Faulty InterLink DX USB Tx

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EvilC57

New member
I have an InterLink DX USB transmitter which seems to have developed a hardware fault.

The rudder trim tabs no longer work properly, leaving all models with an annoying LH rudder offset. The rudder LH trim switch doesn’t do anything, and the rudder RH trim switch generates virtual beeps (via the PC sound card as driven by RF 9.5) when pressed, but has no effect on the actual model rudder trim in the sim.

I’ve opened the transmitter and checked the physical switch behind the rudder trim tab. The switch is working OK, so it looks as though there is something wrong in the electronics between the switch and the USB interface in the DX, as I’ve power cycled (unplugged) the InterLink DX Tx and the PC several times and the fault is still there.

A new InterLink DX is £90 or thereabouts, which seems a lot of money to fix a minor but annoying fault, so does anyone know either what’s gone wrong, or whether RealFlight offer any hardware repair facilities?
 
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The first thing I'd do is turn on the Radio Gadget as described here so you can see what RF thinks is going on with sticks and trim as you move them.

There have been posts about inadequate power on the USB port possibly causing problems for the InterLink DX. If you have a powered USB hub that you can insert between the InterLink DX and the PC, that would be worth a try. Although if that one trim slider is your only problem, then a powered hub probably won't change it.

Ultimately, hardware support will come from Horizon Hobby. In the US, their Spektrum hardware support is excellent. I'm not sure about the experience in Europe.
 
The Radio Gadget just confirms that the rudder trim is stuck hard to the left. Pressing the right rudder trim produces beeps (via the PC sound card), but no movement of the rudder trim as indicated by the gadget. As mentioned in my OP, pressing the left rudder trim has no effect either on the rudder itself, the gadget or the sound.

The DX is plugged diectly into a USB port on a fairly new mains powered Windows desktop PC, so I can't see lack of power to the DX being an issue.

I have emailed Logic RC who are now the Horizon Hobby and Spektrum agents in the UK. I await a response...
 
...Replacement DX controller received today from Logic RC. They agreed there was an issue with the rudder trim control circuitry, and have sent me a replacement DX under warranty.

Unfortunately the replacement doesn't work. When I first connected it, my PC wanted to install USB drivers, which seemed odd because as it's a supposedly identical unit, I expected the machine to think that I had just reconnected the old DX for which drivers were already installed.

RealFlight initially opened and seemed to recognise the new DX. However going into the controller calibration window, RF wasn't seeing any stick or switch inputs to the controller.

I rebooted the PC, and got a 'USB device not recognised, the last USB device you connected to this computer malfunctioned and Windows does not recognise it.' warning message. RF now refuses to open, and just displays a message saying 'Please connect a RealFlight controller device or Windows joystick.'

Obviously I have been back in touch with the agent because as things stand unless I get another (working) replacement, I am at an impasse, and locked out of RF :(.

The old DX that I returned for repair/replacement had a model number SPMRFTX1 on the back. However I notice the replacment unit has the number SPMRFTX1C on it. Presumably this is just an issue number, and the functionality & compatibilty should be the same?
 
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Depending on your PC, you may now be in the situation where you need to plug in a USB hub between the InterLink DX and the USB port on the computer. There is some kind of compatibility issue between InterLink DX and the USB chips used in some computers. The only pattern I've found is that when the PC has a USB-C port, the problem appears. It works fine with an older laptop I have, but not newer computers.

I didn't know that the model number changed at some point. Mine is a 1C, I bought it about a year ago, and I need the USB hub.

Horizon knows there's an issue, and in the US they started including an inexpensive USB hub in the box in the last couple of months.

Just about any USB hub should work. The DX is USB 2.0, so you don't need a 3.0 hub. You also don't need power unless you also have a lot of other USB devices attached to your computer that draw some power.

The InterLink DX is a standard input controller and doesn't need its own drivers installed. When things are working properly, you're not prompted for drivers, although you will see Windows say it's installing drivers the first time you plug it in. The fact that you're having trouble getting Windows to recognize it is a sign of this USB communication problem.
 
Hmm. OK thanks for that flightengr. I’ll try a hub, I think I have one somewhere. All seems very odd to me.
 
Update: I've tried flightengr's solution with a powered USB hub this morning, and it works! So thanks for that flightengr (y).

It still seems strange that this should be the case, but never mind, I'm back in the (simulated) air.
 
It's a known issue, and Horizon hasn't provided any kind of explanation for it. Again, I think it's some sort of conflict between an older USB chipset in the DX and the newer USB-C or USB 3.2 chipsets in PC's. Putting a USB hub device between them solves whatever the problem is.
 
It seems strange that the SPMRFTX1C whould have an older USB chipest from that in the original SPMRFTX1 I bought around 2 years ago. The SPMRFTX1 didn't have any issue connecting straight to my PC. I would expect the 'C' suffix on the end of the model number to denote a later issue, with (if anything) a later chipset.

Still, it doesn't really matter now, you (flightengr) have got to the bottom of it for me now thanks.
 
I wonder if the "C" means "Cheaper". :LOL:

Seriously, maybe they had manufacturing issues and had to change suppliers. Who knows.
 
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