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HELP - Project Speed Controller SE MK2 not working

J

john77

pfm Member
Hi

Hope someone can help, my speed box has gone bang it seems, when I turn it on it just seems to flash where the speed display is (not a steady flash more of a flicker)

So this then only supplies power to the TT in millisecond bursts

Any know what has gone wrong and how to fix or roughly how much to fix

thanks
in advance

John
 
Are all the external connections and power supply o.k? Is it still under guarantee? If so take it back to the dealer. If not try contacting Henley Design the UK distributor, assuming you are in the UK.
 
JADISMAN said:
Are all the external connections and power supply o.k? Is it still under guarantee? If so take it back to the dealer. If not try contacting Henley Design the UK distributor, assuming you are in the UK.
Click to expand...

Thanks for your reply, sadly a few years old now so will have to fix myself, yes every plugged in ok

I will drop H D a line to see what they suggest

Cheers

John
 
From your description, it sounds like a classic switch mode power supply failure.

I would change the electrolytic capacitor(s) between the main filter cap in the primary rectifier section (large, usually around [email protected] rarely fail) and the primary of the high frequency transformer. There is usually one capacitor (maybe 47uf@25-50V) in the inverter or 'chopper' that fails due to the extremely high frequencies involved combined with the temperatures from high parts density. Try that one first.

Other causes of 'the blinks' might be a faulty PWM (pulse width modulation) controller, which is usually an 8-pin chip (either discreet or surface mount), but destruction of these usually results in no output, with no blown fuse and no blinks.

If the switching FET/MOSFET self-destructs, it will always blow the fuse on the supply, so most likely it's not that. Bad caps AFTER the transformer on the output side could also cause the supply to go haywire since the feedback voltage from the output stage doesn't agree with the reference voltage. So, something else to try.

Good luck.
 
Hi Palasr - sorry for the delay been caught up in a house move etc

I will be honest with you that I did not understand a word of it but I have printed it out and will be showing it to someone who will

Many thanks for your help and fingers crossed

Cheers

John
 
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