GB/T 15524-1995 Reliability requirements and test methods for non-broadcast video tape recorders
Some standard content:
National Standard of the People's Republic of China
GB/T155241995
Reliability requirements and testing methodsfor non-broadcast video tape recorders1995-04-06Promulgated
State Administration of Technical Supervision
Implementation on 1995-11-01
National Standard of the People's Republic of China
Reliability requirements and testing methodsfor non-broadcast video tape recorders1Subject content and scope of application
GB/T15524—1995
This standard specifies the reliability requirements and testing methods for non-broadcast video tape recorders (hereinafter referred to as video recorders). This standard is applicable to the reliability identification test and reliability acceptance test of video recorders. This standard assumes that the failure distribution of video recorders in the service life stage follows the exponential distribution law. 2 Reference standards
7 Basic terms and definitions of reliability
GB3187
GB4013 Terms for audio and video recording
GB5080.7 Equipment reliability test Failure rate and mean time between failures under the assumption of constant failure rate Test plan GB/T14306
6 VHS video cassette
3 Terms and symbols
Mean time between failures.
90--Upper limit of the assumed value of mean time between failures. G
-Lower limit of the assumed value of mean time between failures. e--Lower limit of the one-sided interval estimate of mean time between failures. 6p--Expected value of mean time between failures. β--Manufacturers' risk, that is, the probability of rejection when the actual mean time between failures of the video recorder is equal to 9. β--Users' risk, that is, the probability of acceptance when the actual mean time between failures of the video recorder is equal to 9. Dm——Discrimination ratio, that is, the ratio of % to 1, Dm=9%/01. ro-
The upper limit of acceptable failures.
The terms used in this standard are in accordance with the provisions of GB3187 and GB4013. 4 Reliability requirements
4.1 This standard adopts the mean time between failures (MTBF) as the reliability indicator of video recorders. 4.2 The mean time between failures shall be specified in the product standard, and its lower limit can be selected from the following series: 8000, 10000, 12000, 15000, 20000h (excluding vulnerable parts that are damaged when exceeding 1000h: magnetic head, transmission belt, rubber parts, felt parts). 4.3 The lower limit of the mean time between failures of video recorders shall not be less than 8000h. Approved by the State Bureau of Technical Supervision on April 6, 1995, and implemented on November 1, 1995
5 Test types
GB/T15524—1995
According to the different stages of product development and different test purposes, reliability tests are divided into reliability identification tests and reliability acceptance tests. 5.1 Reliability identification test
The reliability identification test is used to verify whether the video recorders designed or produced by the manufacturer meet the reliability requirements specified in this standard. The results of the reliability identification test serve as the basis for determining whether the reliability of the video recorder meets the requirements in the following situations. a.
Design finalization;
Production finalization,
Identification after major changes in design and process. c.
5.2 Reliability acceptance test
The reliability acceptance test is used to verify whether the manufacturer can maintain the reliability level achieved by the reliability identification in continuous mass production. 6 Statistical test scheme
This standard specifies the use of two statistical test schemes, timed truncation and sequential truncation, to verify the true value of the mean time between failures (MTBF) of the video recorder and determine whether the video recorder meets the specified reliability requirements. 6.1 Timed truncation test scheme
The timed truncation test scheme for video recorders shall comply with the provisions of GB5080.7 and Table 1 of this standard. The selection principle shall be in accordance with the provisions of Articles 6.1.1 and 6.1.2.
The video recorder that fails during the test shall be repaired (or replaced) in a timely manner and the test shall continue until the time specified in the scheme is truncation. Table 1
Judgment risk rate
Scheme number
6.1.1 Reliability identification test scheme
Discrimination ratio Dm
Total test time T
(multiple of)
The reliability identification test of the video recorder shall adopt the test scheme 2 in Table 1. According to test plan 2, according to the accumulated Poisson function, we can get: T=nto=6.6891
In this plan, to=668h is taken, and the number of test samples n corresponding to different 91 is shown in Table 2. 2
Judgment standard (number of failures)
(greater than or equal to)
(less than or equal to)
·（1)
n, units
6.1.2 Reliability acceptance test plan
GB/T15524—1995
The reliability acceptance test of the product should adopt test plan 4 in Table 1. According to test plan 4, according to the accumulated Poisson function, we can get: 12000
T=nto=4.2891
In this plan, to=668h is taken, and the number of test samples n corresponding to different 61 is shown in Table 3. Table 3
n, units
6.2 Sequential truncation test plan
100200
133600
(2)
The sequential truncation test plan for video recorders shall comply with the provisions of GB5080.7 and Table 4 of this standard. During the test, the number of failures that occur in the product shall be used to determine whether the test continues, and whether the mean time between failures reaches the lower limit of the assumed value. The sequential truncation test plan is only applicable to the reliability acceptance test of the product. For different test times, see Table 5. The number of test samples can be determined according to the batch size of the product.
Judgment of risk rate
Note: When the number of related failures is 3, all products shall be rejected. Identification ratio Dm
Related failure number,
Cumulative related test time (multiples of e.) Rejection
(equal to or less than)
(equal to or greater than)
Test cut-off time
Related failure number product
≥2 Unqualified, stop test
<2 Continue test
=0 Qualified, stop test
1≤<2 Continue test
=1 Qualified, stop test
=2 Continue test
=2 Qualified, stop test
GB/T15524—1995
Note: ① When the number of related failures ≥3, the test shall be stopped and the batch of products shall be judged as unqualified. 12000
②The test deadline listed in the table is the test deadline of a single sample. During the test, the specific test deadline can be determined according to the number of test samples according to formula (3).
7 Test requirements
7.1 Reliability prediction
Before the reliability evaluation test, the reliability of the video recorder should be predicted. When the predicted value of the mean time between failures (MTBF) is greater than the upper limit of the assumed value of the mean time between failures specified in the test plan, the reliability evaluation test can be carried out. 7.2 Reliability growth test
Before the reliability evaluation test, the test sample should be subjected to a reliability growth test to expose potential design defects and make necessary design and process improvements. In order to expose design defects as early as possible, stresses that are more severe than those in normal use can be appropriately applied during the reliability growth test. These stresses can be applied in combination or individually. Each design defect found in the growth test needs to be carefully analyzed to find out the cause and take effective improvement measures.
7.3 Aging pretreatment
The pretreatment time and pretreatment stress of the test sample and the batch of products it represents shall be exactly the same, and no special pretreatment shall be used.
7.4 Test samples
The samples for reliability identification test shall reflect the design and process level of the product, and their main performance indicators and specified functions shall meet the requirements of product standards.
The test samples for reliability acceptance test shall be randomly selected from the qualified products. All performance indicators and specified functions shall meet the requirements of product standards.
7.5 Test conditions
7.5.1 Power supply voltage
Nominal working voltage ±10%;
Samples using switching power supply can directly apply grid voltage. 7.5.2 Climate conditions
General temperature: 20±10℃;
Arbitration temperature: 20±5℃,
Relative humidity: 45%~75%,
Atmospheric pressure: 86~106kPa.
GB/T15524—1995
Accelerated test can also be carried out at 40±2℃ according to this standard. 7.6 Test equipment
The test equipment can provide and meet the various conditions and test methods required for the reliability test of video recorders. The test room should be clean and dust-free, free of corrosive gases, no obvious vibration and noise, and equipped with ventilation, safety and alarm facilities. 7.7 Test tape
The E-120 tape used for VHS format video recorder test should meet the requirements of GB/T14306, and the tape used for other format video recorder test should meet the regulations of the corresponding system.
7.8 Test time
7.8.1 The time of reliability identification test and reliability acceptance test shall include the time of stress application. 7.8.2 When the time of failure cannot be accurately determined, the time of the last inspection record shall be the time of failure occurrence. 7.8.3 The test deadline t is calculated according to formula (3): t=T/n
Where: T-total test time:
Number of samples specified in the test plan.
·(3)
During the test, if the failed sample is replaced immediately, the test time of the replaced sample shall reach the specified test deadline t, and the test time of the replaced sample shall be invalid.
If the failed sample is not replaced immediately, but is repaired and then put into the test again, the test time of the sample shall be extended by a period of time consumed by the repaired sample to ensure that the total test time (nt) remains unchanged. The test suspension time shall not exceed 24h, otherwise the test will be invalid. 7.8.4 The test results shall be reported in detail in the format specified in Appendix B (Supplement). 8 Test Methods
8.1 Test Signals
Test Card Signals:
b. Color Bar Signals;
c. 1kHz Sine Wave Audio Signal with 30% Modulation, d. Broadcast Television Image and Accompanying Sound Signals.
8.2 Cyclic Working Period
12h is a cyclic working period, of which 11.5h is powered on (3.5h is function operation) and 0.5h is powered off. 8.3 Function Operation Steps
Compile cyclic sequential operation steps according to the basic functions of the video recorder, of which the working time of each basic function is: 2h for recording, 1h for playback, 0.5h for fast forward, rewind, still image, search, in and out of tape, etc. 8.4 Inspection
8.4.1 The test samples shall be inspected at least once in each cycle of work, and judged according to the failure criteria specified in Article 9.1, and recorded in a timely and accurate manner; failed samples shall be replaced or repaired in a timely manner, and the time used for repair must be accurately recorded. 8.4.2 Inspection content
Image and sound quality of self-recording (TV/line input) and self-playing; a.
Operation of each function key;
Function of switches and adjustment knobs;
Function of each input and output jack (can be checked once every two cycle of work). 5
9 Failure criteria and calculation
9.1 Failure criteria
GB/T15524—1995
9.1.1 If any failure that endangers the personal safety of the user occurs, the test shall be stopped immediately and the reliability of the batch of products shall be judged as unqualified. 9.1.2 If any of the following faults occur during the test, it shall be deemed as failure: a.
Any operating key, adjustable component, switch, etc. is damaged or malfunctions: any function specified in the product manual and technical specifications fails, there is no image in the playback or there is an image but the quality is seriously deteriorated, and it cannot be viewed normally, there is no sound in the playback or there is sound but the quality is seriously deteriorated, and it cannot be listened to normally; it cannot receive radio and television signals or it can receive radio and television signals but cannot be viewed and listened normally; it cannot record or the quality of the recorded image and sound is seriously deteriorated, the display function (including light-emitting diodes and buzzers) fails, automatic protection that cannot be released under normal conditions occurs, and the panel and casing are obviously deformed and cracked; the fuse in the same part is blown twice;
Any input, output jack, connector fails 1.
The remote control receiving device fails.
Some minor defects that do not affect the use are not considered failures, but they must be recorded in detail, the reasons must be carefully analyzed, and they must be improved in future production.
9.2 Definition of failure classification
9.2.1 Associated failure: refers to the failure of the recorder caused by the failure of a certain component, device, or the entire unit itself, and also includes failures caused by failures of non-test conditions, test equipment, instruments, etc. 9.2.2 Non-associated failure: refers to the failure of the recorder caused by the failure of some related components, devices, or the entire unit directly or indirectly caused by associated failure.
9.2.3 Typical failure: refers to two or more failures of the same component, device, or entire unit caused by the same basic failure mechanism under the same or equivalent test stress.
9.3 Failure analysis
For each failure that occurs in the test, the failure time and failure phenomenon must be recorded in detail, and the failure must be carefully analyzed to determine the failure location, find out the failure cause, characteristics, and relationship with other failures, and determine the failure type. When determining failure, if necessary, it should be conducted in conjunction with relevant departments.
9.4 Calculation of failure number
9.4.1 When any failure specified in Article 9.1 occurs during the test, it is considered as a failure. When the test time exceeds the life of the wearing parts (at least 1000h), the failure caused by the wearing parts shall not be counted in the failure number. 9.4.2 When a failure occurs during the test, components shall not be replaced or repair measures shall not be taken before it is judged as a failure. Otherwise, each replacement or repair measure shall be considered as a failure. 9.4.3 When calculating the number of failures, only related failures shall be counted. When two related failures occur in the same test sample, they shall be counted twice. Non-related failures shall not be counted in the number of failures.
9.4.4 After the sample with typical failure is repaired, during the continued test (the test time should be greater than the test time of the first occurrence of the typical failure), if the same failure does not occur again and the same repair treatment is implemented on all the batches of products represented by the sample, it may not be counted in the number of failures. Otherwise, it must be counted in the number of failures.
10 Mean time between failures (MTBF) verification value one-sided interval estimation 10.1 Confidence level
This standard recommends confidence level C=1β.
10.2 Point estimate
GB/T15524—1995
The point estimate of mean time between failures (MTBF) () is the total test time T divided by the number of associated failures r. =T/r
10.3 Verification one-sided interval estimate 6
The one-sided interval estimate of mean time between failures (MTBF) 6 is For a certain confidence level C, according to the total test time T and the total number of failures 1, it is calculated as follows:
x(c,2r+2）
Where: x(C,2r+2)——quantile of x distribution. For the values of commonly used distributions, please refer to Appendix A (Supplement). (5)
GB/T15524—1995
Appendix A
One-sided interval estimate of MTBF
(Supplement)
Table A1 Comparison table of T and one-sided estimate of MTBF (C=1-β=0.90)x2
(0.90,2r+2)
20 610
r and MTBF one-sided estimated value comparison table (C=1-β=0.80)x
(0.80,2+2)
Company name:
Trademark model
Unpacking before test
Inspection
Supervisor:
GB/T15524—1995
Appendix B
Reliability test report of non-broadcast video tape recorders (supplement)
Test date:
Production batch number Number of test samples Test time t Total number of failures Production time
Failure occurrence
Test person in charge:
Additional notes:
Complete machine failure
Person filling out the form:Www.bzxZ.net
This standard is proposed by the Ministry of Electronics Industry of the People's Republic of China.
Cause of failure
Test temperature
Relative humidity
Failed part model
Component failure
Filling date:
This standard is under the jurisdiction of the National Technical Committee for Standardization of Recording Equipment. This standard was drafted by the Third Institute of the Ministry of Electronics Industry, the 784th Factory, and the 761st Factory. The main drafters of this standard are Wang Xijiang, Zhang Weixiang, He Qin, and Zhao Longgen.
Date number:
MTBF()
Failed component
Manufacturer2+2)
Company name:
Trademark model
Unpacking before test
Inspection
Supervisor:
GB/T15524—1995
Appendix B
Reliability test report of non-broadcast video tape recorders (supplement)
Test date:
Production batch number Number of test samples Test time t Total number of failures Production time
Failure occurrence
Test person in charge:
Additional notes:
Complete machine failure
Person filling out the form:
This standard is proposed by the Ministry of Electronics Industry of the People's Republic of China.
Cause of failure
Test temperature
Relative humidity
Failed part model
Component failure
Filling date:
This standard is under the jurisdiction of the National Technical Committee for Standardization of Recording Equipment. This standard was drafted by the Third Institute of the Ministry of Electronics Industry, the 784th Factory, and the 761st Factory. The main drafters of this standard are Wang Xijiang, Zhang Weixiang, He Qin, and Zhao Longgen.
Date number:
MTBF()
Failed component
Manufacturer
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