I have a problem with a SMPS. In my console (Acousta DCA100E) there are two power supplies working in tandem. So when one fails the other is still there as a backup.
I recapped one of them about two month ago with the aim to also recapp the other one soon. Everything worked fine until now.
It started with a high pitch noise coming from the module itself and a non working 5v rail. The high pitch noise would only occur a few seconds after power on and would start like a sweep and then run continuously at a certain frequency.
When I poked around with a wooden chopstick to find out where exactly the noise was coming from I thought to have found the noise source either at the resettable fuse or TVS Diode right next to it as the noise changed. But while touching the two components both main fuses on the transformer board tripped. There is no chance that the two components touched each other or anything else so I don't know what lead to the short.
But I realized that the TVS Diode now had continuity in both directions.
Here is a schematic of the SMPS. Can anybody tell me, what could lead to a shorted TVS Diode or overvoltage?
It's the D13 MPTE5 Diode on the 5V rail.
I know there are bidirectional TVS Diodes but this one is not.
As I understand the purpose of TVS Diodes is to go short when there is to much voltage and to trip the fuse before anything else happens. Is that right?
There is a rail going from the 5V rail just before the fuse and diode to a PWM. Could it be, that this one went bad?
I can not really find burnt spots on the board or anything else suspicious.
Could the fact, that one supply was recapped and the other not be a culprit?
Knowing that newer caps are more efficient than older ones?
I recapped one of them about two month ago with the aim to also recapp the other one soon. Everything worked fine until now.
It started with a high pitch noise coming from the module itself and a non working 5v rail. The high pitch noise would only occur a few seconds after power on and would start like a sweep and then run continuously at a certain frequency.
When I poked around with a wooden chopstick to find out where exactly the noise was coming from I thought to have found the noise source either at the resettable fuse or TVS Diode right next to it as the noise changed. But while touching the two components both main fuses on the transformer board tripped. There is no chance that the two components touched each other or anything else so I don't know what lead to the short.
But I realized that the TVS Diode now had continuity in both directions.
Here is a schematic of the SMPS. Can anybody tell me, what could lead to a shorted TVS Diode or overvoltage?
It's the D13 MPTE5 Diode on the 5V rail.
I know there are bidirectional TVS Diodes but this one is not.
As I understand the purpose of TVS Diodes is to go short when there is to much voltage and to trip the fuse before anything else happens. Is that right?
There is a rail going from the 5V rail just before the fuse and diode to a PWM. Could it be, that this one went bad?
I can not really find burnt spots on the board or anything else suspicious.
Could the fact, that one supply was recapped and the other not be a culprit?
Knowing that newer caps are more efficient than older ones?
