Hitec Flash 4 SX Modification
How to turn your Flash 4 SX into a Flash 5 SX
|Why this page ?|
|The Hitec Flash 4
SX and Flash 5
SX are both very good radios. The price difference between the two
radios is only about $30. The problem is that if you own a Flash 4 SX
radio, and one day you realize that you really need a Flash 5 SX, then
suddenly you have to spend about $160.
This page explains to you how to turn your Flash 4 SX into a Flash 5 SX.
|Here are the usual warnings:
If you understand and agree with these warnings then let's get started !!!
|As you may have already guessed, the Flash 4
and 5 are basically the same radio. One good indication is that they share
the same user manual. What you will need to do is:
The microprocessor used on the Flash 4 SX is the same as the one in the more advanced model, so there is no painful software upgrade procedure involved.
|To simplify the instructions, we will assume
that you want to add all the features of the Flash 5 SX (if that's not the
case you may only add 1 or 2 switches instead of 3).
You need to get 3 switches with the following characteristics:
The SW1, 2, 3 and 4 names are identical to the ones used in the user manual.
Let's get started:
|The main board|
There are 2 resistors that must be removed on the main PCB. One of them locks any action on channel 5 and the other one must be a pin that the processor reads to know if the additional features should be enabled or not. The resistors are 0 ohm resistors in Surface Mount Technology (SMT). The label on top read "000". To unsolder the resistor, you must heat both side of the resistor with a soldering iron. There are different techniques to do that. The one I use is to go back and forth between both sides of the resistor with the soldering iron. Eventually, you can add some solder. This helps carry the heat.
|Wiring the switches|
|You must now wire the switches that you
previously installed. On either side of the antenna, you will see 2 small
PCB's. We will call them the left one and the right one. At the top of
each PCB, you will see that there is a connector linking the 2 PCB's. This
is illustrated here below (ignore the additional wiring that you don't
We will number the pins of the connectors 1, 2, 3... from left to right. The connector on the left has 5 pins and the connector on the right has 7 pins. What you must do is end up with the following wiring:
The connections between the Left and Right PCB are already handled by the connector linking the 2 boards. You just need to worry about the upper part that connects the switches. Use a small soldering iron and thin flexible electric wires. The schematic may appear complex but it is actually relatively simple: what you want to achieve is to have the center point of the switches connected either to pin 3 (Left) or pin 4 (Left) through a resistor and, for 3-way switches, left floating at a voltage exactly between 3 and 4. SW2 is represented but you should not have to change its wiring.
All the resistors are 4.7K and can be soldered directly on the switches as illustrated below:
|Detail of the left side showing SW3 and SW4.|
|Detail of the right side showing SW1 and SW2.|
|Before closing your radio you must activate
the new mode. This is the final step of the conversion. This is also the
step that is the least clear to me. Please E-mail me if you have
The programming is done the same way the other programming is done except that there is a secret switch that activates it. If you look carefully at the main PCB, you will see that in addition to the 3 push buttons that are used to program your radio, there is 4th on, left of the 3 buttons. The following picture shows the placement of the 3 push buttons that appear on the front panel. In addition, you can see that there is a 4th one (secret switch) that cannot be accessed directly (unless the front plate is removed).
To activate the programming mode, short-circuit the 2 points marked by the red arrows and turn on the radio. You will get into menus that are similar to the ones used to program the other features of the radio. If you have additional information on the role of the different menus, please let me know. After a few trials, you will realize that your radio has now all the menus that are described in the Flash 5 SX manual. You are done !!!
Put the 8 screws back and enjoy...
|Feel free to link to this page. I recommend
linking rather than copying so you will benefit from additional updates.
If you link to this page, please E-mail me so I will inform you
if I change its location (which I am planning to do soon).
If you have additional information that you would like to share (specially on the programming procedure), please E-mail me.
Updated on 07/02/2001
|A special thanks to Herb for allowing me to
reverse-engineer his radio; and to Karl of the Harbor Soaring Society for teaching me how
to fly my glider.
My name is Bernard. I am French. I fly my gliders at the Fairview park in Costa Mesa, CA. I am a member of the HSS.
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