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Author Topic: Problem with Hitec Laser 4 set for the experts only.  (Read 2541 times)

unbuiltnautilus

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Problem with Hitec Laser 4 set for the experts only.
« on: August 01, 2011, 05:37:26 pm »

One of our members has encountered a problem with his 40mhz Tx, the servos have all deflected to one extreme of travel and will not respond to any inputs. When the xtal is removed from the Tx they all 'relax'. This is the second time the member has encountered this problem, last time one channel only died. The problem has been isolated to the Tx by a process of elimination. I have found mention of this problem previously on an American forum, however the only advice available was to return it to the service agent. The new distributor for Hitec in the UK is J Perkins, however A) They are only dealing with the new 2.4G equipment on multi channel equipment, and B) I may have modified the set with dials and buttons about 6 months ago :embarrassed:
Any input would be greatly appreciated..
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Martin (Admin)

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Re: Problem with Hitec Laser 4 set for the experts only.
« Reply #1 on: August 01, 2011, 06:09:52 pm »


 I had one of these set, that turned out to have a crystal problem, both of which had to be replaced.
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malcolmfrary

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Re: Problem with Hitec Laser 4 set for the experts only.
« Reply #2 on: August 08, 2011, 10:29:11 am »

Quote
B) I may have modified the set with dials and buttons about 6 months ago
This could be a clue.  Generally, the pots and switches are in a sort of ladder arrangement, each offering its wiper voltage to the magic bits in turn.  The wiper voltage derives from a pair of rails carrying a high and low voltage, if one of these rails has become disconnected, then the full voltage of that rail will be presented, and the servo at the other end of the system will obediently go to its full travel.  Removing the crystal also removes the signal, so everything should relax, so the radio part is OK, its the logic end thats broken, possibly in the general area of the wiring for the new dials and buttons.
Theres an encoder drawing here
 http://www.pm.keirle.com/1_gadgets/encoder/encoder.htm
that shows the principle, but almost certainly not the actual circuit that Hitec used.
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unbuiltnautilus

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Re: Problem with Hitec Laser 4 set for the experts only.
« Reply #3 on: August 08, 2011, 10:56:21 am »

That tickles the edge of what I understand, however, it gives me an area of the board to look at closely.
Many thanks for the diagram. I will report back..
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