The "Z-SUS" board of a plasma television receiver is used to form supply voltages on the horizontal addressing scan bars and the corresponding electrodes. The same board with the index "Y" is intended, in contrast to the first, to supply voltage to the scan - bars of vertical distribution.
Necessary clarification: Scan bars are understood as combinations of scan controllers that are "responsible" for the formation of columns and rows of images on the TV screen.
A common power supply is used to supply power to all of its modules. At the same time, the signal processed by the SSB board passes through the modules "Z" and "Y" and transfers it to the scan controllers and further.
The inoperability of modules "Z" or "Y" is most often evidenced by the following characteristic manifestations:
- The display screen suddenly "flashes", and then (immediately or after a shutter speed of 3-5 seconds) - goes out.
- The following violations in the formation of the video signal are observed on it:
- - completely darkened field;
- - flickering ripples, similar to the one that occurs with a weak signal;
- - vertical (horizontal) lines of various colors and widths;
- - oval spots.
In the first case, the cause of the malfunction may be a malfunction of the scanning driver, the motherboard ("MAIN-board"), or the general power supply. In this situation, experts advise to first visually inspect the boards, and then replace the detected "suspicious" parts (capacitors, thyristors, diodes or planar microcircuits). If you did not find anything suspicious on them, the malfunction should be looked for in the "Z-SUS" or "Y-SUS" modules themselves.
With each of the manifestations characteristic of the second type of malfunction, we will try to understand in more detail.
- Dark screen with sound
Such a malfunction indicates that on the "Z-SUS" board the fuse in the "Vs" signal transmission line has most likely "blown", and in the "Y-SUS" module the voltage of 15 Volts has slightly decreased (to about 12 Volts). In the event that the fuse is intact, you should proceed to the examination of the "Z-SUS" module itself, or rather, its hybrid microcircuit. Very often, destroyed triodes Q8, Q9, Q10, Q11 and resistors R3, R4, R9, R10 are found, which are easily replaced with new ones. To do this, you need to scrape off the remnants with a sharp blade and process the landing sites with fine sandpaper, after which they should be well tinned.
It is advisable to change case Q8, Q9, Q10, Q11 for IGBT transistors IRGS4065PBF, which have approximately the same landing size and corresponding characteristics. Instead of burnt out elements R3, R4, R9, R10, you can install SMD resistors with a rating of 5.1 Ohm.
After completing all these operations and turning on the TV, the screen should light up, but the image may be covered with ripples, characteristic of a weak TV signal. At the same time, in the upper part of the display, there is an illumination in the form of a strip approximately 5 cm wide.
In this case, we should reopen the already familiar "hybrid" and examine the diodes D22, D23. which may be in a partially punctured state. It is recommended to install new diodes of the R3000 PBF type instead.
- The presence of characteristic ripples
Another malfunction, consisting in the appearance of ripples on the screen, is also explained by the failure of the elements of the hybrid microcircuit on the Z-SUS board (due to a low voltage level coming from the 15 Volt converter to Y-SUS).
In this case, in the "hybrid", most likely, transistors Q12-Q16 or resistors R3, R4, R10 (5.6 Ohm) and diodes D22, D23 are faulty. All these parts are replaced in exactly the same way as described in the previous example. If the malfunction persists, a complete replacement of electrolytic capacitors located in the "Y-SUS" module can help you. After replacing them, it will be necessary to adjust the position of the upper (Set_up) and lower (Set_down) edges of the image, which will allow you to completely solve the problem with its violations.
Please note: All parts for replacing faulty frameless transistors, electrolytic capacitors and diodes can be removed from an old non-working "Y-SUS" 42V7 panel, for example.
The image shows vertical (horizontal) lines of different colors and widths
The indicated malfunction often manifests itself in the form of one narrow vertical line, which usually appears in the middle of the screen or from one of its edges. The color of this strip can be arbitrary. The cause of the problem must be looked for in the main board ("MAIN-board") or in the logic module. The best solution in this case is to replace both boards with known good modules.
- If one or more vertical wide stripes of different thickness and color are found, the problem should also be looked for in the motherboard (main) board or in the same logical module.
If an image appears on the screen in the form of one or two horizontal lines of small thickness, clearly distinguishable against a dark or light background, the place of the malfunction should be sought in the same main (motherboard) board. At the same time, in a situation where such lines are observed across the line and in full screen, repair or complete replacement of the X-SUS and Y-SUS modules will help to solve the problem.
In a situation where one horizontal dark stripe is observed, occupying almost half of the screen, the source of the problem is the same as in the previous case.
Likewise, troubleshooting occurs when oval spots are found on the Plasma Display.