13-04-2013, 08:59 AM
Hello once again Colin, well when I fixed my friends board I couldn't find any signs of burning or horrible smells either.The symptom were just the same as yours. Its a long time ago but I put the numbers/marking up in google and it came up Mosfets, so I ordered higher rating both in current and voltage from RS and soldered them in position. Mosfets are now protected against static discharge or so the manufactures say. I have used a fair few without any problems, I make my own speed controllers for my 5" gauge battery powered locos using 4 Mosfets in parallel.I have simple little circuit for testing Mosfets using just a car head light bulb and battery and another using a 555 timer in a PWM circuit.I've been thinking (it does happen from time to time) I wonder if your motor would run from a 12 or 24 volt DC supply, give it a try using your car battery,no harm done.Have a look at the commutator segments if they are quite wide that is an indication that it is actually low voltage.If you have ever seen a vacuum cleaner or drill com that will give you another possible indication of the armature/ motor running voltage. There are quite a few different possible mode of motor control, you might go down the Kenwood food mixer route using a Triac and diac. Derrick board const about £100 if I remember correctly,not cheap.If you send me a PM with your email address I'll send you some diagrams.Suns out got to get down the workshop.Ted
