Hartke LH500 amp, 2008, PbF

[N_Cook]

How to remove the preamp board? Looks as though it should come away with the
front sub-panel, leaving front panel in place. But something near the valve
base is holding it in place. Oddly 1 fixing only for the screening can
mounting base (diametric one is floating ,by "design"), looks like a rivet
but is it some sort of push-on stud fitting? I don't want to strain it if
its not.
Otherwise to remove the front panel requires removing the PA to get to one
of the screws holding the rack handles in place. Schematic on Elektrotanya,
as Samson LH1000

In the light of this one I will have to change my PbF attack procedure - I
will have to find a feather. Reported symptom intermittant drop in volume.
No problem on me powering it up. Removed top cover and twizzling lightly
with ballpoint barrel, the output dropped out and back on touching the
prea-pa signal cable. Never occured since with harder prodding / tapping/
tugging at the adjascent "header" cable termination, so I must have
mechanically closed the solder break, for the moment.
From now on with PbF , first twizzling will be litterally with a feather I
think.

 

[N_Cook]

Deliberately made awkward. On reassembly the screws will go up from under
into the alternative existing unused vertical threaded holes of the front
sub panel. With a torch and mirror there are 2 screws access under the pcb,
horizontally threaded. The one under the treble control requires undoing the
toroid's coachbolt to get to. Even then required putting a pozi headed hex
piece inside a nut driver to be long and narrow enough to get to it. The end
one is ok when you know it is there.