Power supply has all new parts, possible not the best replacements used
Not much you can do with the original circuit then!
You could go on the individual boards and increase the local “isolation/filtering” capacitors a bit like C312 on NA-06337.
Also you can double the 220uF capacitors to 470uF.
D701 & 702 = 1620’s
TR701 - 704 = TIP31, TIP32, 2383, 1013
I did give thought to that.
Btw, there are some fusible resistors in that amp.
Make sure they are replaced regardless of what they measure as.
Check FR703 and FR704.
There is much to say on Avionic, Sparkplug and MZB they do have very solid knowledge of the Yamaha products. None of them own a QA product and have any knowledge of how to interpret the test results obtained. Everything they do is based upon a Scope and DVM and final testing is by ear, I am not saying that is all good or bad but not my choice.
I give these guys a great deal of credit and have spent countless hours reading and practicing their means and methods. I couldn’t not have accomplished what I have without them.
Yes of course. However the thread contains some good info on rectifiers and increasing capacitor values and resistors on the Power Board.
So you have a 50vdc power supply with possible high ripple. The ripple may be a few volts -60dbv. So I place the Scope Probe on the 50vdc to see the ripple and select AC Coupling and around 1v scale I should see this? Then I can follow the 50vdc to the different boards filter caps and see where this ripple/noise may be located?
Yes you will definitely see it with a scope.
I just did exactly that on a Sansui AU-D11 narrowing down hum from various sources.
I used RHRG3060’s on the electrolytic board along with Mundorf 22000 caps, thought that would be most ideal. Maybe not.
You had mentioned a couple weeks ago about compiling a thorough test regiment, have you made progress on it?
I would not say it is thorough, but I have used it a little. Right now it has tabs for Power amp and Receiver tests. Was waiting for a preamp to test to get that part done as it is different.
If you wanted me to test it and provide you with the data for you to compare with what you measured, I suppose that would be possible.
This is why I made the offer
I also have a C70 if you would like more of a challenge.
What is included in the work to date?