Indicator Lites, 300 - 400 series tractors

In the past few weeks I have thrown my two cents into other posts concerning the troubleshooting and repair of indicator lites on some 300 and 400 series tractors. Well, now its time for me to put my money where my mouth is .... just bought a 416-8 over the weekend and you guessed it - all indicator lites are nonfunctional and of course all the safety switches have been bypassed

So maybe we can all learn a little more about the electrics / electronics of some of the 1980's wheel horse models.

this is what we start with



closeup of the molex connector wiring area


and of course the test lite switch has also left the building a long time ago


removing the screws that hold the indicator board to the dash panel revels the front of the indicator board


both the front and rear surfaces of the circuit board are coated with a green colored silicone like "mat" which shown here is starting to peel away from the indicator lamp area - guess where the corrosion is going to be !!



lets pull the circuit board away from its connector


and take a closer look at the solder plated copper connector contacts - not looking too good


further inspection of the board can be made by "peellng" the silicone mat off both sides of the circuit board




a view of the component side of the board


all cleaned up




In the next few days, I will post closeup photos of the corrosion on the wiring side of the circuit board. Counting all cold solder joints, totally eroded traces and cracked traces, there are about 12 spots on the pc board that could cause failures of one type or another.

From an initial look see - there are probably less than $5.00 worth of individual components on this circuit board. It is not too far to believe these circuit boards could be repaired by anyone who has a magnifying glass and good soldering skills.

Stay tuned for Chapter 2 - starting the repair process.

I am lisitening, as I had a problem on my 312, it was not nearly as bad, but I am sure it is a solder joint or cracked circuit...just need to find it. my board was not that dirty, so if that could be fixed.....

Very interesting in deed!

Randy

Will,

If I remember right you had just a parking brake issue - this board was completly dead - no wonder after seeing the corrosion.

your issue may be just a broken trace or a single corroded copper trace.

here is what the edge connector looks like closeup - areas like the open circuit pointed out on the right exist all over the board - good news it is all repairable - its just time consuming, if any electronic components are needed, they are all VERY inexpensive. Even the integrated circuit "chip" is probably less than $1.00.

anyone have a good clear picture of the wiring to the test switch ??

Chuck

I will be following this post. I dont have a tractor with the test lights but do have parts for one. Dont know if any good and would be willing to part with if anyone here needs it.

P.J.

Thanks for the offer PJ.

Right now there are so many circuits bypassed on the 416-8 that I'm surprised it even needs gas in the tank to run !! It certainly runs without this board in it !!

I do think there is a request in the classifieds for one of these boards - I have no idea about how to identify them or what models cross with each other - maybe someone will chime in on that subject.

I also have to partially correct my $5 rebuild statement, the grain o' wheat indicator bulbs can be a little pricey at over $1 a piece, but all components I see on this board are very common pieces.

I guess it still all boils down to the question of how much is your time worth.

"I love the smell of solder in the morning - It smells like .................. victory."

I'm lovin' this thread! No problems (yet) with the board on my '97 314-8, but who knows? Part of the reason I like this tractor is the "full instrumentation" !
BTW, I have repaired the intermittent wipe boards on '90s GM trucks with a reheat of the solder points, as well as the $300 IP circuit board on Dodge Neons.
I am eager to see the next installment.....

Sarge: Two not so great pictures of the test switch It has 6 connectors but no all are used. I replaced my board but saved the old one so I too will be following your repairs closely.
One problem with mine was a disconnect in the nylon plug that holds all the wires going to the top of the board. The red wire had burned up its connector.

The coating you peeled off is something called conformal coating and is available as an aerosol.

Instead of having to go back to the tractor, I am going to use a PC power supply, with one of the 4 pin connectors. Since it is 12V DC, I will fuse the leads at 10A and , power and ground the board, and use a jumper to see where my break is.

Will - DON"T DO IT - not with 12 volts applied to anywhere other than the 12 volt inputs on the edge connector! ! Unless I misunderstood your last post.

the pc board must contain a voltage regulator to cut the 12 volts down to +5 volts to support the logic chip in the center of the board - you might end up frying the chip quickly.

I would start with a magnifying glass at the PARKING BRAKE lamp and follow all the traces to their ends - check each junction on the trace and look for areas on the trace that appear lighter than the normal green color - that could indicate a loss of the coating and a possible area of concern

an ohmmeter set to a higher ohms scale ( 10k or above) should allow to probe around the board without too much danger. A lower ohms scale forces more current thru the ohmmeter and your circuit and could possibly damage the integrated circuit chip - especially with older analog meters !!)

if you intend to check this circuit board "live" - you will need to mimic all the voltage levels to all the 12 pins coming into the circuit board to get an accurate response from the logic - again - assuming all is well with the electronics and you only have a wiring issue.

Paul,

thanks for the test switch pics - I think yours is a different setup as I seem to have 5 wires - orange - red - yellow - tan and grey.

From the model # on this tractor , it appears to be a 1987 416-8. Model is 31-16K803.

Rick
thanks for the input on the bad grounds and solder connections - I remember I learned that the hard way AFTER taking out the wiper motor of my 86 MonteCarlo - paying for and replacing the wiper motor and THEN finding the broken ground connection!!

Was that the 416 where the guy kept lowering the price $25 each week? I was wondering who bought that.

Paul

Chuck: I know the pictures are not good. I went an looked again. There are 6 terminals on the switch but only 4 are used (bottom 4). It is a momentary switch..lift toggle lights come on release and it goes back down lights go off.


As to the wire colors....I have 6 WH of my own and work on 2 others..NONE repeat NONE have wire colors that match the wiring diagrams. (I lied there is one exception...my L107 one wire and it matches the diagram

I think that the factory used whatever wire they had available that day or the wire diagramer was color blind....

On the tractor there ar 4 wires 2 red two yellow with red paint....

the wiring chart says I should have red yellow drk green and orange.

Edit: My book shows that the 416 should also have red yellow drk green and orange....Good luck

I would fix the board then coat the whole thing in epoxy. Except the edge connector. Then use a lot of dielectric grease on the connector to protect it from the elements.

I hope your using lead free solder, or have a little ventilation.

got your PM thanks!

A few more pics before troubleshooting the circuit board ...

the connector with a few "extras" added to retain moisture and start corrosion


lets get this connector cleaned up to make a few visual checks and take a few pics for those who will need future wiring assistance




and then take a quick peek down inside the edge connectors to check on the "fingers" that make contact with the indicator circuit board - not the best picture but it gets the idea across


and then check the "punchdown" connectors on the back - for those unfamiliar with this style connector - imagine a v shaped metal slot that when you push an insulated wire into the slot, the insulation is pierced by the sharp v shaped wedge and the copper strands inside the wire are pinched into the v, making electrical contact inside the slot. The wire is held in place only by compression into the v shaped wedge.


on the corroded punchdown connectors - I'm thinking pull the wires - wire wheel the connections with a Dremel miniature wire wheel and repunch the connectors.

On the edge connector fingers, I'm thinking a few strokes of a small piece of 600 grit sandpaper into the connector should clear up any corrosion - then as CaptJake stated above, a little dielectric grease for good luck.

lets open it up for discussion

Chapter 2 - checking the individual components will start next week.

I haven't bought any in a while, but thought that sounded a bit high. Here's a 4 pack for under a buck.

http://www.goldmine-elec-products.com/prod...p?number=G15581

Very interesting thread.

Jim,

thanks - that's a great website - the bulbs seem the right size and specifications - so we are safe to say these boards could probably be entriely rebuilt for less than $10 plus your time to clean and repair the traces. A quick and light wirewheeling with a dremel appears to be the next step. If we could find the replacement part for the edge connector with the punchdown contacts, that would be another step forward. I'll have to head to the toro website to see if they are still available.

Stay tuned.

What is the number on that chip on the circuit board. If you give me all the numbers I should be able to tell you what it is and what voltages it can handle, and maybe what year it was made.

thanks dkopp,

its a quad 2 input exclusive or gate SNJ54LS8AJ made by Texas Instruments - nothing exotic or custom here - military spec's perhaps.




http://focus.ti.com/lit/ds/symlink/sn54ls86a.pdf

not sure what the AJ stands for but I have a few of these in the basement (believe it or not) from the days I used to go to Radio Shack dressed in my green leisure suit to check out the new 8 track players for my 70 Chevelle SS 396. Sorry - memory flood in progress !!

I thinks there's a zener regulator on the board - there is a single larger 1/4 watt resistor on the board - probably for the zener to drop 12 volts down to 5. The spec sheet shows 5.25 volts as the maximum allowed, so I figured I'll find a 5.1 volt Zener on the other side of that 1/4 watt resistor.

pictures to follow - I'm cleaning upi the board as we speak and should be able to reverse engineer it today. The copper traces are a mess and I would consider it a loss other than the educational value to help others who will experience the same issues and not want to pay $160 + for the replacement pcboard.

Old Iron, if you hunt around you can get the board for about $100.00 (hint: jack's small engine).

Also, the reduction of voltage must be done at the board, at the molex I am getting 12V on the red constant. Also with my problem, it is when it is off, when on, the PB light works fine. It just stay on when off.

I looked last night, not major corrosion or breaks...maybe a transistor, look forward to the reverse engineering.

Will, getting close with the reverse engineering. I know you are correct about the voltage regulation being on the pc board. Still drawing it out.

please confirm this is the same sequence of display lamps you have on your tractor - meaning the top lamp is "seat switch" then "parking brake" then clutch pedal" , etc. The picture shows a 416-8.

just want to be sure - the demystification guide sequence is not the same (maybe no surprise there) but my tractor is a 1987 and there is no direct schematic available for an 87'. The 89 and up does not match my wiring - so on and so on.



thanks

Sounds like your up on your electronics old iron. Was not sure if the chip was a 74XX / 54XX series or 4XXX series. The 4XXX series would not need a regulator as they are compatible up to about 15 V. Looks like you got things well under control. Interesting topic. I don't know who designed the method they used to deploy a circuit board like this but they went cheap all around!

yup...thats the order, just verified

Just curious, Have you considered etching a new board? All the stuff you need can be had from Radio Shack for less than $20. Transfer the components from the corroded board or splurge for new ones and you're good for a few more mouse nests,... er,... years.

Jim,

I have not etched a board in the last 25 years. I always wanted to try the photo-etch process.

I was a decent "wire wrapper" in my day and found it easier than etching. Now with the photo process and a good laser printer - I might give it a go. I might have to. Anyone know where I can get decent freebee schematic creation software? My reverse engineering sketch looks worse than that rat's nest in the hood tower !!


Truckin88,

I do have the indicator circuit mapped out for the parking brake and can give you pin by pin resistance measurements to take - I'll post these later today. I'm assuming you have the green coating completely removed from your circuit board since you said you had checked for corrosion and cracks. Just wanted to check.

HOWEVER, something as seemingly simple as the power to the IC chip has me baffled. I know there are folks out there who have an interest in electronics and I'll post a sketch later this morning for some advise. Maybe I'm missing something by not thinking 1970's design philosophy here - but let me recheck my traces before I post later.


Dkopp,
I found out the 54lsxx chips are military spec IC's with a larger temperature range than the standard 74xx series. Probably can't get the mil spec stuff but the chip is still available for 39 cents.

So back to the parts store .... my flux pen dried up my florescent magnified viewer broke a pot metal viewer mount my soldering iron tip is too big and seized to the iron and this new lead free solder .. well... sucks

guess now I better understand the frustration from the mechanical side of the hobby when folks can't get a steering wheel off the steering shaft - a seemingly simple task that turns into a battle royale

Do a search for free pcb and you should see several come up on your search. Eagle layout editor is one. I'm not familiar with it but they do have some demo software. Not sure of the limitations though. PCB123 is another and freepcb is yet another. Not familiar with any of those either, just suggesting. Then you can also get a pspice package that has a pcb designer built-in. Cadence I think has that capability. I have been getting their freeware version for some years, but have not had alot of time to play with the thing. Again, not for sure what limitations there are on all those either. Wish I could be more help to you.


Have you thought about doing point-to-point wiring on a perfboard for the repair and using LEDs for the lights? I realize that you may be going for an original restore, but just asking. Have you found sources for all the repair parts yet?

Dan

I've been looking for this sort of information since I bought my 312-8 back in the spring. I've posted on a different forum regarding Wheel Horse tractors but nobody was able to answer my questions.

Anyway, when I took apart my indicator board, I found out that it doesn't have any grain of wheat bulbs in it. Zero, nada. Do the bulbs just fall out over time? How do you reinstall these bulbs?

My indicator board appears to be in good condition (clean-ish at least, from what I remember). I'm not much of an electronics technician but I can be handy with a soldering iron. I'm interested in trying to get this aspect of my tractor functional again so it is in full working order (without replacing the unit, which is like a $140 piece from partstree.com).

geoff,

the red indicator caps on the dash of the tractor pull out of a rubber grommet - you should then be able to see the grain o wheat bulbs thru the holes in the dash.
if you have the display board out already, you should have 5 bulbs mounted in small rubber "bulb holder / sockets" - below is a picture of one of the holders with a bulb in it - next to it is one of the two posts the next holder will push down over.


The purple lines indicate how the bulb wires are bent thru the rubber body of the holder - as you mush the holder and bulb down over the connector posts, the rubber stretches and grabs the posts and compresses the bulb leads against the posts - the posts supply the ground and power to the bulbs.



so - you should have 5 rubber holders and 5 bulbs to get yourself going. If no rubber holders are to be had - you could solder the bulb leads directly to the posts - or use led's with a voltage dropping resistor - my board is in such poor shape I am considering buying 5 individual 12 volt indicator assemblies and fastening then directly to the dash - then hardwiring them to the posts.

the bulb resistance measures about 180 ohms on a good bulb - so I figure they would draw about 1/10th amp (100ma) each.


Keep the questions coming so I know how to benefit the most people with this post. I will be showing how to check the components on the board in the next day or two - how to check diode function - measure resistors and check transistor with an ohmmeter.

Tuckin88 - I have not forgotten you - I am 80% complete on the circuit reverse engineering and I understand 90% of it - just have to fiqure out how this sucker is actually powered from 12 volts to work a 5 volt IC chip.

I'll post a schematic for commentary in the next day or two.

First pass at understanding how the circuit board works - its only about 80% complete but shows a few things



the 12 pin connector in the upper left corner is the pc board connector
the logic chip consists of 4 identical logic drivers - 2 inputs are compared and an output generated and amplified thru a single transistor which drives the indicator lamp - think of the comparison the cnip makes as the following - if both inputs are the SAME (ground or 12 volts) the output from the logic is 0 volts and the transistor / lamp will NOT be turned on. If the input pins are DIFFERENT voltages - then the output of the logic goes positive and turns on the transistor and indicator.



looking at the image above - if the parking brake is off - the parking brake switch is opened and 0 volts appears at pin 2 of the logic chip - so a logic 0
the pin 1 of the logic chip is forced to logic 0 by being grounded
the chips compares the two - remember - if they are equal inputs - the chip puts out 0 volts and the output transistor Q1 will not be "driven" on to light the indicator.



close the PB switch and current flows thru R3 and R4 - 12 volts flowing thru a total of 1300 ohms = about 1ma of current (1300 / 12). So now there is a voltage drop across both resistors - across the 330 ohm there is (330ohms * .001amps) = 3.3 volts which is above the 2.5 volt threshold the logic circuit needs to see a logic 1 or high input.

so the same comparison is made - if inputs are the SAME - no output - if inputs are DIFFERENT ( which they now are) - the the logic chip powers up the transistor Q1 which turns on the indicator light.

although not shown yet , the test switch bypasses all the logic circuits and forces the transistors to turn on the indicator lamps - i will add the actual circuit later.

Stay tuned for pics of the repaired board - repaired but untested - I need to but a bunch of grain o wheat bulbs - I only have one that is good.

FYI, I am going to move this thread to the FAQ area it's way too good to get lost.

This might not be of interest since your repairing a board but this is what a $160 Toro replacement board would look like.

What software program are you using to draw that schematic? Looks really good so far!

Dan

Been watching this with some interest. SOI would a photo of a perfect original 12 pin connector with wiring help any. My 416-H has this set up and after taking a good look, I can't tell the difference between it and new. If it would help I could get a pretty good photo. Dunk

Old Iron, So am I to assume that I need to replace 1N4004 Rectifier Diode and the 2N3904 resistor. When looking at the PB lead I see a black clyinder with the silver stripe (rectifier diode) that then leads to a 646 2N 3904 transistor.

I bought an Etek digital voltmeter at walmart, what I like is that it has a continuity tester/toner. So I was able to verifiy the traces were ok, when taking measurements compared power diodes, resistors and transistors, the only one I found with major differences was the transistor on the PB circuit compared to the others four, it was only getting about half the readings the others were, (700 compared to 1325 on the other four) I will order a new 2N3904 , replace and let you know whats up.

Truckin88

if you would like to replace some components - the 3904 transistors are probably 20-30 cents each , the black barrels are 1N4007 diodes. If 2N3904's are not available, 2N2222 are good replacements.

the IC chip is a quad 2 input exclusive OR gate - less than 50 cents.

I would replace the transistor and diode first as I suspect your failure may be a "leakage current" thru parts that should be turned off - similar to turning off a water hose and seeing some drips out of the hose nozzle - it's "mostly off" but not completely - that can happen in electronics too.

When you replace the transistor, pay attention to the orientation of the flat spot on the body and copy the placement of the leads
When you replace the diode, pay attention to the silver band on the body as your orientation for the replacement part- the silver band represents the CATHODE of the diode.

All these parts are available from a favorite seller of mine

JAMECO ELECTRONICS

IC Chip
http://www.jameco.com/webapp/wcs/stores/se...freeText=74ls86

Diodes
http://www.jameco.com/webapp/wcs/stores/se...freeText=in4007

Transistor
http://www.jameco.com/webapp/wcs/stores/se...freeText=2n3904

Nick,

thanks you very much for the pic

here is the old vs new comparison



Still looks like less than $20 of components - but much more reliable components - I like the LED's but since they are more "directional" in their light output - you might have to be looking at them straight on to see they are lit. An incandescent bulb scatters the light more so it is easier to see off angle from the indicator face. The LED's may not be as bright in direct sunlight too.

But overall a much better design as far as reliability.

Dan,

I just picked one off the internet to get started.

It's DIPTRACE by Novarm - again, I just picked one from the Google search list.

It has a very good library of symbols and components but the wiring traces don't "follow" the components when you move the components. I haven't done this in years since I started to mess with computers. My favorite programming language used to be SOLDER - I would try to find a hardware solution and solder it together rather than program it in software. I have been doing much more with software these days.

Although I have been thinking of a digital dashboard for the 416-8 to replace that ridiculous decal on the hood. That would make a great spot for a flat panel display. Maybe even a small plasma tv display to watch wheel horse videos on U Tube while mowing !!!

Dunk,

that would be GREAT !!

I would love a clean photo of the test switch - maybe slightly separate the wires from each other so they can be clearly identified as to where they attach to the back of the test switch.

Paul F sent out a photo (thanks) that showed what looked like a newer version than the 1987 version I have - He showed 4 wires to the switch - I apparently have 5 wires and are all different colors. I understand wire colors do not always match the diagrams. Your picture may give us a look at another version of the switch

picking up the 2n3904 at radio shack, I think this is my problem as the resistance on the meter showed a difference in the one on the PB circuit compared to the other 3904's on the board which all had the same. I also suspect leakage, as when the PB switch is functioning normally when the tractor is on, the light is much brighter when it is staying lit and the tractor is off.

Will,

I was just thinking you may want to replace the two green capacitor discs on the board also - about $1 at radio shack - the orientation on these is not critical - place either lead in either hole will work for these caps. Just a thought as these "filter" voltage spikes from the power line and may even act as suppressors for any radio frequency interference picked up from the spark plugs firing. Plus, these are easy to extract and would give you some practice on soldering components onto the PC board

Catalog #: 272-1069 they are .1uf caps rated at 50 volts or greater.

8 cents each at the Jameco site I gave out earlier.

keep me updated

Cool, does that IC chip need firmware or to be programmed or is it good out of the box, and does everyone have the same logic circuitry. Also does it matter how it needs to be installed.

Will ,
the IC is ready to go out of the box - the manufacture creates the chip specifically to perform certain functions - these functions are identified by their 54LS xxxx numbers.

The chips do have a specific orientation - notice there will be a dimple in the chip body - seen near the black triangle on the picture below. Just mark the pc board with a dot to remind yourself where the new one goes.
Buy 2 or 3 chips (in case you mess up the installation of the first practice replacement)




As far as everyone having the same programming - yes, a chip with the same id number (54LS86) will have the same pin for pin function. The 54 xxxxx designates this chip as a military version of the IC - the commercial version will be designated as a 74xxxx which has a slightly less generous operating temperature range. The commercial version won't operate down to -55 degrees like the military version will.

I don't know how experienced you are at DESOLDERING - its different than soldering in new components. Search out desoldering techniques on the internet. You may want to get some desoldering braid from radio shack and maybe even a desoldering iron for a couple $$$ - you can "lift the trace" off the pc board by heating the copper pads too much - it will disolve the adhesive holding the copper to the circuit board - you can repair that issue easily by soldering a wire to the trace and then the component.

Grab a 25 - 35 watt soldering iron and have at it - you will do fine

I think this is the final version of the reverse engineering effort on the 1987 416-8 / 312 status indicator circuit board.

Attached Image (Click thumbnail to expand)

thanks, my 312 is really clean as it sat in a garage for most of it's life, I will take a pic of the test switch if I get a chance this weekend.

Desolder should be ok

GOOD NEWS:

I replaced the 3904 tranistor and it worked like it should.

I had some brand new .1uf caps and a hot solder iron, so I also replaced the two caps, my caps were not green they were smaller and brown, but had the same labelling as the new caps I purchased.

I then tripped the parking break, pto, clutch and seat to make sure they work, which they do, not sure how to trip engine oil. No lights on while off.

I figured it was the transisitor because of the resistance readings, but this post is awesome, thanks old iron!!!!

So in the end a $1.00 fix, biggest thing is to take your time with the solder iron!!!

Great news Will, thanks for hanging in there and working this thru.

I'm pleased this post gave you the confidence and the resources needed to attempt the repair - like I said before -

"I love the smell of solder in the morning ... smells like victory !"

If you have any other questions about what we did - let me know.

The ENGINE OIL lite - that s a good question - From the circuit board I have, it looks like the light is hardwired directly to the wiring of the tractor oil level switch and does not depend on " electronic logic" to make a decision to turn on - I think you would have to either empty the oil from the engine or remove the switch from the engine block to get the oil lite to turn on.

Has anyone tried this on a tractor with the oil level light during an oil change ??

IF THE OIL IS LOW --- Does the ENGINE OIL lite stay on all the time with the ignition switch turned to RUN / ON or does the lite just turn on when you try to turn the ignition switch to the START position ??

This 146-8 is the first functional tractor I have that has these indicator lites and honestly I have not seen any live in person yet to see how they work or when they turn on.
The user manual is a little confusing. It does make a statement about the test switch turning on lites or "flashing lites" - I do know there are some unused blank areas on my circuit board that might support a flasher circuit. This may be a feature available in later model 416's or 312's ??

Maybe someone can chime in with a good explanation for me.