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Spektrum SLT3 - Steering Works, But No Throttle

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Spektrum SLT3 - Steering Works, But No Throttle

Old 11-11-2021, 03:14 PM
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Default Spektrum SLT3 - Steering Works, But No Throttle

OK, so I purchased this transmitter and receiver from an eBay seller who had removed it from his recently purchased Big Rock. It was sold as "For Parts or Not Working" so no refund, but at the same time the seller was unsure whether he was doing anything wrong when it came to binding the transmitter and receiver. As it turns out, he may very well have been doing it correctly, as something does seem faulty somewhere.

I have it binded to the SLR300 receiver no problems. Steering works no problem, as do the steering adjustments. Throttle however... is a literal no-go. There is no response from the throttle at all. When I turn on the ESC (HobbyWing QuicRun 1080) it blinks, usually indicating no transmitter signal, but steering does work. It appears that the transmitter is not sending any signal from the throttle, so the ESC doesn't initiate fully, except the steering.

I've tried calibrating the ESC, but since it's not receiving a "go" signal, calibration doesn't work. I've taken the transmitter apart (since I can't return it or get it replaced under warranty) and I can't see anything obvious. No components are damaged, burnt, missing (I think), the circuit board is undamaged, pretty much nothing out of the ordinary.

I know the trigger potentiometer works as I was able to test it on the steering, so the issue lies from the connector on the board to... where ever it goes after that.

Also, the ESC works fine with other receivers, and the SLR300 won't work with other speed controllers in other cars. I CAN get the throttle to work if I use the AUX buttons for forward and backward, but that's not really useful. So the ESC is definitely working with the receiver to some capacity, but the throttle channel is just... dead.

It COULD be the receiver I suppose, but I don't have any means of testing, without buying another receiver or transmitter.

So I've run out of ideas, after trying for a good 3-4 hours fault finding... I found no obvious faults. Google isn't very helpful as it just loves to omit the word "SLT3" a lot.

Does anyone have any clues? Any ideas? Any thoughts? Even a spare receiver you wish to get rid of. Any help is a good thing. Please and thank you!

EDIT: Just discovered that Spektrum receiver will work in my Tamiya Konghead and my Traxxas Rustler 4x4 VXL. The Konghead has an older Traxxas XL-5 ESC and the Rustler has a new VXL-3 ESC. So for some reason, the Spektrum receiver seems to favour Traxxas ESCs, and not any of the other ESCs I currently use, which include Tamiya, HobbyWing 1060, HobbyWing 1080, HobbyWing MAX10 and a random unknown branded one. How's that happen?

Last edited by PureChaosX; 11-11-2021 at 04:24 PM.
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Old 11-11-2021, 03:45 PM
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You have to re-calibrate the ESC when changing receiiver.
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Old 11-11-2021, 04:26 PM
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I would if I could.. but I cannot. I've tried, many, many times. But the ESC calibration cancels itself because it's not receiving a signal from the transmitter/receiver to arm the motor. Therefore, calibration is unable to take place. So far, I've only been able to calibrate the Spektrum receiver on two different Traxxas ESC's and it works fine on both.
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Old 11-11-2021, 10:58 PM
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Try increasing the neutral width setting on the esc and then attempt calibration again. Also be sure that the throttle trim is centred before attempting calibration (if the radio has one).
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Old 11-12-2021, 12:52 AM
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Try the servo reverse setting.
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Old 11-15-2021, 10:18 AM
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The longer your in the hobby the more tools you end up with - when I got a toro ESC I got this programming box that you can use to monitor the signals at the receiver. Great troubleshooting device. I would bet that there are other PPM monitors out for cheaper.
https://www.skyrc.com/Accessory/Program_Box

Otherwise my only troubles with ESC calibration have been on radios that had triggers setup for 70/30 vs 50/50. Guessing your more basic budget radio is setup for 50/50 which most ESC's handle with no problem. Even then 70/30 trigger ranges shouldn't mess up calibration.....just had one problem in the past on a cheap esc that I think was related to it somehow.
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Old 11-15-2021, 12:35 PM
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set all trims to zero . look at other trim settings in radio.. now try to calibrate esc.. I have had some esc take many attempts b4 calibrating ...try try and try again. contract spektrum maybe they can help
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Old 11-15-2021, 12:54 PM
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All trims are set to zero. I've tried 0% trim, 50% trim, 100% trim... and pretty much everything in between. I've tried Throttle Reverse, as well as the 50/75/100 speed control. But ESC calibration still fails to work and cancels itself after the first push of the Set button, which is to set the Neutral position. And it still works 100% perfect on my two Traxxas ESCs.

I made a YouTube video with a bit more detail, as well as demonstrations of the Tx/Rx behaviour but I'm not allowed to post links yet, so if anyone wishes to take a look, you can do so by searching for "Spektrum SLT3 - Throttle Problem" and it should be the first on the list.
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Old 11-15-2021, 03:52 PM
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Probably why it was listed as "Not working/for parts'. Sounds to me the radio is No Good as described. I have a Futaba 3PK that won't calibrate to "ANY" esc either. Tried every trick in the book. Calibrated same ESC's to another 3PK and works as they should. Bum radio and parts are no longer available for that model of radio.
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Old 11-15-2021, 07:24 PM
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Originally Posted by mushroomed
Try increasing the neutral width setting on the esc and then attempt calibration again. Also be sure that the throttle trim is centred before attempting calibration (if the radio has one).
Did you try what I suggested?
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Old 11-16-2021, 04:59 AM
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Originally Posted by mushroomed
Did you try what I suggested?
Oh I did.,.. believe me, I did. I've tried everything every one has suggested, but still no go with the ESC working with this transmitter. I can't see it being a bad transmitter or receiver, since they work perfectly with my Traxxas ESCs. They work as they should, and so they appear to have zero faults.
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Old 11-16-2021, 08:37 AM
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Originally Posted by PureChaosX
Oh I did.,.. believe me, I did. I've tried everything every one has suggested, but still no go with the ESC working with this transmitter. I can't see it being a bad transmitter or receiver, since they work perfectly with my Traxxas ESCs. They work as they should, and so they appear to have zero faults.
If the radio isn't putting out a PWM signal the HW esc's recognize as an acceptable neutral range they won't calibrate. You bought a cheap very low end radio labeled not working/for parts, while trying to pair it to some of the cheapest electronics. I've seen Spektrum radios do all sorts of weird stuff through the years. Sometimes switching to a different model memory would fix the issue as the problem was corrupt software code, but I'm pretty sure the SLT3 only has a single model memory as it is such a cheap radio. A good friend of mine tried using an SLT3 that came with his rtr 22s camero drag car, and after very little use the steering became intermittent. Just moving the transmitter around (not moving the steering wheel) caused the steering to move erratically.

Have you tried to calibrate any HW esc plugged into the steering channel instead of the throttle channel?
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Old 11-16-2021, 08:56 AM
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I have indeed tried to calibrate the HW ESC with it plugged into the STR CH1 channel, and calibration was completely successful. Even stranger... the steering WORKED in the THR CH2 channel.

After watching many videos and reading several reviews, the Spektrum SLT3 was, supposedly, one of the better budget radios you could buy, which is why I went for it. In hindsight, the fact that ARRMA owners often replace the Spektrum radios should have been a bit of a red flag. Something I keep mentioning, because I always hope someone will see it and know the answer... is that the SLT3 works absolutely, 100% perfectly and flawlessly with my Traxxas ESCs. The XL-5 ESC is also a fairly cheap ESC. I really would like to understand why the SLT3 works with both of my Traxxas speed controllers, and why they are able to receive arm signal from the transmitter/receiver, yet the other speed controllers I own will not.
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Old 11-16-2021, 09:52 AM
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Originally Posted by PureChaosX
I have indeed tried to calibrate the HW ESC with it plugged into the STR CH1 channel, and calibration was completely successful. Even stranger... the steering WORKED in the THR CH2 channel.

After watching many videos and reading several reviews, the Spektrum SLT3 was, supposedly, one of the better budget radios you could buy, which is why I went for it. In hindsight, the fact that ARRMA owners often replace the Spektrum radios should have been a bit of a red flag. Something I keep mentioning, because I always hope someone will see it and know the answer... is that the SLT3 works absolutely, 100% perfectly and flawlessly with my Traxxas ESCs. The XL-5 ESC is also a fairly cheap ESC. I really would like to understand why the SLT3 works with both of my Traxxas speed controllers, and why they are able to receive arm signal from the transmitter/receiver, yet the other speed controllers I own will not.
The only Spektrum product I ever owned was the first product they released, which was a 2.4ghz module for the Airtronics M8. I never had any issues with the module itself, but I did have a receiver that went bad on the throttle channel. It would overload the BEC circuit on the esc and cause the escs to fail (took out 3 different escs, 2 of which were HW). If I powered the receiver with a battery, and disconnected the red wire from the esc to the receiver everything worked and wouldn't overload the BEC. It could be your receiver has an issue, it could be the transmitter. HW and Traxxas escs are going to work differently, so it may be the neutral signal isn't right for the HW esc while it is acceptable for the Traxxas esc. Sounds to me like the receiver is bad if everything worked when you swapped channels.
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Old 11-16-2021, 05:39 PM
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Suggest you down load the manual for that radio. Page 4 shows how to do a factory reset so you can start fresh...
Read thru the manual, pretty simple instructions... so you understand the switch setting so you can make sure you have 100% on throttle & brake... and spectrums are pretty touchy in regards to having enough neutral..
Good luck...
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