Relay 68V-81950-00-00 - some musings...

[fairdeal]

My F225TXRD has a "main relay" 68V-81950-00-00

so I've just learned several interesting things about this part.

Looking at the Boats.net listing, it appears it was introduced with the 2000 model F115,

then used with the 3.3 F200/225.

Checking the Yamaha listing for the latest 3.3 F225XA,

it seems that engine "still uses" the same relay -

but

- wait for it -

there are now FIVE

The mind reels.

[rodbolt17]

if I called it a sub particle electron switch would it be any different.

it is a STUPID relay.

it simply allows a very small current(heat) to control a much larger current.

Yamaha actually uses them.

they tend to use them on various fuel pumps,ign circuits,throttle motor circuits and other functions that the ECU controls.

[fairdeal]

it is a STUPID relay.

it simply allows a very small current(heat) to control a much larger current.

Good morning, rodbolt!

well, I would say its a good deal more interesting than a "simple" relay -

what with the two taps for the magnet winding - and the diodes.


I think I finally understand what its doing on my F225TXRD -

no thanks to the SM.....

[rodbolt17]

if you understand how an ign coil works you will understand why the diodes are there.

[fairdeal]

if you understand how an ign coil works you will understand why the diodes are there.

Cryptic!

I wouldn't think they would be needed in every application -

but mine seems to be connected to the (AC) tach signal output....

[rodbolt17]

how does that relay work you ask?
it works due to a CURRENT in a winding.
that current FLOWING creates a magnetic field.
that field pulls the contactor closed and allows a much higher current to flow.

now sooner or later we gotta shut that field current off.

that is where the diodes come in.

we all know that when we turn OFF that field it collapses.
we also all know that a collapsing magnetic field can generate a vary large voltage.

if ya don't belive it grab an ign coil wire secondary.

all the diodes do is prevent a back feed of voltage and insure a clean cut off.

that is all for todays lesson .

[fairdeal]

got it. thanks!

[boscoe99]

Good for Yamaha for using a relay designed for one model on a number of other models. Keeps the number of part numbers down.

Yams usual modus operandi is to use as many different part numbers as they possibly can. Nothing like continually reinventing the wheel.

[boscoe99]

Cryptic!

I wouldn't think they would be needed in every application -

but mine seems to be connected to the (AC) tach signal output....

Oft times in a Yamaha illustration the diodes won't be depicted within a part that is an assembly. But they may very well be in there.

There are instances of diodes being part of a wire harness (say for the trim and tilt relays that don't use internal diodes) but sometimes the wire harness does not depict their presence.

More on the subject of a diode being used for high voltage suppression.
https://en.wikipedia.org/wiki/Flyback_diode

[99yam40]

back in my working career I ran into problems with this kind of stuff a few times.
once a battery charger failure on some instrument battery banks started sending out some frequencies that caused some important instruments to think some one was talking to /reprogramming them.
shutting valves that cause whole plants to shut down.
Bad caps in one of the redundant battery charges was what we finally found if my memory is correct.


Another time it was a Dc to AC power supply did not like the back feed from some control circuits of the very large rectifier units in the area I think.
all related to the back feed of large voltage spikes back feeding up the wires. Diodes and caps do a lot more than you would think

[pstephens46]

how does that relay work you ask?
it works due to a CURRENT in a winding.
that current FLOWING creates a magnetic field.
that field pulls the contactor closed and allows a much higher current to flow.

now sooner or later we gotta shut that field current off.

that is where the diodes come in.

we all know that when we turn OFF that field it collapses.
we also all know that a collapsing magnetic field can generate a vary large voltage.

if ya don't belive it grab an ign coil wire secondary.

all the diodes do is prevent a back feed of voltage and insure a clean cut off.

that is all for todays lesson .

Wonder if this collapsing magnetic field is what drives the function of a stun gun? Or a training dog collar...
Supposedly they operate at thousands of volts. Driven by a small battery. Slow night....

[rodbolt17]

step up transformers,diodes and caps can make a tiny 9v battery into a stun gun.

I did have a bit of training in the USN.
I spent 6 yrs as a CIWS tech.