Bryan Posted September 11, 2018 Report Share Posted September 11, 2018 I have a 24v M20K model that was in avionics today for a firmware upgrade. When they hooked me up to the GPU to supply power, my bus voltage was well below what it needed to be on the GPU at 27-28v. They tested it with the relay open and found several volts dropped just across the relay. With a load, the GPU was unable to keep the voltage up across the relay. What could cause this and how do I get it fixed? Looking at the IPC for my model, 25-2026, it shows a part number: 6041H202A (Solenoid - 24V) for item #26. Is this what is going bad? I would think a solenoid would either work or it wouldn't. Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted September 11, 2018 Report Share Posted September 11, 2018 A solenoid could be closing but have a high resistance from corrosion or arcing, which causes the voltage drop. 1 Quote Link to comment Share on other sites More sharing options...
Yetti Posted September 12, 2018 Report Share Posted September 12, 2018 Never gets used. Corrosion on the contact. maybe plug and unplug GPU several times. Did they check the GPU voltage? Quote Link to comment Share on other sites More sharing options...
Bryan Posted September 12, 2018 Author Report Share Posted September 12, 2018 Yes, we checked the voltage on the plug side of the solenoid and then on the other side. Voltage drop, it seems, inside the solenoid probably what @teejayevans suggested. Quote Link to comment Share on other sites More sharing options...
Yetti Posted September 12, 2018 Report Share Posted September 12, 2018 There are also the GPU pins on the plane side that are pretty well coated with a layer of yuck. You could always take the moment to pull it all apart and make all the connections shiny bright. Bad ground to the airframe could also be causing issues. Electrons flow from Negative to Positive. Quote Link to comment Share on other sites More sharing options...
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