I figured that I'd share some of what I went through in doing a couple fixes to my FT-100.
**** Change the Battery: ****
I started out by writing down all of my normal settings and the Hidden Menu "F" settings (reference the FAQ to get at the "F" settings. For what it's worth, I didn't lose any of these settings. My old battery (about 15 years old) measured 2.5 volts, the new one measured 3.6 volts.
I did, however lose the programmed frequencies. I forgot to write them down!
To changed the battery on the Control Unit, you need to removing both the top and bottom cover and remove the 4 screws that hol
d the Sub Panel and Front Frame from the front of the unit (with the front tuning panel removed). There are 3 wide white cables that connect it to the top of the unit. To remove these, you need to lift up gently on the upper ring around the connectors (both sides), then pull the cables straight up. There is also another white cable (narrower) that is connected toward the bottom of the Control Unit. Remove this when you tilt the Control Unit down.
From there you can unsolder the two tips of the battery and remove it. I purchased a CR3032 battery with tabs. I trimmed the length off just a bit so they wouldn't hang over, soldered it in place and put the unit back together. As I mentioned, none of the settings in the Function swi
tch or the "F" settings changed for me.
Re-assembly is just the reverse of the removal. Pull the ring around the connectors up, slide the flat cable in place (make sure that they are all the way down) and press both sides down to clamp on the cable.
**** Intermittent Speaker Connection ****
The speaker jack on the back of my FT-100 has been getting intermittent so I wanted to fix this problem.
You will need some fresh heat sink compound to replace to old dried out stuff that will be on the transistors.
With both the top and bottom covers removed,I would strongly suggest that you carefully study the cable layouts across the PA Unit board. Take a few digital pictures if you need to.
Disconnected all of the coaxial cables to the PA Unit (with the final output transistors), the two fan connectors
The "JP3002" connector does not come off, so you need to remove the other end of the cable on the OTHER SIDE of the unit. I did NOT remove the cable that is connected to JP3001, it was very long and would be difficult. I found that I could tilt the board away in order to do the soldering to the speaker jack.
There was another white flat cable on to the board, through to the bottom. This was fed through a flat ferrite core.
I removed the connector (lift up on both sides and pull it straight up).
Remove the 4 screws in the corners of the board and all of the screws that hold the power transistors and the voltage regulator. There are 2 screws on the HF power transistors that are somewhat hidden. I had to cut the white glue that held the torrid core transformer down (over the top of the power transistors) and pulled out some stiff masking type tape from under that transformer. This allows you to get at the other 2 screws on the HF power transistors. I placed all of the screws on a clean sheet of paper, roughly placing them relative to where they came out so I would know which ones went where.
Pull the power cable out from the back, as well
as the pigtail connector cable. This cable you can pull up to the front of the unit go get it out of the way.
From this point, you should be able to lift the board out GENTLY starting at the center of the unit (the speaker and other connectors are in the back of the unit, so you have to lift at the center and pull it out toward the front. Watch out, there is STILL JP3001 that is connected on the far side, near the HF power transistors.
Tilt the board over to get access to re-solder the 3 pins on the speaker jack connections.
Clean off the old silicon heat sink compound using a light dose of a
lcohol on a small rag. Replace the old compound with a very thin coating of heat sink compound.
Again, gently re-insert the board back into place, DON'T FORCE anything! Put in the outer 4 corner screws (DON'T TIGHTEN ANY SCREWS YET!). By the way, if you haven't already, you might consider putting some inside lock washers on these outer 4 screws to assure a very good RF contact. I got this hint from an old forum somewhere, or in the FAQ, I don't remember where...
Put in the screws loosely in all of the power transistors and the voltage regulator. Once they are all started, you can then go through and start tightening them all down. Get them tight, but don&
#39;t over do it!
Carefully re-route all your cables back into place, making sure that none can be crushed under the covers.
I did try to glue the torrid transformer down, but I think that it might be better to use just a small bit of silicon seal to keep it in place.
I powered my rig up and checked for power on all bands... No problems.