Service modes LPM type Z PANASONIC VCRs, device and repair. Scheme, description

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Service modes LPM type Z PANASONIC VCRs, device and repair. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Телевидение

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In recent years, MATSUSHITA has been producing VCRs and video players with Z-type CVLs equipped with a diagnostic system. In the article published here, the author talks about this LSM, service modes and gives recommendations for the repair of these devices.

MATSUSHITA devices with the PANASONIC trademark are well known in Russia and other countries of the former Soviet Union. The equipment of this company is also found with the trademarks NATIONAL, QUASAR. Recently, stereophonic video recorders from Europe (used) with "stuffing" from MATSUSHITA under the trademarks BLAUPUNKT, GRUNDIG, etc. have also been brought to us.

Until the mid-90s, PANASONIC devices used a tape drive mechanism (LPM) of type G (modifications G-REV, G-II). From the middle of the decade, the company began to use mainly the K mechanism in SUPER DRIVE models. It is also used in modern high-end S-VHS video recorders, for example, the NV-HS960. At the end of the 20th century, the Z mechanism appeared, characterized by simplicity and a relatively small number of parts used. All modern models of VCRs and video players of the company are equipped with these LSMs, including the very popular NV-FJ8AM stereo video player, in 2003 - a modification of the NV-FJ8AM MCP.

Obviously, the Z mechanism is the latest development of the company, designed for analogue video recorders. Fumio Otsuba, CEO of MATSUSHITA ELEKTRIC INDUSTRIAL, recently stated, "We are putting an end to the VHS market that we have developed, and today we are taking the first step towards creating a DVD recorder market." The company will gradually curtail the production of VCRs and switch to the production of DVD recorders. Their advertising has already appeared on our television.

The appearance of the Z mechanism of PANASONIC VCRs is shown in fig. 1 and 2 using the PANASONIC - NV-HD640EE VCR as an example. The numbers in Fig. 1 are marked (their nomenclature designation is indicated in brackets): 1 - belt tension regulator assembly (VXL2793); 2 - software bar (VML3166); 3 - feed guide rack assembly (VXA6040); 4 - prism of the central LED (VMD2738); 5 -- gear rack for the drive of the tape filling units (VXL2447); 6 - node of the receiving guide rack (VXA5854); 7 - BVG; 8 - refueling engine assembly (VEM0604); 9 - "worm" of the refueling engine; 10 - program gear (VDG1220); 11 - pressure roller lever (VXL2785); 12 - cassette loading rail drive lever (VML3165); 13 - lever guide rack P5 (VXL2677); 14 - program bar drive lever (VML3167).

Service modes LPM type Z PANASONIC VCRs, device and repair

The numbers in Fig. 2 are marked: 1 - mode change lever B (VML3177); 2 - winding and rewinding unit (VXP1850); 3 - belt (VDV0372); 4 - brake lever (VXZ0430); 5 - receiving rack drive unit (VXL2670); 6 - feed rack drive unit (VXL2672).

Service modes LPM type Z PANASONIC VCRs, device and repair

Z-mechanism VCRs are equipped with a self-diagnostic fault system that allows you to identify some defective components or devices. If a malfunction occurs, the system provides an indication of its code on the display in the form of a Latin letter and two digits. The fault codes indicated by the self-diagnosis system are presented in Table. 1, which is taken from service manuals with a typical translation into Russian.

Service modes LPM type Z PANASONIC VCRs, device and repair

It should be noted that the number of possible malfunctions that actually occur in practice, of course, is much larger and the practical benefit of such a system during repairs is relatively small. In addition, the recommendations indicated in the table are rather difficult to use, since it is not always clear how to implement them. Therefore, it is advisable to specify and supplement them on the example of NV-SD570, NV-HD670 and NV-FJ620 video recorders (model 2001, 2002).

Code U10. The humidity sensor is not installed in all models of VCRs. In those devices where it is, when the code U10 appears, the voltage is measured at the corresponding output of the LSI control system, for example, at pin 1 of the MN675567VRWD microprocessor. This LSI is used in PANASONIC - NV-SD570AM / EU, PANASONIC - HD670BD video recorders, however, the humidity sensor is placed only in the NV-HD670BD model. In 570 models, pin 1 of the microprocessor is connected to a common wire. If it is impossible to replace a faulty humidity sensor, the corresponding output of the microprocessor can also be connected to a common wire.

Code U11. In addition to what is indicated in the table, the reasons for the appearance of such a code may be the destruction or wear of the video heads, the violation of the contacts of the connectors connecting the preamplifier to the main board of the device, the malfunction of the preamplifier itself and the image channel.

Code H01. First of all, you need to check the presence of voltage UNREG 14 V (+14 V) at the output of the power supply. For the 570s and 670s, this is pin 15 of the P1103 connector. It is also necessary to check the integrity of the L1121 inductor and the D1121 diode in the power supply (in the NV-FJ620 model - positions L1250, D1250, D1251). The reasons for the failure of the BVG drive motors are often malfunctions of the Hall sensors. Their names are not in the specifications of the service manuals. The company recommends replacing the entire motor stator (motor type - VEK8840). However, suitable sensors are available on radio markets.

Often, malfunctions appear due to broken contacts in the connectors and the appearance of microcracks in the printed conductors, so it is necessary to check ("ring") all the circuits connecting the BVG motor with the AN3811NK (IC2501) electric drive microcircuit. Failures of the microcircuits themselves are not excluded, however, in practice this occurs very rarely, the microcircuits of the MATSUSHITA BVG electric drive are highly reliable.

Codes H02, F05. The straightening of the tape, i.e. winding it into the cassette, occurs when the VCR is turned off with the POWER button. Moreover, in the process of spreading, the guide racks go half way to the initial position (it is shown in Fig. 1), and then return to the straightening position (in this case, the tape covers the BVG), after which the device switches to standby mode. When implementing the EJECT mode, the straightening process is brought to an end (the rack guides take the position as in Fig. 1), and then the cassette is ejected.

Lack of winding of the tape by the feed spool during straightening can have both "electrical" and "mechanical" reasons (a symptom of a malfunction is the ejection of a cassette with an unthreaded tape loop). "Electrical" refers to malfunctions in the drive motor drive system, auto-adjustment and control systems of the VCR, "mechanical" - breakdowns and wear of parts and assemblies of the LPM, as well as improper assembly of the mechanism during repair. Because Z-mechanism VCRs do not have access to the bottom of the Z-mechanism during operation, it is not possible to see what is happening when the tape is unfolded.

You can check the rotation of the drive motor indirectly by connecting an oscilloscope to the motor speed sensor circuit (usually pin 4 of the P2001 or P2002 connector on the NV-FJ620). The amplitude of the sinusoidal signal coming from this sensor is a few millivolts, so it is more convenient to observe the sensor signal amplified to 0,6 V at pin 84 of the MN675567VRWD microprocessor (TL2015 test point in models 570s and 670s) or at pin 86 of the C2CBHF000199 microprocessor in NV-FJ620 machines (same reference point).

The most probable "mechanical" reasons for the lack of tape winding can be called slippage of the drive belt 3 and wear of the winding unit 2 (Fig. 2). The check proposed in the table for the presence of pulses from the bobbin rotation sensors in this case has no practical meaning, since if the tape is not reeled up, then obviously there will be no pulses.

Codes F03, F04, F06. The load motor control unit is part of the AN3844SB drive motor drive chip located on its stator board. The connection of the load motor with the main board is provided through a two-pin P6002 plug-in connector (in the NV-FJ620 model - P2001), the LOAD M (+), LOAD M (-) circuits, pins 9 and 8 of the P2001 connector of the leading motor (in the 620th model, the connector P2002) and pins 19, 21 of the AN3844SB electric drive chip. Control signals to this microcircuit are received via the LOAD and UNLOAD circuits from pins 70 and 72 of the MN675567VRWD microprocessor (from pins 87 and 86 of the C2CBHF000199 processor). Loading and unloading modes are implemented at a high level (+5 V) in the corresponding circuits.

To check the phasing of the mechanism, you need a service manual (experienced craftsmen, of course, do without it). The assembly section is quite voluminous and it is not possible to reproduce it in the magazine. The mode switch, in other words, the software switch, is installed on the main board and it is problematic to check it. It is only necessary to clean its contacts in conventional ways.

Code F09. It is also not possible to test the microprocessor in practice. The information exchange bus with the timer chip consists of three circuits connecting pins 63 (TEST TALK), 64 (TEST LSN), 65 (TEST CLK) of the MN675567VRWD microprocessor with pins 13, 14, 15 of the BIS M355000FP timer. The range of pulses in all circuits is about 5 V.

When the letters H or F appear, the VCR switches to standby mode. When the power is turned on again, the display returns to the operating mode. The fault code (two digits) is memorized by the EEPROM and retained even when the power is turned off. It can be displayed in service mode. In the event of subsequent faults, the code of the last one will be stored in the memory. To erase the code, you must simultaneously press the FF, REW, EJECT buttons and hold them for 5 s.

For more accurate fault localization, PANASONIC VCRs have a service mode both in models with the K mechanism and in models with the Z mechanism (this does not apply to video players, since they do not have displays on the front panels). The technology for carrying out work in service modes for various models of video recorders is generally not the same. However, the methods of entering the service mode and the procedure for working with it are the same for entire lines of VCR models, and they can completely or partially coincide with devices with K and Z mechanisms.

Entering the service mode for most models occurs by simultaneously pressing the FF, EJECT buttons and holding them for more than 5 s. In some devices, you need to simultaneously press the FF, REW, EJECT buttons. In addition, in most models with the K mechanism, the service mode can be entered when the control points TP GND, TP SERV are closed.

Let's consider one of the options for working in the service mode from the maintenance manual for VCRs with the Z mechanism. code. The latter most often corresponds to one of the fault codes listed in Table. 1: H01 - 01, H02 - 02, F03 - 03, F04 - 04, F05 - 05, F06 - 06, F09 - 09. In the table. 2 lists service data and modes with comments that can be used to judge the location of faulty nodes (table from service manuals).

(click to enlarge)

Sequential selection of service modes occurs when you press the EJECT button while holding down the FF button.

In service mode 1, the operation of the phototransistors and the central infrared LED of the cassette receiver is checked. Code 00 indicates a malfunction of the central LED or its power circuit. The supply voltage to the D6001 LED in the 570s, 670s models is supplied through the R6012 resistor. The same code will be displayed if both phototransistors fail. Code 01 indicates the absence of an identification signal from the left phototransistor, and code 02 - from the right one. Since the phototransistors are connected directly to the pins of the microprocessor, the presence of such codes indicates a malfunction of the phototransistors themselves, although in repair practice there are cases when the cause of the malfunction is severe contamination of the surfaces of the LED and, although less often, phototransistors. Code 03 indicates that the cassette presence identification system is working.

Service mode 2 is used to check the operation of the mechanism in various modes listed in Table. 2. They do not require comments, except for STOP modes. They are sold in standby mode with a loaded cassette and tape. The operating modes STOP and PAUSE are obtained without retracting the roller from the tone shaft.

In service mode 3, the program switch is checked. During the change of modes of operation of the LPM, it is not required to observe the change in codes. The serviceability of the program switch and the correct assembly (that is, in other words, phasing) of the mechanism must be indicated by code 00 after each operation is performed.

Service mode 4 provides a test of the control buttons on the front panel of the device and the remote control. Service data appears when commands are received from the buttons on the microprocessor. The number of codes is quite large, but listing their meanings is hardly appropriate. The correct execution of commands is verified by changing the values of the codes when the buttons are pressed.

In service mode 5, the electric drive of the drive shaft is checked. Some problems with it have already been mentioned above, as well as problems with the BVG electric drive detected in service mode 6.

The described procedure in the service mode applies to a large number of models of VCRs with Z and K mechanisms released before about 1998. In later models of devices with the Z mechanism, the procedure for operating in the service mode may be different. Let's briefly describe it using the NV-HD640EE model (1999-2001) as an example.

To enter the service mode, keep the FF, EJECT buttons pressed simultaneously for more than 5 s, and switch modes as indicated above. In service mode 1, the displayed codes are the same as those previously discussed. In mode 2, the display shows codes: cassette unloaded - 2 00 00, cassette loaded - 2 04 90, playback, recording, pause, look ahead, stop 3 - 2 04 80, reverse view mode - 2 02 AO, fast forward - 2 06 90, rewind - 2 06 AO, stop - 2 03 AO. In mode 3, the established value of the code is 3 01 0-. In mode 4, when any buttons are pressed, code 4---- is displayed, and in mode 5 - 5 ----. In mode 6: play - 6 10 91, stop 3 - 6 n1 11, look forward - 6 10 91, look back - 6 10 9-, fast forward - 6 n- 91, rewind - 6 n- 99.

In order to exit the service mode, you must disconnect the VCR from the network.

In VCRs with a Z mechanism, measures have been taken to ensure that a cassette jammed in a defective unit can be unloaded. In many models with the K mechanism, this is problematic.

There are two ways to remove the cassette from a Z-type CVL machine. The first way - after setting the service mode 7, press the STOP button. If the cassette is not removed, a more complicated second method is used, associated with the removal of the upper cover of the apparatus. First, manually rotate the "worm" 9 (see Fig. 1) so that the program gear 10 rotates clockwise, and until the guide racks 3, 6 take their original position (as in Fig. 1). Then, through a specially provided hole in the bottom of the case, the flywheel of the driving motor is rotated with a screwdriver until the remaining loop of the tape is refueled into the cassette. And finally, the "worm" 9 is rotated again until the cassette is removed.

The Z mechanism is quite reliable. Of the typical malfunctions, it should be noted defects associated with contamination or wear of the S6002 (VSS0520) program switch, which often leads to the self-diagnosis system triggering with the F03 code displayed. Troubleshoot by cleaning or replacing the switch. However, most of the faults can be called "uncharacteristic". It is not easy to diagnose them. For successful work, it is necessary to have a good understanding of the principles of operation of the components and systems of specific models of VCRs and to have at your disposal technical documentation. At present, in many cases this is a solvable problem, since diagrams and service manuals for many types of equipment are available both in paper and in electronic form (CD-ROM, Internet).

Author: Yu.Petropavlovsky, Taganrog

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