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Discussion Starter #1
Just wondering if anyone has had a similar problem and knows how to fix it:

After 4 years of sitting due to installation of new pistons and cams (long story), I've got my SP2 up and running again. The only problem at this point is the digital display: none of the LCD items (tach, speed, ODO) work. The FI, low fuel, and bottom row of lights all work as expected, so it's just a problem with the LCD items. I've got the whole display apart right now messing with it, trying to figure out what might be wrong. So if you have any ideas or maybe even know how to repair such a thing, please let me know. (New display costs about $500, so hoping to avoid that).

Thanks!
 

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If you look at the service manuals you can find ways of testing the circuits at the harness where it plugs into the back of the display. Doing it with one circuit should tell you where you need to look.

My speedo reads 0mph while everything else works. I've replaced the sensor but have not yet taken apart the front end to start checking there. Previously, it would read for a while then stop so testing it sometimes would not have been productive at all. A member here was selling the circuit board from inside the display so I sent him the $$. Hoping to have it working in a few weeks.
 

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Discussion Starter #4
If you look at the service manuals you can find ways of testing the circuits at the harness where it plugs into the back of the display. Doing it with one circuit should tell you where you need to look.
I did all the checks on the wiring that goes into the back of the unit. In other words, I checked that power, GND, and continuity on the plug pins all checked out, as the manual describes. The plug is fine. I think the actual problem is with either the LCD display, the IC that controls it, or the circuits between the two.
 

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There is a tiny piece of rubber with wires embedded in it that fits between the two circuit boards just like in an old 80's Texas Instrument calculator. You can separate the two boards and then clean the two areas that mate with the rubber piece with contact cleaner and then reassemble the units. This solves 95% of the conditions like you have indicated.
 

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There is a tiny piece of rubber with wires embedded in it that fits between the two circuit boards just like in an old 80's Texas Instrument calculator. You can separate the two boards and then clean the two areas that mate with the rubber piece with contact cleaner and then reassemble the units. This solves 95% of the conditions like you have indicated.
That is awesome info. Will have to give that a try on mine. If that solves my issues then it is one huge worry off my chest. :)
 

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Discussion Starter #7
There is a tiny piece of rubber with wires embedded in it that fits between the two circuit boards just like in an old 80's Texas Instrument calculator. You can separate the two boards and then clean the two areas that mate with the rubber piece with contact cleaner and then reassemble the units. This solves 95% of the conditions like you have indicated.
Hey, thanks for the advice LDH; I have the display separated out from the circuit board, so I'll try that out.

By the way: I was a member on Rogue once I got my RC in '07. Got a lot of good tips and advice off that board; thanks for running it! Most sport bike enthusiasts probably think the 51 is past due, but I still love mine and plan to keep it forever.
 

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Hey, thanks for the advice LDH; I have the display separated out from the circuit board, so I'll try that out.

By the way: I was a member on Rogue once I got my RC in '07. Got a lot of good tips and advice off that board; thanks for running it! Most sport bike enthusiasts probably think the 51 is past due, but I still love mine and plan to keep it forever.
OMG LDH® feels the same way! He won't say it, but his actions say more than his loudly typed words :D :p
 

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Discussion Starter #10
There is a tiny piece of rubber with wires embedded in it that fits between the two circuit boards just like in an old 80's Texas Instrument calculator. You can separate the two boards and then clean the two areas that mate with the rubber piece with contact cleaner and then reassemble the units. This solves 95% of the conditions like you have indicated.
Bummer; looks like I'm in the 5%, no dice on this solution.

The display did work on the first ride, but was glitchy; the LCD portions would blink on and off a little. Then on the second ride, no LCD stuff worked; just the LED's at the bottom of the display.
 

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@MikeinCtown might shortly have a used speedo PCB for sale from his bike...
 

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Bummer; looks like I'm in the 5%, no dice on this solution.

The display did work on the first ride, but was glitchy; the LCD portions would blink on and off a little. Then on the second ride, no LCD stuff worked; just the LED's at the bottom of the display.
I'd give it a second cleaning then. You got the display to work some after the cleaning so it is working. Before spending any money I'd be taking some 1,000 grit to the contacts and making sure everything is double clean.
 

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I'd give it a second cleaning then. You got the display to work some after the cleaning so it is working. Before spending any money I'd be taking some 1,000 grit to the contacts and making sure everything is double clean.
Might have to hit the rubber/wire piece with some alcohol too. Some times the corrosion spreads to that as well.
 

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Discussion Starter #14
Well for better and worse, I went ahead and bought a new display. Cost me $500, but it works. The thin silver lining here is that I'm starting at 0 on the odometer, and since I essentially have a new engine, my mileage reads right. Additionally, the frame on the original display had that sun damage that apparently the early bikes seam to get. So, not happy about spending that much, but at least my bike is back on the road.
 

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That sucks you had to spend that much. I finally got my stands in today and tried out the fix I had done. No dice on cleaning the board with rubbing alcohol. Took everything back apart and cleaned it all with electrical contact cleaner, but rather than use the old board yet again, I put the board in I got from Stig. I now have a speedo that works!!! Mileage is 4k more than my original ODO, but I'll just save the board and maybe try it again down the road if I find a cheap used gauge cluster.

No to do the block off plates, remove all the flapper hoses and crap, and then wire in the new CBR coils and I'll be good to go.
 

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Spoke too soon. Was working on the bike tonight, started it up and put it in gear. Zero on the speedo. Touched the front harness connector and it started reading. As I wiggled my way around the wires at the harness I could see the speed drop from 12mph to 8 then to 0 and back up depending on how I wiggled the wires. Now I need to find a wiring schematic to figure out which wires are for the speedo and see if I can either reconnect them or maybe connect them via a new weatherpack connector or some other way.

Now I'm wondering if my original one was good all along and that the harness was really my problem the whole time.
 

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If you have a speedohealer also check the connections there. Mine has in the past shown the same symptoms, with maybe 8 km/h showing when it was doing well over 10 times that, or flashing seemingly random numbers loosely related to road speed - with accuracy changing when going over bumps. It was a bad connection with the speedo-healer in my case. Doesn't sound to me that it was the speedo's PCB after all. Still, at least you have one now to pass on to someone else who may need it - after finding your loose connection... :)
 
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