Missing capacitor ( what will i replace it with )

[garrymc123]

Hi there i have received a disco light power board for repair but someone has been here before me and removed the fuse and a capacitor c3 ive got the fuse no problem but unsure what size or kind of cap it should be there any ideas

thanks in advance

[R_J]

Re: Missing capacitor ( what will i replace it with )

It is most likely the same as the blue one (c4?) next to it. It should be fine to try without that cap. They are just the x & y capacitors, Looks like C4 goes across the line and C3 goes from line to ground

[budm]

Re: Missing capacitor ( what will i replace it with )

It is most likely the same as the blue one (c4?) next to it

+1, it is X/Y safety cap for EMI and it will not affect the operation of the unit.

[R_J]

Re: Missing capacitor ( what will i replace it with )

My money is on bad U2 that blew the fuse

[garrymc123]

Re: Missing capacitor ( what will i replace it with )

thanks for your reply's how would i test the u2 chip thanks in advance

[R_J]

Re: Missing capacitor ( what will i replace it with )

Easiest way, put in a fuse, I cant make out the ic number

[budm]

Re: Missing capacitor ( what will i replace it with )

Check R17 (1R2) Source pin resistor for that SMPS U2 IC to see if it is still show around 1.2 Ohms.
Also check resistance between Pin 4 (S) and pin 5/6 (D) of U2 to see if it shows a shorted circuit.
It is best to get the U2 spec to verify my pin out.

[stj]

Re: Missing capacitor ( what will i replace it with )

check the bridge diodes first - because they are the first thing power passes through.

[garrymc123]

Re: Missing capacitor ( what will i replace it with )

Hi guys thanks for your reply's checked diodes all good at 0.583 one way R17 1.3 ohms and no short between ic at pins 4 to 5/6 t reads 0.559 one way anything else i should check before putting the fuse in and trying it

[stj]

Re: Missing capacitor ( what will i replace it with )

inline lamp trick?

[garrymc123]

Re: Missing capacitor ( what will i replace it with )

Thanks stj.. how is it you do again I've got a fair idea but just want to be sure before I do it. All info is much appreciated. Thanks