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Rcexl sensor problems

Old 03-12-2017, 08:46 AM
  #101  
av8tor1977
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I myself didn't doubt it, though I had the good fortune to never run across one. (Yet)

Bill from CH once told me, "About 95% of the time the sensors either work or they don't, but about 5% of the time one will act "screwy".

AV8TOR
Old 03-14-2017, 04:32 AM
  #102  
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Glad I could help. Took 7 years for me to have anything worthwhile to say.

The sensor came in yesterday. I checked it on the scope and it's fine. Transitions are clean both ways. It will be a couple days before I can test it on the engine. Like mine, I see several folks with 35RA's find the timing to be in the 34-36 deg range from the factory. I'll start there. I want to see how it runs at that setting with a good sensor, go from there.
Old 03-14-2017, 11:09 AM
  #103  
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Recently I was helping my brother restore an old Kawasaki 650 four cylinder motorcycle. It wasn't running properly at all and I suspected bad ignition coils. (They are 40 years old after all...) But the coils are pricey and a bit hard to find, so I wanted to be sure before we bought them. So I rigged up one old non-automatic advance CH dual ignition and two old single units, and used the POINTS on the cycle to trigger them, That way I could test the points and the advance system on the bike, while eliminating the coils and associated wiring. It ran perfectly and we even test drove it that way! We subsequently bought new coils, installed them, and the cycle now runs great.

It was an interesting experiment and use of our little ignition units.

AV8TOR
Old 03-17-2017, 12:19 PM
  #104  
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I have sold several ignitions for twin and single cylinder bike engines, They seem to work well.

Milton
Old 03-17-2017, 12:43 PM
  #105  
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I have often wondered what the long term reliability would be using them on a car or motorcycle. The only test of running them for hours straight that I know of would be Maynard Hill's adventure. (38 hours, 52 minutes.)

https://en.m.wikipedia.org/wiki/The_..._Butts%27_Farm

AV8TOR
Old 03-17-2017, 02:26 PM
  #106  
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I have found that the model plane ignitions fail before 500 hours of flying time. I've run thru several over the years and that seems to be the max, according to my flight logs. Most of mine failed starting around 250 hours. I normally don't fly for more than 15 min. per flight, so long term use may shorten the life. Of course, if they are subjected to more heat I would expect a shorter life for sure. Heat is the enemy of electronics.
Old 03-17-2017, 02:57 PM
  #107  
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What is the point of failure? If it is the coil itself, substituting a better coil, (when using them on for example a motorcycle or something), might be the answer. I wonder how long the older CH units using just the circuit board and the much heavier duty little Zenoah coils separately last?

AV8TOR
Old 03-17-2017, 03:33 PM
  #108  
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I have no idea what the point of failure was because the modules are sealed and potted. I would suspect that the high voltage insulation broke down, or the capacitor failed.
Old 03-18-2017, 12:52 PM
  #109  
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I agree with your suspicions. Nice job by the way, on your extensive documentation and impressive accumulation of flying time. You MUST be an engineer to do such meticulous scientific record keeping....

AV8TOR
Old 03-18-2017, 01:25 PM
  #110  
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Originally Posted by av8tor1977 View Post
I agree with your suspicions. Nice job by the way, on your extensive documentation and impressive accumulation of flying time. You MUST be an engineer to do such meticulous scientific record keeping....

AV8TOR
I am an engineer, after retiring from the Marines and Air Force, I went to Lockheed Martin and became an Avionics and Weapons engineer. After I retired from there, I went to work for Elbit Israel, and did avionics repair, design, and even UAV design. Now, I just play with my toys. I got used to logging flying time when I started working on my pilots license way back in the 1960's. I log all of the changes I make to my planes as well as all of the repairs. I also do a "root cause analysis" on failures. Old habits are hard to break.

I love the o'scope shots of the faulty Hall sensor. You don't see many of those. I forgot to do that with the bad one that I had, I just sent it back in for replacement.

Last edited by Joystick TX; 03-18-2017 at 01:30 PM.
Old 03-19-2017, 12:14 PM
  #111  
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I too am a pilot, and log that time, but I don't log my model flights. I do also maintain a log on my model fleet though with all pertinent info, changes, mods, maintenance, important flight comments, etc. I could never keep track of them if I didn't!

AV8TOR
Old 03-19-2017, 06:33 PM
  #112  
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All I can say is WOW!! you two, I log but very little
Old 03-19-2017, 06:41 PM
  #113  
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One thing that really helps model engine and parts manufacturers make design or parts improvements is knowing as much as possible about the failures and the "time" it takes before the failure is very critical. Often, that is why so many improvements are delayed, they just don't have enough information to make a change.

Our hobby suppliers don't have multi-million dollar budgets to do failure analysis studies and environmental testing like the government. If they did our planes would cost about $100,000 each and our hobby would die.

Just like this sensor problem, I'm pretty sure the vendor didn't know it was a problem before we did because they don't test 100% of their products before they ship them and the engine manufacturers don't do any testing either, or it is very limited.

They need us to help them out as much as we can to keep the prices down and the reliability up. If junk is out there, we have these great forums to point it out. We also can also find out what works good before we lose a plane.
Old 11-17-2017, 11:31 PM
  #114  
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I was just helping troubleshoot a DLE-20 that would not idle below 3K rpm. The owner thought it was a carb problem. Cleaning didn't help and swapping out the carb also didn't help.

A check of the timing revealed that it was set to 40 Deg BTDC. A check with the timing light indicated an ON at 53 and OFF at 40 deg for a difference of 13 degrees. The max settings for this Hall sensor was 38 to 46 Deg BTDC.

A known good sensor was put in the same location on the engine and gave 34 Deg BTDC. The timing light indicated an ON at 59 and OFF at 34 deg for a difference of 25 degrees. The max settings for this Hall sensor was 30 to 39 Deg BTDC.
Old 11-18-2017, 04:36 AM
  #115  
ahicks
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Sorry, at a loss here for your point. Are you noting the differences between the 2 sensors, or are you saying the new sensor fixed the idling issue?
Old 11-18-2017, 05:46 AM
  #116  
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Sorry for the confusion.

Yes, the new sensor fixed the problem, the engine won't idle correctly with the ignition set to 40 degrees instead of 28 degrees BTDC.

The adjustment range, from full CCW to full CW, for the old "bad" sensor is 38 to 46 Deg BTDC. That creates a problem since it can't be adjusted to the 28 degrees per the manual. The engine won't run right since the timing will be off a minimum of 10 degrees.

Most of the sensors that I've tested have a "span", from ON to OFF, of 22 to 25 degrees, this one is only 13.

The new "good" sensor can be adjusted from 30 to 39 Deg BTDC. It can't be adjusted to 28 degrees without modification, such as making the slots wider, but at 30 degrees the timing will be close enough for the engine to operate correctly.

Last edited by Joystick TX; 11-18-2017 at 05:50 AM.
Old 11-18-2017, 12:22 PM
  #117  
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Joystick, good info above. Back in post #12 in 2015 I referred to what I called the "sweet spot" or the area above the magnet in which the sensor would operate. I expressed it as an area where you expressed the effect in degrees. Either way, the effect is the same and the RCXP sensors give a wider range of adjustment than many of the RCexl ones. Also, the older RCexl sensors pretty much acted like the RCXP ones, they worked normally. I have not tested any of the newer RCexl sensors in some time now. I hope their issues were resolved over the years.
Old 11-18-2017, 12:46 PM
  #118  
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Truckracer - The sensor that was "bad" was just purchased and installed on an old engine this year. The plane crashed and a new sensor and ignition module was put on because the owner didn't trust the old ones.

I tested five more sensors that I had in my shop and found another one with only a 13 degree span. It was from a DLE engine from two or three years ago at least. I remember that I had to hog out the holes on the mounting bracket to get the timing set right, but I never thought much about it at the time.

There is a possibility that the little Hall circuit inside the holder has moved backward which would cause the problem. I need to take one apart and see where it is in relation to the front of the mount.

I found that it is not really necessary to do an actual timing test, which involves pulling the prop, putting on a degree wheel, finding TDC, etc. in order to find one of these "bad" sensors. I can just use my little timing light to see when the light goes ON and OFF with the magnet and the relation to the sensor mount. The light should come ON before the magnet is all the way under the sensor, usually about half of the magnet can be seen when the light comes ON. Same for when the light goes OFF, it should not go OFF until about half of the magnet is out from under the sensor.
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Old 11-18-2017, 02:49 PM
  #119  
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I usually just use the toner / light method when timing engines. Its sometimes difficult to time the A-02 ignitions using the spark as they don't always spark when the engine is turned at low speeds. The A-01 and a CH ignition will always spark at any speed.

If you dissect a later RCexl sensor you will probably find the Hall device surface mounted to a small circuit board ... to which the wires are soldered then this assembly is molded into the plastic housing. Earlier sensors and the RCXP ones just have the wires soldered to the Hall device. Some are then molded, some hand assembled into the housing. I believe all the bad ones I have seen had the surface mounted sensor. On some RCexl sensors you can even see the ends of the circuit board coming out to the edge of the molded sensor housing.
Old 11-18-2017, 03:08 PM
  #120  
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Update on the "bad" sensor. I took it apart and pushed the chip as far forward as it would go and put it back together. Now it has an adjustment range from 32 to 40 degrees.

When I said the adjustment of 28 Degrees BTDC is per the manual, that is not the DLE manual, it is the RCEXL manual. The DLE-20 (side exhaust) manual says the timing should be 38 to 40 Degrees BTDC. It also says the adjustment range is from 41 deg full CW to 37 deg full CCW. I think they use a degree wheel made out of rubber or they need glasses. Who are you going to believe, the world class engineers who designed and built one of the best model plane engines money can buy, or an old retired, half-blind, fat guy?
Old 11-18-2017, 03:18 PM
  #121  
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Originally Posted by Truckracer View Post
I usually just use the toner / light method when timing engines. Its sometimes difficult to time the A-02 ignitions using the spark as they don't always spark when the engine is turned at low speeds. The A-01 and a CH ignition will always spark at any speed.

If you dissect a later RCexl sensor you will probably find the Hall device surface mounted to a small circuit board ... to which the wires are soldered then this assembly is molded into the plastic housing. Earlier sensors and the RCXP ones just have the wires soldered to the Hall device. Some are then molded, some hand assembled into the housing. I believe all the bad ones I have seen had the surface mounted sensor. On some RCexl sensors you can even see the ends of the circuit board coming out to the edge of the molded sensor housing.
I didn't have to do a complete tear down on the sensor, since it was not seated properly in the holder.

The A-02 ignitions remind me of the new ignitions on lawnmowers, they won't spark unless they are turned at over 400 rpm. The idea was to cut down on lawsuits from people playing with the blade without pulling the spark plug wire off first. I don't know if the A-02 designers had that in mind or not, it may just be a function of the design and not on purpose.

The wind is howling out there and has been for several days, it should die down tomorrow, I'd rather be flying my new plane instead of jacking with an engine.

Last edited by Joystick TX; 11-18-2017 at 03:21 PM.
Old 11-18-2017, 05:42 PM
  #122  
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Originally Posted by Joystick TX View Post
I didn't have to do a complete tear down on the sensor, since it was not seated properly in the holder.

The A-02 ignitions remind me of the new ignitions on lawnmowers, they won't spark unless they are turned at over 400 rpm. The idea was to cut down on lawsuits from people playing with the blade without pulling the spark plug wire off first. I don't know if the A-02 designers had that in mind or not, it may just be a function of the design and not on purpose.

The wind is howling out there and has been for several days, it should die down tomorrow, I'd rather be flying my new plane instead of jacking with an engine.

The A02 Module from RCexl does not have the feature of NO spark under XXX RPM.
ALL DLE engines need to be timed 28-30BTDC when magnet leave the sensor period .
The A02 CDi is designed for 28-30 BTDC and should spark when magnet leaves the sensor.
NEW NGH CDI is timed 40 BTDC but the CDi is made that way.
OS CDI have the build in feature for NO spark if under 200 RPM if I remember correct.
If you getting a erratic spark replace the sensor first.

To test the CDI :

Power CDI direct, PUT A SPARK PLUG IN TO THE CAP !!!!!, Disconnect the sensor from the CDI.
On the BLACK and WHITE wire make a little jumper ( DO NOT TRY the RED WIRE!!! in any combination BK/RED, RED WHITE)
Every time you release the jumper from the BK/WHITE you need to get a spark.
If in flight you start to experience misfire, engine runs poor...or shut down and restarts after you got down safe... the CDI is overheating, place it in a area
where can have some air. It has a thermal fuse build in for overload protection to not catch in fire and burn the plane down with it.
That was a requirement from UAV when CH made those units.

Any other issues please feel free to call, email me and I will help the best I can .

Thanks
Adrian ( CH Ignitions/Keleo Rings)
561 927 6171

Last edited by CH Ignitions; 11-19-2017 at 05:11 PM.

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