Hi All,
I am halfway through the repair of an Allen and Heath MPS14 and have reached point where I am stuck. I am not at all an expert in SMPS. Currently the issue seems to be on the primary side. R13, R76 and TR1 all get extremely hot under load after about 10 secs. When switching the power supply on Cold (supply caps drained) a screeching sound can be heard as the supply ramps up over 1 - 2 seconds then the sound stops. Hard to pin point which component is making the noise. I have an identical working supply which rules out the console as the issue and does not scream / ramp-up on power up. The issue looks to be in the PFC, I could be wrong.
I have attached the schematic below, can provide any information required.
The Supply does operate and supplies all the correct rails. The rapid heating of the mentioned components does not occur in the working supply.
I have replaced all the electrolytic Capacitors as a matter course.
Thanks any help appreciated.
I am halfway through the repair of an Allen and Heath MPS14 and have reached point where I am stuck. I am not at all an expert in SMPS. Currently the issue seems to be on the primary side. R13, R76 and TR1 all get extremely hot under load after about 10 secs. When switching the power supply on Cold (supply caps drained) a screeching sound can be heard as the supply ramps up over 1 - 2 seconds then the sound stops. Hard to pin point which component is making the noise. I have an identical working supply which rules out the console as the issue and does not scream / ramp-up on power up. The issue looks to be in the PFC, I could be wrong.
I have attached the schematic below, can provide any information required.
The Supply does operate and supplies all the correct rails. The rapid heating of the mentioned components does not occur in the working supply.
I have replaced all the electrolytic Capacitors as a matter course.
Thanks any help appreciated.