Electrical Fuji

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MFD Repair

Courtesy addicted
I had some segments going out on my MFD on my 94 SL750. Having been to school on electronics some years back, I pulled the unit and tore into it. First problem is that it was glued up real good so it was a bear to break open. From the top I ran an exacto knife around the inner plate and the outer housing. Then I had to cut away a little of the side housing to expose the seal between the top plate and the outer housing. Then I wedged a screwdriver inbetween the 2 and carefully pryed it up. After numerious attempts I finally was able to pop the top off. The top had everything screwed to it. I removed the screws and took the circut board off. As I suspected, the LCD was joined to the circut board with 2 conductive rubber strips. I removed them making sure I placed them so I could put it together just like it came apart. I could not see any signs of corrousion, but cleaned everything with a stashed away can of TF solvent anyway. Contact cleaner if you will. I cleaned the LCD contacts, the circut board contacts, and both sides of the rubber strips. I then put the LCD, strips and board back together and screwed them down. I then positioned the housing as it would be if it were in the ski and drilled 2 water drain holes in the lowest part of the back of the housing. I threw away the pouch of silica that was in the housing. I then put weatherstrip adheasive(black) on the part pf the housing that was glued to the face plate. I then Stuck the faceplate down into the housing and let it dry. Hooked it up and Whoo-hoowee!!! All segments worked.

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Starter Bendix Application

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Wiring Schematic 95 SL750

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Ignition Trouble Shooting

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Stator Testing

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Limiting to 4200 RPM

Courtesy Watcon

I remember the PRO's had this quite a bit as well as the 750's with the buzzer for overheat, I have a simple testing procedure for it.
First disconnect the tan wire to the CDI and see if this solves the limiting problem, if so, check the temp sensor but more importantly the tan wire and it's routing for crimps, pinches and shorts. If you find no problems with the overheat temp sensor or wiring be sure to check for restrictions in the cooling system. You can of course disable the wire BUT you risk missing the overheat.
Verify the tan wires on the terminal board are NOT grounded. If they are you will need to correct the problem. There should be no ground to the tan wires unless you have an overheat condition present.
If all checks good, replace the CDI and test it all over again.

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Terminal Board/Module Function

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MFD Troubleshooting/Reset

Never replace the 1/4 amp fuse with one of a higher rating.
You will cause irreparable damage to the MFD if something goes wrong.

Power surges or spikes are the most common cause for a blown fuse.
The power surges can be caused by loose connections in the electrical box (remove and re-crimp all connectors, I'd also replace the board as it's so inexpensive). Poor ground at the engine plate (scrape off the paint and clean the connector), even corroded or loose battery connections will cause this issue (remove and clean the connections).
Anytime the charging path is interrupted there's a potential for a voltage spike.

I think 14.1 is too much charging output, check the actual value with a "GOOD" meter (Fluke comes to mind) and make sure of the voltage being charged to the battery.
When you split the electrical box, it's also not a bad idea to replace the voltage regulator.

While on the subject of MFD's and LOPr.

The LOPr will only come on when the battery voltage is under 10.9
Remember power fluctuations (usually caused by loose connections) or electrical noise caused by the ignition system may cause the MFD to lose voltage calibration data. These "events" will also show LOPr.

Check and correct the charging system, battery, battery connections, fuse connections, MFD pin connectors, (pay particular attention to power and ground connections at the MFD).

To re-set the MFD
Press and hold the MODE and SET keys until the CAL displays. The CAL display will usually show after 4 seconds
Press and hold the SET key
While continuing to hold the SET key ans within 2 seconds of pressing the SET key, press and hold the MODE key
Don't release either key until the MFD shuts down
After the MFD has shut itself down, press the mode key to turn the MFD on
Depress the MODE key repeatedly until voltage is displayed and verify that the voltage reading has been restored.

Display is stuck on one function/display shows all 8's/buttons don't work
This malfunction can occur when the battery has been disconnected or removed.
It may freeze on any function, or with all 8's the MFD is running its self check during power up.
This will usually happen when there is a power glitch and the micro-processor temporarily malfunctions.
It will usually correct itself when you disconnect the battery for a few minutes, it usually takes 2-3 minutes to re-set the micro-processor.

When connecting the battery negative cable, make sure it is a "clean connection.
Meaning only let the terminal contact the battery once. DON'T repeatedly contact the battery!! Hold pressure on the cable until the bolt is tight.

If you have problems connecting the battery terminals you can disconnect the MFD, install the cables and then plug the MFD back in (my recommendation)

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MFD Directions

addicted

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MFD Style 1&2

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Electrical Boxes with PRO CDI

bd
650 Box


750Box


Pro Box


Pro CDI to 650/750/780 wiring directions.
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I'm showing the working RPM's of the 97 PRO785 is 7500RPm and the limiter is set at 7800 RPM. It also has 32 degrees advance at 3,000 RPM so I think it's going to work VERY well with the triples on the 750 (I can't wait). We'll see if I'll run it on 92 or if I need a little VP110.

The PRO wires up much easier than I initially thought and goes as follows.
Blue/Red from CDI to Blue/Red from the stator
Red/White from CDI to Red/White from the stator
Green/Red from CDI to Green/White from Stator
White/Yellow from CDI to White/Yellow from Stator
Black/Yellow from CDI to Black/Yellow from Stop Switch
Black to Battery Ground
Black to Box Ground

I then seperated the wires from the coil pack and wired with individual pig tails as follows.
Black/Green from CDI to Black/White on PTO Coil
Black/Orange from CDI to Black/White on Center Coil
Black/White from CDI to Black/White on MAG Coil
Black from CDI to Black from Coil Grounds.

I capped off the following wires from the CDI as I have no use for the exhaust valve electrical signals
White/Black
White/Red
Light Green
Green
Red/White

The last couple of wires
Tan from CDI to Tan from Temp sensor
Red/Purple from CDI to Red/purple at LR23
Yellow/Black from CDI to Yellow/Black from CDI (you read correctly)

[christian79]

How I fixed my MFD

[Update by K447] See this updated thread for further instructions as a complement to this original post.
Thanks again Christian!

First off I want to stress that this is what I did to correct my MFD issue and by no way is the only or best way to go about this. Also this not a simple matter of removing some screws. If you do not have a steady hand, you are better off allowing one of the talented MFD repairmen do it for you.

That being said lets begin.......

Step 1
Collect all the tools you will need.


Step 2
Install the cutting wheel on the Dremel.


Step 3
Using a small flat bladed screw driver carefully pry the bezel away from the base retaining tabs.



Step 4
Using the Dremel cut just below the clear plastic screen while being careful to leave some of the black plastic lip for reassembly.

[Edit by K447 - A better/safer place to cut open the case is just behind the front lip, at the Green or Red arrow in this photo. Do not cut any deeper than necessary to just cut through the plastic thickness. There are fragile ribbon wires just inside the case, which you do not want to cut.
See this updated thread for additional info]




Step 5
Use a flat piece of material like the back of a razor blade and carefully pry the two pieces apart. This is a time for finesse not strength. You may have to make several passes with the Dremel before you can get the pieces apart just be sure to save some of the plastic lip.


Step 6
Once you separate the two pieces disconnect the two wiring harnesses from the PCB. Also save the white packet of Silica Gel for reassembly.



Step 7
To remove the PCB you must disconnect the two front buttons as shown and remove all four screws.



Step 8
Using a Q-tip and a liberal amount of electrical component cleaner clean the contacts on the PCB as shown.


Step 9
Reverse Step 7 and pay special attention to tightening the four screws securely while remembering that they are set in plastic and if stripped will ruin the display. I would imagine that the two screws above the PCB and LCD connector come loose and cause intermittent contact resulting in a garbled LCD screen.


Step 10
Test out your MFD on you Ski. If it works great if not you should try to tighten the screws or send it out to the professionals. Also you may have to plug it in a few times as I had to.
[Edit: Sometimes it just needs a firm press of a button to wake it up after power has been applied]



Step 11
If you did not save enough of the lip you can make a form for one out it Popsicle sticks and a paint stirrer as i have here.


Step 12
Once you have tapped over everything you do not want Epoxy on use a Popsicle stick with a liberal amount of Epoxy to fill the void created by the Dremel. Once the void has been filled use as clean stick to remove any access Epoxy.



Step 13
Allow the MFD to sit and the Epoxy to dry. Sit the unit face down to allow gravity to keep the two pieces together.


Step 14
After the Epoxy has hardened sand down the edge as need to allow the bezel to fit. Note the bezel may no longer stay in place and may need to be glued down with some kind of rubber cement. I would not use Epoxy or Super Glue as those products will make it impossible to remove the Bezel at a later date.


THE MOST IMPORTANT STEP:
Clean up your mess and never let the wife know you used her kitchen counter as a work bench.


Enjoy
Time: 2 hours
Skill: Hobbyist
Fun: Depend on your notion of fun

[K447]

More MFD repair photos from Christian79