Tech Net T


Query: Sometimes the tach works, sometimes not. Would it help to make it cam-shaft driven?
Comments:
Try alternate system by energizing the field wire. (Windsome)
Put a bleed resistor on the field wire because the tach may be insensitive to low AC power. (Dyad)
Use an incandescent bulb on the field wire. (Discovery)
Use a 10 watt/100 Ohm resistor. (Salty Paws)

Issue: My tachometer tops out at 1100.
Comments:
Tap the gauge to see if it's mechanically stuck.
Its unlikely to be a regulator problem since you're reporting the other systems are fine.
Solution: The thumping solved the problem.

Issue: Tachometer died then came back to life showing too low numbers.
Comments:
Check for electrical problems between alternator and tachometer.
Check all connections for corrosion.
A hand held laser tachometer works well for testing. Inexpensive.

Issue: Tach stops working when batteries are fully charged.
Suggestion:
Use a light bulb in the field wire circuit. This will provide a base load to the alternator. (C_Language)
Solution: Solved by switching off the solar cells when motoring.

FYI
Check wiring connections. Had a problem with erratic tachometer which affected the alternator and accelerated belt wear-out. Traced the problem to a wiring connection. (Fiscal Stray)

TESTING
Calibrating Engine Tachometer with 120 v LED Christmas Lights:
LED lights are polarity sensitive devices, allowing current to flow only in one direction, and illuminate only when current is flowing. The typical string of LED Christmas lights does not have rectifiers and filters to turn the 120 volt AC into continuous direct current. This results in the LEDs flashing at 60 times a second (assuming 60 cycle supply) as they will illuminate on one half of the cycle when the voltage is high enough to forward bias the LEDs. It is this flashing that allows the lights to be used as a strobe light for calibrating a tachometer.
Procedure:
1. Since this will be done with engine running, take care not to get your hands near moving parts such as drive belts.
2. Select a time of day or otherwise limit the amount of ambient light.
3. Before starting the engine, place a piece of light-colored tape or paint a white stripe on the surface of the crankshaft pulley.
4. Plug in the lights (inverter is okay as it is likely an accurate 60 cycle source) and arrange them so the mark on the pulley is clearly visible but will not get entangled when engine is started.
5. Start the engine and slowly increase rpm until you see only two marks nearly stationary and on opposite sides.
6. At this point the engine is turning at 1800 rpm (1500 rpm if 50 cycle). Now adjust (assuming your tach is adjustable) so that it indicates 1800 rpm.
Other operating points can be verified. When there is only one mark, the rpm is 3600, three marks is 1200, 4 marks is 900.
Rick (C_Language)

(also Article: Intermittent Tachometer Signal from Alternator)

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Self-Amalgamating tape. Lowes carries a variety of 3M tape. Much cheaper than the premium brand and works just as well. About $2 for a 100' roll.

14 Day masking tape is good for projects.

Duct tape can now be found in multi-colors and patterns.

Black reflective tape for bootstripe. The Reflective Tape Store carries a variety of colors and widths at good prices. (Salty Paws)

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Issue: Motor quits when throttle is put in idle.
Comments:
Check the spring and brass fitting on the throttle linkage cable.
The spring may be corroded.
Lube the fitting and reset the idle set screw.
Check the linkage on the fuel stop valve.
Check the control cables.
Check fuel filters, if clogged, they may cause vacuum at low rpm.
Use vacuum gauges on filters. Designated Engineer carries them.
Update: Solved. The common fuel pickup was clogged.

Issue: The throttle control won't stay in forward position due to vibration.
Suggestions:
Adjust the friction screw in the handle under the housing.
Use a small bulldog clip on the cable, adjusting tension as necessary.
Reduce strength of the throttle return spring.
If there is no friction screw available, make one.
On the throttle, drill, tap, and use a brass insert with a screw into the hub.(C_Language)

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Query: How to remove a plastic thru hull that was attached with 5200?
Comments:
Soak in P.B. Blaster. It will soften the 5200 and stain it so you can see the remains of the 5200 for removal.
Use a small wire as a garrote to cut through the 5200. A small fishing leader will do. Or try a utility knife.

Issue: Forespar Marelon 3/4" thru hull failure. All other sizes are fine.
Comments:
Failed part can be replaced underwater. A wine cork, as a tool, will be of help. (Valkyrie)
The 3/4" thru hulls from the factory are just too tight. Lube them with silicone vacuum grease.

Issue: Growth inside the thru hull on sail drive.
Comments:
Jury rig a hose with a hose repair fitting; back-flush sail drive.
Physically scrape out the thru hull.

TEMPORARY BLOCKING
Use a wooden plug.
Plug the hole from the inside with a rag. A screwdriver will hold it in place.
Attach a hose and lift the other end above the water level.

(also strainers)

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FYI
Sometimes these can unwittingly transfer proprietary programs to incompatible computer systems, i.e. Mac to PC. (Fiscal Stray)

Thumb Drives/Flash Cards with the USB end, are perfect for toting digital information. Use on a chain around your neck with a floating key chain. (Salty Paws)

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The website Easy Tide provides tide information for anywhere in the world and it's free. (Discovery)

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Harbor Freight Tools is a good online source for cruisers. (C_Language)

Craftsman tools. Sears online is a great place to buy tools. Quick delivery though U.S. mail.

TOOLS THAT WORK
Super Shears These super scissors are a great cutting tool. Will even cut through a penny. (C_Language)

Clamp on DC current meters are easy to use and are helpful for solving diverse problems. Range is 400 amps. Sears (Craftsman) carries it for a reasonable price. (C_Language, Cat Tales, Anania, Dyad)

Mastech MS-2108 is also a very good model. It reads true RMS voltages, and has a useful in-rush current function and measures up to 660 amps. Very hand size, and a nice build. (Born Free)

A handy tool to have onboard is a flexible scope for looking into small or inaccessible areas.

DeWalt makes a very heavy duty utility knife. It costs more, but lasts longer and is more sturdy. No danger of the blades snapping off. (Valkyrie)

For additional leverage, slide a small piece of PVC on handles of small tools. (Salty Paws)

Use a standard drill bit, run in reverse, to make a countersink hole in wood. (C_Language)

An electric toothbrush with batteries makes a nice polishing/cleaning tool for smaller items. (Salty Paws)

FOR YOUR TOOLS
Dip-it works well for waterproofing tool handles, etc. The unused product in the container will set up after use.(St Jude)

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Issue: Difficult reception on DTV locally.
Comments:
Needs line of sight. Place antenna higher.
Sometimes reception is better offshore.
Combine digital converter with an analog antenna.
Digital TV is optimized for a specific frequency, use a digital antenna.
Update: I took an in-line amplifier out of it. It worked much better, so it may have been an over modulation problem.
Query: How to maintain a signal?
Comments:
An omni directional antenna works well, such as Shakespeare 2125.
The Shakespeare 2030 omni works best at a dock, as it's motion sensitive.
Copper loop (hoistable) to coax, and use a down-haul on it.
Use low-loss cable and amplifier.

THINGS THAT WORK
Use a USB connector with a stub antenna to receive digital TV on your computer. (Iolar)

(also antennas)

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