GPL B&W Projector


This projection set was used to televise closed circuit programming in hotels during the 1950's. Fifty of these units were manufactured for Theater Network Television by General Precision Laboratory in 1954, it is a Model PB-610, serial #23. The main rack is 5'x2'x2' the complete unit weighs 570 pounds.

Chassis #1 is the Control Unit, #2 is the TV Receiver, #3 is LV Power Supply, & #4 is the Sync and Sweep. The unit to the right is the 40KV HV Supply.


The high voltage power supply is an RF type unit, capable of producing up to 40KV for the 5AZP4 CRT. A 6BG6G is used as the oscillator which drives four 807's, the HV section which is enclosed in a Lucite box is a conventional voltage tripler circuit.


The optical barrel is very similar to the RCA PTU-1 system used in their 1949 model projection sets. The mechanical focusing is adjusted by moving the chain which moves the CRT closer or farther from the spherical mirror. Electrical focus is on the control unit and adjusts the CRT focus. The unit is designed to project a picture up to 9' x 12' and is probably capable of much larger screen size.


Each chassis is on pull out slides for servicing, and they can be turned upside down while in operation. Shown here is the receiver chassis, it appears to be an RCA clone from late 40's. There is no audio amplification, a 600 ohm balanced output is available to attach into the theater sound system. A separate audio rack was also available for locations that did not have its own sound system. In addition to the receiver there is also connections for two video and two balanced audio inputs that can be selected from the control panel.


Cabinet rear view


 TNT Logo on side of cabinet


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