Discussion Category: Centrifuge
J2-MI lid release
Hi Don,
I’ve got a J2-MI that won’t release the lid, except manually through the emergency access hole. The solenoid that releases the latch handle doesn’t operate, though it does move freely by hand. I also noticed the motor won’t start. Everything functions on the operator panel, but when I press start nothing happens with the drive. The timer begins counting down, but then gives a “Speed” error after about 15 seconds. The drive belt is ok, the safety connector is joined, and the motor turns freely by hand. The lid switch is secure and ohms out good, and I can hear it click over when the lid eyebolt contacts it. The compressor runs with the lid open. Does the high voltage board discussion on the recent J2-21 thread apply here as well?
Jeff
Reply byHi Don,
I finally got around to replacing all the IC's but noticed that two of the H11A1 optoisolators have pin 6 broken off. There are six of these on the board so I'm guessing they're specific to motor phasing. Do you recall anything about that? It appears to be deliberate (i.e., the two chips aren't blown) even though neither one appears to use that pin in circuit.
Jeff
Reply byThe H11A1 IC's are optical isolation chips and it was not unusual for Beckman design engineers to remove pins from IC's that were not going to be soldered. Go figure but it's just what they did.
Where are you at lotherwise with any of the centrifuge issues that you have had?
Don
Reply byHi Don,
I went ahead and broke off the pins on the new isolators and reinstalled the board with all new chips - no help.
Jeff
Reply byJeff, The one thing that I did not ask is what does your 24 volts DC look like? The door latch runs off of 24 volts so if it isn't working then nothing is going to work. The power supply is located inside of the back panel of the centrifuge and once you drop that panel you will have complete access to check things out. Unlike the old analog centrifuges that tapped off of the 24 volts for all other voltages, the J2M series has separate power supplies so you may just have a bad regulator. Check it out and let me know.
Don
Reply byHi Don,
The power supply is at the top right corner of the back, with a transformer and a couple of big blue electrolytics? (they don't looked cooked)
I checked the 4-pin interconnect block in the door switch circuit inside the front panel for 24V (looked easier). There is 6V across the two sockets and 0.3V across the two pins. Looking down on it with the sockets on the bottom, there is 6V across the left socket and pin, and 0.3V across the right socket and pin.
Jeff
Reply byJeff, You need to check the +24 volts right on the power supply. If it's not there then it's not going to be anywhere. All of the system voltages are generated on the power supply so start right there. It sure sounds as if you have some kind of issue going on there. I don't remember ever replacing any caps on the PS but anything is possible.
Don
Reply byWell I've never seen the back side of a regulator in circuit before - I wondered where those wires were going. :)
+24 is 23.74, fluctuating +/- 0.05.
+5 is 4.86,
+12 is 12.16,
-12 is -11.92,
-30 is -31.55.
Jeff
Reply byDon,
Is there anything more I can look at here?
Jeff
Reply byJeff, Your power supply voltages are all within spec's, especially considering that there are no adjustments possible. It would appear that you still have some kind of interlock issue going on but without my prints, I'm dead in the water. However, I will be back at my old stomping grounds at the end of this week and I'll see if I can't come up with my old service manual in order to help you out. I can see the storage bin that it is in but I will have to do some lifting in order to actually get to it again so if you can, bear with me a few more days.
Don
Reply bySounds good Don, thanks!
Jeff