Hi,
Happy End.
State of affairs:
Yesterday I picked up the amp and now he appears to be running properly within its capability. "Within its capability" means that the rattle is not completely gone. But you have now already about 20 - 30 cm be directly to the ear at the level of the Cabinet / Speakers to at all to locate the rattle,
it gets lost in the rest of the background noise of the amp.
But a Bugera V55 (250,- Euro?) runs silently here! More about this see below.
Praise and criticism:
I was good.
Because I could find confirmed by my research, my guess is that it was the final stage or its power supply. As far as I was able to locate and isolate the fault. I, however, was not consistent enough
to pinpoint the exact source of error. Here I was able to afford the targeted brain work, but not by measurement to prove the source of error. Therefore, the path led me now to Enzo Morgana and here I have to say that my decision was right to bring the amp to the Enzo. Because ...
Technical:
...Enzo has demonstrated not only the exact source of error measurement technology, but he has now built here "his" measured out HV diodes and completely, of course, equal to the missing, the diodes in parallel connected, installed capacitors. Here he has regarding the diodes built its know-how, which I would not, because I probably would have re-soldered the types specified in the schematic. My very best thanks again to take this opportunity to Enzo!
Marshall:
A clear statement: Since I exclude another error that has led to the misconduct of the rectifier diodes AND from the mp3, which I got thankfully from another 2266VM-user with the same problem (!), I conclude that Marshall concerning the interpretation and dimensioning of the power supply has not handled correctly here his homework. See Schematic regarding the marked fields. I 've attached the schematic of the power amplifier and the power supply twice. "Original" is more or less the factory wiring diagram, you can see here the circuit as for the 2266VM and 2466VM should be, including all comments. In "2266VM wiring" I have everything removed, which is not present in the amp on the boards and you can see now that is good, what is left - in particular in the power supply!
The HV rectifier diodes in the power supply are not of sufficient size, the series circuit is unfavorable for the occurrence of HF interference, and it is the appearance of this one scattering in the final stage RF interference favored also by the absence of their capacitors connected in parallel. For me, clearly a deficiency in the circuit design. What is even more annoying, since this issue since the mid-80s, bridge rectifier diodes well known in amplifiers (I actually could have come right on it ...).
So "keep your eyes on" for the 2266VM what if applicable terms of such disorders!
With best regards
Michael