Kenwood TS-950sdx SDXCC 6Kc TX Unit

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There's Modness to ar Methods!!   TS-950sdx TRX Re-flow Mod   There's Modness to ar Methods!!

Gotta Re-Flow dat VOOODOOOO!!!

More boring 'BS'...

Disclaimer Notice
These modifications should be accomplished by qualified personnel who
have had enough knowledge and practice in SMD soldering techniques, at the owners risk.


We are not responsible for any personal injury incurred while performing these mods.
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mod errors, or possible mod misinformation via these pages.

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we cannot guarantee that the instructions will work on every radio presented.

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TRX History:

Well, this is a problem that is very common on all TS-950SDX rigs.
The TRX sub board (X59-3680-00) which is located on the Control Unit (X53-3380-00)
gets very hot during operation. So hot in fact, it will actually melt the solder on its components.

The TRX Board generates the Transmit and Receive DC voltages for the Rig.
It develops the Receive DC voltage called RXB and the Transmit DC voltage which is called TXB.
When the Rig is in Receive mode, the RXB voltage is switched to all the receiver circuits.
Once the Rig is keyed for TX, the TRX board turns OFF the RXB voltage to all the receiver circuits,
and then turns ON the TXB voltage to all the Transmit Circuits.
Once the rig is un-keyed, The TXB is turned OFF, and the RXB turned back ON.

From a combination of poor solder flow at the Kenwood factory, and the heat generated on this board,
the solder tends to melt ultimately causing an intermittent connection.
This normally happens on the two resistors R155 and R156, but we have seen this on all the components.
The symptoms of this problem are the rig will operate normally at first start up when its cold,
then it will not key up when the rig gets warm. The Receive may also drop out in extreme cases.
This will progressively get worse as time goes on.

The fix is simple, just reflow all the solder connections on the components with solder.
We use a high melting point silver solder, but regular solder will do just fine.
The TRX Board can be accessed by GENTLY bending it back, and GENTLY bending the board above it away.
Of course the Control Unit will have to be removed to accomplish this.

Be careful with R155 and R156, they are usually very loose and just touching them with
the soldering iron is enough to knock them off of the board!

Reference the pictures below to locate and repair the TRX Board...

TRX Board Location
This is the location of the TRX Sub-board on the Control Unit.
Notice the TRX Board was GENTLY bent down and the board above was GENTLY bent up.

R155 and R156
Marked in yellow are R155 and R156 Resistors the main culprits.
We have seen all the components have trouble so we re-flow all of them.

TRX Board
If you look closely, you can see the bad solder joints on this TRX board, especially on the resistors.

You fixed it!
These mods are getting easier and easier!
Ya'll Take Care!!

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