Hey everyone,

I was wondering if anyone has seen a K machine running through test fail actuator temp low hard only. It seems that the temperature dips down to trip low alarm, but won't reset to current temperature from low hard drop (out of alarm condition). Tried swapping all boards in cardcage (utilizing T+C mode for sensor bd) but still failing temp low hard only. Tried NTC-2 and NTC-3, and heater rod due to DAC needing to be set for about 70 to achieve 37 degree stability, which I have never had to go lower than about 110 DAC. Any suggestions? Thanks

70 for the DAC value is also lower than I have ever seen also. Check the deair and flow motor pressures, and the deair orifice. Did you just change down to the 70 DAC, or was that the value that was set in the machine when it came in? At when it is set at 70 will the machine maintain the 37 degrees on the independent meter and the machine display after it fails the test?

It had to be changed to 70 to calibate to 37 degrees. After calibration, it runs a little high (37.4-37.5 degrees), had me thinking calibration not holding (possibly IC20- Function Bd.) Eventually, after it fails low hard it comes back up for high soft and low soft and passes both. Meter and display agree after test. It's strange because it trips low hard alarm but doesn't seem to want to reset to pre alarm state temperature, pretty much like when the blood pump bd. LP955 fails, blood pump won't start back up after tripping alarm condition. In this case, temperature won't come back up after tripping low hard. Thanks for help, will recheck pressures on pumps and orifice o-ring tomorrow.

Have you checked the Actuator and Sensor Board ribbon wires? If you have spares try swapping in those over the top of the machine(they are both long enough to this) without actually installing them, maybe one has been damaged (usually right in the fold over the sharp corner of the board) and you may not be able to see it well. If that isn't it, I wonder about power supply issues like the triac or the power control board. If you have a spare power supply you can also put it on the top of the machine and temporarily install it to see if it resolves the problem. The power logic,heater, and rainbow wires are all long enough to reach the power supply whenn it is sitting on top of the machine. And, one last thing, and don't take this wrong, it sounds like you are experienced and knowledgeable. When you do the K machine temperature control calibration and you change the DAC value you have to confirm that DAC value. You do not have to that with an H machine, so it takes some getting used to if you work on both machines. The machine leads you through this step by step, but the screen does not say Confirm at that point, and it will not acutually change, and may go back to the default value (125?)or the original set or calibrated value. And the 37.5 temperature is suspect, that is the temperature that we see on machines that have been calibrated and someone has not matched the meter and the screen to 37.0 at the end of the cal. Sometimes that happens with the K's because when you confirm the DAC value during a change it is very easy to hit confirm twice and move one step further along the process then you want to be. That is the difference between the interior temperature at the sensor and the temp at the independent meter which is outside of the machine. The temperature loss through the hoses is about .5 or .6 degrees, and obviously you want the temp at the dialyzer where the blood is exposed to it to be 37.0, not the interior of the machine. Good Luck!!

This message has been edited. Last edited by: Ktech,

Ktech,
I believe your mistaken about the heater bar wiring. I'd be completely amazed if you can get the heater bar to work with just only one wire hooked up. The brown wire is your hot wire and the blue wire is your neutral,...-they are both needed or you won't have a complete current path for it to work.

Yeah, I was not thinking, maybe not enough caffeine, yet! I just deleted that portion of my previous reply!

I have a K that gives a similar result. Calibrates to 37.0 with a DAC of 197. Heater is 11ohms and physically perfect, replaced NTC-2 and NTC-3, functional board, sensor board, test board, powerlogic board, actuator board, actuator cable, sensor cable all from working machine. Calibrated flow, calibrated dearation and loading pressures. Machine runs stable at 37.0, reaches 84 in heat disinfect. Conductivity stable at 13.8 (with a 2.25k concentrate set to 140 and 40). ACTUATOR * TEMPERATURE LOW FAILURE comes up during alarm tests, but while watching the debug screen 5 during alarm tests, temperature drops and recovers as it should when compared to another machine. All tests and calibrations done with covers on, using fresh acid and bicarb. Verified with two independent external meters (Neo-1 and a Neo-2). Anyone?????