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floyd

floyd
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Have just installed a new set of odometer gears.

Had to open the instruments a few times.....as I was missing a gear and had to wait for it to finish the job.

Before opening the instruments this time around (I have been in there many times before) the GPI and neutral light were functioning 100% fine.

After reassembly the other day the gear indicator would only show 1 3 and 5 as I went through the gears.

After todays reassembly there is nothing at all on the GI lcd and no neutral light....

GPI switch tests fine with a multi meter through the gears....

there is continuity through the loom from switch to instrument connection socket...

When I jump all 4 wires on the switch end of the wiring loom (to simulate neutral) nothing happens. 

all connections cleaned with deoxit

Any ideas?


........

Based on Ducks write up here  looks like the GPI circuit board may be gone....


__________________________________________________
K100 with lots of K1100 bits - mongrel of a thing...
    

charlie99

charlie99
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don't panic yet Floyd

the gpi board has a sacrificial - voltage dropping resistor ...used to drop voltage to the zenner diode (used to regulate the voltage to just a few volts (in this case 5.0 or so )

it could be that either of several things may have happened

possibly the resistor has gone open circuit ...could be that a pin connection shorting thing happened  ...look for a now black looking resistor  and is unable to supply current to the gpi circuit

the zenner diode it there to both protect the circuitry from high voltages and regulate the voltage to that 5.0 volts

possibly the zenner has achieved a higher than expected current flow (shorting pins possibly ) and has become now short circuit itself ...causing no ...or very low voltage to get to the electronic gizmos that do the decoding and display ...because the current drawn through the resistor is too high and is dropping too much voltage

you could be right and the chips that do the work are now blown up

heres the thing ...the chips are cheap as erm chips ( omg did I say that ?) 

so for a few bucks they can be replaced at many times under the cost of replacing the board

take it all apart ...yes ...again and get us a good photo of what you see

some of us can lookup the circuitry or component values .... and recommend a replacement  as such

without some soldering skills this could be difficult to replace a chip  without lifting - destroying the board tracks ...ouch !...

but with basic skills and tools shouldn't be too hard

remember it is often better to cut off the legs of a chip and pull each pin separately  than it can be to remove the chip as a whole item ...and less destructive in any case

maybe if we get the pics, and the diagnosis is clear ,  we can suggest send the board for the replacement process , to someone who knows how and why .

chin up mate it aint hard for some

horses for courses I say


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OGear Indicator and Neutral Light mystery  Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

floyd

floyd
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Thanks so much for your reply Charlie. Fantastic support yet again!

Finally got around to stripping it all down again (as I had to do anyway due to my new odo gears not working properly) 

Heres the pics.....nothing looks obviously blown to my eyes.....


Gear Indicator and Neutral Light mystery  Img_2011



Gear Indicator and Neutral Light mystery  Img_2012


__________________________________________________
K100 with lots of K1100 bits - mongrel of a thing...
    

floyd

floyd
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does the fact that it went to only odd numbers (1,3 ,5 with no N) and then finally nothing at all indicate anything?

any idea which is the sacrificial resistor?


__________________________________________________
K100 with lots of K1100 bits - mongrel of a thing...
    

Inge K.

Inge K.
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@floyd wrote: does the fact that it went to only odd numbers (1,3 ,5 with no N)

This would happen if you loose the connection on the yellow/blue wire.



@floyd wrote: and then finally nothing at all indicate anything?

Have you checked that you have both ground and power all the way to the
GPI PCB?


__________________________________________________
Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

floyd

floyd
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@Inge K. wrote:Have you checked that you have both ground and power all the way to the
GPI PCB?


not yet mate, not sure how to....


__________________________________________________
K100 with lots of K1100 bits - mongrel of a thing...
    

Inge K.

Inge K.
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Measure the connectivity between the connector points as shown in the picture.
Or better connect a battery or other 12V Source to pin 6 and 13, and measure
at the related connector points to the GPI PCB.

Also check that it isn't any corrosion where the male connectors to the GPI is
riveted to the conductive film.
Also check that the female ground/power connectors at the GPI PCB have good
tension and grip to the male pins.


Gear Indicator and Neutral Light mystery  Gpi_kr10


__________________________________________________
Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

charlie99

charlie99
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the board looks ok Floyd

I think inge is onto it  with the internal connections suggestion

but hesitate  for a minute to remind that the gpi connector is one of those 4 pin thingys  that the fuel tank uses and known for intermittent connection issues (probably more to do with the current through them ) than  just signal switching stuff like in the gpi cables from the switch to the instruments
you have cleaned that connector with deocit before going into the instruments ?

doesn't explain why it disappeared though ?!

check ...test as inge suggests internally ...but also put the connector as a suspect ....unless you identify a cracked outer casing of the gpi switch at the rear of the gearbox ?
I think we have seen some corrosion on the rubber conductive piece from the circuit board up to the lcd display once or twice too .


just some suggestions


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OGear Indicator and Neutral Light mystery  Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

Born Again Eccentric

Born Again Eccentric
Life time member
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@charlie99 wrote:
but hesitate  for a minute to remind that the gpi connector is one of those 4 pin thingys  that the fuel tank uses and known for intermittent connection issues (probably more to do with the current through them ) than  just signal switching stuff like in the gpi cables from the switch to the instruments
you have cleaned that connector with deocit before going into the instruments ?

doesn't explain why it disappeared though ?!

check ...test as inge suggests internally ...but also put the connector as a suspect ....unless you identify a cracked outer casing of the gpi switch at the rear of the gearbox ?
Floyd,

My immediate thought was the 4 pin plug & socket as Charlie describes above (right hand side of bike next the fuel tank connector - by rear brake reservoir/coolant expansion tank). But I kept quiet because your first post suggested that you had cleaned it up and checked continuity etc. 

As Inge says, if the yellow/blue wire loses connection you get the partial read out - if you disconnect the plug & socket completely, then you will get nothing at all on the GPI or neutral light. I believe in simplicity - and your symptoms point to this plug & socket being the villain rather than the more complicated electronics in the instrument cluster. If the GPI switch at the rear of the gearbox was cracked/allowing in moisture (it is in a rubbish place on the bike), then I would expect you to be getting erratic readings on the GPI/neutral light rather than no reading at all (I had this problem - which was fixed by replacing the GPI switch - and sealing it up good last time I had the swing arm off to grease the splines). By the way - there is an excellent picture of the internals of the GPI switch on Crazy Frogs K100 rebuild page (about half way down after all the gearbox stuff) which helps explain what goes on back there.
http://hrsbstaff.ednet.ns.ca/bvogel/K100/K100.htm

Of course, the GPI and neutral light are a nice to have (Ok a very handy nice to have) and providing you pull the clutch in when starting, their absence shouldn't affect the running of the bike (just unplugged my GPI switch and fired up my bike with no problems).

Good luck with your fault finding.


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Gear Indicator and Neutral Light mystery  Uk-log10 Gear Indicator and Neutral Light mystery  Sco-lo15Gear Indicator and Neutral Light mystery  Eu-log10
                              Paul  Gear Indicator and Neutral Light mystery  905546712

"Heidi" K100LT 1991 (Grey) (VIN 0190172 Engine No. 104EB 2590 2213) - 5th owner. January 2014 (34,000 - 61,000 miles and counting....)
"Gretel" K100LT 1989 (Silver Grey) (VIN 0177324 Engine No. 104EA 2789 2211) - 4th+ owner. September 2015 (58,500miles and counting....). Cat C Insurance write-off rebuild Feb 17
"Donor" K100LT 1990 (Red)  (VIN 0178091 Engine No. 4489 2024) - 6th & final owner (crash write-off now donor bike).   June 2012 (73,000 miles) to November 2013 (89,500 miles)
    

charlie99

charlie99
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good post born


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OGear Indicator and Neutral Light mystery  Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

floyd

floyd
Life time member
Life time member
Thank you all. This forum makes me all warm and fuzzy hehehe

Will try all suggestions today.


__________________________________________________
K100 with lots of K1100 bits - mongrel of a thing...
    

robmack

robmack
Life time member
Life time member
Hi, 

Just joining in to confirm what Born says.  A defective connector between the TGPI switch and  the instrument cluster will give the symptoms you see, as will lack of power to the GPI board.  There is a False Neutral detect circuit on the GPI board (same as on the boards I designed and build).  When the transmission is between gears and also if no ground input is registered on ALL the input wires, then the false neutral detect kicks in and blanks the display.  Same symptoms would happen if no power got to the board from within the instrument cluster.

With no ground inputs into the GPI board, the display driver will try to output a "7" on the display, but an auxiliary circuit activates the Blanking Display input on the CD4543 chip, effectively preventing the 7 from being displayed.

One possible confirmation is to try and ground selected pins in the right side TGPI connector leading to the bike's harness.  Find a long thin wire, bare both ends and connect one end to bike's ground.  Take the other end and touch pins in the connector.  By touching the pins corresponding to Yellow/Black, Yellow/White and Yellow/Blue,  you may get one of  <Blank>, "3" or "5" or possibly "6" on the display.  If you ONLY get is <Blank>, the problem most likely is the power.  If you get any of the other displayed numbers, instrument cluster is fine and the connector is the culprit.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

floyd

floyd
Life time member
Life time member
Thanks again to all of you....

Think I have it (kinda) figured out....

I am now back to where I was.....only 1, 3, 5 is showing....but thats better then nothing.

I believe 2 things happened at once....first the GPI switch broke and is only sending 1, 3, 5. This is a real pain in the proverbial as I had the swing arm off a week ago to add more silicone to the switch. Maybe I have sealed in moisture or something...dont know...but when I test the switch connector through all the gears its not working as it should.

Then, there is a fault somewhere in the wiring in the instruments. The GPI board its self is fine. The wiring in the instruments had connectivity (thanks Inge) but still displayed blank regardless of what I tried. 
I changed out the circuitry for some from my 'spares' instruments. Now it displays 1, 3, 5 and I can 'trick' it into displaying all gears and neutral by shorting the various lines in the wiring loom connector. 

cheers


__________________________________________________
K100 with lots of K1100 bits - mongrel of a thing...
    

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