Kubota BX2370 instrument cluster repair
Kubota BX2370
wiring diagram
https://www.manualslib.com/manual/1774272/Kubota-Bx2370.html?page=321
water damaged instrument cluster discontinued part #K2731-62510
main problems water from leaky lens had collected in bottom
- lens seal compromised
- galvanic corrosion to constant 12v pin #2 destroyed pin and damaged connector
socket
- corrosion to other pins and socket
- trace from switched 12v through diode to hidden trace under stepper motor
completely destroyed by corrosion leaving different parts to right of stepper
motor [bottom view] including T720M05Q 5v regulator without 12v
- stepper motor armature seized with powdery rust
instrument cluster pops out by inserting two screwdrivers between cluster and cowling with a little pry and pushing back of cluster to release clip tabs/cluster
most of the ic's are obsolete/no longer listed making it difficult to
know what you are looking at
replaced missing pin #2, cleaned and tinned other pins using acid flux
then cleaning off flux and wiping pins smooth
inserted sewing pins with heads cut off bent in u shape to prevent being
pushed into female connector in pins #2 and #9 to assist in electrical
connection to damaged female connectors
opened cluster by removing four phillips screws at back and carefully prying
off lens
general inspection/clean with alcohol and dry
connect +12v to constant 12v pin #2 and switched 12v pin #9, ground to
pin #16 > generally explore for voltage, especially left pin T720M05Q
5v regulator
[removed T720M05Q 5v regulator to determine whether 2.5-3.1v output was
shorted component or no source voltage to left pin > regulated 5.04v
to 400ma load when 12v power off instrument cluster board]
[removed 14v varistor S14K14 to verify not shorting with applied voltage]
sourced where 12v for left input pin T720M05Q 5v regulator came from and
found switched 12v from cluster pin #9 went through diode to large trace
which went under stepper motor but fed nothing to right of stepper motor
> after testing with reduced currents permanently installed jumper from
anode of diode to trace connected to left pin T720M05Q 5v regulator >
now supplied regulated 5.04v / everything lit up
opened stepper motor to remove powdered rust seizing armature > this
requires proper procedure
remove top case of stepper motor and before doing anything else
note/mark rotation position of armature [important to have gauge return
to 0 after fix]
remove/lift and clean blue gear between armature and gear to gauge
needle
lift out magnetic armature [having previously marked rotation position]
and remove powdered rust attracted by magnet of armature / powdered rust
on metal around armature
lightly air blow out other powdered rust [don't use magnet which
might magnetize metal around armature]
reassemble armature noting marked rotation position and blue gear
insuring gauge need is at 0
replace top case of stepper motor [to prevent losing/damaging parts]
reinstall in kubota and start varying engine speed both to verify functioning
and to collect more powdery rust on armature > found armature/gauge
needle quickly seized requiring repeating above removing and cleaning off
powdery rust on magnetic armature [more than once]
remove silicon lens seal and replace with new seal [used rtv which allowed
repetitive opening of cluster]
other than scraping tinned pins #11 and #12 for intermittent turn signals, that pretty much restored the instrument cluster [probably similar for other water damaged instrument clusters].....