[dreier3]

Zitat:Original geschrieben von kahlo

Ach Menno... du hast es schwer.

Die 10R-Widerstände sollten nicht heiss werden. Wenn sie es werden, ist irgendwas oberfaul. Æhm, kaputt wollte ich sagen.

Wieso sind C11 und C12 350V-Typen? Das reicht nicht. Sind sie noch ganz?
Leben die Gleichrichterdioden noch alle? C8 und C9 sind mir unheimlich...

C11 und C12 habe ich 450V typen verbaut.

die gleichrichterdioden hatte ich vorm wechsel der 10 ohm dinger mit dem dmm geprüft...sind alle in ordnung.

erklärung zu c8 und c9

-> quelle: http://bjl.audioconcept.free.fr/Archives...its%29.pdf

Now for the interesting part; the high-voltage
supply. It all looks pretty run of the mill ?
rectifier, reservoir capacitors, series resistors R23,
R24, also fuse Z2 and the stand-by switch ? but
what about resistors R21, R22, and capacitors
C8 and C9? A power transformer has a wide
bandwidth, and will pass a gamut of signals
besides the desired 50 c.q. 60 Hz mains voltage.
Spurious signals enter through two separate
pathways. Before all, capacitive coupling between
primary and secondary will cause so-called
?common-mode? noise, which can be eliminated
through static shielding in the transformer or the
network around R21, R22 and C8, C9. The
second form, ?differential? noise, is caused by the
all-too-wide frequency response of the power
transformer. These noise voltages appear between
the red and yellow connections of the secondary.
Again, the filter network will deal with them.
And, the transformer can be blamed for much,
but not everything; the third noise source is the
rectifier bridge D1-D4. While these diodes act as
fast switches, they will generate sharp transients
during zero crossings, which are dampened by
C8, C9 and C10.
In summary, this modest little circuit acts as a
highly effective interference suppressor. It is
well known that a vacuum diode, like the
GZ34, sounds smoother than its solid state
counterpart, when used as a rectifier. There are
two reasons for this; its relatively high internal
resistance has a similar effect as resistors R21
and R22. Furthermore, the gentle switching of
vacuum diodes is not prone to generating
transients. So the network around R21, R22,
C8 and C9, does its very best to mimick
vacuum rectifier behaviour, and with good
effect, as the mild sound of this amplifier
proves