Moving on neutral

[alvinlwh 5894]

Recently, a number of my cars are not staying neutral when the TX (CR3P) is at neutral, I wasn't even touching it. The ESCs are set properly if they can be set (ex TBLE) , or are of the type that cannot be set (ex 1060, Autosport20). Now, I only noticed this recently and so far only in bench tests, so "too close" interference could the reason? 

If not read on. On turning on, auto set ESCs  will set neutral (no auto set were already set previously) and it will usually be OK and stay still. However after giving forward or backward command and returning to neutral, not touching the TX, the LED will still flash, indicating commands are being received, sometimes with the sound that it is trying to turn the motor, sometimes at enough speed to turn the wheels, sometimes fast enough to cause a runaway if the wheels are on the ground. 

It had been suggested that the servo is drawing too much power and causing interference and I should use a glitch blaster. First I built one using a 4700uF capacitor. Didn't really work. So I doubled up and used two in parallel, still the problem is there. This happens with different servos and none of them are particularly high draw or power. 

I did notice that most of the time, if I went slightly to the opposite direction to the original direction before returning to neutral seem to stop the problem, but not always. 

I had not tried a different TX and RX combo yet. Thought I will ask here first to see if there are any ideas. 

[M 800STD 586]

Does it do it when you suddenly release trigger/throttle suddenly?  Not returning to neutral via finger control.  

[alvinlwh 5894]

10 minutes ago, M 800STD said:

Does it do it when you suddenly release trigger/throttle suddenly?  Not returning to neutral via finger control.  

As in "let go " from throttle? I will say yes, but I can try using finger to return to neutral if that will help with troubleshooting. 

[M 800STD 586]

Lets say you are on throttle, then you suddenly let go so stick/trigger returns to centre by way of Tx springs.

Do you have the problem then?

On older Tx I noticed when using finger control, there was a slight creep but if I just let go then not so.

Maybe re-calibrate and or test with another Tx.

 

[alvinlwh 5894]

25 minutes ago, M 800STD said:

Lets say you are on throttle, then you suddenly let go so stick/trigger returns to centre by way of Tx springs.

Do you have the problem then?

On older Tx I noticed when using finger control, there was a slight creep but if I just let go then not so.

Maybe re-calibrate and or test with another Tx.

 

Yes, definitely if it "snap back" to neutral. 

I don't think this is a age related problem as this is a relatively new TX, only 3 or so months old with relatively light use (once a week in the past 3 months?). It is also a current model that is still being made and sold. 

Calibration is unlikely to be an issue as I had recalibrated the ESCs that can be calibrated multiple times, and the problem still exists. Also, there are other ESCs that auto calibrate  on every power on that has the same problem. 

I have a BL program card that can measure neutral range. Will doing a test on that help with the trouble shooting? I do not know what the readings should be so the numbers will mean nothing to me. 

Also, at this point, are you discounting the "too close" problem (which I knew existed on some really old AM systems) and servo drawing too much power? 

[M 800STD 586]

Hmm, ok.

I do know some esc's you can extend the neutral range.  Maybe you have to do this.

[alvinlwh 5894]

10 minutes ago, M 800STD said:

Hmm, ok.

I do know some esc's you can extend the neutral range.  Maybe you have to do this.

No, not on these. The Autosport20 has no settings whatsoever. As for the TBLE, only throttle neutral, high and low range. 

I don't actually think I had ever seen this on any brushed ESC and as for brushless, I had only seen it on one (although I only own two). 

[SupraChrgd82 1425]

Did you inadvertently bump the throttle trim?

[rwordenjr 1890]

Check your throttle trim and your battery level on the tx. Low battery voltage on tx will make car do weird things 

[alvinlwh 5894]

5 hours ago, SupraChrgd82 said:

Did you inadvertently bump the throttle trim?

 

5 hours ago, rwordenjr said:

Check your throttle trim and your battery level on the tx. Low battery voltage on tx will make car do weird things 

No, definitely not the trim. In fact I tried to trim the problem out, no joy. Plus some ESC retrim themselves on startup. 

However I will check the battery level. These batteries had not been charged in a while but had not triggered the low level alarm yet. 

[alvinlwh 5894]

OK did the test before charging the batteries. On startup, Tx is 4.7V.

Plugged the RX into the program card. 

On startup, PPM is 151x to 152x us. 

Full throttle is 1163 - 1164 us. 

Full reverse is 197x - 198x us. 

After "snap" return to neutral, it can vary from 150x to 152x us. Same with gentle return. 

Forward to reverse tends to stay towards the lower range while reverse to neutral, the higher range. 

To test further, I removed the servo and the neutral range is 150x to 153x us, even wider! 

Plugged the glitch blaster in, same numbers. 

I am now going to charge the batteries in the TX and see what happens. 

[hIghQ 149]

Could actually be the transmitter itself, for some reason not always really properly going back to neutral, and then, depending on the ESCs sensitivity, keeping to give a big enough throttle input for the car to start actually moving. Hard to diagnose (do you have another radio to cross check with?)

[alvinlwh 5894]

36 minutes ago, hIghQ said:

Hard to diagnose (do you have another radio to cross check with?)

Yes, will do that after lunch. Batteries just finished charging so checking the low voltage theory first. 

[alvinlwh 5894]

On on fully charged (5.5v)Tx battery, the problem seem less serious. From forward to neutral, it still makes some slight "trying to turn motor" noise/beeps, but had not seen any actual turning of wheels yet. 

One more thing I forgot to add, all these tests in the past few hours were on an Autosport20 where the problem is less serious. I will need to go test the TBLE too, that one is so serious that it can be a runaway on switch on and it was correctly calibrated and recalibrated multiple times. 

[alvinlwh 5894]

Tested the TBLE and things went really strange. First I lost reverse (did not touch the setting at all). Turned reverse off and on again and it came back. Then when I enter EPA to check and immediately the problem came back AND EPA on the TX shoes as 65%. As this is a hi low point settable ESC, there is no reason for me to set it to 65% in the first place. It was at 100% and I have no idea why it changed. 

Reset EPA and hi low points and the problem seems to be mostly gone with some odd beeps like the Autosport20 described above. 

There is a possibility that the low voltage theory is the cause in the first place, but I had been unhappy with the TBLE as well. I suspect it may not be too good. It acts funny when reversing, and yes, I am double clicking correctly. It does not always go into reverse requiring triple or more clicks. Even a fellow forum member who had more experience than me commented on this strange behaviour last week when he test drove the car. 

[hIghQ 149]

Just generally speaking here, as it will not help you with the problem at hand: issues like these make me keep telling beginners who come looking for advice, that one of the best investments is good electronics, especially a good radio (not saying yours isn't, I'm just not familiar with it). Doesn't need to be be absolute high end, top of the line stuff, but it's definitely worth putting some more cash into than the bare minimum. Of course problems can come up even with top-level equipment, but I believe it happens less often there. On most ESCs I use, I can adjust the neutral range for when the radio should have a problem in keeping neutral (a risk that should also be reduced by a good quality radio).

[alvinlwh 5894]

Just now, hIghQ said:

especially a good radio (not saying yours isn't, I'm just not familiar with it). 

 

4 minutes ago, hIghQ said:

On most ESCs I use, I can adjust the neutral range for when the radio should have a problem in keeping neutral

My radio is one (or the Flysky GT3 equivalent) that is most often recommended to beginners here, along with the 1060 ESC, and that one also does not have neutral adjustment either. Personally, I had not seen a brushed ESC with neutral range adjustment before (BL ESC yes), maybe they do exist on the extreme top end ones. I know you are familiar with the high end gear, so will not expect you to know about this budget controller, even if recommended by many often as it is probably out of your normal range. 

[ad456 331]

I’d try it with a separate BEC if you have one, that would absolutely rule out power issues(if no BEC a 4xAA battery pack would do).
Rebuilding the servo might not hurt either, check for anything sticking or being too tight or squint(assuming no warranty exists). Even small bits of swarf inside the alloy body. 
 

I feel it’s feedback from the servo, how to sort that might be trickier. What’s the rated input voltage on it? 4.8-6v?

[bavee 1032]

3 hours ago, alvinlwh said:

Personally, I had not seen a brushed ESC with neutral range adjustment before (BL ESC yes), maybe they do exist on the extreme top end ones.

The HW1080 has this functionality. This week I switched out a 1060 for a 1080. Works like a dream.

[alvinlwh 5894]

1 hour ago, bavee said:

The HW1080 has this functionality. This week I switched out a 1060 for a 1080. Works like a dream.

I do not have a 1080 so, as I said, I had not seen one personally. However, I believe that something is wrong somewhere that is causing the problem and am trying to troubleshoot to find out what it is. CR3P (or GT3) + TBLE is not an uncommon combo because, as I had seen, the radio is often mentioned in recommendations for beginners and that ESC comes in many Tamiya kit. Just last week, there was someone with the same exact set up as mine in the forum. However I had not seen this moving on neutral issue appearing here or other forums with this setup. 

[alvinlwh 5894]

2 hours ago, ad456 said:

I’d try it with a separate BEC if you have one, that would absolutely rule out power issues(if no BEC a 4xAA battery pack would do).
Rebuilding the servo might not hurt either, check for anything sticking or being too tight or squint(assuming no warranty exists). Even small bits of swarf inside the alloy body. 
 

I feel it’s feedback from the servo, how to sort that might be trickier. What’s the rated input voltage on it? 4.8-6v?

I can do a servo test on the program card if it helps. 

[bavee 1032]

6 hours ago, alvinlwh said:

Personally, I had not seen a brushed ESC with neutral range adjustment before (BL ESC yes), maybe they do exist on the extreme top end ones.

 

10 minutes ago, alvinlwh said:

I do not have a 1080 so, as I said, I had not seen one personally.

Never mind. Just trying to be helpful.

[alvinlwh 5894]

21 minutes ago, bavee said:

 

Never mind. Just trying to be helpful.

What I am meaning is I don't own one and therefore had not seen one personally, that's all. Don't mean anything else into it. 

And also I had not see this problem popping up with people with the same radio and ESC combo as me. 

Anyway, you just proved my point, they exists on the top tier ESCs, a 1080 is twice the cost of a 1060.

[alvinlwh 5894]

@ad456 did a servo test, it peaked at 3.3A. I think that is the problem. The BEC for this ESC is only rated at 1.5A. I also got a pair of fans running off it at 2 x 0.3A. Going to drop a regular servo in to see if things will improve. 

[hIghQ 149]

It doesn't have to be the combination or any part in general. Maybe it's really just your transmitter (not the general make and model, but the very one you hold in your hands) that has a little defect, not keeping a clean neutral any more... What works a million times can fail on the 1,000,001st try.