Generator intermittent

How to keep the Cessna 170 flying and airworthy.

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GAHorn
Posts: 20967
Joined: Fri Apr 12, 2002 8:45 pm

Re: Generator intermittent

Post by GAHorn »

That Echlin switch would be appropriate for Land/Taxi lights. It would also work as a Master/Generator switch by operating in an "OFF/Bat-Only/Bat&Gen" Switch, (similar to the later "split" switches Cessna used in later airplanes) but that is an admittedly (minor) alteration. I only posted that link as an example of how automotive switches were used when our airplanes were on the assy line.
It's also worth knowing that the earlier "piano" switches are actually toggle switches activated by the piano-key and NAPA and automotive suppliers also carry those items. The "AN" series of toggle switches are offered by Spruce:
https://www.aircraftspruce.com/catalog/ ... ey=1128579
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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n2582d
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Joined: Mon Apr 29, 2002 4:58 am

Re: Generator intermittent

Post by n2582d »

lowNslow wrote:Gary, I found this same info a while back but could never find a new 50047 switch for sale anywhere, there were several places to buy the 50047-1. Have you found these for sale anywhere other then the used ones on eBay?
Still looking. Seems that they only sell it as a bulk order.
Gary
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n2582d
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Joined: Mon Apr 29, 2002 4:58 am

Re: Generator intermittent

Post by n2582d »

gahorn wrote:That Echlin switch would be appropriate for Land/Taxi lights. It would also work as a Master/Generator switch by operating in an "OFF/Bat-Only/Bat&Gen" Switch, (similar to the later "split" switches Cessna used in later airplanes) but that is an admittedly (minor) alteration. ...
George, I agree with the first sentence but am struggling to see how the NAPA ECH SW83 switch would work as master switch. Here's an example Cessna wiring for a two position landing light switch:
Two Position Landing Light Switch
Two Position Landing Light Switch
It appears to me that it is similar to this four terminal light switch for boats:
image_247148.jpg
NAPA ECH SW83
NAPA ECH SW83
NWMDC.jpg (34.7 KiB) Viewed 8987 times
Here's how I would diagram it:
IMG_0065.jpg
In contrast, here's the Cessna wiring for a master switch:
172 Master Switch.jpg
Note that there are two separate circuits being operated with the pull of the switch, the generator field circuit and the battery master solenoid is connecting to ground. Even with the later split rocker switches there are two separate circuits; one for the battery and one for the alternator. In my opinion NAPA's ECH SW83 will not work as a master switch.
Gary
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lowNslow
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Joined: Mon Apr 22, 2002 4:20 pm

Re: Generator intermittent

Post by lowNslow »

I see your point Gary, by using that switch you would be feeding constant battery voltage into the field circuit effectively bypassing the regulator.
Karl
'53 170B N3158B SN:25400
ASW-20BL
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GAHorn
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Joined: Fri Apr 12, 2002 8:45 pm

Re: Generator intermittent

Post by GAHorn »

Without a schematic for the Echlin switch at-hand, I was merely "supposing" that two circuits were being operated. The switch would have to be "rung out" to be certain. I was not making a statement that the Echlin switch was definitely appropriate...only that a two-circuit switch could be so-used similarly to the split-Master switches Cessna later introduced. As it appears to not be controlling two separate circuits, Gary... you are correct. Thank you.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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