master/power stuck on

[Yetti]

31 minutes ago, eman1200 said:

for the record, are there people who have replaced the oem master with the Lamar sts-m12?  from the specs:

"Silver Contacts provide 300A in-rush & 150A continuous-duty capability Much higher than OE units

which is higher in-rush but fewer continuous.  I think other than starting the plane this should be more than enough but just wanted to check.

technically the one you have is rebuildable.  Maybe.     Taking the fuse out kind of means it is still working.   You have another wire somewhere that was providing 12 volts to the master.  It could have been as simple as water from the com panel falling on the master switch.  I would spend some time with a test light/VOM before I replaced the solenoid.

I would be replacing the master switch prior to the Master Relay.

What the heck is that third relay for?  That is not stock.     

[eman1200]

5 minutes ago, Yetti said:

technically the one you have is rebuildable.  Maybe.     Taking the fuse out kind of means it is still working.   You have another wire somewhere that was providing 12 volts to the master.  It could have been as simple as water from the com panel falling on the master switch.  I would spend some time with a test light/VOM before I replaced the solenoid.

I would be replacing the master switch prior to the Master Relay.

What the heck is that third relay for?  That is not stock.     

we did plenty of multimeter zapping and right now everything is pointing to the relay.  the switch seemed to be ok, although I don't think it would be a bad idea to replace it. the oem part has 4 posts as well. this is the 'new' one, which kind of lines up with how the existing one is wired.  sort of:

 

[Yetti]

8 minutes ago, eman1200 said:

we did plenty of multimeter zapping and right now everything is pointing to the relay.  the switch seemed to be ok, although I don't think it would be a bad idea to replace it. the oem part has 4 posts as well. this is the 'new' one, which kind of lines up with how the existing one is wired.  sort of:

 

this would be the more accurate one      https://peerlesselectronics.com/6041h105-relay?gad_source=1&gad_campaignid=20663341848&gclid=CjwKCAjwlaTGBhANEiwAoRgXBbhuWKo-Lr1UUFUmSylE4m2OjCHjmOhe2gzIn47Nnb8yoD3thidkdxoCuMEQAvD_BwE

sky geek is a little less dollars.   https://skygeek.com/eaton-aerospace-6041h105-relay-12v-1-15-electromagnetic.html?gad_source=1&gad_campaignid=13706325759&gclid=CjwKCAjwlaTGBhANEiwAoRgXBRz5hEL80QIv2peWx0foyLVmYs_eV-jhmk7bUAO7C4QKbzg-2ih1shoCJYwQAvD_BwE

 

[Yetti]

started as cutler hammer bought by Eaton.

 

At one point I found it at McMaster Carr for $200.00

[eman1200]

20 minutes ago, Yetti said:

this would be the more accurate one      https://peerlesselectronics.com/6041h105-relay?gad_source=1&gad_campaignid=20663341848&gclid=CjwKCAjwlaTGBhANEiwAoRgXBbhuWKo-Lr1UUFUmSylE4m2OjCHjmOhe2gzIn47Nnb8yoD3thidkdxoCuMEQAvD_BwE

sky geek is a little less dollars.   https://skygeek.com/eaton-aerospace-6041h105-relay-12v-1-15-electromagnetic.html?gad_source=1&gad_campaignid=13706325759&gclid=CjwKCAjwlaTGBhANEiwAoRgXBRz5hEL80QIv2peWx0foyLVmYs_eV-jhmk7bUAO7C4QKbzg-2ih1shoCJYwQAvD_BwE

 

I'm curious why you recommend those two, I see no specs on those links.  so while yes, they 'look' the same, without specs how can you compare?  I know other people have probably already done that, but other than mounting brackets, if the specs are the same but one is 1/4 the price......  it would be nice not to have to remount it but that's not worth the extra price to me.  BUT, if that's simply the better choice, then that's what I'd go with.  the one I listed is listed as the pma replacement for the cutler hammer according to lamar.

[RangerM20]

A '64 C model I worked on several years ago had this same problem.  Turned out to be the master switch itself.

[Justin Schmidt]

While people that don't know call everything a solenoid.  In reality a solenoid uses electrical force into physical motion.  Starter (what ingages with ring gear) is a solenoid. 

[Yetti]

3 hours ago, eman1200 said:

I'm curious why you recommend those two, I see no specs on those links.  so while yes, they 'look' the same, without specs how can you compare?  I know other people have probably already done that, but other than mounting brackets, if the specs are the same but one is 1/4 the price......  it would be nice not to have to remount it but that's not worth the extra price to me.  BUT, if that's simply the better choice, then that's what I'd go with.  the one I listed is listed as the pma replacement for the cutler hammer according to lamar.

What is the AP/IA comfortable signing off on is the best answer.           We used to run high amperage solenoids to switch the power to high amperage radios.    The metal cans would fail at a higher rate than the black plastic ones.     

[skykrawler]

The solenoid in the master relay could be internally shorted to ground.

I would remove the wire from the master relay that provides the ground path that energizes the relay (re: to master switch).   If the relay opens it implies there is a a ground being applied through that wire from something other than the master switch.   If it stays energized, it's probably an internal short to ground.

 

 

[eman1200]

The solenoid in the master relay could be internally shorted to ground.
I would remove the wire from the master relay that provides the ground path that energizes the relay (re: to master switch).   If the relay opens it implies there is a a ground being applied through that wire from something other than the master switch.   If it stays energized, it's probably an internal short to ground.
 
 

I’ll try this, ty.