Re: Enermax Platimax
Oh okay, that looks normal for when the APFC circuit is not running.
Correct, the TOP267 is for the 5VSB (it's an off-line switch, so always expect it to be used for 5VSB/standby PS when you open a PSU with one of these chips.)
Yeah, that's normal for many companies nowadays. Forget the service manual. Just download the TOP267 chip datasheet. The 5VSB circuit in your PSU should look pretty close to what is in the Typical Application schematic in the datasheet.
That said, the first things to check out would be the voltage on the "V" pin of the TOP267. This is what powers the TOPSWITCH IC. Without it, the TOP267 wouldn't work. Typically, you have a resistor network from the "+" of the big cap (the 320V DC you measured) going through a resistor network (2 or 3 series resistors) and then connecting to the "V" pin. Check these resistors to make sure they are not open-circuit. Usually they have a high resistance value of 100 KOhms (according to the datasheet, they even use 2x 5.1 MegaOhm.)
Next, there will also be a primary-side auxiliary winding on the 5VSB transformer. This winding is connected to HOT ground on one side (the negative lead of the big cap) and the other side of that winding gets rectified through a diode and then also feeds into the "V" pin of the TOP267. Some designs also opt to put a series resistor or Zener diode before or after this diode. But in any case, the pri.-side aux. winding is what provides power to the TOPSWITCH IC after it starts running. So with that said, check the rectifying diode on the pri.-side aux. winding, as well as any series resistors or Zener diodes attached to it.
If everything checks out okay, measure the voltage on the "V" pin on the TOPSWITCH with respect to HOT ground and post it here. See if it is fluctuating or steady too.
Last but not least, also make sure the output rectifier (diode) on the 5VSB is not shorted and that the 5VSB line itself is not shorted to ground due to some other component.
Keep us posted what you find with these suggestions.
*EDIT*
found the TOP267 datasheet here:
https://cdn.badcaps-static.com/pdfs/...10aeaa6766.pdf
Originally posted by madan1
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Originally posted by madan1
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Originally posted by madan1
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That said, the first things to check out would be the voltage on the "V" pin of the TOP267. This is what powers the TOPSWITCH IC. Without it, the TOP267 wouldn't work. Typically, you have a resistor network from the "+" of the big cap (the 320V DC you measured) going through a resistor network (2 or 3 series resistors) and then connecting to the "V" pin. Check these resistors to make sure they are not open-circuit. Usually they have a high resistance value of 100 KOhms (according to the datasheet, they even use 2x 5.1 MegaOhm.)
Next, there will also be a primary-side auxiliary winding on the 5VSB transformer. This winding is connected to HOT ground on one side (the negative lead of the big cap) and the other side of that winding gets rectified through a diode and then also feeds into the "V" pin of the TOP267. Some designs also opt to put a series resistor or Zener diode before or after this diode. But in any case, the pri.-side aux. winding is what provides power to the TOPSWITCH IC after it starts running. So with that said, check the rectifying diode on the pri.-side aux. winding, as well as any series resistors or Zener diodes attached to it.
If everything checks out okay, measure the voltage on the "V" pin on the TOPSWITCH with respect to HOT ground and post it here. See if it is fluctuating or steady too.
Last but not least, also make sure the output rectifier (diode) on the 5VSB is not shorted and that the 5VSB line itself is not shorted to ground due to some other component.
Keep us posted what you find with these suggestions.
*EDIT*
found the TOP267 datasheet here:
https://cdn.badcaps-static.com/pdfs/...10aeaa6766.pdf
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