Help needed with XW MPPT 80/600

[geo62]

Hello.
New here. I need some help with a problem i have on the XW MPPT 80/600 CC
The controler came up with F79. F75, F55 etc faults.
All related to temprature issues.
Inside the controler is using three NTC probes for temprature control.
Two on the top for the power tranzistors and one on bottom for the diodes.
The top ones are reading at 67Kohm @ 25c and the bottom one 100Kohm
Has anyone ever checked the vales of these?
I intend to buy new ones to replece all of them but i'm not sure what to order!
Thanks
George

 

[400bird]

From the manual I just googled:
F55: Heat sink over temp
F75: Fan over voltage fault
F79: Fan over current

Considering only one of the 3 faults you listed is directly related to a thermister, I'd suspect there was some power or ground in common causing these faults. Maybe you lost 5 volt or 3.3 volt reference for the measuring circuit on all these?

Sorry, I don't have a known good value for those thermistors. Please continue to share what you find!

 

[geo62]

I have got a second hand replacemend and i was able to check the values of the thermistors and they seem to be good!
The XW 80/600 has one thermistor checking the temp off the six diodes on the bottom of the unit this must be in the 100Kohm
Two thermistors are on the top cheking a twin array of power transistors and these are in 60Kohm range.
The funny thing is that when i tryed to replace the lower NTC i used a 20Kohm one in series with a pod to adjust the resistance until the unit started to work fine that was around 45 Kohm.
So there must be a problem with the circuit that reads the value of the NTC
I dont have knolege on electronics my backround is electrical and A/C
Not shure what to do next as here in South Australia are no repair centres or suport!
Thanks