a basic test you will need a multimeter with a diode test setting.
From each phase you should get 0.6 to 0.7 forward voltage drop ( red test lead to each yellow and black test lead to black) and open circuit if you reverse the connections.
Do the same for ground wire (green) to each phase yellow . Red test lead to green black test lead to each yellow. Swap the test leads around an you should get open circuit with each of the 3 phases.
Regards
Dave
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Dave got his colours wrong,earth should be green and the positive to starter solenoid/ battery red or red/white BUT its old and dirty so all bets are off, take the ring terminal as ground along with the mounting bolt
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I was struggling to sort out the colours there.
According to the schematic it could be a red with white tracer wire running back to the starter solenoid where it joins the red wire on its way to the main switch.
Sometimes a cotton bud with cif cream on it will sometimes shift a bit of grime to reveal the main colour and tracer.
My colour vision test has expired now and won't be done again since I have retired. Had to have it to get authorisation to work on electrical systems. I was always borderline so got done every 3 years.
Regards.
Dave
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Dave, Honda dont tend to use industry "standard" colours like black for switched live and green for ground plus after 50 years of added aditive(sh1te) its very difficult to tell.
Having been brought up on St Joseph Lucas, prince of darkness, electricals fault tracing becomes second nature!!
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thank you both, as it is diodes and no `bare` electricle parts, could it be placed in an ultrasonic bath to clean, then placed in a bag of rice to dry completly, and laquered (all after test to make sure its all working?
thank you again.
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It doesn't require any cleaning. You can test its diodes, but if it does what it is supposed to do, why bother?
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It doesn't require any cleaning. You can test its diodes, but if it does what it is supposed to do, why bother?
It has the `Green` copper contamination, like rust on steel, I think it should either be nuetralised, or cleaned? my option would be to clean it all off so it does not `creep` over time and as Dave advised, laquer to protect afterwards? just my thoughts as I am going through all the electrics now and changing parts like bullit and terminal block connectors while trying to sort out other electricle `add ons` that should not be there :-) thank you for your comment.
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Carefull with laquer, it does get hot
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Thanks Brian, not sure if it works yet, has alot of the green corosion which is afecting the terminals, think I will try the sonic clean first and see how I go.