My Komatsu PC28UU-1 Isn't charging Need assistance.

[Danny Correll]

007, last night when returning to my machine I noticed an arch from the removed control panel to ground and immediately noticed that when replacing the ground wires all back on the terminal block that I neglected to put the ground strap back w/the rest of the grounds. When starting it back up the charging system was back on line. However, the charging light was still on. I then replaced the old indicator/charging relay w/a new one. At this juncture, I'm still back to the light remaining on and the fused area that keeps blowing fuses. I'm hopeful that I can go back to your suggestions mentioned earlier and look for that ground. Replacing the boards on the dock comes first then the machine. Thanks again.

 

[tim3250]

007........... i am aircraft electrician , island of hawaii, and i appreciate the running electrical tutorial you are sending to all of us here on this stream, and i second every concept you have spun .
that 'charge indicator', we have them in vintage aircraft also... the guts of the story is you need a light to light when theres no electricity available, which is a contradiction ( no electricity normally means no light).
so you power the light through a "normally closed" contact on a relay , from 12volts somewhere ( the fuse block)
and that contact , being held closed internally with a spring lights the lamp with the key 'on'.
but . once the alternator spins up and the ' current limiter' (commonly called the regulator) sees voltage building,
the regulator puts 12 volts on that wire (Y for yellow) which excites the indicator relay, opens the contact, and out goes the light.
thanks for your training 007

 

[007]

Hi Tim, Thanks for the complement.
Yes you are correct but i don't think he has got that far to trace that circuit yet.
This type of system is old like me and seemed to come out about 40 years ago mainly on tractors and stationary engines.
We used to be so impressed with them back then but mind you generators were all the rage at that time so we were easily impressed.
The current limiter does function differently to the modern regulator by the way but achieves the same end result.
The modern charge indicator relays have Zener diodes in them to extinguish the light at a pre determined voltage but i think this thing is not that smart and would just have a diode or two in there just to turn the AC into DC to power that indicator relay.
These systems work fine until you add some spot lights or other non original equipment to the machine and they fall in a heap with the extra electrical demand.
Lots have people have just replaced them with small alternators which is no big deal to install.
Not sure if we will hear from Danny again as we might have done his head in!!
Cheers

 

[tim3250]

greetings 007
i have 2 more questions (at least) on diesel engine electrical:
refer to pc128 schematic diagram.........

is the timer a delaying relay? i surmise that a wire with power is fed through to the 'heater light 'via contacts
it does.nt show that pin 2 of timer has power coming from the starter switch 'C' in that case. assuming that starter switch pin r1 is being powered from battery when rotated that way.
in other words, is timer pin 3/4 the coil and 1/2 the output contacts?

2. the safety relay, from what i am gleaning here the safety relay will not allow starter excitation ( wire 33W , pin 1 of safety relay) if there is charging indicated by current limiter (pin 6, L25BR).
that's a guess,
safety relay pin 2/4 is a coil, pin 1/5 normally closed contacts?
thanks again
tim3250

 

[007]

Hi Tim,
I have to best guess this as there are a couple of odd things there.
What is odd to me is why they have a connection from the cranking position of the key switch going to the Timer.
They don't normally energize glow plugs when you are cranking but no problem if they are as long as battery and wiring has sufficient capacity to do so.
When i have seen them do that they usually have the timer remove power from the glow plugs after a period so as not to over heat them.
Which is not possible the way this is wired so i would think this machine is more old school where the timer and light is just for giving the operator an indication on how long to hold the glow plugs on for in the R1 position.
So a better description for the timer would be run down, or time out timer as that is what is doing. It energizes 0 delay and disengages after a time out period.
The normal heater enable would be through R1 but is that relay also back feeding the heaters on L25R, not sure but the size of the wires would give a clue as would be large if they were.
That's the same for the wire from the cranking position (C) to pin 2 of the timer would also have to be large if they are switching the heater current through the timer.
What makes more sense would be R1 provides power to Pin 4 to be used to operate the timer and pass B+ out to pin 1 the light.
Maybe C to Pin 2 is a glow light test when cranking?
They used to do dash bulb checks like that.
This is luxury as before this they used to have a bezel on the dash with some resistance wire in it and the heater current would pass through the wire and make the wire glow red hot and you were good to go.
All your assumptions on the safety relay operation are correct.
Bear in mind that on an older machine like this the safety relay is probably just a relay but do not assume that with the modern machines as what they call a safety relay now has often got electronic card inside with some smarts checking multiple safety switches and performing logic functions.
Do you have one of these machines there or you just got interested in his circuit?.
Cheers

 

[tim3250]

i m going to buy a legacy mini, circa 2000 or so but i 'm studying as much as possible about what problems i'm going to bring home.
that proved for me to be an effective strategy in early 2000 when , as a mechanic, i sought an airplane project.
this is a 1959 piper.
problem here is ocean shipping will add $ 3-4000 dollars to a unit into our harbor from west coast, in fact it's even $1000 more to ship from seattle because they still crane equipment onboard, matson steamship told me.

 

[007]

Don't know any thing about planes but that looks like a good project if you managed to refurb that.
In my opinion i would not even dream about doing up an old mini as it will brake your heart and bank account.
Even if the machine is zero cost to purchase.
They get parked not because of age or hours they reach a point where they have worn out every single part and are almost impossible to bring them up to a reliable level.
Adding even more to the challenge is your remote location.
When i was looking to buy my mini i came across plenty of almost new machines that had been written off from damage or abused from like hire company's and the like.
I was looking at a ex hire machine that was still under warranty but did not have a straight panel on it, and someone had pulled a tooth of the bucket doing some thing stupid and twisted the stick as well just above the bucket quick hitch.
The prices on these machines are hard to walk away from on most and they would make a good project i think.
When you repaired the obvious damage the rest of the machine is still fairly fresh and you are left with something worth having after you plowed all your hours into it.
The machine would have a few scars and never be pristine but when your finished at least all the hydraulics would be strong and ready to do some work.
I have seen some late model machines that are fire damaged, so if your good with wires and making up your own hydraulic hoses they would be tempting also.
Cheers

 

[tim3250]

while we're waiting for danny and his alternator repair ,

1.
I see an IHI on craigslist, high hours but the photos show very little abuse, 30jx on the cowling but the controls are center mounted in front of the operator, does that mean the controls are not pilot?
2.
like propellers on planes, i see the final drives can cost 10-11000 for a pair. can the wear on the teeth on the sprocket give any clue to the health of the finals?. Just because there is no wet fluid the drives are good?
What concerns me is the 90 weight and the 10 weight oil that meets inside there, how can you tell if that seal is good, etc..... again,
any experience with kobelco? there's also a case cx36b with 4100 hours. i can't tell if its an isuzu or yanmar engine from online specs. what did you think of isuzu diesels.
thanks for the insight

 

[tim3250]

good afternoon australia.

i have several diagrams from a nippondenso search showing a alternator solution for the pc128uu problem.


this diagram , a 4 wire type, is a great education in itself....
everything in the dotted lines is internal to this denso type alternator, so to hook this up to the komatsu
would just take pc128UU ignition switch wire (acc) and connect here to the IG wire of a newly purchased harness.
This will power the internal regulator (so it can power the internal field coil and make the appropriate magnetism to create the current flow into the battery to hold 14 or so volts).

secondly, the large wire from the battery has to be connected to the large "B" terminal.
aside from mounting and finding the correct pulley/belt etc..... this is a
DONE DEAL.

anyone requiring the indicator lamp ?
that can be the next discussion, it 's all here waiting to hook up also, but not required.

 

[007]

Just as a by the way you can send messages directly to members on this site if there is someone you want to chat to and not degrade a thread.
Yes they are not pilot, very reliable but i don't like them.
They get the job done fine but they are not as nice to operate as pilot controls.
If it is a play machine just live with them if you like the machine.
I am not an expert on final drives but if you post a specific question on drives someone will jump in and give answers.
The drive cog gives no clue as to there state.
I believe lack of oil and regular oil changes is the most common cause of most failures.
There is a lot screaming around in there so they work very hard.
When i changed my oil in my drives on a brand new kubota the oil looked like metallic paint with millions of flecks of metal in the oil.
The Dealer said this was fine and normal and i have read other people on this site with same.
So i sure hope that is normal.
I am trying to change the oil more frequently to bring the metal level down.
I think you find out real quick if the seal is leaking as the Hyd pressure fills them and the bleed every where.
Not sure what 10 weight oil is 68 grade hyd fluid is used most places here in Aus as well are a hot country.
I think mine was shipped with 46 grade.
I would walk away from a machine if the seller told me he had replaced final drives.
I think if the gear side fails that's fine but if the motor side failed did they clean the total Hyd system of all the metal properly?
On large machines most people suck it up and spend the time and money to clean them out but on mini's and old machines people cut corners to save money.
Isuzu diesels are fine as with most main stream brands.
I would not be thinking like you if it was me.
If it is a project machine you probably won't put the hours on to wear out any of them.
The real issue is where is your nearest dealer and which brand has reasonably priced spares.
The engines are easy, any one can them going again but hydraulic pumps, spools, final drives etc is where the problems start.
I know i am going to get monkey stomped by someone for saying this but machines under 5 ton are generally coincided worn out after 2000hours.
Obviously if someone loves there machine and is gentle this is not true but most little machines work very hard.
Because the machines bucket breakout force is often more than the machines weight, the whole machine is thrashing around when in rocky conditions.
Larger machines of course are not straining so much and spend most of there time cycling through a dig cycle.
Just to give you a guide i was advised directly from Yanmar dealer that the design life of the main pumps was 4000hours on there mini range.(not larger machines of course)
Probably similar for most brands i would think.
So you need to weigh up each machine you come across as some are in such good condition they are worth the risk and others not so.
Machine hours of course mean nothing if you adopt the attitude of some of the Indian and Asian country's like you see on Utube, they keep operating the machines till the buckets fall off.
Some of those guys are such skilled operators as the machines are flopping every where with flogged out every thing you can think off.
Funny to watch but i could not operate like that.

 

[tim3250]

good morning australia,
007, i ve learned a lot on this forum , thanks very much.
as far as the pc128uu....................
i also looked up an '8162' alternator that has no external regulator power, just one wire from the battery to the "B" terminal. the attached diagram shows what is mandatory in aircraft, a 50 amp breaker protecting the alternator/ battery connection from welding to the frame or fire. Circuit breakers are easier and way more reliable than fuse blocks
especially in corrosive environments (oceanside etc) the potter brummfield WX23 series is great for any DC work.
mounts in a 3/8 hole with 2 8/32 terminals, rock solid.
i suspect the biggest hurdle then would be mounting and aligning the new pulley, etc.