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I've got a friend's vehicle I was looking at (MA01) with no forward and reverse working.
I picked it apart.
The main transistor on the 'transistor card' was toast. I replaced it with a MJH11020G which was pin for pin the same, just needed a new heatsink. My only doubt is the hfe value - which probably will be right, but I'm not sure. Didn't fix the forward and reverse issue.
The main controller board had a burnt trace - fixed that.
turning the key switch yielded the main contactor adjacent to the transistor board starting to work again. I got it to go forward once, (out of many tries) but only once.
Looking at the relays on the transistor card, -putting the unit in forward and reverse shows minor movement of the relays. Relays test okay; but they are only getting driven with 7V for a 12V relay. Hence - I have a power supply issue.
I ran over all the 'dodgy' solder joints I could find, but to no avail. I need some sort of a manual. It is the SCM2-91 variant, 24V.
I've looked online for a manual, but I have come up negative. Is there anyone who could point me in the right direction for this?
Thanks
albee,
did you ever figure out what ails your truck?
update on initial issues.
the f/r relay control card was defective with rotted circuit paths on the pc board itself as well as corrosion on the relay connectors.cleaned connectors and did point to point wiring and it works well now.
seems some corrosive agent got on it and ate up the copper traces here and there.
the main controller card also had physical damage which required point to point wiring as well.
i'm still chasing gremlins at this point however.
truck work fine in both forward and reverse but if put in either reverse or forward without pressing the accelerator,nothing happens.
if i press the accelerator until i hear the micro switch and then put it in F or R it then works normally.adjusting the pedal so it keeps the micro switch just closed makes it work fine but drawback is that the drive system never shuts off until F/R lever is put in neutral.
tried known good main control board,voltage regulator and f/r card,accel unit with no success.
next step is to chase down bad connections and wiring i guess,or perhaps the R/C board!
truck has only 1100 hrs but seems to have had a hard life.
I got the factory manual and gone thru most all tests. 98% sure it is the main controller card (transistor card in the book). Going thru the test procedure shown in the book for the CH1 gives exactly the revers of the correct voltages.
Where do I get one? The owner previously sent it out to a company called: " Flight Systems Industrial Products" or possibly "THV Parts" and as far as I can tell there was absolutely nothing done to it. After a return trip to said repair company at least we were able to determine that they had managed to break the lead off one transistor. Replacing it did not help.
I DID find earlier that fuse #12, supposed to be a 1 amp, had been replaced by a 30 amp one. That might explain why 2 traces on the card were smoked and replaced with external wires. (This all prior to my customer buying the machine.)
The only thing I have not tested is the little box that is called the contactor detecting circuit. Tests shown in the book requite building a small harness to test it off line.
Any one have one for sale?
TIA,
Al
alribee is my name. provider is Google. I guess there must be some trick to this, which I am not savvy.
Where would I be able to buy parts for this? Is the directional switch available for a 1985 model? Any idea price?
Al
The directional switch definily makes the small relays move on what is referred to as the (transistor card), the card where the multi wire cable from the front lands, next to the power steering motor relay.Thing is we put a new main (rebuilt) card in it and it worked fine. The steering cylinder was leaking, so I took it out and to a rebuilder. after all that was finished, now the machine will not move.
did I wreck something? There is always that concern! this is a beautiful machine, low hours, sat most of its life. Nice paint, even.
email:
[email address removed]
bought a used manual on ebay but got lucky i guess.
get me your email and i can send you relevant pages.
sounds like your f/r switch is not working properly if it works fine when you push the F and R relay in manually.
1 relay is for forward and the other is for reverse.
also check the tracers on printed circuit of relay card.mine had some compound/poting on it that ate through the copper.hard wired the connections and good to go.
Where can I find a service manual for one of these, Nissan MA 01?
Or just trouble shooting chart?
Mine will just not move. Mechanically closing the right hand relay, it works forward and backward, not sure if the steering action coordination of the drive motors works in that situation.
Albee
One last thought on this subject is the concern of running a lift while blocked up and free wheeling. There is a hefty voltage spike when the current is removed from a high rpm running motor and some MFG's do have a warning in the service manuals describing such voltage as some can reach upward toward a 1000 or more. Most later model trucks are equipped with a flyback diode that eliminates this. I have seen a few ev-1 systems zapped because of winding one up while blocked.
As far as load test is concerned i have always performed the load test using hydraulics as they are the amp hog of most lifts including this one. I do not like to see much over 3 volt drop in voltage when performing a deadhead check. Low battery voltages can lead and will lead to card failure eventually. Lower than voltage rated will lead to heat thus smoke. A battery going out will most time drop of 5+v when checked on "full" charge with hydraulics dead headed. You will also have other tell tell signs such as rotten egg smell when lift is charging and or running and deformed tops on the cells. Just my 2 cents worth.
yep i'm sure the card cured the problem for now, think about what trashed the card to start with.
as long as you run golf cart batteries the capacity will always be an issue because the machine was not designed to run off golf cart batteries in the first place.
As for the load testing, i'm quite aware or what the manual's say about having the wheels off the floor, that is more for safety reasons than getting an accurate test and some drive tests can't be done with the wheels on the floor. Sure you can use the brake system to hold the motor and take a load test but if the motor slips then your test is NOT accurate, besides i see no point in putting undue stress on the brake system alone. Setting the machine up against a stationary object , accompanied by brake use will get you an accurate test result as well. I prefer this method because doing it the 'factory way' sometimes is not the best way.
Me being a factory tech i try not to do the kind of work on machines like was done here. From time to time we do learn tricks outside of the book so to speak. If it cannot be repaired back to factory specs then i won't bother with it.
Nuff said....
good luck
see you back soon ;o)
thanks to rcav8tor for sending me a main controller card.cured everything that ailed this truck.
all is working fine and he even sent me spare voltage regulator,pump control and f/r control cards to boot to ensure this nearly 30years old machine will keep going!
thanks a million.
battery capacity was never an issue in this case as contactors would drop out the instant accelerator was touched without the motors even having time to spool up.also,the different behavior of the truck depending on the position of power/economy switch and steering switches indicated greater issues than supply power.
nissan's service manual also dictates that drive tests be done with truck lifted of the ground.
will be sending my old card for rebuilding now and keep as a back up.
you dont load test with wheels off the ground
it needs to be in natural state for proper load test
get them golf cart batteries out of there and test it with the correct size battery!
until you get this in the right configuration your testing is just going to run you around in circles chasing ghosts due to incorrect readings because of the battery issue.
sighs
good luck
Please keep us posted on what you found out. I am betting it is a main print card ;]
perhaps i'll find a defective brush or spring.still have 6 brushes to check thoroughly.
when i last checked the top ones visually they seemed ok.perhaps one of the bottom ones.i can hope.
surge suppressor on contactors all check out fine.
the checks on ch 2,3 and 4 of controller come back good.just ch1 comes back iffy with the mps readings not quite correct on the minimum and maximum but still fluctuate like they should depending on throttle position before it drops out if pedal is too low or too high.
rubindenis at yahoo dot com.system removed it from last post.
voltage drops to only 24.6 or so.testing done with tires off ground so system is not under heavy stress.
pulled the 2 top brushes on left motor and they still have 7.5mm before reaching wear mark so they are worn about 5mm from new.will jack up and try to get to the bottom ones as well and order new springs just in case they are weak.springs check out ok but??
good thing i like this lift cause it's driving me NUTS.
may try another commutation capacitor if i can find something with similar specs.
[email address removed]
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