|Nov 17, 2009, 11:58 AM|
Joined Nov 2009
Assan 2.4 Ghz module in a Hitec Prism
I've just installed a new Assan 2.4 Ghz module in my Hitec Prism 7. It works well, apart from the following irritating fault, and I'd like to know if anyone else has encountered this problem.
When setting servo reverse it appears to accept the instruction, but on switching the Tx off and then on again, it reverts to the original setting. On the other hand, if I take the module out and set up servo reverse again, it remembers the setting, even once the module is reinstalled.
Is this just a peculiarity of the Hitec/Assan combination, or is there a fault in my transmitter?
|Nov 17, 2009, 02:26 PM|
Sounds like the TX not the RF module. The TX RF module only deals with converting the PPM signals to RF to be transmitted over the air to the RX and its servos. There should be a option to save your settings somehow, when you make a setting change such as reversing servos.
usually the setting is changed when you press the correct button on exiting a menu selection. But you could exit without changing the setting too.
|Nov 17, 2009, 07:48 PM|
Joined Aug 2002
Assan module problems with Eclipse & Futaba TX, problem is with the decoupling capacitors of the module which spike power to the electronics of the radio when you switch it off and prevents memory being saved. Until Assan fix their module to be fully compatible with all TX, the quoted temporary "fix" (within TX power system) voids TX warranty and most likely against FCC regulations in USA.
Suggest Spectra 2.4/Optima 7 Combo, which includes telemetry functions, for converting Eclipse, Optic 6 & Prism TX to 2.4Ghz (also suitable for Futaba and other TX with same module types) is best option.
Alan's Hobby, Model & RC FAQ Web Links
|Nov 21, 2009, 03:45 PM|
There are posts in the very long ASSAN thread that suggest the problem (it was id'd as "loss of trim memory" on power down of TX, but could well affect other settings as well using memory. The fix involves adding a diode (1n4001) will do fine to the +vcc line to the RF module. Looking at the TX back, it's the second long pin from the right in the module cavity. You will need to open the TX and find the correct lead, cut it, slip some heatshink over, then solder the diode with the polarity band toward the exterior. Shrink the tubig ... done. Then just close it up. This deal affects the Eclipse 7, maybe the Optic 6 and at least one Futaba TX.
This is apparently caused by a capacitor in the ASSAN RF module, which allows a voltage spike to feedback into the TX memory area on power down of the TX. Not really an ASSAN problem, but an integration issue, which ASSAN and Hitec will likely both ignore. In any case the fix is simple and cheap. (1n4001 diodes are ~ $0 .03 in qty of 100.)
Also, see page 292/post 4369.
There were a number of other posts describing the issue, but I could not locate them quickly, so just gave the fix info.
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