1
speedo and instrument connections Sat Dec 22, 2012 3:27 am
charlie99
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many of us have tried to repair the speedo intermittent operation seems to be the big issue
so whilst the loom to sensor connection is always worth checking and cleaning
and inge's sugestion to resolder or bypass the film pcb connections seems a positive step
i thought to examine the multipin connection between loom and the input connectors to the instruments
the first 4 pins at the lower right are related to the speedo ...( the top pin of this lot i believe is the more dc feed out + signal return , the next is the less dc out -ive going signal return , and the third is the ground reference. starting at the 4 th pin working down ) after all it just counts pulses .
i had measured the suspect film pcb on the multipin connector to speedo driver board then to speedo motor assembly . and found .....nothing ....well meaning that it measured under half an ohm on all connections...no amount of fiddling bumping or what not would make it change ...the connections looked in good shape and no corrosion evident ...(for some this is not a common thing ...especially in wet type atmospheres in other parts of the world )
also the same result was noted from the connectors to the speedo amplifier board .
![speedo and instrument connections 2012-111](https://i.servimg.com/u/f12/16/13/61/46/2012-111.jpg)
i took a closer examination of the pins that do the connection from the loom to the instruments
ahah!
![speedo and instrument connections Speedo10](https://i.servimg.com/u/f12/16/13/61/46/speedo10.jpg)
what i found was corrosion on the junction at the pins ..in fact the nickle plating was long gone .
i suspect the different metals ...dc current (with some ac signal comming back ) had chewed out the mating contact surfaces ...( i recon the socket part will be corroded) but i thought to try replating ...reflowing some solder to make a better, conductive joint .
![speedo and instrument connections 2012-112](https://i.servimg.com/u/f12/16/13/61/46/2012-112.jpg)
maybe not the most professional attempt at this .....and im sure there will be different teckniques ....(i was looking for some compound to replate the pins chemically like a silver based compound ...but no success in finding it with the short time i have available )
i dont know if this is the ultimate solve just yet .....but makes sence to me
i would dearly love to have a socket to replace the female type connector as well
well the instruments are back on ...deoxit and cleaner to attempt to solve the plating issue on the socket side ....lets see what happens huh ?
some madman stuff for sure ....
so whilst the loom to sensor connection is always worth checking and cleaning
and inge's sugestion to resolder or bypass the film pcb connections seems a positive step
i thought to examine the multipin connection between loom and the input connectors to the instruments
the first 4 pins at the lower right are related to the speedo ...( the top pin of this lot i believe is the more dc feed out + signal return , the next is the less dc out -ive going signal return , and the third is the ground reference. starting at the 4 th pin working down ) after all it just counts pulses .
i had measured the suspect film pcb on the multipin connector to speedo driver board then to speedo motor assembly . and found .....nothing ....well meaning that it measured under half an ohm on all connections...no amount of fiddling bumping or what not would make it change ...the connections looked in good shape and no corrosion evident ...(for some this is not a common thing ...especially in wet type atmospheres in other parts of the world )
also the same result was noted from the connectors to the speedo amplifier board .
![speedo and instrument connections 2012-111](https://i.servimg.com/u/f12/16/13/61/46/2012-111.jpg)
i took a closer examination of the pins that do the connection from the loom to the instruments
ahah!
![speedo and instrument connections Speedo10](https://i.servimg.com/u/f12/16/13/61/46/speedo10.jpg)
what i found was corrosion on the junction at the pins ..in fact the nickle plating was long gone .
i suspect the different metals ...dc current (with some ac signal comming back ) had chewed out the mating contact surfaces ...( i recon the socket part will be corroded) but i thought to try replating ...reflowing some solder to make a better, conductive joint .
![speedo and instrument connections 2012-112](https://i.servimg.com/u/f12/16/13/61/46/2012-112.jpg)
maybe not the most professional attempt at this .....and im sure there will be different teckniques ....(i was looking for some compound to replate the pins chemically like a silver based compound ...but no success in finding it with the short time i have available )
i dont know if this is the ultimate solve just yet .....but makes sence to me
i would dearly love to have a socket to replace the female type connector as well
well the instruments are back on ...deoxit and cleaner to attempt to solve the plating issue on the socket side ....lets see what happens huh ?
some madman stuff for sure ....
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