Wow. Now I was also affected by it: My power amplifiers from the FT-817 blew up. After several hundred SOTA and /p activations it happened at home while I was listening to SSB satellites.
Especially with the old non-ND versions (like mine) the power amplifier starts to oscillate by itself and destroys itself by self-oscillation then. The older MITSUBISHI RF POWER MOS FET 2SK2975 were not that good. I had already read a lot about this on the internet. The FT-817 suddenly became very hot and had a permanent current consumption of 2 amps. It was clear then that the FETs were short-circuited. I measured about 90°C with the IR thermometer.
I then desoldered the power amplifier module and the FT-817 could be used as a receiver (with 300mA current consumption) again. I looked on the Internet for spare parts. It is not easy to get the newer RD07MVS1 fets individually these days. They cost about 20-30 euros in a pair.
Luckily Yaesu offers the entire SMD board (v2 CB1333002 and v3 CB1333005 with RD07MVS1 instead of the older 2SK in the non-ND) with capacitors and coils. I paid 45 euros for one board. I ordered with superb service from Frank Dathe here in Germany. I can only recommend him.
Removal took about 15 minutes. The installation took about an hour. I set the first bias regulator to 42.4 mA and then to 84.8 mA in total. I think these are good values. After that, I adjusted each band to a full 5 watts in each of the four power levels. It is good to know that I have now installed the more robust version of the FT-817ND and FT-818. With that, not so much should happen on the road. By the way, as a backup (and for satellite operation in full duplex) I just bought another FT-818.
73 and good DX!
Mine has not failed but I am more and more afraid that this will happen and I will not find the piece that is already scarce. I will greatly appreciate your comments to start imagining how to bring it to Peru.
73!