Discussion Category: Centrifuge
beckman coulter j2-21m cooling on start up
Hello,
New to the forum. Any ideas as to how to solve cooling on start up of Beckman J2-21M centrifuge? This happened out of the blue; everything was working fine one day, then all of a sudden cooling kicks in on start up no matter what temperature is selected and continues until unit is turned off.
Is it advisable to remove relay by the black box near the AC compressor to stop cooling?
Thanks,
Jenner
Reply byJenner, If the compressor comes on and stays on then chances are that the solid state relay U701 on the power supply may be defective and is keeping the refrigeration solenoid energized or the SSR is receiving a signal to turn on and stay on and if that is the case then you have circuit board issues. Pin 3 of the relay is tied to +12 volts and it gets the return signal on pin 4 so if pin 4 is at or near ground all of the time then there is an issue with the backplane board. If not then the relay itself is probably defective. There have been issues with those relays as I carried them in my car stock all of the time. get back to me and let me know what you find and NO, do not disconnect anything or you will not have any cooling at all.
Don
Reply byDon,
Appreciate your input. I'll check your suggestions out with the help of an electrician and respond on findings. From your last sentence, if the relay is unplugged, there will be no cooling, but the centrifuge will run? We don't really use cooling much.
Thanks again,
Jenner
Reply byI understand that you may not need cooling very much but depending on what rotor you are using and the speed at which you are running it at may cause significant rotor heating but without that information there is nothing else that I can add as to whether or not you need it.
Don
Reply byLong delay here - our electronics person was able to check out your suggestions. He believes the problem lies in the circuit board as you state. Is there a schematic available? Thanks.