Samsung sf 650 displays rd and then turns on and off by itself continuosly

Should be some answers here for you. Good luck.
https://support.hp.com/ca-en/drivers/selfservice/samsung-sf-650-laser-multifunction-printer-series/17157193

The copy density has been set too high or the scan has been set too dark.

unplug power cord for 5 minutes and then plug it back in

Start whit your power supply. need to be replaced. had that problem a few times. it is almost nerver the mainboard

Check the cartridge and for a paper jam in front of fax.

"Can the Samsung SF-650 A4 LaserJet Printer & Fax With Handset be used as a printer?"

I'm not being cute, but a USB port must be present. :)

If you don't see one, then the answer is no.

Print configuration report "Menu>Reports>Configuration/System Data"
Check the firmware version. 1.07 or lower is likely to have this problem
Upgrading the firmware is quite simple.
Get the update from samsung website Samsung.com>Support>Search Box "SF-650">on product support page find tab "firmware" and download upgrade file.
If you feel competent to do the upgrade (read the instructions in the txt file twice) do it.

Be aware that the upgrade will likely want to do a memory clear once it is complete so you will loose address book etc. Also do not power off unit during upgrade or you will damage the firmware and possibly make the unit unusable.

Hope this fixes the issue.

you can get the driver from this following link,just click on any of the link below and i downloading will be display, follow all the instruction in download the drivers
www.fixya.com/.../t784067-printer_drivers_samsung_sf_560r
www.printcountry.com/drivers/SAMSUNG_SF_560_DRIVER_DOWNLOAD
www.bioticaindia.com/sf-560r
forums.driverguide.com/showthread.
www.toggle.com/lv/group/.../Samsung_SF-560_Printer_driver
www.giveawayoftheday.com/samsung+sf+560+print+driver
www.ps2netdrivers.net/manual/samsung.sf-560
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sound like its trying to tell you
R refridgerator compartment
D defrost

have a look at this samsung fridge freezer problem youtube channel

here's a link to the user guide to download:
http://www.samsung.com/us/support/search/supportSearchResultView.do?group=&group_cd=&type=&type_cd=&subtype=&subtype_cd=&model_nm=&dType=&mType=&model_cd=&menu=download&prd_ia_cd=&disp_nm=SF-560R&isEqualsY=Y