Mackie ppm1008

[clintronics]

I have the schematic but they didnt include what are the measurements at the test points on the power supply. My U1 burned, I replaced it but its still inop. Anyone have test points?

[mozwell]

switch-mode supply, check all mains side transistors & diodes (mains off & any DC bus capacitors discharged), and all secondary side diodes.
Power up through a light bulb limiter until we can work out the supply is ok.

schematics attached so others can see what to measure & where.....

[clintronics]

I have the schematic but they didnt include what are the measurements at the test points on the power supply. My U1 burned, I replaced it but its still inop. Anyone have the test points measurements? <corrected> mainly tp11,13, 14. tp7,8,9,10

[mozwell]

TP7 is a gate drive, so +15V when the mosfet is turned on, 0V or -15V (or so) when the mosfet is turned off, switching freq >20kHz
TP8 is the 0V reference for TP7
TP9, TP10, as for TP7 & 8
TP11 should be somewhere between 12VDC and 20VDC (from C25 which is a 25V cap)
TP13 and TP14 are a drive for the primary of T2, this runs from the voltage of TP11, so i would expect a square wave of polarity + and - whatever voltage you measure on TP11

Clint, (not knowing your technical expertise) may i suggest a warning here, ALL the parts on the primary side are at mains supply voltage, do NOT hook an earthed scope lead to test-points, unless you know what you are doing, you can very easily get a severe electric shock from the primary side of a switch mode power supply.

A switch mode supply will have current limit, so if one of the outputs is shorted, the supply may not start up properly, and it will look like it is dead.
With mains power off, and the DC bus caps discharged Check all the primary side diodes & mosfets, and all the secondary side diodes.
You can also unplug the outputs of the power supply & see if the supply starts up, it may be a dead mixer board, or power amp board pulling the power supply output down, making you think the supply is dead......

[clintronics]

Thx for the help mozwell, looks like U1 blown and D24 shorted. I dont have this diode in stock so I wont know if thats all for a few days.

[ratlordfx]

Hey there, I have a PPM1008 power supply on my bench right now, and when I apply power I get an audible ticking at capacitor C51. I am going to discharge everything and check the diodes and mosfets now, but does anybody have an idea of what this could be?

[clintronics]

Its probably a shorted fet or diode like mozwell said.

[ratlordfx]

Its probably a shorted fet or diode like mozwell said.

D23 was the culprit. Ordered some replacements and a KA3525A just in case its bad too.

How do I know if that chip is bad?

Thanks,
Jason