EIA TEP194-1986

INTRODUCTION

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

Prior to 1970, the glass envelopes used f or TV picture tubes
were designed to provide the required attenuation of X-radiation
for the normal operating condition of TV receivers and the maximum
ratings of the picture tubes. Beginning in 1970, the attenuation
was increased to assure that the X-radiation from TV receivers did
not exceed the Federal Performance Standard ⁽¹⁾ under
abnormal or failure mode operating conditions. Such abnormal
conditions often resulted in the picture tube being subjected to
anode voltages which exceeded its maximum ratings.

In order that the TV set designer could make maximum utilization
of the JEDEC X-radiation Limit Curves, these curves were developed
for anode voltages well in excess of the maximum anode voltage
rating of the picture tubes. curves thus provided picture tube
characteristics to the TV set designer for anode voltages nearer to
those voltage values actually encountered under failure mode
conditions.

The JEDEC curves for tubes utilizing glass produced prior to
1970 were developed and published to provide a historical record of
the X-radiation characteristics of such tubes as they were
originally designed and manufactured and to provide the necessary
reference guidelines for developing information for the service
industry with regard to the use of replacement tube types. The
X-radiation characteristics were not always included in the
defining data for tubes types registered with JEDEC prior to
1970.

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