Martin MAC 500 Service Manual page 27

S/N for
Implementation
New head shell
The plastic in the shell of the MAC 500 head was changed to another type that withstands higher tem-
peratures and has better heat conduction properties. The new shell may be identified by the
embossed Martin logo and by the number of ventilation slots over the lamp housing: the old shell has
four slots (9 mm wide) and the new shell has 6 slots (3 mm wide).
The new shell (2 x P/N 374075-020000) is not fully compatible with the old shell. If replacing the old
shell, the following parts must also be replaced:
2 x MVI018-050000: "Counterbalance, plate 1, MAC 500 painted" (the plates for the 1/4-turn locks)
1 x MXI007-030000: "Back plate for bulb housing, MAC 500, after-treated" (the plate that the lamp
971219-000
The lamp socket must be removed from the access plate in order to pass the lamp wires through the
back plate. When realigning the lamp socket, remember that initial alignment is achieved by adjusting
the module with 38 mm between the back of the access plate and the front of the adjustment plate.
For optimum cooling with the new type shell, the rubber spacers under the top air-flow plate must be
replaced with the following:
4 x 361812, M4 x 20 mm taptite
4 x 393012, 9 x 14 mm rubber spacer
Finally, it may be necessary to file 2 - 3 mm of material away from the inside-front edge of the air vents
over the lamp housing in order to achieve a good fit.
Halo fixes
970924-000 The fixed open gobo and the center hole in the module plate have been enlarged slightly.
971001-000 The open rotating gobo has been removed. The rotating gobo gear wheels are painted black on light
exit side (no S/N info available).
On MAC 500s produced before these changes went into production, the halo is only visible when the
iris is fully open. By setting SPEC/IRR (iris reflection reduction) to ON, the iris closes slightly from full
to reduce the reflected light that causes the halo. This does not affect the beam noticeably when
focusing on the open gobo.
1998-08-03
access plate screws to)
Major Hardware Changes
Changes
25