HPR4182: Replacing backup batteries in my Kenwood TS940S HF Radio Part 1

Hacker Public Radio

Note: all pictures are thumbnails which can be clicked to show the full-sized image

Picture 1

Shows my beloved Kenwood TS-940S notice that the display on the top right of the radio displays the words “TRIO-KENWOOD” this indicates that the backup battery has failed. Under normal condition it would display the time.

Wikipedia article about an S0239 connector. This being the Antenna connector which I had to remove before being able to work on the radio.

Link to the YouTube video I used that described the process of removing the two backup batteries in a Kenwood TS-940S. The video was very useful and was very informative however as per usual it looked far easier than it actually was or perhaps I’m just rubbish at taking radios to bits.

Picture 2

Shows a view of the radio with its top cover removed

The backup battery for the clock is tucked away underneath the front top lip of the radio directly behind the display that showed “TRIO-KENWOOD” This being above the front panel keypad.

The second backup battery is for the PLL (Phase-locked loop memories) it is located underneath the speaker and switches to the right of the speaker. Wikipedia article about PLL (Phase-locked loop)

The Antenna tuning unit which I briefly mention is located at the back right hand side of the unit. You can see the four holes on the top of the panel presumable to allow for adjustments. To the left of the four holes you can see the two motors that drive the tuning adjustments when the auto tune (AT.T) button is depressed. Wikipedia article about Antenna Tuners

Wikipedia article about soldering that mentions dry joints

Link to TechMoan You-tube episode about a piece of audio equipment that is destroyed by a leaking battery (Sony’s self-destructing MD Recorder from 2070).

Picture 3

Shows a view of inside the radio with the bottom cover removed. The radio is very analogue compared with modern radios. It contains many adjustable ferrite cores which I would imagine would be a bit of nightmare to setup. It also has a lot of electro mechanical relays. These days it would all be done with solid state electronics and with a small number of large scale integrated circuits. They truly don’t make radios like this any more.

The connector which I removed from the timer board to allow the front panel to rotate down can be seen in Picture 2. The timer board is a small printed circuit board that sits on the top of the radio slightly to the right and behind the clock display.

Picture 4

Shows the three internal side screws that need to be removed in order to allow the front panel to be rotated down this being done to gain access to the clock backup battery.

Picture 5

Shows a close up of the failed clock backup battery (silver disk with orange rim), the cable harness with the black rigid plastic cable tie which was already open. I can’t remember which connector was removed either the one to the right of the battery or the one just out of sight at the extreme bottom left hand side of the picture.

Picture 6

Shows the radio hanging over the desk with the front panel now rotated down. I now have clear access to the clock backup battery which I’ll cover in my next episode.