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Mad Ax

Turnigy GT5 throttle fail and fix

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I was going to post this under a "recommend me a radio" heading a while back, but I ran out of time and money to be considering such things, so I left it.  As chance would have it, while at the Tamiya Junkies meet at RHR yesterday, I was pitting next to somebody with a FlySky GT-5 radio just like mine and I asked if he'd had trouble with the throttle.  He told me yes, indeed, he had, he'd had it with 3 of them, and had been able to fix them all.

But that's all to come - for now, here's the back story:

The GT-5 radio was a happy budget purchase for me a few years ago when I decided to try RWD drift.  The receiver has a built-in gyro which can be programmed from the Tx, and as I was running out of model memory for my Spektrum DX3C and receivers are no longer available due to some updated law, it seemed like a good option for all my future runners.  It works with the cheap, readily-available FlySky/Turnigy iA6 receivers (of which I already had several), it has 5 controllable channels, and a neat crawler mode which can switch on-the-fly between off, crab steer and rear steer.  All the other usual functions like EP adjustment, expo and steering rate made this a great option.

Unfortunately, despite good reviews from all round, I immediately had problems.  The gyro in particular gave me all manner of gyp on track.  Often it would say "not available" when in the gyro settings page, despite it being a gyro-enabled receiver, so I couldn't change any of the settings or calibrate it at all.  On track, it would give seemingly random steering inputs.  There's a neat "priority" setting which determines if steering input from the Tx should override the gyro's input or be mixed with it, but as I couldn't get into the settings I couldn't change this.  Basically it was rubbish, and after a couple of failed drift club runs (which are over an hour each way) I gave up and fitted an Onisiki gyro instead.

And continued to have steering problems.  Even with no gyro at all, it would randomly give steering input.

But here's a neat feature on the GT-5: it shows a graphic display of where all the trims are at.  And I could clearly see that when I gave throttle input, the steering input changed. Ah-ha!  This was interfering with the gyro operation and putting unwanted inputs when I was trying to control a slide.  I pulled the handset apart and found the culprit - the wiring loom from the steering daughterboard was running past the top of the throttle tensioner assembly, and when I moved the throttle it was pinching the wires.  This was obviously enough to upset the steering signal.  A quick bit of re-routing and I was drifting like a pro.  Well, no, like a complete novice, but like a complete novice with a gyro that worked properly.

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My problems with the GT-5 weren't over yet, though.

It didn't really get a lot of use since that last fix - I mainly used it for drifting, and latterly for any conventional 2-channel car that I built which didn't warrant a stick input.  I prefer using a 4ch stick controller for things like crawlers and monster trucks, where toggle switches are more convenient for winches and lights as they're less likely to be touched by clumsy fingers while traipsing around the woods.  Since all drifting stopped during Lockdown 1.0 and I haven't had a chance to go back since, it's only been used on things I've built in lockdown and not really used.

Until the season has got going again this year.  I noticed before the Junkies meet in May that the throttle wasn't centring properly, but it was an intermittent problem.  It is, however, a really annoying one.  A car might creep forward on the starting line, or it might be impossible to get reverse.  An ESC might self-calibrate on power-on and a moment later the goalposts are moved.

So a couple of weeks ago I tore it down (for the second time) to try to find the cause of the problem.  Which is this:

sm_P6130025.jpg

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The throttle potentiometre, which has gone all wibbly-wobbly.

I quickly took it out and went through my parts stash, even pulled apart an old Losi-branded Spektrum handset, to find that I don't have a matching pot.  That part number isn't helpful as it seems to be internal to FlySky.  It's a curious size, very narrow but with a very long flatted D shaft.  After a few hours searching numerous discreet component vendors I gave it up as a bad job and was making the tough choice between buying another GT-5 (which may well be just as unreliable) or going or another brand and having to buy all new receivers.  Or, indeed, going back to sticks on my race cars with another FS-I6 transmitter (I love these for crawlers, monster trucks and lorries but still prefer the immediacy of a wheel for racing).

However, as mentioned in my opening paragraph, this weekend I met a kind GT-5 user who has furnished me with the part number from Aliexpress, where his wife eventually tracked down the correct part.

So - watch this space as the GT-5 is given a new lease of life :) 

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I thought I'd resurrect this thread, as the GT-5 handset spent an awful long time in pieces in an old ice cream box up on my top shelf, waiting for me to find a replacement pot.  More than a year after the last post, in July 2022, I finally took delivery of what looked like a promising replacement.

As you can see, there's very little go to on on the original part (left).  Only a part number that yields naff all (apart from many clearly incorrect parts) online.  The one on the right is the replacement from Aliexpress.

sm_P7270001.jpg

As last - a pot with the exact same dimensions as the old one - even the extra long D shaft!

sm_P7270002.jpg

Alas, the pot is not compatible.  It has the same resistance as the old part, but over a longer range of travel - so when fitted into the GT5 it is both way off centre and also doesn't give a full range of steering.

I tried cutting off the locating tab so I could trim the pot by turning it on the fitting boss, but it wouldn't give the full range of steering.

sm_P7270010.jpg

Back to the ice cream tub for you, GT-5!

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I had pretty much given up all hope of getting it fixed - I wasn't prepared to keep buying poorly-described pots of Aliexpress in the vain hope that eventually one would fit, as I had already spent over £20 on parts that wouldn't fit and was still no closer to getting it working.  And then someone on here (apologies, I can't remember who and I can't find the thread) pointed me to the FlySky website, where spares are listed (I think this might be slightly a new thing, as I'm sure spares weren't available when this thing stopped working a couple of years back.

Anyway, it took a few weeks to arrive, but here it is:

sm_PC200163.jpg

Just what I need!  A throttie trigger!

sm_PC200164.jpg

New part comes complete with a whole new trigger assembly and spring, so no soldering or complicated fiddling about required, just plug-and-screw into the handset

sm_PC200165.jpg

It works!

sm_PC200168.jpg

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This is great news - I've got a few GT-5 receivers, which are technically compatible with my other Turnigy/FlySky i6 transmitter, but they have the built-in gyro, which has a habit of enabling itself when bound to a new receiver, and can't be adjusted or turned off from the i6 transmitter, which renders them effectively useless.

I've run out of receivers and slots on my i6 for new models, so now I can bring a few more cars to life :)

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I think I told you about Flysky spare parts.  Glad it worked out regardless!

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I'm just responding here so I can more easily find this thread should mine have the same issues 🤣

 

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