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<\/a>To hold the disc in place whilst testing it is a good idea to use a magnetic spindle lock as shown by the service manual (\u2018Disc clamping piece\u2019 4822 532 60775), however this part is no longer available.\u00a0 Instead there is a STL 3D model of an alternative holder available\u00a0here<\/a> that can be 3D printed.<\/p>\n Since the upper-deck of the player is removed during this procedure you will also need a \u2018front loader simulation\u2019 part (4822 267 50706).\u00a0 This causes the player electronics to detect the disc tray is closed.\u00a0 This can be made by simply placing a 2.54mm jumper onto the drive processing module R between pins 3 and 4 of the R3 connector on the top-right of module R.<\/p>\n You will also require a 2-channel oscilloscope to make the required measurements and some small flat screwdrivers to adjust the various potentiometers and variable induction coils on the RGB module.\u00a0 A collection of small test probe clamps and attachments also assists with connecting the scope to the various test pins.<\/p>\n The following picture shows the component-side of the RGB module and the location of the various adjustment points:<\/p>\n Note that this is a modification level 9 board and, unlike the board in the service manual, it has two additional potentiometers marked R89 and R90 that are not present in the documentation.<\/p>\n R89 is connected to pin 16 of 7203 and controls the saturation of the picture (i.e. the overall amplitude of the red, green and blue signals).\u00a0 R90 is connected to pin 19 of 7203 and controls the contrast of the picture (i.e. the peak-to-peak gain of the video signal).\u00a0 If these extra potentiometers have not been adjusted it\u2019s probably safe to leave them as-is.\u00a0 Otherwise adjust both to their centre-points (you can do this by simply looking at the position of the potentiometer).\u00a0 Since both affect the overall output, it\u2019s better to do this first before any other adjustments.<\/p>\n All the measurements required for the calibration are video signals coming from various points of the module.\u00a0 To reproduce the traces shown in the service manual it is necessary to trigger the oscilloscope based on the video \u2018lines\u2019 (this is what the service manual refers to as \u2018line triggered\u2019).\u00a0 To do this connect the first channel of the oscilloscope to 1B1 (pin 1 of connector B1) and earth the probe on 2B1.<\/p>\n Note that the service manual is a little confusing around this signal.\u00a0 For the RGB module B the CVBS input signal example is shown with a peak-to-peak of 2Vs and a base of 2.8Vs, however this signal is generated by module C and in the module C documentation the output to the CVBS signal is shown as being 2.6V peak-to-peak with a base of 3.5V.\u00a0 The signal is going to be based on the output from the Laserdisc itself (and discs other than the official Philips test disc will give slightly different results).<\/p>\n If your oscilloscope does not provide video signal triggering then you can use the edge of the signal under the base-line (i.e. the negative square sync pulse) to trigger the scope.\u00a0 In the following picture, you can see a capture of the expected signal; the channel offset has been placed at 3.5V causing the base of the signal to appear around the centre-line of the trace (note: a 30us delay is used to show the whole signal):<\/p>\n Once this signal is measured and confirmed it can be used as the trigger for the rest of the measurements.\u00a0 In the following sections channel 2 of the scope is used for the measurements with channel 1 used only for triggering (unless otherwise noted).<\/p>\n It should be noted that each \u2018band\u2019 in the trace above represents a colour in the test bar pattern (the trace is one line of the displayed output from the current frame).\u00a0 Starting with the negative square pulse (this is the video \u2018sync\u2019 pulse) the bars are white, yellow, cyan, green, magenta, red, blue and black respectively.<\/p>\n Since the black-level of the signal represents the base-line of the R, G and B-Signals it\u2019s a good idea to adjust this first (otherwise the other measurements will be offset by this).<\/p>\n To measure the black-level connect channel 2 of the oscilloscope to pin 4 of connector B3 (this is the B-Signal).\u00a0 Ground the probe using the probe ground marked \u2018MAS1\u2019 on the module PCB.\u00a0 In the following trace, you can see the output from this.\u00a0 The original CVBS signal on channel 1 is included so you can see the relationship between the signals.\u00a0 Adjust B3045 until the base-line of the B-Signal is as close to 0V as possible (plus or minus 50mV):<\/p>\n To adjust the notch filter leave channel 1 of the oscilloscope connected (and triggering) on the CVBS signal (as shown above) and connect channel 2 of the oscilloscope to pin 10 of connector B3.<\/p>\n Now adjust 5002 until the chroma rests are as narrow as possible:<\/p>\n Next use the oscilloscope to zoom into the start of the positive peak (the long line from the base to the top of the signal shown in the previous diagram). \u00a0Adjust 5003 until the under and overshoot of the line is as equal (in amplitude) as possible:<\/p>\n To perform the bandpass adjust leave channel 1 connected to the CVBS signal as per the previous steps.\u00a0 Using a test clip connect channel 2 of the oscilloscope to pin 15 of IC 7201 and set the channel to AC coupled.\u00a0 Adjust 5004 until the peak-to-peak range of the chroma signal is 0.4V including the overshoots:<\/p>\n The delay line adjustment is a little tricky as it is designed to be performed using a video vectorscope which is no longer a common piece of equipment.\u00a0 Instead the test can be performed using an oscilloscope (but it is important that the scope configuration is correct).\u00a0 In addition this adjustment, and the following oscillator adjustment require the delay line (L5008) to be shorted in order to disable it.\u00a0 As there are no test points visible on the board the author suggests a simple (optional) modification to the board.\u00a0 In the following picture you can see a 2 pin 2.54mm header soldered to the back of the module between pins 3 and 4 of L5008.\u00a0 This allows a simple switch to be connected to the module when under test (so the delay line can be easily disabled and enabled).\u00a0 This modification can be left in place after adjustment for future use:<\/p>\n The VP415 service manual shows the following vector diagram which should be produced for the test colour bar pattern:<\/p>\n Connect channel 1 (X) of the scope to pin 9 connector B2 (this is the R-Y signal on the x-axis of the vector diagram) then connect channel 2 (Y) of the scope to pin 10 connector B2 (this is the B-Y signal on the y-axis of the vector diagram).<\/p>\n Switch both channels 1 and 2 into AC coupled mode and invert both channels (in the vector diagram the X axis runs from positive on the left and negative on the right, the same for the Y axis; this is the opposite of a normal scope in X-Y mode). Finally switch the scope into X-Y mode (in the horizontal settings).<\/p>\n Make sure both channels have zero offset and that the vertical and horizontal scaling is equal.\u00a0 If all goes well you should see the vector diagram on the oscilloscope:<\/p>\n Now (with the delay line enabled) adjust 5007 until the overall dimensions of the \u2018spots\u2019 are as small as possible:<\/p>\n Next adjust 3015 until the distance between the spots on the vector diagram with the delay line on are twice as far as with the delay line off.\u00a0 To do this you should turn the delay line on and off and either measure the display with a ruler (between two opposite spots), or use the oscilloscopes cursors (if available).\u00a0 Once measured turn the delay line back on and adjust 3015 until the distance is double the previous measurement (note: 3015 has no effect on the signal when the delay line is off).<\/p>\n The following trace shows the vector diagram with the delay line disabled:<\/p>\n The following diagram shows the vector diagram with the delay line enabled (after adjustment of 3015):<\/p>\n Using the same configuration as for the delay line adjustment, disable the delay line and adjust C2015 until the dimensions of the spots are as small as possible on the vector diagram:<\/p>\n To perform this adjustment, reconnect channel 1 of the oscilloscope to the CVBS signal on pin 1 of connector B1 (as described in the black-level adjustment above).<\/p>\n Connect channel 2 of the oscilloscope to the G-Signal (pin 3 of connector B3). The luminance of the G-Signal should also be adjusted to a peak of 700mV above the base-line black signal level by adjusting the 3080 potentiometer as shown in the following trace (note: the trace is zoomed in to the initial part of the signal):<\/p>\n Connect channel 2 of the oscilloscope to pin 2 of B3 (the R-Signal) and adjust the R-Signal (potentiometer 3082).\u00a0 For this adjustment the aim is to get the amplitude of the yellow signal to be as close as possible to the amplitude of magenta and red:<\/p>\n Connect channel 2 of the oscilloscope to pin 4 of B3 (the B-Signal) and adjust the B-Signal (potentiometer 3084).\u00a0 For this adjustment the aim is to get the amplitude of the cyan, magenta and blue signals to be as close as possible:<\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":" Overview Adjustment of the calibration and levels of the RGB module in the Philips VP415 is required if repairs or modifications are made to either the RGB module (B) or the Analogue I\/O module (U).\u00a0 Furthermore, since the player is quite old, settings tend to drift over time so recalibration will greatly improve the picture produced by the player. The Continue reading B – RGB Module calibration<\/span>Adjustment points<\/h2>\n
<\/a>Setting up the oscilloscope<\/h2>\n
<\/a>Adjusting the black-level<\/h2>\n
<\/a>Notch filter adjustment<\/h2>\n
<\/a><\/a>Bandpass adjustment<\/h2>\n
<\/a>Delay line adjustment<\/h2>\n
<\/a><\/a><\/a><\/a><\/a><\/a>Oscillator frequency adjustment<\/h2>\n
<\/a>Luminance signal amplitude adjustment<\/h2>\n
<\/a>Adjusting the colour difference signal amplitude of the R-Signal<\/h2>\n
<\/a>Adjusting the colour difference signal amplitude of the B-Signal<\/h2>\n
<\/a>