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Post by torriem on Mar 11, 2021 23:10:15 GMT -6
This week I dug out a Starfire 3000 I had bought a while back to stick on a tractor to replace an iTC. However it came up with a TCM fault and autotrac refused to work with it. I remembered that the guy I bought this from (who worked for some dealership somewhere in the US and I've long since forgotten his contact info) said he had replaced the TCM in it which is why it had a different new yellow dome on it than my other 3000s. I was getting ready to contact AgExpress when I wondered if the TCM module just might have come slightly unplugged from shipping or something. Plus I wondered what the TCM module really was. I've never seen inside these receivers and I've never seen any tear down pictures of them either. From the factory starfire globes are sealed up good. The yellow dome plastic is bonded to the green base. The only way to open them is to cut them open, which is what the seller had done. I wondered if the glue he used to put on the new lid could be coaxed with some heat to come apart. And sure enough it did. I quickly found the module and re-seated its little connector which was a bit loose and everything worked! The TCM module turned out to be an off-the-shelf 6 axis gyro and accelerometer, available for about $700 CAD on digikey. I don't recommend changing the module yourself because it's hard to open up the receiver and I have no idea where to get replacement yellow domes to glue back on. Plus the prices AgExpress charge are quite reasonable given the high cost of the module itself. But for those just interested in the tear-down, and in case anyone in the future wonders what this TCM module really is, I put pictures and a write-up on my blog at torriefarmprojects.blogspot.com/2021/03/starfire-3000-tcm-what-it-is-and-how-to.html. |
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Post by lanwickum on Mar 12, 2021 9:08:57 GMT -6
AgExpress is tough to beat for quality work and price. I also enjoy tearing down electronics to learn. That learning has real value also when we have the time. Thanks for sharing! School of hard knocks is much cheaper when others do it  |
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Post by Beerwiser on Mar 12, 2021 9:46:10 GMT -6
I don't have much interest in the JD stuff, but you have quite the interesting blog Torriem. Some cool projects on there. I am sure you know this already, but heat works well for removing potted electronics too.
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Post by torriem on Mar 12, 2021 14:16:34 GMT -6
Thank you.
Yes. I've been meaning to try removing the potting on my broken Capstan solenoid coils. I think all the failures amount to the wire breaking between the pigtail and the coil. Seems like I lose about 6-10 solenoids a year and they are $130 CAD a piece.
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BJT
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Post by BJT on Mar 12, 2021 19:29:49 GMT -6
I would also like to open up a capstan solenoid
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Post by torriem on Mar 12, 2021 21:27:15 GMT -6
I'll see what I can do. I'm not hopeful, though. Solenoid winding wires are tiny usually and I hate dealing with varnished wires.
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Post by Beerwiser on Mar 12, 2021 23:35:29 GMT -6
Yeah potted electronics and coated copper are two different beasts. Do you have a link to the solenoid BJT? Got my curiosity.
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BJT
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Post by BJT on Mar 13, 2021 7:35:16 GMT -6
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Post by torriem on Mar 13, 2021 9:24:09 GMT -6
Usually when they fail they go open circuit or get an intermittent connection. There's very little that can fail in a solenoid. If something's wrong internally you'd expect a dead short. The fact they fail open means it's probably the connection at the base of the pigtail that's failing from vibration. The entire end of the solenoid is potted. I was thinking of boiling them in water to soften them up but I need to find an old pot to use. Don't want to contaminate my good cooking pots!
The capstan monitor can detect failed solenoids. But it can also detect plugged or jammed solenoids using only the solenoid coils themselves. It must do that by analyzing the current wave form. As the plunger moves it must create a recognizable pattern that is changed when either the plunger doesn't move all the way or at all.
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Post by Beerwiser on Mar 13, 2021 9:56:34 GMT -6
Thanks BJT, that is what I wanted to know. I never dealt with those before. Don't think boiling the end would help much to make the potting soft. Hot air rework station works great to remove the potting. I used it to remove potting on a plastic encased wheel speed sensor very similar to the way that solenoid is made without wrecking anything.
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Post by torriem on Mar 13, 2021 15:53:37 GMT -6
I'll try several variations and see what works. Several people online have successfully removed potting by boiling in water. Mainly it's the temperature that they are wanting. Apparently most epoxies start to soften at 100C. Hot air would do the job too of course.
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Post by torriem on Mar 13, 2021 18:58:05 GMT -6
Well good news I know how the solenoid is constructed. Bad news is there's no possible way to non-destructively replace the coil, let alone fix a broken pigtail connection. I removed a lot of potting but finally gave up and cut it in half with a saw. Every step of manufacture involves potting. The coil is inserted into the can and then potting goes around the edges and covers it. Then a metal lid is place over that and a nut holds it tight against the potted coil. then that is covered with more potting. Finally the can itself is dipped in potting, and then that is covered with some kind of heat shrink plastic as a finishing touch.
I guess it's way too small of a market for anyone to be interested in making third-party solenoids which wouldn't be hard at all.
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BJT
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Post by BJT on Mar 13, 2021 19:50:33 GMT -6
My capstan guy told me to flip the breaker for system before starting sprayer, he thinks the initial startup wrecks them. 🤷🏼♂️ Mine are on deere sprayers.
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Post by Beerwiser on Mar 13, 2021 20:18:31 GMT -6
Post a picture Torriem, I would like to see how bad they potted it.
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Post by torriem on Mar 13, 2021 21:14:26 GMT -6
I'll see what I can do later about a picture. I kind of destroyed the thing. Maybe I should cut another bad module without trying to remove any potting so you can see. Hmm interesting, BJT . It's possible I guess. I'd think it would affect the controller unit more than the solenoids, though. I think the coils fails more from vibration breaking wires in the pigtails though. Also when the system comes on initially, the coils are all de-energized as the nozzles are all shut off usually (12V to turn them on). I'm always amazed the system works at all, and works as well as it does. When it's running and the coils are at 100% duty cycle, the total amp draw is 40 amps at 12V. |
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