Some electrical equipment on WITHOUT the master switch ON?
 

Hello everyone. Back again with more questions. While checking ignition leads with a lead tester, I removed the protective boot off of the, Battery side of the MASTER solenoid as a power source for the tester. WITHOUT the master switch on my turn coordinator started spinning up, my coordinator make noise when it first starts. I disconnected the battery positive lead from the master solenoid, to stop the turn coordinator/gear light, and replaced that solenoid thinking I had arched the connector plate inside. With a used solenoid from my other (parts) skymaster. It did the same thing-turn coordinator and gear down light came with the positive lead connected. My solenoid PN: S1578-1, having four (4) large connections posts, two upper and two on the bottom, and one small connection post, this type was ONLY used thru SN: 0525. On SN: 0526 the solenoid was replaced, by Cessna to a more standard solenoid, having two large posts and one small one, like the starter type solenoid.
Has anyone seen this type problem before? I did disconnect the two connections on the bottom two post from the PN: S1578-1, one wire is a jumper to the positive side post and the other goes to the "Generator" fuse. When I placed the generator wire on the opposite side of the positive post of the solenoid the turn coordinator and gear light does not come on until I throw the on the master switch on-BASICALLY solving the original problem BUT I'm NOT sure if the "Stand-by'-Run" switch will be affected?? Thanks for reading!
BILLS

Wierd
 

Bill,

I will have to look at the wiring diagrams tonight and respond. What is your S/N? I have not heard this before, but to be honest, I always connect right up to the battery. Basically, that is what you did, but for some reason it is activating the solenoid. Do you have a picture of your solenoid in the aircraft so we can see how it is hooked up?

Jeff

Some electrical equipment on WITHOUT the master switch ON?
 

JAG. Thanks for the reply. My 1965 C337 is SN: 0200. I can get a picture of the solenoid BUT I've already removed the wires from the bottom posts? If you check the BATTERY CIRCUIT and/or Charging system schematics for SNs 001- 0525 they're the same. Cessna changed the part number and type of the solenoid, ie, from S1578 ( SNs 0235-0525 I think) to a newer PN is S-1580-1 which has been superseded several times since (But they are basically the same type). My worries are that moving the "generator" wire to a fuse from the Positive side of the solenoid to the load side may affect the RUN/STAND-BY switch? LET ME KNOW IF YOU STILL WANT THE PICTURE??
BILLS

No Picture required
 

Hi Bill,

Since you already disconnected the wires - no need for the picture. I will go to the hangar tomorrow and take a picture of mine - so that we can compare. I will look at wiring diagram tonight. Likely back to you by tomorrow afternoon.
Jeff

Some electrical equipment on WITHOUT the master switch ON?
 

JAG-Many thanks for the assistance! I look forward to hearing from you again. ALSO I see you're in Texas-where? I went to High school in Ft, Worth, TX, many decades ago!
BILLS

looking at wiring diagram...
 

Bill,

Here is a snap shot of your wiring diagram. Is this how it was wired before - or does this reflect how you have moved the generator wire now to the other side? The four posts on the older solenoid, was simply a way to get the standby power to the system when the master was off - solenoid relaxed.

This is a very strange problem - then again, electrical issues are always a challenge. Are you able to check to make sure the diode on the positive side of the solenoid is working?

Jeff

More...
 

Bill,

Yes, if you move the generator fuse wire to the downstream side of the master solenoid, it will impact the standby/run system, as it will no longer be connected directly to the battery. For this system to work right, it needs to be direct to the battery (should you ever require it).

I am located in Houston, Texas. My aircraft are based at Fair Weather Field, TX42, just west of Houston.

Jeff

Some electrical equipment on WITHOUT the master switch ON?
 

JAG. Yes my solenoid WAS wired the way the schematic shows. So IF the diode is bad do you think that's how the power is getting through? How is the diode checked? I'm thinking there is a special selection on a Multi-meter??
Many thanks, Happy Holidays.
BILLS

Sorry for the delay
 

Bill,
Somehow, you are creating a ground with your lead tester, and if that diode is bad, it could be closing the solenoid. I am having a difficult time though now that you tell me yours was wired properly in the first place...

Yes, a good multi-meter will have a diode checking capability. The setting usually has a symbol of a diode - and you use that to check to see if it is working properly.

Jeff

Some electrical equipment on WITHOUT the master switch ON?
 

JAG. Thanks for the reply. My multi-meter does not have a diode tester but I did see on Youtube that a diode can be checked using the Ohm (resistance) selector on the meter, it shows resistance on one side and when the leads switched there will be no resistance. I think it's the diode going into the master switch that maybe the problem although I haven't had a chance to do the test. ITS VERY COLD HERE IN PENNSYLVANIA!! I'll let you when I do the test on the two diodes-let hope! BILLS

Some electrical equipment on WITHOUT the master switch ON?
 

JAG. I took the diodes from my PARTS Skymaster, it was fairly simple, someone mentioned going through the Avionics cover and the diodes are on a plate of phenolic screwed to one of the massive stunts forward of the hydraulic power pack. I checked the diodes using my multi-meter okay! Now I'm waiting for somewhat warmer temperatures outside to check the diodes on my flying Skymaster. LETS HOPE IT IS INDEED ONE OF THOSE DIODES! I'll let you know what I find-REGARDS- BILLS

Some electrical equipment on WITHOUT the master switch ON?
 

HELLO ALL. Good news, the wiring problem has been fixed!!:D
JAG: I checked the two diodes one was bad, so since I was in the area of the diodes I extended the length of the three wires and moved the mount atop of the Yoke rail near to the firewall, MUCH easier to deal with the diodes there. Since I have a "parts" Skymaster I checked those diodes and found one was okay and installed it. Re-wired the battery contactor to original configuration and now the bus is not hot when I re-connected the battery! Many thanks.
Regards, BILLS

Good work!
 

Bill,
Glad to hear you found the problem. That is such a strange issue to actually notice, but now you are assured your system works as it should, when it is needed. So nice to have the "parts" plane, that sure makes a difference when troubleshooting.
Cheers,
Jeff