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Relay 5v wont go off

Posted by mnikola2 
Relay 5v wont go off
January 26, 2024 06:53PM
Hello! Im using simple 1channel relay module to turn on/off 400w led psu using SKR 1.4t board and external 5v psu. Everything start working from start but.. not! G80 code trigger relay normaly,there is click sound, green led on, PSU start. Later G81, green led go off, click sound but PSU stay on working. When i turn everything off and unplug, ohm meter reading show terminals are still connected like they are triggered. Is is posible that PSU is too strong to relay (fake 10A 250VAC?) so it welded contact inside relay? I tried another similar cheap relay, i got same result, there is clicking sound, wont go off, psu stay forever ON. I tried different things, nothing work and im out of ideas :/ Any suggestions,tips,work around? Tnx in forward!
Relay im using is same as on image.
Attachments:
open | download - rlay.jpg (49.4 KB)
Re: Relay 5v wont go off
January 28, 2024 03:14PM
Update: Tried another 5v relay, same thing.. tried 3v relay, same thing.. PS_ON pin on skr 1.4t give 0-3.3v which is enough for actuating 5v relay. I tested it outside circuit and it clicks, work but.. when i put led psu on COM-NO it wont go off and COM-NO stay closed even if everyting ih switched off. I have no solution, lost 3 days banging head what could be wrong here! Best regards
VDX
Re: Relay 5v wont go off
January 28, 2024 04:04PM
... look into the datasheet for common use/schematics -- sometimes you'll need resistors or a specific polarity of the transistor/mosfet ...


Viktor
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Re: Relay 5v wont go off
January 28, 2024 05:18PM
Tested another 5v relay but now using arduino, it work perfect. So it was not problem with something like high inrush current of PS and cheap relay. It has something to do with SKR 1.4t board but im not sure what they hell. It gives normal reading from pwrdet: 5v,gnd,1.0(PS_ON around 3.3v) but more mistery is why after everything off, relay is still closed and not returned to position.

Edited 1 time(s). Last edit at 01/28/2024 05:18PM by mnikola2.
Re: Relay 5v wont go off
February 01, 2024 11:54AM
Solution to problem for people with skr boards.
PS_ON pin on skr 1.4t give "weak" power so i used simple npn transistor as switch between relay + and Signal in. Weak PS_ON from skr board is applied to npn transistor base. It work normal now. Thnx anyway. Lock
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