# Demon Possessed Car/Electronics



## tfrahm (Nov 14, 1998)

OK -- after being in this hobby for about 15 years, I've found the ultimate in demon possession... We just started racing 12th scale after about 4-5 years of no 'rug' to race on... I picked up a JR XR2i radio so I could use one radio for both cars (they both had AM receivers, etc. but the old XL2P radios I had used were just too "old school" and I had sold them)... *Everything is 27Mhz -- usually the most compatible band -- everything I've ever used on 27 has has been universally compatible...?*

One car works just fine -- NO problems... XXL receiver, Atom ESC, Futaba servo... ZERO problems -- worked all day at the track...

The other car (call it Satan) went absolutely nuts from the very first time I tried to setup the radio for it... The servo would go full lock one way an freeze up, the ESC would glitch horribly... (Black Airtronics receiver, Tekin ESC, Hitec servo)... Tried a Blue Airtronics receiver -- same demonic behavior... Tried an XXL receiver -- SEEMED to work on the 'bench', but at the track, erratic glitching on every run -- not all the time, but almost undrivable...

Back home, on the workbench... Tried a different XXL receiver -- glitch! Tried a different servo (Futaba) -- glitch! Tried a different ESC -- glitch!... Tried a different servo (Airtronics) -- glitch! Tried different crystals (same channel, changed channels) -- glitch!, glitch!

Tried the radio with another car (XXL receiver, Tekin ESC, Airtronics servo) -- no problem... 
Tried it with another car (JR receiver, Tekin ESC, Aritronics receiver) -- no problem...

Decided it MUST be the transmitter... Grabbed my one remaining XL2P -- SLIGHTLY better, but still -- glitch!

I've tested without a motor, with a motor -- glitch!

At this point, I am officially NUTS! HELP!  :freak:


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## hankster (Jan 1, 1998)

Have you tried using a receiver pack?


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## tfrahm (Nov 14, 1998)

That is the one thing I haven't tried... (I don't have one for a pancar...)


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## tfrahm (Nov 14, 1998)

I guess one other thing I haven't tried is a Novak ESC in "Satan"...

I'm just totally baffled, since the other car works PERFECTLY (second qualifier, 2nd in the A-main)... And then "Satan" just glitches no matter what I do... I mean I even tried a totally different "set" of electronics and same-o, same-o...


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## Tres (May 10, 1999)

Sprinkle with Holy water and say 15 Hail Marys!

Yes, try swapping the ESC also..

Also from the Tekin site:

G10-Pro Brake glitches:

Some of the G10 units had inconsistent braking or glitches. Setting at least one click of drag brake in the G10 programming will eliminate this and provides no noticeable braking action.


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## tfrahm (Nov 14, 1998)

The most 'visible' symptom is with the steering... On the workbench, the ESC light flickers a bit, but nothing is detectable on the track... The servo makes BIG twitches on the workbench, and on the track, the car will dart to one side without warning... (Odd fact -- 90+% of the time, it jerks to the car's right -- almost never to the left..?)

OH -- all symptoms are magnified greatly by just bringing the transmitter close to the car... This even shows on the track -- one of the more predictable 'glitches' would be on the front straight, passing the driver's stand... (About 3/4 of the time, the car would jerk to the right as it passed the driver's stand..!)

Sure wish the new MX-A was "out"...

PS: I did call JR (Horizon Hobbies) 'Tech Support', and they say the XR2i *SHOULD* work with *all* 27Mhz AM receivers (that band IS "universal", with no funny fequency shift issues or anything)... They can only say "send it in and let us look at it" -- of course that shuts down my 12th scale for a few weeks... I won't do that as long as one of the cars works OK....


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## sheath (Jan 1, 1970)

Try putting ALL the electronics from the 'good' car into the 'demon' car and see what happens. If it still glitches, check wire routing, receiver placement, antenna placement.... or maybe it just IS posessed.
Maybe do the opposite... take all the problem electronics and place them in the 'good' car to see if they still glitch there. Hopefully you can rule out something by process of elimination.


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## rcone4u2 (Sep 25, 2001)

Tom, this is Mitch...

Get rid of the Hitec Servo...just a thought.


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## erock1331 (Apr 1, 2002)

Have you Tried grounding the speedo.

Take a small peice of wire from the negative terminal on the speedo and run it to something on the car and tighten it down.


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## tfrahm (Nov 14, 1998)

Mitch -- I tried a Futaba servo with very little if any change in the glitch...

Erock -- VERY interesting... That's a new 'trick' I don't remember hearing of before...

Thanks to all... Keep 'em coming...


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## erock1331 (Apr 1, 2002)

I know the first time I raced at Sandhills I was glitching to no end. 
I put the antenna outside the car, turned the receiver on its side, etc

The only way you can run there without a PCM radio is to ground your speedo to the chassis. That took out about 99% of the gltiching problems.

The next year I went back with a PCM and had some problems but it was my keyence that went bad causing the car to glitch. so don't rule out the speedo.


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## RCRacer45s (Oct 22, 2002)

I remember i bought a speedo from someone and plugged it in and my car servo cranked one way and froze actually murdered the servo...all it was was the wires that go into the plug you insert into the reciever were wired the wrong way. Make sure your wires that go into the reciever are the right way.


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## Dustin (Aug 9, 2004)

I have a JR Racing XR2. Not the XR2i. The only glitching problem I had was when I had the antenna wire running along my graphite chassis and up into the antenna. It sounds weird but your chassis may conduct electricity. After I fixed that I have not had any glitching probs........unless someone with the same frequency turns on there radio! :jest:


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## Matt Bayless (Feb 15, 2004)

Tom I didnt see that you tried a difrent battery.It may be ground it self out on chassis especially if you sanded the cell plate on the 12scale chassis.the battery would be sitting low and + /- will send current threw the chassis.this is a more of common on 12 scale than 10 scale. I hope this helps Matt Bayless


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## tfrahm (Nov 14, 1998)

OK -- another day at the track after a week on the workbench... Still GLITCH! Car takes spells of being barely drivable, but at erratic times it just us totally hopelessly undrivable...

So far, I've tried the following on the track in real conditions:

4 different battery backs,
3 different motors,
3 different recievers of two different brands, (Airtronics, Novak)
2 different servos of two different brands, (Hitec 225BB, Futaba S132H)
2 different ESC's of two different brands, (Tekin 410s, Novak Atom)
2 different transmittter of two different brands, (JR XR2i, Airt. MX-A)
different crystals in the transmitter(s) and the receiver(s)...

(Please insert expletive here...)

HELP!


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## Rich Chang (Sep 25, 2001)

Have you checked the order of the wires going into the plugs for the servo and speedo to make sure all three wires are oriented properly for the particular reciever you are using? 

-Rich


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## tfrahm (Nov 14, 1998)

Rich Chang said:


> Have you checked the order of the wires going into the plugs for the servo and speedo to make sure all three wires are oriented properly for the particular reciever you are using?
> -Rich


Yes -- Everything works on the workbench, but GLITCH! on the track... (Some combinations glitch like crazy even at home on the workbench...)


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## eri3f0g (Feb 12, 2004)

just throwing something out there that may or may not help. Have you tried a receiver pack? Just something to try as I can't see why you still have glitching after all you've tried.

Good luck!


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## erock1331 (Apr 1, 2002)

try grounding that speedo !!!


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## tfrahm (Nov 14, 1998)

erock1331 said:


> try grounding that speedo !!!


I assume you mean connecting the *Black (-)* wire to the chassis...? Hmmm...


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## erock1331 (Apr 1, 2002)

Solder a small wire where your negative battery wire attaches to the speedo, then take that small wire and attach it to the chassis where one of the screws meets the graphite.


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## tfrahm (Nov 14, 1998)

Cool! Thanks :thumbsup:


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## tfrahm (Nov 14, 1998)

Well -- some more "clues" surfaced after about 3-4 hour thrash in the workshop...

The most frustrating (and that is a mild way of saying it) thing is that it seems there has been a change in radio design at Airtronics... My NEW MX-A works GREAT with the included 92727 reciever, but will NOT work with Airtronics 92921 receivers... *Whatsupwithat?* I tried 2 or 3 different 92721's, including one "new in the box" -- absolutely will NOT work with the MX-A... I dug out an ancient Airtronics XL2P, and the "possessed" car appears to be very solid -- not a single glitch on the workbench! I'll try that at the track tommorrow and see... WTF? *Guess I need to contact Airtronics and see what their "story" is...?*

The Novak XXL that I was having trouble with seems to have had a problem with a damaged "leg" on the crystal socket. It wasn't completely broken, but it was "cracked" at the back of the socket. I found this out when I wiggled the socket and the "leg" broke off completely... Potentially solves part of the puzzle..


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## tfrahm (Nov 14, 1998)

Problem/solution is confirmed... Car ran fine all day at the track with the OLD Airtronics XL2P radio -- will NOT work at all with the NEW MX-A. (Car is equipped with a blue Airtronics 92921 receiver)...


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## erock1331 (Apr 1, 2002)

Glad u finally got it all worked out !!
So was the new radio defective then? or was it a receiver compatibility issue?


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## tfrahm (Nov 14, 1998)

From what I can see, the new radio is not "defective", just UNCOMPATIBLE with the older receivers! Does that "bite" or what? The MX-A works just fine with the new model receiver that comes with it, and it works with a Novak XXL (I used the MX-A/Novak combination for another car Sunday with NO problems)... This is just too weird!


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## erock1331 (Apr 1, 2002)

hmm wierd, oh by the way I responded to your question u had for me about mounting the GTX in my car over in the GTX thread


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## tfrahm (Nov 14, 1998)

Airtronics has been able to recreate the problem with the older 92721Z receivers... It seems a different 'chip' was used in the new MX-A radio/92727Z receiver combo -- as I learn more, I'll pass it on...


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## OvalmanPA (Mar 21, 2000)

One nice thing about my Futaba AMs. Seems to work just fine with every receiver I've tried from 122 to 142 to Novak Polaris.


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## kybob (Dec 11, 2003)

My futaba's so far no problems so i better go knock on soem wood before my next race


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