First thing I have worked on has been checking and trying to adjust all reference oscillators. It seems a common problem with FT-ONEs is that crystals get out of specs so they can't be put right on frequency. And, yes, in my unit there are so far four oscillators which couldn't be adjusted properly: 19.7475MHz (IF UNIT), 20MHz (PLL UNIT), 48.615MHz (PLL UNIT) and 54.28MHz (PLL UNIT). Here you have some pictures of them:
19.7475MHz oscillator is on the metal cage at the upper side.
As you can see, I have an extension card, very useful to work on IF board (and others as well). FT-ONE full extension boards kit consists of 5 units and an extension cable. I have just 3 units I got some years ago at eBay. Hope I don't need the other ones!
This is the PLL UNIT, where most of the reference oscillators are located:
Well, I have tried some tricks to get the oscillators back to where they should be... it has worked in two of them: 19.7475MHz oscillator in the IF UNIT has been tweaked by means of an associated coil. In the PLL UNIT I have tried to change fixed capacitor plus trimmer pairs used in all oscillators to a larger range ceramic trimmer, so I could go lower and higher in capacity, as you can see in next pictures:
It has worked fine for the 20MHz oscillator but other ones are too far from right frequency and are still wrong, as they stop oscillation when trying to find the right spot. I guess only way to deal with this is to get new crystals. Hope I can still find them!. Any help locating them will be happily received.
One of the known problems rig had when I bought it was an unworking S-meter. It was not the meter itself as it worked as ALC indicator. Some work on the schematics revealed a possible culprit: there is a quad operational amplifier (MC3403P or UPC3403P) which is used for several functions, all related with signal metering: AGC, RF GAIN, S-meter indication. I had not it in stock so I tried lots of things to be sure it was faulty. It is not a simple circuit as inputs and outputs are interconnected. Here you have the partial schematic and also the pinout for the amplifier:
When it seemed most probable there was some fault in the IC, I ordered some... which arrived a week later.
Here you have the original IC, a Fairchild unit dated 1980:
Then I cut its pins and carefully removed them, soldering on its place a good quality AMP socket:
And then I put the new IC, a Texas Instruments one:
Upon powering up the unit, S-meter worked :-)!!!. It obviously needs calibration, but as AGC also works, I have been able to finally receive some LSB signals in 40 meters with RF GAIN turned up (before, this generated garbled signals, due to saturation).
This is the picture of the IF UNIT back in place (well, yet on extender board):
I have also ordered replacement crystals for almost all the oscillators, as most of them have been already checked and are out of frequency and, anyway, I don't trust they will be available for long time.