NicoN Posted June 2, 2019 Report Posted June 2, 2019 Our 1980 M20K has a Century 21 A/P with a DG installed. Seems to be that INstrument: 52D54 The Horizon above it is definitvely lighted, but the DG is dark. I found a wire near the DG which is hooked to the instrument lighting, But I do not find a connection diagram for this DG. May be, the DG has simply no lighting. I am not sure. Nobody of my co-owners has it seen with working light, but they are asking for repair. Has somebody an idea on the wiring and technical details ? Quote
carusoam Posted June 2, 2019 Report Posted June 2, 2019 It’s been a while and no advice has been offered yet... so maybe, some less technical discussion may be helpful... PP thoughts on instrument lighting... not an instrument technician. The Modern Mooneys typically got IFR panels that are capable of night IFR... The Best way to handle this requirement was to use individual instruments with internal lighting... The next best way was to use individual post lights... There aren’t any less important instruments that would get no light for flying in the dark. If your ASI is internally lit, compass is internally lit, Expect that the DG is most likely internally lit... unless something has changed. Looking up the DG that you mentioned.... https://sarasotaavionics.com/avionics/4000c-52d54 They don’t mention anything about lighting on those pages.... Most modern instruments come in various versions... voltage required and internally lit are important options... as are AP outputs and things like that... You will be able to look up the exact model number of the DG and compare it to data on the internet... this should tell if it has a light bulb inside of it. Often instrument lights are separate from all the other wires used to make it operate. You might see the same wire going to the back of each lit instrument.... In the earlier Mooneys, each instrument or post light was wired to one spot behind the panel... a dimmer supplied voltage to that spot, and individual wires brought the dimmed voltage to the instrument... How complex changing the bulb out of an individual instrument? Could be easy, might require an instrument shop... For some reason, instrument builders have made this bulb opportunity as expensive and challenging as possible... Can you find what the part number of the DG is from your POH? If it was added to the plane later, it should be listed in the logs... it sounds like the original DG or HSI May have been changed out for something with no bulb in it... The K instrument panel is electrically more complex than J and earlier models... but, the wiring diagrams are available in the maintenance manuals... Find the dimmer knobs and see where they go... (in the diagrams) In older Mooneys, lights mounted at the top of the cabin were pointed towards the instrument panel... mostly because internal lighting for instruments was widely available to us... Briefly, dark instrument, and wire that looks like it might deliver electricity to a bulb in the instrument... find out what that wire is, what is at the other end... it’s probably connected to a post that all the other instruments are connected to... check the voltage there and twist the dimmer switch... if the voltage changes with the dimmer switch you have most of the answer... Was this at all helpful? PP thoughts only, not an instrument tech. Best regards, -a- Quote
kortopates Posted June 2, 2019 Report Posted June 2, 2019 Don’t know any specific on this instrument but Many if not most instruments use a separate and replaceable light bar that screws on to the top of instrument. Anyone qualified Merely has to pull it out to find out. 12v and 24v light bars are available at Spruce and are very inexpensive. Sent from my iPhone using Tapatalk Quote
FloridaMan Posted June 5, 2019 Report Posted June 5, 2019 There’s another member here who sent an instrument off for a light repair and ended up dilated from the process. Quote
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