Replacing the FT-817's power amplifier yourself

In the somewhat unlikely event that you do have to replace the finals in your FT-817 (being that the vast majority of '817 users have had no problems at all with theirs) it is worth knowing that a hobbyist with reasonable soldering skills, modest equipment, and attention to detail can, in fact, do the job his/herself.  An example of this was Mike, PA7XG, who undertook the challenge - despite initial reluctance to do so.

Of the task, Mike said "Thanks for your homepage. It convinced me that I could do the job. (It's tricky work for a senior citizen (me) with bad eyes and dodgy fine motor functions but otherwise straightforward.  Nor would I recommend it for a rank beginner..."

Mike kindly emailed me a file that describes in detail how it can be done, along with permission to post it for all to see, and I do thank him for doing so:

• FT-817 Final Replacement - .PDF, 21k

Addendum:

More recently (March, 2012) I received information from another amateur who undertook the project of replacing the finals in his FT-817 and he noted a few differences from the above procedure no doubt reflecting the more recent revisions of the radio and PA board:

• In the above document, a black, plastic adhesive shroud was noted:  This doesn't seem to be present in all FT-817's.

• The above document also refers to unsoldering ground pad "B" and a copper spring:  Some versions of the final don't have either a connection to ground pad "B" or a copper spring.

• The above document mentions using a supply voltage of 11.5-12.0 volts for bias adjustments while the FT-817 service manual specifies 13.8 volts.

• When it comes to setting the bias, there seem to be a number of different specifications to be found:   Practically speaking, the amount of bias isn't terribly critical and its exact value will depend somewhat on the supply voltage and it will tend to inversely vary with the final transistors' temperature, so don't worry about it being 10 milliamps off the aforementioned specification.
• First, sett both VR5401 and VR5402 for minimum current on the PA.
• After this is done, VR5401 is then adjusted for an idle current of 45 +/-2 mA.
• THEN adjust VR5402 for an idle current of  85 +/-4mA - but don't readjust VR5401.
• Considering that at DC, both final transistors are in parallel, one would adjust the second control (VR5402) to approximately double the current. 

• As of May, 2013, reports indicate that the part number for the PA board is "CB 133001" and it cost $43.88 from Yaesu, U.S.A. not including shipping/handling which, for one reader, brought the price up to $52.31.  According to him, the swap out took less than two hours and, as other email attests, quite easy as long as one pays attention to detail.
• When replacing the final unit, make certain that there is voltage on the "13US" line (which may be labeled as connection "E") and is connected to J3003 - the 3-pin connector that feeds to the RF/PA board from the main board.  This should be an "always on" voltage and if it is not present, suspect a burned trace on the "main" board or elsewhere.