Wiring diagram for an O/B.

Discussion in 'Electrical Systems' started by LP, Apr 10, 2009.

  1. LP
    Joined: Jul 2005
    Posts: 1,418
    Likes: 58, Points: 58, Legacy Rep: 584
    Location: 26 36.9 N, 82 07.3 W

    LP Flying Boatman

    Well, here it is three years and two states later. The boat has been in mothballs and used primarily as a storage vessel for my shop. Other projects are mostly out of the way and I've been mentally preparing to get this project back under way.

    I tracked down missing components for the old MerControl that came with the project outboard that I purchased over three years ago. $40 buck for a Thunderbolt 500. The guy threw in an extra prop said, "That's worth 40 bucks by itself." I may have paid the guy to haul off his junk. We'll see. Anyway, the motor controls are all rewired and functioning. I gave the starter a quick shot of juice to see if anything would come to life. Only the starter solenoid perked up. I pulled the starter out. It's armature would not move. I opened up the starter and coersed the armature off of it's end bearing. Obvious signs of moisture on the insides. I cleaned things up inside and most of it looked serviceable. The were two brush springs that had lost their tension. The brushes and the commutators looked good. I put it all back together not knowing what to expect. I tried the starter and got a momentary reaction from the starter and then nothing. I would like to track down some brush springs before doling out for a replacement starter. I'm not even sure the motor will run, though the seller assured me it was running when he pulled it off of the boat. I may have to buy a $250 parts motor for my $40 motor. :rolleyes:

    Sorry for the tangent. Wiring ic progressing quickly. The instrument panel gauges are installed and wired now. A switch plate was made from stainless to day and polished. I need to order a couple more switches and I'll be able to finish wiring the accessories. It's exciting to get back into this project as it has lain dormant for such a long time. Attached is a photo of the panel and the associated working mess.

    IMG_1738.JPG
     
  2. LP
    Joined: Jul 2005
    Posts: 1,418
    Likes: 58, Points: 58, Legacy Rep: 584
    Location: 26 36.9 N, 82 07.3 W

    LP Flying Boatman

    Getting my Tachometer to function.

    I'm having trouble getting my tachometer to function.

    The first photo is a wiring diagram of the engine and engine control circuits. I have faithfully in rewiring the controls and subsequently, the engine. The only deviation I made was to wire the tach leads outside of the control unit and send them forward to the instrument panel.

    You'll note that the tach lead (brown) runs back to the G terminal at the engine. It is then jumpered over to E in the engine compartment. This lead goes to the switch box and is most likely the controling signal that leads in from the ignition driver. E is also the line that goes to ground when the engine is turned off and kills the control signal from the ignition driver.

    Mercury500Wiring.jpg

    This is the installation diagram for tachometer thst is similar to mine. I can't find exact documentation for mine. Combine the A and B+ and build the hour meter into the tach.

    TachInstall.jpg

    This is the pin code for the dip switch. Somewhat meaningless as i have an eight pin dip switch and this is for a unit with a ten pin dip switch.

    TachDipSwitchChart.jpg

    I'm contacting Beede to get a specific pin setting for this unit with my motor. In the interim, I'm trying to decide if there is something inherently wrong with system as I'm building it. It's pretty simple:a positive lead, a negative lead and a signal. I'm using the tach signal as it specified in the motor wiring diagram and sending it straight to the tach. The tach powers up and the needle zero's, but no movement when the engine starts.

    Do I have an incompatible signal?

    Is there any way to check the signal? ...without an O-scope?

    Any ideas?
     
  3. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 148, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    The instructions from Beede suggest you can use either the ignition pulse, the alternator AC output or a magnetic pickup as a signal source. I have doubts about that because the magnitude varies from a very small pulse (magnetic pickup) to a 200+ spike (ignition).

    If you have a good digital multimeter that can measure frequencies you should get a good reading between SIG and ground.
     
  4. LP
    Joined: Jul 2005
    Posts: 1,418
    Likes: 58, Points: 58, Legacy Rep: 584
    Location: 26 36.9 N, 82 07.3 W

    LP Flying Boatman

    CDK,

    Thanks for your response.

    Which part do you have your doubts about? The range of possible signal input? My tach operation as it is wired with this devise?

    It may be time to replace my 35 year old Radio Shack analog multimeter. It's been such such a reliable old friend.

    Would you speculate that the signal strenght from the ignition driver 12v pulse? It wouldn't have to be, but for this vintage of system, I would guess that they used 12v for most controling inputs.

    ==========================================================================================================================

    Additional information. It looks like I need at least 8 volts of amplitude in the signal for the tach to register. I am now curious about the output level from the ignition driver. Can a digital multimeter also read the amplitude of this frequency?
     
  5. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 148, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    The signal from a 12V ignition unit is several 100's volts because of the coil's inductance, so there should be plenty juice for the tachometer. The big question is does it get there?

    A cheap DMM cannot measure pulse height but shows the average value, which is quite low because the pulses are narrow. The simplest check is short the signal to ground with the motor running; if it stops the wiring is OK.
     
  6. LP
    Joined: Jul 2005
    Posts: 1,418
    Likes: 58, Points: 58, Legacy Rep: 584
    Location: 26 36.9 N, 82 07.3 W

    LP Flying Boatman

    Very insightful. I had to read your post twice before to electrons got through. Time to pull the boat out. :idea:
     
  7. LP
    Joined: Jul 2005
    Posts: 1,418
    Likes: 58, Points: 58, Legacy Rep: 584
    Location: 26 36.9 N, 82 07.3 W

    LP Flying Boatman

    All of the pieces are starting to fall together for the Tachometer. I've been on this forum thread.

    http://forums.iboats.com/showthread.php?t=577778&p=3970599#post3970599

    Sounds like the current set-up needs the signal conditioned for the tach to read it or to pick up a signal generated at the stator. I'm looking at connecting a lead to the stator and using that for the tach lead. Another bit of the puzzle was here:

    http://www.beede.com/TS-Tach.htm

    It specifically mentions pulling the tach lead from the stator. The dip pin selector can most likely now be set up for a 12 pulse per rev generator. I'll run a test lead to the gauge and see I get results.
     
  8. Frosty

    Frosty Previous Member

    All this grounding stuff ---you need to be careful what you ground or you will be in for a new black box (ignition unit).

    Tachos I remember had wires that wrapped around spark plug leads and you could set it to 2-3 or 4 cylinders
     
  9. LP
    Joined: Jul 2005
    Posts: 1,418
    Likes: 58, Points: 58, Legacy Rep: 584
    Location: 26 36.9 N, 82 07.3 W

    LP Flying Boatman

    Actually, CDK's suggestion to send the signal to ground was spot on. The tach lead and the kill lead are spliced together on the engine side of the harness and it takes the signal to ground, killing the engine. Touching the signal to ground is doing the same thing as turning the key to OFF.

    Progress today. Took the signal to ground. Engine died. Took a test lead from the signal terminal of the tach and took it directly to the same connection that the ship's wire goes to. No tach indication. I anticipated no response. Then took the lead to one of the stator outputs. Tach jumped to 1000 rpm. Sounds a bit high for idle, maybe. Now, it's a matter of setting dip switches. I need to take a frequency reading on the ship's tach signal to compare the tach reading via the stator output so I can get a comparison of the two indications.

    Most likely, I will split the tach line from the kill line so I can run the tach from the stator output. The two are jumpered together at the cowling plug. It's great to get things figured out. It was nice to see the tach come to life. Bit by bit, I guess.
     
  10. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 148, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    There is a small program rpmsetup.exe on the internet, free to download.
    It uses the engine noise to calculate the exact rpm. Setup is a bit tricky because engine noise has lots of harmonics, but once you have the correct parameters the program does a proper job.
     
  11. LP
    Joined: Jul 2005
    Posts: 1,418
    Likes: 58, Points: 58, Legacy Rep: 584
    Location: 26 36.9 N, 82 07.3 W

    LP Flying Boatman

    Thanks, I may go dig it up. Are you talking audible noise or electronic noise?
     

  12. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 148, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    Audible noise like resonance of thin metal parts, valve train noise etc.
    The program uses the mike in your laptop to calculate the exact rpm.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.