Electrohome Marquee Series

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      >> Tim Martin Modified LVPS Installation
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LVPS

The low voltage power supply is a fairly reliable module within the Marquee projectors. It supplies all of the voltages to the various areas of the set. There are a series of red LEDs on the front of the power supply. Under normal operating conditions, these LEDs are always off. It’s normal for them to blink at power-up or down.

The fans on the LVPS will stay spinning at a low speed when the set is plugged in but turned off. This again is normal. My fellow tech at www.etechvideo.com offers a fan modification to quiet these power supplies down if you find them noisy.

Filament voltage check. A number of Marquee 8110 and 8500/9500s were produced with a poor quality part installed in the LVPS that will cause the CRT filament voltage to slowly increase over time, from a nominal 6.3 volts to as high as 7.0 volts or more. This greatly reduces the life of the CRTs, and of course is expensive to repair when tubes need to be replaced. While this problem only affected the productions runs of sometime in late 1995 to sometime in 1998, there’s no saying that an older Marquee 8000 didn’t have a power supply failure in the past, and that a newer defective supply was installed at a later date, so it’s a good idea to check the filament voltage in the sets. Tim’s website shows how to do that here: http://www.etechvideo.com/techtip1.htm

While it might be tempting to simply tweak the filament voltage trimpot (I’m not showing you how to do that for that reason), a bad filament circuit will continue to drift, potentially causing damage down the road. If the filament voltage is too high, pull the LVPS out for modification, it’s a simple and permanent repair. A properly built LVPS will not need the filament voltage adjusted during the life of the projector.