Yamaha F90 Rectifier Fails Twice

Electrical and electronic topics for small boats
aidan545
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Yamaha F90 Rectifier Fails Twice

Postby aidan545 » Sun Apr 09, 2017 5:59 pm

Hi. I own a 2015 Yamaha F90 and use it quite frequently, at least once a week. A regulator-rectifier [asembly] failed on the engine, and battery charging stopped. There was no smoke or overheating signs on the rectifier. I replaced the regulator-rectifier.

Then the trim-tilt switch on the outboard failed. The new regulator-rectifier has just failed again. I have a new trim/tilt switch ordered. I checked and cleaned the engine and battery connections--they were clean anyway.

The boat's battery is less than 12-months old and is a dual purpose 12-Volt cranking and deep cycle battery. To the boat I have added:

--Yamaha F90 engine wires
--Rule pump wires (not fused)
--[entertainment device] wires (in-line fused); device stays in stand-by mode when engine is off
--GPS [receiver] in-line fuse; receiver draws power even when engine is off
--boat lamp wires

All wires tightened down with wing nuts to battery and tightened with pliers and always seem to be tight.

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Phil T
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Re: Yamaha F90 - regulator/rectifier failure twice and trim switch failure

Postby Phil T » Sun Apr 09, 2017 6:29 pm

Was the motor installed by a certified Yamaha mechanic?

Were the replacement rectifiers OEM replacements installed by a certified Yamaha mechanic?

Have you discussed this with Yamaha directly?

I think the main fuse under the cowl maybe suspect.
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aidan545
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Re: Yamaha F90 - regulator/rectifier failure twice and trim switch failure

Postby aidan545 » Sun Apr 09, 2017 6:50 pm

The engine is not under warranty as it was a fishing camp return engine.

The new part was ordered from Yamaha. The Yamaha dealer said it is not common for rectifiers to fail, and don't have any idea what causing it.

I installed the rectifier--very easy: four screws and one plug connection.

I will replace main fuse just to make sure it [is] not causing [the failure of the rectifier].

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Re: Yamaha F90 Rectifier Fails Twice

Postby jimh » Sun Apr 09, 2017 7:14 pm

Thanks for the narrative describing your experience with your Yamaha F90 charing system. I didn't see a direct question, but I infer you are seeking some advice about the cause of the failure of the rectifier and if there is some sort of association of that device failing and the failure of the trim-tilt switch.

I don't see any basis for a connection between the failure of an outboard engine trim-tilt switch and the failure of the engine's rectifier.

Also, use of wing nuts to make connections to the terminal posts of a marine battery is not a good practice.

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Phil T
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Re: Yamaha F90 - regulator/rectifier failure twice and trim switch failure

Postby Phil T » Sun Apr 09, 2017 7:15 pm

How many hours on the motor?

The blowing of electrical driven parts indicates an electrical problem. The fact that it was a rectifier and then a trim switch leads me to think they are the symptom.

Many shops like to replace parts. Troubleshooting is time and skill intensive.

Before swapping out parts, basic electrical inspections are needed using a volt meter to determine if there is a fault in the circuits. If above your skill, it is worth paying the shop for 1 hr of electrical testing only.
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jimh
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Re: Yamaha F90 Rectifier Fails Twice

Postby jimh » Sun Apr 09, 2017 7:20 pm

With the failure of any electrical component, before replacement of the failed component is made, the cause of the failure should be identified. As described in this thread, if a failed electrical component is replaced WITHOUT knowing the cause of the failure, there is a good chance the replacement component will fail, too, as a result of the same problem that caused the initial part to fail.

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Re: Yamaha F90 Rectifier Fails Twice

Postby jimh » Sun Apr 09, 2017 7:26 pm

Typical causes for failure of the rectifier in an outboard engine charging system

--excessive heat

--excessive current

--excessive voltage

Most electrical components performing rectification and regulation will tend to generate heat, which must be carried away to prevent the device from overheating. This heating occurs even with all other parameters in normal bounds.

Too much current being drawn from the regulator can destroy the rectifier or regulator. A short circuit is a common cause of excessive current.

Too much voltage, often occurring only for a very short time--a voltage transient--can destroy the rectifier or regulator. An open circuit is a common cause of high voltage-transients.

Short circuits in outboard wiring are often created by abrasion.

Open circuits in outboard wiring are often created by loose connections, particular at the battery when wing nuts are used.

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Re: Yamaha F90 Rectifier Fails Twice

Postby jimh » Sun Apr 09, 2017 7:28 pm

Assuming that the failure of the two rectifiers was not due to an internal defect in the two regulator, the cause of the failure must be external to the rectifier. This external defect will continue to destroy rectifiers until it is found and remedied.

It seems reasonable to assume that both regulators did not contain internal defects. In the case of the first regulator, one assumes it has been working for the entire service life of the engine prior to the failure. Usually with solid state electronic devices, once the device has operated properly for a few hours, it will probably not suddenly fail in normal operation. In the case of the second regulator, it seems unlikely it would fail out of the box.

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Re: Yamaha F90 Rectifier Fails Twice

Postby jimh » Mon Apr 10, 2017 8:49 am

In the narrative about this problem it is mentioned that the Yamaha dealer has said "it is not common for rectifiers to fail." This also tends to indicate that the cause of the rectifier failure is not due to an internal defect in the rectifier or that the rectifier component is a marginally-rated component. If failure of the rectifier is unusual, then failure of two rectifiers in the same engine in a short time must be very unusual. This, again, points to some cause of failure that is external to the rectifier assembly.