I wrote before about some issues with my FTDX-101D (https://xarc.us/2023/08/grounding-good/). Though grounding may or may not have had anything to do with my problems with the virtual comm ports. I still have plans to do some changes in that area. But I came across some information that may be the key to eliminating further issues.
I came across a video by Chris Day, ZL1CVD. Actually two videos, where he explains the issue. Here are the links:
There is some repetition in these two videos, as Chris explained he had requests for more info. They are well worth the watch if you have ever had a comm port problem with your FTDX-101D/MP, and I believe the FT-710 and FTDX-10 can also have this issue. Possibly to FT-991, FTDX-3000 as well.
The short story is that the Silicon Labs chip that provides the two virtual comm ports can be programmed by their OEMs to provide a custom ID in the port properties. Yaesu does not use this feature, they used the default ID. But to allow a 1 time programming of the chip ID, Silicon Labs indicated a 4.7mF capacitor must be connected between pin 16 and ground. Yaesu included this capacitor in the circuit. Chris theorizes that some anomaly (RFI, voltage spike) causes the chip to go into programming mode and thusly making the chip unusable.
Since I use the comm ports all the time for digital modes, and mine had failed twice already which had me have it repaired twice by Yaesu USA (once under warranty, once not, and 3 shipments to west coast and back, see here for that story), I thought I would undertake the mod suggested by Chris.
Since Chris had formerly been a repair tech for Yaesu and others, and I watched his videos, and he had made this mod a his personal rigs, I trusted the logic behind the change.
It only involves removing one surface mount capacitor, which was not too difficult. Everything is sooo small though, but I got it done. Two covers needed to be removed, and I was able to get the cap out without removing the AF Board.
I won’t go into details here, watch Chris’ videos, and if you want to do it yourself, you will need to follow his direction and be able to identify the part on the schematic and board layout drawings.
So far, everything is working normally, which I expected. With luck, I won’t be afraid to use my EFHW now, which I had suspected might have been related to the onset of the problem.
