TC 40D

[ENTS]

Jim,

Didn't realize that assembly came apart. I'll try that in the a.m. The whole thing is currently on the bench (no small task taking it off what with the parking brake, springs, etc. in the way(and the allen screws are recessed so the mud wasps have covered them over(and the fact I'm up to my elbows in mud))). The fact that the solenoid itself SHOULD be replaceable is my major burn (since it comes apart). In any case, working with just the solenoid will make the job a bit easier.

Later and thanks for the input.

Fred

 

[ENTS]

...driving a small brass wood screw into the end of the wire in the potting....

just curious, why brass??

... and then attaching a wire to it ...

mighty small area to work in and very tiny piece of wire.

Working on your idea, right now I have a 1/16 drill stuck in the middle of that wire (well, darn close enough since I can no longer see the wire (broke off in side the potting)) and I have continuity (about 10 ohms) between the two wires. I quit about this time since I was hungry and thirsty. I'll pick it up again in the a.m.


Thanks for the idea,


Fred

 

[barbqranch]

Fred ask why brass?

I would use it because you can easily solder to it and it doesn't rust and it is a good conductor of electricity. Any corrosion problems would be prevented by a coating of silicone.

 

[jinman]

Fred, I'm going to be a bit of a contrarian here in regards to using brass. Brass has a higher wetting temperature than copper and is harder to solder to. If you can expose enough copper wire so that you can solder copper to copper, you are much better than trying to solder to brass. I don't know if you have a controlled temperature soldering iron, but this is a delicate process best done by someone with experience and the tools to get the job done without overheating the coil windings enough to melt their insulating varnish layer. Copper to copper soldering with electronic tin-lead (SN60) solder is best accomplished with soldering tip around 600 degrees F. The copper must be heated to a temperature of 500 degrees before the solder will properly wet the base metal. You must also use flux to ensure the wire does not oxidize and refuse to wet at all, leaving you with a cold solder joint. SN60 solder will melt at about 360 degrees F, but it will not wet the copper until all parts of the joint are at 500 degrees F. An experienced person doing soldering will make all this look easy because they have all the tools and know just what to look for. I'm just afraid that if you try to solder in a brass screw, you are going to wipe out the whole coil. The brass screw has a lot of mass compared to the wire and heat will have to be applied for a long time. Two small clean copper wires, a small hot tipped soldering iron, thin solder, and resin flux are needed to make a good solder joint. You might get lucky and get this done with other methods, but my years of teaching soldering and high reliability techniques makes it necessary for me to give you my "full" lecture.

 

[barbqranch]

I may not have said so, but I was actually thinking of soldering to the screw shank before driving.

 

[ENTS]

Jim,

Thanks for the soldering leason. I did a lot of soldering on a frame at the telco and stuffing Heath kit (I'm showing my age) circuit boards, but nothing as delicate as this. IF I can expose enough wire I'll make an attempt at it. However, that lead broke off well inside the potting. I barely got it soldered the first fix when there was a small bit of wire still exposed.

BQ, figured you meant to solder to the screw and not screw to wire.

I haven't been out yet this morning (wow, it's already afternoon) since I had some honey-do painting to do. I'll take a crack at it later.

Hope your new year is a great one.


fhs

 

[ENTS]

Here's where I'm at--I ground out the material from where the broken wire was (including the dam that held the material) down to the start of the coil. I ended up with a stub about 1/16th of an inch. There is no way I'll be able to solder anything on that. So, tomorrow I'll try embeding a screw in it. I have a feeling this will fail under every day use but it's worth a shot.

I did remove the coil from the whole. Really a rip off that one has to replace the whole thing instead of just the coil. I can see why it's expensive, there's a lot of milling in the block. But making just the coil available would be a no brainer. $300+ vs. the cost of a coil (maybe $50). Oh well.


Later,


Fred

 

[jinman]

Fred, could you actually see the coil wire attached to the input lead wire? How was it connected? Just curious. . . your doing about all you can do with this situation. I agree with you completely that it's a rip to have to buy the whole part.

 

[ENTS]

Jim,

I ground down until I exposed the coil and stopped. The area I exposed is a little off from where the stub shows so I don't know how it's connected. I'm afraid to grind any closer to the stub in case I knock that off (not that it much matters, I'm pretty much SOL here). I'll try to post a pic. some time this afternoon.

The only bright part of this is that I can put the block back on the tractor w/o the coil. That way I can at least use the tractor.

 

[jinman]

The only bright part of this is that I can put the block back on the tractor w/o the coil. That way I can at least use the tractor.

Yep! As I'm sure you are aware, turtle-low and turtle-hi range are far better than nothing. It's too bad you can't figure out some way to mechanically shift the spool inside the valve without the electro-magnetic coil.

You might carefully heat up the blade of an Xacto Knife and do some delicate surgery on the plastic around the coil as a poor man's hot knife. Since you measured 10 ohms, you know the coil draws probably 1.2 to 1.4 amps at 12 to 14 VDC. If there is any way you can dig out the end of the coil wire and get a good connection, you'll probably be good to go.