This standard specifies the technical requirements, test methods, inspection rules and marking, packaging, transportation and storage requirements for the erasable heads of video tape recorders. This standard applies to the erasable heads of VHS video tape recorders. GB/T 15858-1995 General technical requirements for the erasable heads of VHS video tape recorders GB/T15858-1995 Standard download decompression password: www.bzxz.net

ICS33.160.40
National Standard of the People's Republic of China
GB/T15858—1995
General specification for full trackerasing heads of VHS video tape recorders Issued on 1995-12-22
State Administration of Technical Supervision
Implementation on 1996-08-01
National Standard of the People's Republic of China
General specification for full trackerasing heads of VHS video tape recorders1 Subject content and scope of application
GB/T15858—1995
This standard specifies the technical requirements, test methods, inspection rules and marking, packaging, transportation and storage requirements for full trackerasing heads of VHS video tape recorders. This standard applies to full trackerasing heads for VHS video tape recorders. 2 Reference standards
Packaging storage and transportation pictorial marking
GB2828
3 Batch inspection counting sampling procedures and sampling tables (applicable to continuous batch inspection) GB2829
GB4013
Periodic inspection counting sampling procedures and sampling tables (applicable to the inspection of production process stability) Audio and video terminology
VHS type 12.65mm spiral scanning cassette video system GB7399
GB/T14306VHS cassette video tape
3 Terminology
The terms used in this standard comply with the provisions of GB4013. 4 Technical requirements
4.1 Conditions of use
Ambient temperature: -5~+55℃,
Relative humidity: 40%~80%;
Atmospheric pressure: 86~106kPa.
4.2 Appearance requirements
4.2.1 The contact part between the head and the tape should be smooth, without pinholes and scratches. The roughness of the working surface of the head should meet the requirements of Figure 1. 4.2.2 The appearance of the head should be smooth and flat, without obvious mechanical damage, deformation, cracks, and burrs. The potting glue should be full and moderate, without obvious bubbles. The lead pins should be straight and firm, with good solderability.
4.2.3 The marking should be clear and firm.
Approved by the State Administration of Technical Supervision on December 22, 1995 and implemented on August 1, 1996
4.3 Related dimensions
—1995
GB/T15858-
The relevant dimensions of the head should meet the requirements of Figure 2 and Table 1. C
款±0.3
4.4 Basic parameters
The basic parameters of the full degaussing head shall comply with the provisions of Table 2. Table 2
Basic parameters
Class A impedance
Rated value
Degaussing current
≤200
Measurement conditions
10mA,70kHz
Class B impedance
Degaussing effect
Basic parameters
4.5 Environmental adaptability requirements
Rated value
Degaussing current
GB/T15858—1995
Continued Table 2
《150
Measurement conditions
10mA,70kHz
70 kHz
Degaussing current×120%
4.5.1 When the magnetic head is left at 70℃ for 48h, the change of its impedance after recovery shall not exceed ±15%, and the degaussing effect shall comply with the provisions of Table 2.
4.5.2 When the magnetic head is left at 40℃ and relative humidity of 93% for 48h, its appearance after recovery shall comply with the requirements of Article 4.2, the change of its impedance shall not exceed ±15%, and the degaussing effect shall comply with the provisions of Table 2. 4.5.3 When the magnetic head is left at -25℃ for 24h, the change of its impedance after recovery shall not exceed ±15%, and the degaussing effect shall comply with the provisions of Table 2.
4.5.4 When the magnetic head is subjected to the temperature test of 70～-25℃ for five cycles as shown in Figure 3, the change of its impedance after recovery shall not exceed ±15%, and the degaussing effect shall comply with the provisions of Table 2. TC
f,rair
After the vibration test is carried out according to the provisions of Table 3, the change of the impedance of the magnetic head shall not exceed ±15%, and the demagnetization effect shall meet the requirements of 4.5.5
in Table 2.
Frequency range
10~30~10
30~55~30
Displacement amplitudebZxz.net
Number of sweep cycles in each axial direction
Vibrate in three mutually perpendicular axial directions in sequence according to the working position
4.5.6After the magnetic head is subjected to 1000 impact tests with an acceleration of 250m/s2 and a pulse duration of 6ms, the change of its impedance shall not exceed ±15%, and the demagnetization effect shall meet the requirements of Table 2. 4.5.7 After the small packaged magnetic head is subjected to a drop test at a height of 1m, twice on the front, back and side surfaces, the change in its impedance should not exceed ±15%, and the demagnetization effect should comply with the provisions of Table 2. 4.6 Life requirements
The life of the magnetic head should be greater than or equal to 2000h.
5 Test method
5.1 Measurement conditions
Center temperature: 15~35℃,
Relative humidity: 45%~75%,
Atmospheric pressure: 86~106kPa.
5.2 Test equipment
5.2.1 Measurement video recorder
Belt speed: 23.39mm/s, tolerance 0.2%;
Wow and wow rate: <0.25%,
Other performance should comply with the requirements of GB7399. 5.2.2 Test tape
GB/T15858—1995
a: The test tape shall comply with the provisions of the superior tape of GB/T14306; b. Audio playback azimuth calibration tape: 10kHz, -10dB. 5.2.3 Arm length ratio meter
Magnification: 30;
Accuracy: 0.01mm.
5.2.4 Interference microscope
Measurement of surface profile micro-roughness range: 1~0.03μm. 5.2.5 Audio signal generator
Frequency range: 20Hz~20kHz
Amplitude error: ±0.5dB,
Frequency error: ±2%, ±1Hz;
Harmonic distortion: 0.1%;
Output impedance: <6002.
5.2.6 Wideband signal generator
Frequency range: 20Hz~200kHz
Amplitude error: ±1dB;
Frequency error: 2%;
Harmonic distortion: 0.5%.
5.2.7 Measuring amplifier
Maximum gain: ≥60dB
Measuring range: 10μV~30mV (full scale); Frequency response: 20Hz~20kHz, 0.5dB; Harmonic distortion: 0.2% (250Hz~2kHz); 0.5% (other frequencies)
Signal-to-noise ratio: ≥60dB (when input voltage is 1mV and source impedance is well-shielded 600Ω); Input impedance: >500kΩ;
Input capacitance: <30pF.
5.2.8 Bandpass filter
Center frequency: 125Hz, 1kHz;
Selectivity: attenuation from the center frequency to 1 octave is more than 30dB, 4
GB/T15858—1995
Signal-to-noise ratio: ≥60dB (input voltage is 1mV). 5.2.9 Millivoltmeter
Measurement range: 0.3mV~100V (full scale); frequency response: 10Hz~200kHz, 5%,
Measurement error: 3%;
Input resistance: >10MQ;
Input capacitance: <30pF.
5.2.10 Color TV signal generator
Output signal amplitude: 01.0V (peak-to-peak) adjustable: Output impedance: 752
TV format: PAL;
Signal content: color bars or other signals.
5.2.11 Image monitor
Horizontal resolution: greater than 350 lines.
5.2.12 Measuring thermometer (point contact)
Temperature range: 0~100℃.
5.3 Appearance and related dimension inspection
5.3.1. Check the appearance of the magnetic head by visual inspection or using a low-power magnifying glass. 5.3.2. Measure the working surface of the magnetic head with an interference microscope or a roughness sample block. 5.3.3. Test the lead pins by visual inspection or pulling with tweezers. Its solderability is tested by the following soldering method: When the soldering iron temperature rises to 350℃, use a 3.8mm rosin core solder wire to contact the lead end of the magnetic head with the lead for less than 3s, and it should be able to be welded firmly.
5.3.4. Use an arm length comparison meter to measure the relevant dimensions of the magnetic head. 5.4 Basic parameter measurement
5.4.1 Impedance
a. The measurement block diagram is shown in Figure 4;
Full demagnetization head
Yearly quality 1
Trademark source
A current of 70kHz and 10mA is passed through the magnetic head, and the reading U2 of the millivolt meter 2 is divided by 10mA to obtain the full demagnetization head impedance Z: b.
5.4.2 Temperature rise
(1)
After the measured magnetic head is passed with a specified current according to its impedance for 1h, the temperature of the arc surface of the working gap is measured with a thermometer. The temperature difference before and after power-on should meet the requirements of Table 2.
5.4.3 Demagnetization effect
a. The measurement block diagram is shown in Figure 5,
GB/T15858—1995
b. Select the best bias current: record the rated recording current of 6.3kHz and the bias current on the reference tape. When the bias current increases, the output level shown in Figure 6 is obtained. The bias current that drops 5dB after reaching the maximum output is the best bias current; c.
Record the tape at the test frequency with the reference tape to reach the saturation level; give the demagnetization head under test a specified frequency and current to partially demagnetize the above-mentioned tape recording signal; measure the difference in the playback output level between the undemagnetized part and the demagnetized part through the bandpass filter, expressed in decibels. oo
Just amplifier
no filter resistor
brother machine
now
live
monitor
bandpass filter
In the figure: the filtering effect of L1 and Ci should be greater than 30dB, R should be able to make the recording current constant. P: Output signal generator, bias current, 5.5 Environmental test method 5.5.1 Test sequence and test items a. The environmental test is carried out in series, and the test sequence is in the order of this standard, 6 GB/T15858-1995 b. When the production batch is large, it is allowed to carry out environmental tests according to the parallel test scheme specified in Appendix A (Supplement). When there is a dispute, arbitration shall be made according to the series test; c. The test items after each environmental test shall be in accordance with the corresponding provisions of Article 4.5. 5.5.2 High temperature storage test
Put the sample under test in a high temperature box, and gradually raise the box temperature to 70±2°C at an average rate of 0.7~1°C/min. After the sample reaches temperature stability, leave it for 48 hours, then lower the box temperature to normal test atmospheric conditions at an average rate of 0.7~1°C/min. After recovering for 2 hours, test according to the provisions of Article 4.5.1. 5.5.3 Constant humidity test
Put the sample in a humidity box, and gradually raise the box temperature to 40±2°C. After the sample reaches temperature stability, humidify it to a relative humidity of 93% and leave it for 48 hours. Then reduce the relative humidity in the test box to (75±3)% within 0.5 hours, and then adjust the temperature and humidity of the test box to normal test atmospheric conditions within 0.5 hours. After recovering for 2 hours, test according to the provisions of Article 4.5.2. 5.5.4 Low temperature storage test
Put the test sample in a low temperature box, and reduce the box temperature to -25±3°C at an average rate of 0.7~1°C/min. After the sample reaches temperature stability, leave it for 24 hours. Then raise the box temperature to normal test atmospheric conditions at an average rate of 0.7~1°C/min. After recovering for 2 hours, test it according to the provisions of Article 4.5.3.
5.5.5 Temperature cycle test
Put the test sample in a high and low temperature box and perform a temperature cycle test according to the requirements of Figure 3. Repeat five times. After the sample recovers for 2 hours under normal test atmospheric conditions, test it according to the provisions of Article 4.5.4. 5.5.6 Vibration test
a. Fasten the test sample on the test bench in the working position and place the test frame in the center of the platform; b. Perform sweep frequency vibration of 10~30~10Hz and 30~55~30Hz according to the provisions of Table 3; at a sweep frequency rate of 1 octave/min, the time for a cyclic sweep frequency (f1~f2~f1) in a certain frequency range is: Where: T—
-time, min,
f1——lower limit frequency of sweep frequency, Hz;
f——upper limit frequency of sweep frequency, Hz.
T-6.6445（)
c. After the test, perform the test in accordance with the provisions of Article 4.5.5. 5.5.7 Impact test
According to the requirements of Article 4.5.6, six samples are tested separately in the three mutually perpendicular axis directions of the test sample, so that each sample is subjected to 1000 impact tests in one direction, and then tested in accordance with the provisions of Article 4.5.6. 5.5.8 Drop test
Make the test samples in the factory small packaging box evenly distributed, and fill the other empty spaces with non-test samples. Lift the test samples to the specified height in turn according to the front, back and side of the packaging box, and the test surface is parallel to the ground. While ensuring that the initial velocity in each direction is zero, suddenly release the test sample to make it fall freely on the flat cement floor, and repeat the fall twice on each side. After the test, test it according to the provisions of Article 4.5.7. 5.6 Life test method
The head life test method is to be determined.
6 Inspection rules
6.1 Inspection classification
Product inspection is divided into finalization inspection, delivery inspection and routine inspection. 6.2 Finalization inspection
Product finalization inspection should be carried out when the design is finalized and the production is finalized. 7
6.2.1 Inspection items
GB/T15858—1995
Type inspection shall be carried out for each item specified in 4.2 to 4.6. 6.2.2 Sample extraction
The batch of finalized production shall be no less than 10,000, and the number of samples shall be greater than 100; the number of samples for design finalization may be less than the number specified in this standard. Samples shall be randomly selected from the finalized batch of products, and the number of samples for each group of tests is shown in Table 4. Table 4
6.2.3 Processing of inspection results
Appearance and related dimensions
Basic parameters
Environmental test
Life test
If all the tests of each group of samples are qualified, the type inspection is judged to be qualified. Number of samples
For items that fail in the finalization inspection, the reasons shall be found out, and after taking improvement measures, the item shall be re-inspected until it passes. 6.3 Acceptance inspection
After the production is finalized and the production is stable, the continuous batches of products that have been qualified by the production unit shall be subject to acceptance inspection. 6.3.1 Inspection items
The acceptance inspection items include the items specified in Article 4.24.4 (weldability and temperature rise are not tested). If any of them does not meet the requirements, it will be judged as a defective product.
6.3.2 Qualification determination
The acceptance inspection adopts a single sampling plan. The inspection level and qualified quality level are in accordance with the provisions of Table 5. Table 5
Inspection level
6.3.3 Product submission
Qualified quality level (AQL)
The size of the product submission batch is determined by the manufacturer. Generally, the same model of products produced in the same batch (when the quality of materials and parts and the process flow remain unchanged) should be submitted as a batch. 6.3.4 Sample extraction
Based on the size of the batch to be inspected, the sample size shall be determined according to the inspection level specified in Table 5, and samples shall be randomly selected from the batch. 6.3.5 Processing of inspection results
When the sample for delivery inspection meets the requirements of Article 6.3.2, it shall be judged as qualified for the submitted batch, otherwise it shall be unqualified: the products judged as unqualified shall be repaired or sorted according to the unqualified items, and after the unqualified products are removed, they may be submitted for inspection again. b.
6.3.6 Strict and relaxed inspection
a. The delivery inspection specified in this standard generally adopts normal inspection. When the normal inspection conditions are not met, strict inspection shall be adopted. When the relaxed inspection conditions are met, relaxed inspection may also be adopted; b. The transfer rules of strict and relaxed inspection shall be implemented in accordance with the provisions of GB2828; the sampling plan, inspection level and qualified quality level of strict and relaxed inspection shall be consistent with normal inspection. C
6.4 Routine inspection
Routine inspection is conducted by the quality inspection department of the manufacturer (or with the participation of the user), and is conducted every six months for continuously produced products. Routine inspection should be conducted when there is a change in the structure, material or manufacturing process of the magnetic head. 6.4.1 Inspection Items
GB/T15858—1995
Routine inspections shall be conducted for each item specified in Articles 4.2 to 4.5. 6.4.2 Qualification Judgment
Routine inspections shall adopt a two-step sampling plan, and the discrimination level and unqualified quality level (RQL) shall be in accordance with the provisions of Table 6. Table 6
Discrimination Level
6.4.3 Sample Sampling
Sampling Plan
Judgment Array
The samples submitted for inspection shall be randomly selected from the products produced and put into storage during the same period, with no less than six samples each time. For the sampled samples, if it is found to be unqualified, it shall be replaced by a randomly selected qualified product. At the same time, analyze the unqualified products, find out the reasons, and record them in the routine inspection report, but they are not used as the basis for judging whether the routine inspection is qualified or not; b. According to the discrimination level, ROL and judgment array specified in Table 6, according to the sample size specified in GB2829, draw them separately (including the samples of secondary sampling), and draw them all at once. 6.4.4 Processing of inspection results
a. If the test samples of routine inspection meet the requirements of Articles 4.2 to 4.5, they are qualified products. If the number of qualified products meets the requirements of Table 6, the routine inspection is judged to be qualified, otherwise it is unqualified; b. If the routine inspection is unqualified, the products produced in this period are judged to be unqualified products. Unqualified products shall not be shipped and production shall be stopped. Production can only be resumed after the reasons are found and effective measures are taken. The first batch of products after the resumption of production must be re-inspected for routine inspection, and production can only be continued after the inspection is qualified.
Products judged to be unqualified must be repaired or screened, and only after passing the routine inspection can the product be considered qualified; c. For products produced during this period that have failed routine inspection but have been shipped, the manufacturer shall bear the quality responsibility. The specific handling method shall be negotiated and resolved by the supply and demand parties.
d. Products that have undergone routine inspection shall not be shipped as genuine products. 7 Marking, packaging, transportation, purchase and storage
7.1 Marking
The model and trademark shall be marked on the finished magnetic heads. 7.2 Packaging
a. The inner packaging of the magnetic heads shall ensure that the working surface of the magnetic heads is not scratched and the magnetic heads do not collide with each other; b. The markings on the packaging boxes shall comply with the provisions of GB191. 7.3 Transportation
The packaged magnetic heads can be transported by normal land, sea and air transportation. During transportation, they should be avoided from direct rain and snow or exposure to the sun. 7.4 Storage
The packaged magnetic heads should be stored in a warehouse with a temperature of -15~40℃, a relative humidity of no more than 80%, and no acidic or other harmful gases around. The storage period shall not exceed six months, otherwise, the product shall be inspected again before leaving the factory, and can only leave the factory after passing the inspection. A1
GB/T15858
—1995
Appendix A
Parallel environmental test
(Supplement)
The parallel environmental test program shall be in accordance with the provisions of Table A1. Table A1
Test items
Temperature cycle test
High temperature storage test
Constant damp heat test
Low temperature storage test
Vibration test
Impact test
Note: p——cycle, month;
n——number of samples, piece;
c——number of unqualified products.
Additional instructions:
Test conditions
70～-25℃, five cycles
70℃, 72h
40℃, 93%, 96h
—25℃, 72h
This standard was proposed by the Ministry of Machinery and Electronics Industry of the People's Republic of China. This standard is under the jurisdiction of the Electronic Technology Standardization Institute of the Ministry of Machinery and Electronics Industry. This standard was drafted by the Third Institute of the Ministry of Machinery and Electronics and Chengdu Radio Factory No. 7. P
The main drafters of this standard are Song Hua, Liu Wenxuan, Liu Guizhi, Zhou Dan, Huang Xinqun
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