h machine-changed the function board got a cond ref error could not calibrate had to put in old function board to get all data back-?????????

Did you transfer the original data RAM chip over to the new functional bd. when you initially changed it out?

BTW.....that's IC #5 (RAM) - in case you weren't sure!

yes, still gave me the error-tried to calibrate -low flow error-which was the problem to begin with

Were you initially replacing the functional bd. for a low flow error? .....If that is the case, (of course I could be wrong since I don't know what all you have done), - I would wager that your low flow error problem is in the hydraulics. It's much less common for a low flow error to be a functional bd. problem -(if that was even why you were replacing it to begin with???)

i also had a 24 volt low error

Does the 24V low error come up as soon as you power the machine up?....If so, try unplugging the dear and flow motors before powering up and see if the 24V alarm goes away.
It could be anything that operates on 24 volts that causing the alarm, - which includes all your valves and modules.

that problem is gone, now i have the low flow again-i'll try the hydraulics

You can also check the voltages at the 12V converter bd. (small bd. front left side of motherboard) 24V-A is pwr for Display panel, 24V-B is pwe for Hydraulics, and 24V-C is pwr for the modules. Whichever one of these is low, -will be where the problem is. Hope that helps some! Let us know what you find.

Tech159,
Let us know what all you have tried and checked and maybe someone can give you some pointers.

-Are you going by the trouble-shooting guide?
-Is the problem in dialysis mode only, rinse or disnifect mode as well?
- Have you checked for Loading, deaer. and flow pressures?
-Is there any drain flow?
-Have you checked for any valve errors in debug screen #5 and #17?