HK elec retract problem - RC Groups
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Feb 13, 2013, 08:40 PM
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Figure9's Avatar

HK elec retract problem

My retracts (1out of the3) will not go up. The only way they will go up is if I limit the travel so it does not make the micro switch. If it makes the switch and stays on it, it will not move on the next cycle. Anybody have this issue?
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Feb 15, 2013, 08:13 AM
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Cougar429's Avatar
Not sure of your unit, but the behavior of many of mine, including Eflite 60-120's, is for the drive to back the motor up a touch from the limit switch at either end before completing the cycle.

Check if that is the case with your other two functional retracts and with the faulty one at the other end. If true check to see if there is some mechanical binding or resistance to motor rotation with the pin at that end. This may require disassembly.

If mechanical you may be able to make adjustments to free it up. If electrical check the switch at the faulty end. Sounds like it may not be sending the correct signal to the control board. I suspect this is the case due to the fact you are mechanically preventing the gear from sweeping till the overcurrent or timeout occurs, (what happens if you have something caught in the gear mech). When it sees overcurrent or no switch trip within a certain amount of time the control shuts down power to the retract motor and will not fire up again till it sees the signal to run the reverse direction.

I have to ask a couple of questions to see if I'm pointed the right direction. When that faulty unit hits that end does it take a few seconds to trip off or will it shut down normally and only then give you problems when asked to switch direction?

Also would help if you can spec the model and/or provide a pic.
Feb 15, 2013, 11:23 AM
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Figure9's Avatar
These are the retracts that I have. I have taken it apart and manually pressed the end of travel switch, and it stops like it should. If I limit the travel by inhibiting the full travel, it stops, then the motor rotates the opposite direction just a few revolutions, then stops. A command in the opposite direction works in either of these cases. When the travel is not inhibited and allowed full stroke of the retract, is when it won't travel in the opposite direction. What I don't know is if the limit switch is being made. Strange
Feb 15, 2013, 12:38 PM
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Cougar429's Avatar
From what you describe it sounds like the switch is not being contacted. I would check by adding a dollop of clay or some other soft substance to the switch and approach path to measure where the traveler stops. It may be that the switch was out of position a touch when soldered to the board.

If that's the case, swipe the top of the plunger with a razor to roughen it up and a VERY careful application with a drop of thick CA to the top, (if it penetrates game over) may be all that's required to build it up enough to meet the traveler. You may also be able to add a drop of solder to the traveler itself, (if brass) and shape till it makes proper contact. Problem there is it may be short term as solder is relatively soft. If alloy perhaps that dollop of thick CA would work in it's place. All this is to physically close the distance between traveler and plunger.

I had the opposite problem on my Eflite 60-120 sets as they all would stop before reaching full mechanical lock, basically just into the lock groove. I filed the attack side of the plunger till the sweep length made me comfortable. A minor fix.
Feb 15, 2013, 01:17 PM
Registered User
Figure9's Avatar
Great input! Thanks for your time. I'll check it out tonight

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