Dave xxxx wrote:
Keith G wrote:
Absolutely not, Dave's an 'old friend'....

ta old chap I am piggy in the middle

more information

Primaluna Prologue Two amp has gone mental again, i.e. broken down

It's the same problem as before where one or more output valves start
glowing on and off like buggery, loudspeakers drivers being thrown
fully out and back again, loud pops. this is happening with or
without music playing

OK.. that really does help. I looked up the Owners Manual and spent a
bit of time with it... Allow me to ask a few questions, but I will
still go out on a limb at the end of them.

a) When this happened before, how did you fix it?
b) Or did it go away spontaneously?
c) What have you done so far this time?
d) This made some/little/no difference?
e) Do you have any means to check tube function individually? It would
be nice to be sure that (a) bad tube(s) is(are) not the cause.
f) Has this amp experienced any accident recently? A coffee spill,
miswatered plant, dog lifting its leg, a person sweating over it? (I
have to ask).
g) Is this amp operated with the tube cage in place? Could any foreign
body/insect/bit of dirt gotten into it, with specific reference to the
tube wells?

Now for the climb out onto the limb: I have stated on two prior
occasions that I do not think this is an electronic problem. Given the
vintage of this amp, I am even less inclined to believe it is
electronic.

I do not know how adept you are at repairs, even whether given the
descriptions of others whether you would care to try. But here is where
I would start:

Before doing any of the following: Remove all tubes (valves) and clean
the pins and sockets, Do this one-at-a-time so that they go back to
whence they came. Make sure each one is bottomed and centered in its
socket. If you find anything untoward in this process such as a salt or
carbon track, partially cooked housefly or carbonized dog hairs, you
may have just found the problem. If not:

1. Isolate the amp from all input devices, leaving just your speakers
connected. Verify that they are connected properly, there are no frayed
speaker cord ends or other silliness.
2. Turn on the amp with the volume all the way down, and the selector
set to an arbitrary position to one extreme or the other, say... CD all
the way CC.
3. Turn it on. Time exactly when the problem begins.
4. If there is no problem at the outset, gradually increase the volume
(but *not* past 3/4 way) until it appears. Take your time with this.
5. IF, by some chance, it does not appear, add back one input device
at a time, removing each one in turn before installing the next.
6. Turn off.

Report Back.

On the assumption that the problem occurs at stage one, no volume:

WITH THE UNIT TURNED OFF AND UNPLUGGED!! Open it up:

Check for _any_ mechanical problems. I note there are several PC boards
and quite a bit of point-to-point wiring. On the output driver-to-amp
stage, if there are any broken/shorted connections, this will drive
your amplifier tubes nuts, blue glow, internal meltdown and worse. So
go over this section, all pin connections and board traces with a
magnifying glass, look for carbonization, anything that might indicate
a problem.

Report back.

This appears to be a very nice amp, and reasonably well built (from the
pictures). I certainly do not want to make suggestions that involve
changing or modifying or repairing components without a thorough
physical examination first.

Peter Wieck
Wyncote, PA