ECIA TEP194

SEE EIA TEP 194-2 FOR ADDENDUM 2

INTRODUCTION

Since the advent of commercial television, the picture tubeoperating anode voltage in TV receivers has been increased fromtime to time, requiring that more and more X-radiation shielding beprovided by the glass envelope of the picture tubes. These periodicchanges are delineated by the grouping of JEDEC X-Radiation LimitCurves for monochrome TV picture tubes according to the timeperiods when tubes were produced from glass manufactured, (1) priorto 1959, (2) between 1959 and 1965, (3) between 1966 and 1969, and(4) beginning in 1970. TV picture tubes are grouped according tothe time periods when tubes were produced from glass manufactured,(1) prior to 1970, (2) between 1970 and Similarly , the JEDECX-Radiation Characteristic Limit Curves for color 1973, and (3)beginning in 1973.

Prior to 1970, the glass envelopes used f or TV picture tubeswere designed to provide the required attenuation of X-radiationfor the normal operating condition of TV receivers and the maximumratings of the picture tubes. Beginning in 1970, the attenuationwas increased to assure that the X-radiation from TV receivers didnot exceed the Federal Performance Standard ⁽¹⁾ underabnormal or failure mode operating conditions. Such abnormalconditions often resulted in the picture tube being subjected toanode voltages which exceeded its maximum ratings.

In order that the TV set designer could make maximum utilizationof the JEDEC X-radiation Limit Curves, these curves were developedfor anode voltages well in excess of the maximum anode voltagerating of the picture tubes. curves thus provided picture tubecharacteristics to the TV set designer for anode voltages nearer tothose voltage values actually encountered under failure modeconditions.

The JEDEC curves for tubes utilizing glass produced prior to1970 were developed and published to provide a historical record ofthe X-radiation characteristics of such tubes as they wereoriginally designed and manufactured and to provide the necessaryreference guidelines for developing information for the serviceindustry with regard to the use of replacement tube types. TheX-radiation characteristics were not always included in thedefining data for tubes types registered with JEDEC prior to1970.

Therefore, when a substitution tube type was required as areplacement in a TV receiver it was not always obvious that theoriginal X-radiation shielding was being maintained. Now, by theuse of these curves and JEDEC registration data, reliable picturetube replacement charts for use by the service industry can bepublished.

Edition:

86

Published:

01/01/1986

Number of Pages:

169

File Size:

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