ashimotoK0
Veteran Member
My friend in the UK has lots of big Hondas but himself and his partner both have their cherished CD250U's, which they ride regularly.
One of their CDi's packed up and after various aftermarket units and used genuine units failing of not even working, I am tasked with de-potting the original, plotting out the circuit , diagnosing the fault and then repairing/refurbishing.
Luckily, the potting is only semi-hard (probably polyurethane) ...in the past, as part of my 'day job' I have had to de-pot hard epoxy encapsulants using a boil up in a cocktail of solvents including T.H.F. (tetrahydrofuran). This is quite aggressive and can destroy plastic coated parts and their markings, so I decided to not use solvents and just a blunt screwdriver and a kebab wooden skewer.
After several hours whilst watching TV and picking away, I am down to the main PCB, identified and measured most of the component values and gathering data before I sit down and trace out the circuit. BUT before I do this wonder if anyone on here has already traced it out? The unit uses an integrated circuit (LD/MB4213) which is still available from China (see attached for datasheet) for the pulse conditioning, thyristor triggering, advance timing etc. The main thyristor (SCR) which dumps the high voltage capacitor charge into the ignition coils is an NEC 3P4MH , which is still available too. There is an additional small thyristor which I suspect may be to do with some kind of limiter or cutout but all will be revealed once I have a circuit diagram. I have not found any component failures yet but there were a few soldered joints which may have been 'dry'. I plan to replace the parts anyway with uprated ones (capacitors particularly), I may even do a new epoxy-glass PCB, as I have been designing and making these most of my career.
Last time I did something like this I was hurled abuse on the CX500 forum with the usual unhelpful comments ... 'why bother ...anorak/nerd, MacGyver etc' twaddle. I have been an engineer in the electronics industry for 40 years and I am always intrigued by these things and the IC they used in this CDi is a new one on me, so I am doing it because I want to ...so no negative comments please.
One of their CDi's packed up and after various aftermarket units and used genuine units failing of not even working, I am tasked with de-potting the original, plotting out the circuit , diagnosing the fault and then repairing/refurbishing.
Luckily, the potting is only semi-hard (probably polyurethane) ...in the past, as part of my 'day job' I have had to de-pot hard epoxy encapsulants using a boil up in a cocktail of solvents including T.H.F. (tetrahydrofuran). This is quite aggressive and can destroy plastic coated parts and their markings, so I decided to not use solvents and just a blunt screwdriver and a kebab wooden skewer.
After several hours whilst watching TV and picking away, I am down to the main PCB, identified and measured most of the component values and gathering data before I sit down and trace out the circuit. BUT before I do this wonder if anyone on here has already traced it out? The unit uses an integrated circuit (LD/MB4213) which is still available from China (see attached for datasheet) for the pulse conditioning, thyristor triggering, advance timing etc. The main thyristor (SCR) which dumps the high voltage capacitor charge into the ignition coils is an NEC 3P4MH , which is still available too. There is an additional small thyristor which I suspect may be to do with some kind of limiter or cutout but all will be revealed once I have a circuit diagram. I have not found any component failures yet but there were a few soldered joints which may have been 'dry'. I plan to replace the parts anyway with uprated ones (capacitors particularly), I may even do a new epoxy-glass PCB, as I have been designing and making these most of my career.
Last time I did something like this I was hurled abuse on the CX500 forum with the usual unhelpful comments ... 'why bother ...anorak/nerd, MacGyver etc' twaddle. I have been an engineer in the electronics industry for 40 years and I am always intrigued by these things and the IC they used in this CDi is a new one on me, so I am doing it because I want to ...so no negative comments please.