Trouble-shooting the Protective Control Box in a 5-ton

[cranetruck]

You probably used a "Megger", pretty expensive piece of equipment for a normal mortal....

 

[OSO]

Had to get a cert to use that meter . Nick name was biddle /bond meter. A t tool crib had to leave brass tool check with ss# on to make sure it got back to tool crib.

 

[Oldvw2]

Had to get a cert to use that meter . Nick name was biddle /bond meter. A t tool crib had to leave brass tool check with ss# on to make sure it got back to tool crib.

And you also don't want to let your coworkers near it when it is signed out - we had a new mechanic in the maintenance shop try to demonstrate his toughness by shocking himself with it and...you guessed it he dropped it in the process. Talk about some unpleasant conversations in the Manager's office!

 

[cranetruck]

Got a junk control box today from a parts M925 in Mt Airy, NC.
I'll cut it open and see what I can find about what makes it tick or not.
It is a WSU-4003UT ord number 11669304. The M925 is a 1996, I think.

 

[steelsoldiers]

Fantastic Bjorn. I look forward to your report! Hopefully you can tell me how to rebuild mine

 

[cranetruck]

Corrosion.
All components are corroded and the printed circuit board has no conformal coating.
It is a fallacy to assume that a welded steel box is water proof when the connector is installed with a gasket. Water molecules will enter and water accumulate.
This one has a 1/8NPT pipe plug (also not sealed), which should be removed to allow the box to breathe, that's really all one can do.

If the box had been hermetically sealed or vented, it would probably suvive a lot longer.

 

[steelsoldiers]

Sheesh. They would have been better off mounting the solenoids to the firewall and encapsulating the circuit-board in a separate smaller housing. At least that way you could change out the part that fails instead of the whole box, but alas that is not the military way.

 

[acetomatoco]

components alone $25... assembled $300 in a box...relative values only.. Which one would you like to sell to the gummint? That is the answer on a lot of stuff... The new light switch for example... a multihundred dollar piece of electronic failure prone crap to replace a simple switch which has lasted for 55 years...and could be operated in the dark with positive handle operation...no bells no whistles...

 

[cranetruck]

Another example of hiding compromises in design.
On the right is the new flasher circuit, assembled with Radio Shack parts and encapsulated in black epoxy. This one didn't even have overload protection, it blows like a fuse when exposed to a shorted light filament (circa 2001).

The circuit assy on the left is a 1960's era power amplifier from a VIC-1 intercom AM1780, mil spec parts throughout.

.....and ACE, I agree with you 100% on the light switch design, maybe one day the steering wheel will be replaced by two pushbuttons, lighted, so they can be seen in the dark.

 

[cranetruck]

An example where a commercial relay was used when perhaps a mil spec relay should have been used.
Catalog sheets from the 1970's show what was used and what was available. Cost must have been a big factor....

 

[Crash_AF]

So did anyone figure out how to bypass this box? I can jump my 936A2 by wiring the solenoid open and using a remote starter switch to get it started, but that doesn't help me check the gauges and switch installation...

Also, does anyone know where I can get one of those boxes?

Later,
Joe

 

[Dmaxcc6spd]

Is this box unique to the 8.3 powered 900 series trucks? It seems as if the newer trucks have the more complicated PCB.

 

[73m819]

Is this box unique to the 8.3 powered 900 series trucks? It seems as if the newer trucks have the more complicated PCB.

No the 809s have them along with all the 900s, you can use a 900 PCB on a 809 series but you CANNOT use a 809 PCB on a 900

 

[Stein12501]

I just got a 84 923A1 and the new batteries were trashed. I found that it was the control box. I opened mine up and it contained 2 relays with a capacitor and diode on each. I replaced the lower relay that runs off the battery switch with one for a golf cart. Been 2 months all is well. The truck was rebuilt in Ft. Riley in 2010.

 

[73m819]

The big difference between the 809 and the 900 PCB is the 900s have a neutral safety lockout as well as the oil pressure lockout, the 809s have only the oil pressure lockout.

 

[Stonepicker1]

Looks like my PCB not working in my M923A1...tried to start it the other day and it just clicked.
I thought it might be dead batteries because I haven't started it in over 4 months. I put the 24 volt battery charger on the batteries overnight and still get just the clicking noise.

Time to troubleshoot the start system to make sure. Always something.

 

[minimade]

i have a couple Control box nsn 6110-01-395-9585

Anyone know what these are for ?

By The Way, my local truck supply can get the 24VDC continuous duty, and intermintant duty 200 and 400 amp relays.

I looked for invoice with parts no"s but dont have them handy,...will stop in and ask to get my past history of purchases and will post

the hardest part was opening the statrer control box so it would be easily re-sealed when repaired,..,.

after repair, we have had no issue with the 2 repaired units

 

[KickerM]

Just curious if the golf cart relay is still working, I want to take my old one and fix it so I have a spare on hand, The replacement pn for mine was 6110-01-444-2546 in a 1991 BMY 923A2.

 

[Rmtaunton]

I hope he doesn't mind but "danman" has proven to be an expert and testing on these

 

[Stein12501]

Yes mine is still working for going on 4 years. No problems so far. I do more start/stop than I put miles on. I hope I didn't curse myself for saying that.