Mackie mixer power supply no power

[R_J]

Re: Mackie mixer power supply no power

It is likely ok, I can't see any real way it could fail as there is very little current in that circuit. probably used to slightly adjust the power supply with temperature. I see values from 2k to 200k for similar ntc or ptc devices.

[garrymc123]

Re: Mackie mixer power supply no power

I've checked the thermister with my multimeter in the ohms selector and this is what i get is this ok

[petehall347]

Re: Mackie mixer power supply no power

heat it and cool it and see if value changes

[budm]

Re: Mackie mixer power supply no power

So did you replace C9 as suggested? What dc V reading between the two legs of that C9?

[garrymc123]

Re: Mackie mixer power supply no power

i will do those checks and let you know

[garrymc123]

Re: Mackie mixer power supply no power

cheers guys Finally got a chance to do some checks on c9 I have 15.35vdc on the optocoupler I have 2.403vdc on the hot side and no voltage on the secondary side and on the thermister, its 99.60hms cold and 24.3ohms hot then rises back to 99.6ohms still to check u100 ic and u101 ..what do u mean by hot ground

[sam_sam_sam]

Re: Mackie mixer power supply no power

Take a very close look a the transformer with the yellow tape on it

In the last photo that was posted it looks like one of the terminals that is to the board does not look very good

or the way the light is hitting it but it looks duller

(and there looks like a lot of flux is there )

than the other terminals that I can see I would recommend resoldering all of the pins for that transformer

I would also think about replacing U100

What is your voltage on the Optic Sensor on the input side which most of the time is pin 1 and 2

[stj]

Re: Mackie mixer power supply no power

so did you change c9?

[garrymc123]

Re: Mackie mixer power supply no power

Thanks, everyone for all your help. STJ was correct all along, new caps arrived today so replaced c9 10uf 50v which was open and now power supply up and working will stick it back in the mixer tomorrow and let you know if it powers up ok ..Thanks Again

[sam_sam_sam]

Re: Mackie mixer power supply no power

It might be a good idea to replace or check all the caps on this board

[garrymc123]

Re: Mackie mixer power supply no power

cheers I have checked the other caps and all seem to be within spec I have plugged the power supply back in the mixer and it has powered up ok.. I will let it run for a couple of hours and just to be sure..thanks to everyone again for there help and advice

[sam_sam_sam]

Re: Mackie mixer power supply no power

I am glad that you got it working again

[check12]

Re: Mackie mixer power supply no power

Great you got it going ..what happened with your two behringer desks Garry?