nfranz10 Posted March 16, 2017 Report Share Posted March 16, 2017 Hey All, I wanted to relay some electrical issues more as an advisory note, less as a question. At first, we thought the battery was getting drained somehow. I would get in the plane and the master switch would do nothing. So we looked at the Alternator, Regulator, and recharging the battery. After those fixes, the problem would come back in a few weeks. The next thing I heard was possibly the field wire, but my A&P actually looked at the Solenoid, which was an original part from 1969. So we replaced it with a new SkyTec solenoid. Within two weeks, I had the same problem. Get in the plane, and master switch would do nothing. I took it to a different A&P located on my field (my regular A&P is located at another airport) and he said the brand-new solenoid was bust. So we replaced it with another SkyTec solenoid. With the 2nd new solenoid, I ended up flying over an hour to San Luis Obispo with another pilot. When we got up there, we then had the opposite problem, when I turned the master switch off, everything would stay on, JPI, Gear Indicator, etc. We went inside to ask for an A&P, they didn't have any, and when we returned to the plane, everything had turned off and seemed normal. But we decided to head home and drop it off at Long Beach with my regular A&P since my annual is due the end of this month anyways. That was on Friday, he gets in the plane on next Monday, and nothing happens when he turns master switch on. He has since got back to me and thinks its a SkyTec related issue, so we are going to try a different brand. I will let you know the results, but wanted to give fair warning, lest anyone has been encountering a similar problem or knows what's going on here. Thanks in advance. Best, Quote Link to comment Share on other sites More sharing options...
1964-M20E Posted March 16, 2017 Report Share Posted March 16, 2017 OK let's get to the basics. The problem is when the plane is sitting you battery runs down. Correct? Have you verified it is a dead battery? I assume you have by either charging the battery or jump starting the plane. Master solenoid (power relay) the big wire connects to + terminal on the battery and one wire small wire connects X1 and the + of the battery. X2 connects another small wire to the master switch which grounds out the X2 terminal on the solenoid coil to activate it. The other big wire feeds the plane 12V when the master solenoid is energized. So if small wire to the master SW is bad it will activate master solenoid at odd times when it shorts to ground. You did make one statement that when you turned off the master SW everything remained energized after a flight. This is symptomatic of a stuck solenoid or a shorted wire to the master SW but this was after replacing the master SW wire and solenoid.??? If you lift the big wire off load side of the master solenoid with the master SW off you should read 0V on the load terminal and 12V on the line side terminal. Turn on the master and should should read 12V on the load terminal. If that is happening the master solenoid and wiring are fine. Swapping solenoids most likely will not help you and they are not cheap. There is usually a small wire to feed +12V to the avionics panel this is used for clocks, and other items that may need 12V all the time to maintain memory, settings or what have you. You will need to identify this wire and check it out. Another thing maybe your cabin light is coming on and you are not noticing it or there is a problem with the wire to the light on some planes this is connected to the battery directly. Quote Link to comment Share on other sites More sharing options...
carusoam Posted March 16, 2017 Report Share Posted March 16, 2017 (edited) Sounds like the master switch is NOT really connected very well to the master solenoid... you turn the switch off and stuff stays on... you have changed out the solenoid and it seems to be capable of working... I think a worthy mechanic can deliver voltage to the solenoid to demonstrate it working in the plane. Are you able to test your electrical system parts? Probably want to work closely with your mechanic on this... If you decide to test the solenoid and switch yourself, turning everything else off first... when delivering power to the correct post, the solenoid should give a pretty audible click as it changes state. proving the new solenoid is working, next step is test the switch. Expect a loose or broken wire. Oxidation would be next on the list of things to clean.... PP thoughts only, not a mechanic... Best regards, -a- Edited March 16, 2017 by carusoam Quote Link to comment Share on other sites More sharing options...
nfranz10 Posted March 16, 2017 Author Report Share Posted March 16, 2017 (edited) John - thanks for the response. Apologies - I did not relay the story as best as possible, here's a recap: Original OEM Solenoid Failure Symptom: Dead battery after sitting Cause: Solenoid, due to age, was weakened and started engaging, therefore causing the battery to be drained Fix: Install new solenoid 1st SkyTec Solenoid Failure Symptom: Seemed like a dead battery after sitting... Initial Fix: Recharge battery overnight, and install back in plane Result: Nothing happens when master switch flips on, so it's not a dead battery problem True Cause: KFUL A&P diagnosed that solenoid was not working properly, that it had effectively failed and I should get a refund Second Fix: Ordered new solenoid Second Result: Everything appeared to work normally again, until... 2nd SkyTec Solenoid Failure Symptom(s): After being installed approximately one week, plane was receiving electrical power and starting, but when master switch is turned off, electricity was still being sent throughout the system. When plane was dropped off for annual, A&P got in it and tested out master and it was back to not working again. Initial Diagnosis: From the KLGB A&P performing the annual, says that he thinks its a SkyTec related issue, and we should try a different brand Follow-up: I will send him your notes John After googling a dead battery, I saw that the cabin light is a common cause, so that was the first thing I checked. Also - Lakefront is my favorite airport in the country and NOLA is my favorite city! I want to make French Quarter Festival in 2018... Edited March 16, 2017 by nfranz10 1 Quote Link to comment Share on other sites More sharing options...
Yetti Posted March 16, 2017 Report Share Posted March 16, 2017 The solenoids that Skytech don't look like they are high amp constant duty. McMaster Carr has the original mooney replacement solenoid. There are some metal can type solenoids that will do high amp constant duty, but there is no way to tell. The four terminal metal can solenoids were used on old four tractors. You can read about them on some of the tractor forums. There is a metal can four terminal on my 75F that runs the gear actuator. The 4th terminal supplies voltage to the brake to turn it off while the motor is running. . Quote Link to comment Share on other sites More sharing options...
Yetti Posted March 16, 2017 Report Share Posted March 16, 2017 Sounds like the second time your solenoid welded shut which is a good indicator that it is not high amp constant duty. I have about 5 years of practical experience with solenoids. I put myself through college installing radios in mixer trucks. We used a solenoid to isolate the radio gear from the rest of the truck. We replaced a lot of the metal can solenoids with something else. 1 Quote Link to comment Share on other sites More sharing options...
carusoam Posted March 16, 2017 Report Share Posted March 16, 2017 (edited) Search around this site for skytech solenoid... This may have come up before. Sounds vaguely familiar... Best regards, -a- Edited March 16, 2017 by carusoam Quote Link to comment Share on other sites More sharing options...
1964-M20E Posted March 16, 2017 Report Share Posted March 16, 2017 20 minutes ago, nfranz10 said: John - thanks for the response. Apologies - I did not relay the story as best as possible, here's a recap: Original OEM Solenoid Failure Symptom: Dead battery after sitting Cause: Solenoid, due to age, was weakened and started engaging, therefore causing the battery to be drained Fix: Install new solenoid 1st SkyTec Solenoid Failure Symptom: Seemed like a dead battery after sitting... Initial Fix: Recharge battery overnight, and install back in plane Result: Nothing happens when master switch flips on, so it's not a dead battery problem True Cause: KFUL A&P diagnosed that solenoid was not working properly, that it had effectively failed and I should get a refund Second Fix: Ordered new solenoid Second Result: Everything appeared to work normally again, until... 2nd SkyTec Solenoid Failure Symptom(s): After being installed approximately one week, plane was receiving electrical power and starting, but when master switch is turned off, electricity was still being sent throughout the system. When plane was dropped off for annual, A&P got in it and tested out master and it was back to not working again. Initial Diagnosis: From the KLGB A&P performing the annual, says that he thinks its a SkyTec related issue, and we should try a different brand Follow-up: I will send him your notes John After googling a dead battery, I saw that the cabin light is a common cause, so that was the first thing I checked. Also - Lakefront is my favorite airport in the country and NOLA is my favorite city! I want to make French Quarter Festival in 2018... let me know when you plan on coming down we can meet up for a beer or two or three.............. as well as any other MSer.. I don't mind being a tour guide lets me be a tourist in my home town 1 Quote Link to comment Share on other sites More sharing options...
carusoam Posted March 16, 2017 Report Share Posted March 16, 2017 +1 for John's guidance around NOLA. best regards, -a- Quote Link to comment Share on other sites More sharing options...
Yetti Posted March 17, 2017 Report Share Posted March 17, 2017 I would put the 200amp one of these in before one of the Skytec metal can ones. https://www.mcmaster.com/#solenoids/=16scf3q I thought at one time I found the exact replacement for the Mooney one. Quote Link to comment Share on other sites More sharing options...
nfranz10 Posted March 17, 2017 Author Report Share Posted March 17, 2017 Thanks for all the replies. I'll point my A&P to the McMaster equipment. John - I'll definitely take you up on that when I'm in town. Best, Noah Quote Link to comment Share on other sites More sharing options...
orionflt Posted October 8, 2019 Report Share Posted October 8, 2019 (edited) wrong forum Edited October 8, 2019 by orionflt Quote Link to comment Share on other sites More sharing options...
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