Old Hotness, New Busted Junk

Oh, where do I begin? So, at Christmas I received an RC4WD 4 channel radio, for use with the truck-cat. I was immediately unimpressed with the build quality. The hand grip area would creak in my hand, if I squeezed it a little. Alright, whatever. This particular radio is meant to be a budget option. It’s a four channel pistol grip radio for less than a hundred dollars. It meets the budget, and both auxiliary channels are three position. Good for running winches and multi-circuit light controllers. Everything seems to work, it does what I want it to, so I installed it, and didn’t look back. I was always careful with how I handled the unit. I managed to make it through the age of AM radios, without ever breaking one of their fragile telescoping antennas. I didn’t want to break this new radio.


Skip to a few months later; The steering is going nuts in a left turn. Hey, I’m not a fan of stock car racing either, but…. Plug in a spare servo, and get the same result. Problem is the radio. I went so far as to pull the potentiometer that controls steering  apart, just to make work right again. I actually had it working okay. For a month or two.

The throttle potentiometer started getting noisy, around center. Let got of the controls, and more often than not, the truck would roll forward or backward. Tap the side of the throttle trigger, and it would usually stop. Usually. Sometimes, I’d just smack the damn radio, to make it stop. One time, I hit the steering wheel. That was the end of my steering pot.


Markings on the backs of the potentiometers called them out as being 5K ohm linear taper models. Readings with a multimeter showed the steering pot to be way out of spec; 7.2K ohms. I tried both a 5K ohm and a 10K ohm pot in the steering. Both resulted in the same reduced range of throw for the steering servo. That was clearly not a linear taper pot. Whatever. I can make due with it, there are ways to adjust the linkages to work around the reduced throw.


Clearly, I couldn’t just replace the throttle pot, and expect proper function. But it just kept getting worse. Were the truck a basher, that I just use to tear around in some dirt patch, it wouldn’t have been a big deal. But, I use the thing for a crawler. I need it to stop when I tell it to, and not have it go running over the ferns. This took my prime source of relaxation, and turned it into a source of frustration. Combined with a temper that has mellowed but not gone away over the years, and I began to abuse the transmitter more and more. Tuesday night, I actually drop kicked it, resulting in the battery box being torn free. That probably wouldn’t have happened, if the battery door weren’t more of a vague suggestion, that falls off so easily. Was a quick enough job to re-solder the power leads, and put everything back together. I’d had to do similar the night before, when the transmitter failed to power on. Somehow, just sitting around, it had managed to break one of the leads up at the main board. I don’t know how that happens. I’d like to limp this thing along, until I can replace it with a nicer one. I’ve got my eye on a Spektrum, whose price has come down, since last year.

Wednesday night comes, and as the throttle control continues to wig out, when I try to stop. I can’t contain my ever-growing frustration with this radio. I use it like a hammer against the nearest solid object. Did I mention that the drop kick from the previous night had nearly ripped the top part off the radio?




So, after the impact, the top section of the transmitter, the part with most of the functioning bits in it, is now hanging from the top of the handle, with just a few wires keeping it from plunging to the ground. Probably easily enough fixed, with some more glue, and a little soldering.




I swapped out the servo, to go back to my 21-year-old AM Airtronics radio. It’s only 2 channels, so I can’t control my lights, but at least I’ll can control my throttle. Now, due to its age, and the glitchy nature of AM radios, and the weird way I have to run the antenna, it’s not without its own issues. But, at least it stops when I let go of the throttle.


The “new” radio? Well, it fell into my way, a couple of times, while I was trying to get the truck converted back to the old radio. I was already in a bad mood, so “moving” it resulted in further damage.



On the left, the new busted junk, now in three pieces. On the right, the old hotness. That is an Airtronics Rival-2P. It was the first radio I ever bought, when I got into hobby grade RCs, back in 1994. It still works, after years of service. It’s got a little piece on top, that slides back, so the antenna can be extended. Unfortunately, it was made before servo plugs were standardized, so current Futaba style plugs won’t work with it. Universals won’t either, as those are just Futaba plugs with the orienting tab removed.


I want to pull out the toggle switch, from the old radio’s handle, and reclaim the potentiometer I’d installed. I need to reconnect the power leads long enough to measure the voltage going into the LCD’s back light, so I can maybe use that in something else. And, I need to wire up a temporary manual control for the truck’s lights, that I can reach from the outside.


My new Spektrum radio should be here, next week. With luck, there’s an outside chance it might get here Saturday, but I’m not really expecting it before Monday.


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August 2015
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