I purchased a Meanwell S-350-27 from Hifimediy to power both T1 and T2 amplifiers. When I initially energize the power supply it gives a 27v output but the power quickly drops out. When I deenergize the power supply the output briefly goes back to 27v. I am feeding the amp 120v with the voltage selector switch in the correct position and no load at the output. What is the malfunction?
Generally "YES"
Most SMPS are PWM (Pulse Width Modulated). The SMPS will try to regulate its output by increasing or decreasing the Pulse Width to maintain regulation. If there is no load then, even with the narrowest pulse, the output will rise above the cutoff threshold and the SMPS may shut down.
Try loading the PSU with lightbulbs and see what you get.
You can simply use 110V mains bulbs (within reason).
Most SMPS are PWM (Pulse Width Modulated). The SMPS will try to regulate its output by increasing or decreasing the Pulse Width to maintain regulation. If there is no load then, even with the narrowest pulse, the output will rise above the cutoff threshold and the SMPS may shut down.
Try loading the PSU with lightbulbs and see what you get.
You can simply use 110V mains bulbs (within reason).
Assuming the issue is what Andy mentioned (which is likely) I have a suggestion - I don't know anything about your amps, but I suspect when there is silence, not "sound" of music playing, that they will not place enough of a load on the power supply. Thus, you may need a dummy load, something that just uses enough power to keep the PSU in regulation. The typical method is a power resistor of the appropriate wattage across the PSU leads positive and ground OR positive to ground and negative to ground if a dual rail supply.
I'd go ahead and add the resistor to the PSU itself instead of the amp since it is the PSU not the amp that actually needs it, and once you have it, the PSU should stay on without it hooked up to the amp for testing.
How much load the PSU needs (current drawn) might be in the PSU spec sheet, or the manufacturer might be able to tell you, or if all else fails you can find the value experimentally with a rheostat or parallel or series resistors till you reach a minimum current level needed - aiming for the minimum so there is the least electricity and heat wasted.
I'd go ahead and add the resistor to the PSU itself instead of the amp since it is the PSU not the amp that actually needs it, and once you have it, the PSU should stay on without it hooked up to the amp for testing.
How much load the PSU needs (current drawn) might be in the PSU spec sheet, or the manufacturer might be able to tell you, or if all else fails you can find the value experimentally with a rheostat or parallel or series resistors till you reach a minimum current level needed - aiming for the minimum so there is the least electricity and heat wasted.
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