Indicator Lites

[Save Old Iron 1,566]

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.

[truckin88 104]

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.....

[Operator 7]

Very interesting in deed!

Randy

[Save Old Iron 1,566]

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.

[Save Old Iron 1,566]

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

[bitten 134]

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.

[Save Old Iron 1,566]

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."

[rick 235]

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.....

[pfrederi 17,865]

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.

[truckin88 104]

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.

[Save Old Iron 1,566]

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.

[Save Old Iron 1,566]

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.

[Save Old Iron 1,566]

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!!

[pbradley68 1]

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

Paul

[pfrederi 17,865]

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.

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

[captjake 1]

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

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

[truckin88 104]

got your PM thanks!

[Save Old Iron 1,566]

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.

[linen beige 14]

the grain o' wheat indicator bulbs can be a little pricey at over $1 a piece,

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.

[Save Old Iron 1,566]

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. :scratchead:

[dkopp 1]

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.

[Save Old Iron 1,566]

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.

[truckin88 104]

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.

[Save Old Iron 1,566]

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 :scratchead:

[dkopp 1]

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!