Hi folks
I am trying to repair a SMPS that came from a Martin Ego x5 Disco light
From what evidence I can see this unit has had some sort of fluid get into it at some time. It is dead. No power.
Actually if you power it up you do have 350V DC on the mains bridge but that dissapears as soon as you turn it off, and there are no low voltage outputs
I think I have traced the problem down to two components on the PSU
These are marked as R3N and R46
I imagine they are drivers for the output stage which consists of two IRFP460A
At first I thought the IRFP460A were short circuit, but having removed one of them it checked OK on the Atlas DCA as a N Channel Enhancement MosFET
There are two pairs of these R3N/R46 devices and one pair seems to be short circuit
I lifted the legs on what appear to be the good pair and they test on myAtlas DCA as R3N = NPN Bipolar Transistor and R46 = PNP Bipolar Transistor
I lift the legs on the other pair and they are R3N short circut base-emitter and R46 short circuit collector-emitter
I can't see any other obviosuly (visibly) damaged components and with these legs lifted the short circuits around the second IRFP460 have gone away so it is probably good though i haven't pulled it to test on the DCA yet
Problem is I can't find any info/datasheet for the R3N and R46 devices???????
Can anyone please help - see pics attached
I powered up the light unit from my 5V/12V bench PSU (without the bulb fitted as it needs 24V 250W from the PSU) and the unit went through it's power on self check OK and appeared to start operating so I suspect everything else still works OK
Rich
PS - there is something very odd (to me) about this Switch Mode PSU - it doesn't have any large electrolytic(s) on the 350V DC rail coming out of the mains bridge rectifier!!- see last pic. Is that weird or what?
I am trying to repair a SMPS that came from a Martin Ego x5 Disco light
From what evidence I can see this unit has had some sort of fluid get into it at some time. It is dead. No power.
Actually if you power it up you do have 350V DC on the mains bridge but that dissapears as soon as you turn it off, and there are no low voltage outputs
I think I have traced the problem down to two components on the PSU
These are marked as R3N and R46
I imagine they are drivers for the output stage which consists of two IRFP460A
At first I thought the IRFP460A were short circuit, but having removed one of them it checked OK on the Atlas DCA as a N Channel Enhancement MosFET
There are two pairs of these R3N/R46 devices and one pair seems to be short circuit
I lifted the legs on what appear to be the good pair and they test on myAtlas DCA as R3N = NPN Bipolar Transistor and R46 = PNP Bipolar Transistor
I lift the legs on the other pair and they are R3N short circut base-emitter and R46 short circuit collector-emitter
I can't see any other obviosuly (visibly) damaged components and with these legs lifted the short circuits around the second IRFP460 have gone away so it is probably good though i haven't pulled it to test on the DCA yet
Problem is I can't find any info/datasheet for the R3N and R46 devices???????
Can anyone please help - see pics attached
I powered up the light unit from my 5V/12V bench PSU (without the bulb fitted as it needs 24V 250W from the PSU) and the unit went through it's power on self check OK and appeared to start operating so I suspect everything else still works OK
Rich
PS - there is something very odd (to me) about this Switch Mode PSU - it doesn't have any large electrolytic(s) on the 350V DC rail coming out of the mains bridge rectifier!!- see last pic. Is that weird or what?