Behringer SPS1000 shuts down when disconnected from PA

[Luis_vxd]

I have checked C16 and C20 earlier and both are good.

[x-pro]

Any switching power supply is an oscillator. It doesn't matter what waveform is at its output. It is rectified by a diode and stored in a capacitor. You get the required DC voltage.

[x-pro]

So. Disconnect R8, connect a 51-100 ohm 5 watt resistor to C18. Connect a voltmeter there. Connect the UPS to ic2.
To be safe, unsolder one of R11,R12.

[Luis_vxd]

That's my overall simple understanding and that's why I asked for help.

[Luis_vxd]

Итак. Отключите r8, подключите резистор 51-100 Ом 5 Вт к c18. Подключите туда вольтметр. Подключите ИБП к ic2.

English please..

[Luis_vxd]

Connect the UPS to ic2

Please clarify.

[x-pro]

The translator is so arbitrary. I have to write then convert twice.
Put power to IC2.

[Luis_vxd]

Good morning

I will not be able to do anything until later in the afternoon.

If I understood correctly you suggested to remove R8 and connect a 51.. 100 Ohm 5W resistor to C18. This resistor will be connected one side to C18 and the other side? Is it replacing R8? And the voltmeter?

Thanks

[x-pro]

This resistor should be in parallel with C18. it will be a load.

[x-pro]

We need to find out why the UPS on IC2 turns off.

[Luis_vxd]

I have removed R8 and R11, solder a 62 Ohms 5W resistor (what I had) across C12, turned the SMPS on. Voltage across the new resistor was unmeasurable as you have explained. A few seconds later IC2 stopped working. Same behavior as before.

[x-pro]

Check all items related to IC2. They are D4, D26, R31, R30, C48, C49. Is D7 serviceable? Try replacing C16 or solder a different capacitor to C16, 2.2uF-10uF 400V capacitance!
If that doesn't change anything, then you need to change IC2. It may be degraded.

[Luis_vxd]

Replaced IC2 and the SMPS is working well.

Thank you so much for your support and patience.