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Eppendorf 5417R Centifuge - flashing LED's on Open and Soft buttons

avatar: JohnE47
JohnE47
12 posts
Replied to JohnE47's post on August 18th, 2016

I have been asked to look at a Eppendorf 5417R centrifuge which when switched on, LED's are flashing on the "Open" and "Soft" buttons.

There is nothing showing on the digital display.

When the power is turned off, the above button LED's are still flashing for about 20 seconds, then they turn off.

Any ideas anyone?

Thanks

avatar: medphysteo
medphysteo
239 posts
Replied to JohnE47's post on October 7th, 2016

That's a new one. The lamps staying on for 20sec after power off may not be unusual - Eppendorfs are like that.

Did this start during a run? Was there a power failure? Is the lid closed? Can you open the lid with the Open key? If it's closed and the open key doesn't work, use the manual release - it's a white nylon plug on the underside of the front left corner of the base. Pry it out and pull the string. See if you get any change on the display, cycle the power/plug.

I'm off til Tuesday, so I won't be able to follow up til then. There are user and service manuals in the Documents tab of the product info page - hope they can help. (http://www.labwrench.com/?equipment.view/equipmentNo/2420/EPPENDORF/5417-R/display/manuals/)

avatar: JohnE47
JohnE47
12 posts
Replied to medphysteo's post on October 10th, 2016

Thank you for your reply.

As my original post was nearly 2 months ago, I asked my client to contact Eppendorf Service. I have not heard back from them.

I did look at the service manual, but did not find any solution.

avatar: wbeaty
wbeaty
18 posts
Replied to JohnE47's post on August 11th, 2017

That's a typical fail.   The main switching supply (and the +5VDC output) are constantly re-starting, because the bootstrap capacitor has lost too many uF from overheating and old age.   Putting that capacitor too close to a hot MOSFET is a design flaw.

In my unit here it's a tiny 22uF 35V capacitor found near the UC2844AD switching supply IC.   That cap is supposed to apply around 20V to the chip for startup.  But in mine the capacitor value has been baked down to 4.5uF, not 22uF.   The momentary supply voltage falls too rapidly down to 10V, and the chip shuts down before the main supply can rise above 16V.  Then the whole cycle repeats.

The actual symptom is...  the centrifuge works fine for months, but then someone turns off the power, or perhaps there's a momentary outage.  The unit can't ever wake up again, since it's power-start system has gone bad.  (Sometimes these units will start up if you unplug the LCD/buttons cable, turn on power, then plug the cable back in.  But this requires removing the plastic case!)

Yes, the LEDs keep blinking when 120VAC is removed, since the system wattage is tiny during startup.  It's running off the HV stored by the big filter capacitors.