More shots of the new devices mounted up and epoxied in palce:
Once you've made sure the epoxy has set, you can solder in the new diodes. DOUBLE CHECK TO MAKE SURE YOUR POLARITY IS CORRECT.
You also want to solder them in as quickly as possible. I would take a 30 second break between leads. If you overheat the new devices they will fail and your work will be a waste.
Also compensate the 2SC485 with a 100pf 100v capacitor between the collector and base. This gets rid of a small oscillation that will occur at higher frequencies, and is absolutely critical if you have to replace the pre-driver transistors. On some boards there is actually a provision for this labeled c810.
While you're in here, look at the initial audio amp transistor near the input leads of the board. if its a 2sc458 REPLACE IT. These transistors are notorious for becoming noisy and opening. This will cause all sorts of pink noise and crackling. Replace it with a 2sc631 or 2sc2240. I prefer the later for its low noise and low leakage characteristics.
And there you have it!
That is what is required to update the F-1040 series boards so that they operate safely. Again, if the amp has blown out, just find another board. The success rate at which the board can successfully be repaired and reliably work again is very low.
Hopefully this will be of use to the folks who have the skill to perform this task. This is NOT for the novice. Try it out on a 5000 series you don't care about, or have a parts unit standing by in case of a failure. If you install the diodes backwards or overheat them, the amp will self destruct when you power up.
After the installation, the old bias procedure is no longer valid. measure between the emitter (blue lead towards the bottom at the back of the driver board) on the final output device and ground. Adjust VR-02 for 12mv adjust again after 15 mins. I will use a variac to slowly power up and monitor bias one channel at a time.