n5756k Posted July 13, 2017 Report Posted July 13, 2017 When I turn on the electrical master switch, quite often I need to cycle the switch numerous times for power to come on. Sometime when I put the switch on I have power, but if I then put the radio master on or the starter on the power will fall off. I can always hear the battery solenoid clank on but no power. Sometimes it work fine, but I never know when I go out to the airplane if today it will work or not. I have replaced a perfectly good Concord battery, a perfectly good Electrical Master switch, I have replaced two new Sky-tek battery solenoids. I have replaced both wires from the Electrical Master switch all the way back to the battery. I have had the shop replace numerous grounds. No one can figure out what the problem is; anyone ever run across thjis before? any suggestions?
tony Posted July 14, 2017 Report Posted July 14, 2017 (edited) For what it's worth, I'm really not sure how a J model is configured but on my F model the ground to the battery was tied to the avionics shelf. The shelf was completely painted. I don't believe they knew what a faying surface was. It wasn't making a good ground to the airframe after 50 years. I removed the shelf, cleaned both surfaces on both sides of the shelf and reinstalled. Its been working like a champ ever since. Hope that helps you. Edited July 14, 2017 by tony
Guest Posted July 14, 2017 Report Posted July 14, 2017 21 minutes ago, tony said: For what it's worth, I'm really not sure how a J model is configured but on my F model the ground to the battery was tied to the avionics shelf. The shelf was painted completely painted I don't believe they knew what a faying surface was. It wasn't making a good ground to the airframe after 50 years. I removed the shelf, cleaned both surfaces on both sides of the shelf and reinstalled. Its been working like a champ ever since. Hope that helps you. Two halves to every circuit, battery ground is often overlooked. Clarence
Drew_Wagner Posted July 14, 2017 Report Posted July 14, 2017 Did you recently replace your solenoid behind the battery box with one from SkyTec? That was my issue, they had an issue with the contact in the solenoid not fully seating and creating intermittent power when engaging the master. Went through 3 of them before I went with the outrageously expensive Mooney version that has worked flawlessly. I guess you get what you pay for....Sent from my iPhone using Tapatalk
Drew_Wagner Posted July 14, 2017 Report Posted July 14, 2017 Sorry saw you replaced with the SkyTec, that is 100% your issue. Run like the plague they are garbage.Sent from my iPhone using Tapatalk 1
Yetti Posted July 14, 2017 Report Posted July 14, 2017 Flip it on in a non working condition and chase with a VOM. Start at the battery till you don't see voltage. You may have a starter solinoid on the pilot side firewall. It would be possible for one of the lug terminals to have corrosion and never see it. When I pulled the Alternator the big wire fell out of the terminal lug. Based on it dropping out when you add a load that is usually a bad connection. All terminals need to be shiny bright. including the battery. Wire brush is your friend.
carusoam Posted July 14, 2017 Report Posted July 14, 2017 Hit switch, listen for click... the main power solenoid should give a healthy clunk... (you got clunk!) Find the solenoids back by the battery. A simple volt meter will be able to test their status... it should flip on with the master switch. If it doesn't you have found your issue. (Clunk happened but internal fault doesn't allow switch to close) see Drew's note above. There are a few solenoids used in our planes. The next most common one goes with the avionics switch. Maybe a starter solenoid is more common... What you may be noticing is the avionics solenoid is really interesting. It is connected to the master in a funny way. This funniness allows the avionics to be on in the event a master solenoid fails... 1) the avionics master is Normally on. 2) Turning on the master switch, opens the avionics master. 3) Turning on the avionics switch, closes the avionics master. 4) Hence... a failed master solenoid allows power through the Normally closed avionics solenoid... Does that help? If not, I'm only a PP, not an electronics guru... Best regards, -a- MS is a great source of knowledge, and memory!
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