SAMSUNG TV HL-85687W picture is dim
(Please check your model number - it appears to be incorrect, I believe it's HL-S5687W)
1) How old is the lamp? (how many hours on it)
2) Is the lamp an original equipment lamp, or aftermarket?
It's either the Lamp itself (it's not common for a sudden reduction in brightness), -or- the Lamp Ballast has gone bad. This is the power source for the Lamp, and although they usually die completely when they do go, sometimes they will act just as you have described... they fail into a "low power" mode.
If the lamp IS an original mfr lamp, and if it's nowhere close to being near "end of life", then I'd say it's likely the Ballast.
Prices for the original Samsung lamp run around $100 onamazon and others.
The Ballast p/n BP47-00037A has a cost of around $50 to $100 online.
Google those p/n in "Shopping"
The Ballast can be replaced without great knowledge, but will require some dis-assembly, and CARE.
WARNING - Dangerous, and even lethal voltages are present inside your TV set. Do not attempt this unless you are trained in these kinds of repairs. Leave the TV unplugged for several hours (or preferably a full day) before attempting such repairs.
on Jan 12, 2013