Pioneer LD-V4300D Calibration – Grating temporary adjustment and tracking balance adjustment

Purpose

Set the laser beam which is divided into three by the grating so that it is directed to the optimum position on the playback track.

Set the offset voltage of the tracking servo to 0V.

Symptoms when incorrectly adjusted

Disc play impossible. Track jumping.

Gating temporary adjustment procedure

Note: This is a major mechanical adjustment to the player – it is suggested that you do not perform this adjustment unless other calibration procedures are not possible due to misalignment!

Note: This adjustment must be performed with the player placed horizontally.

Connect the oscilloscope to TP1-9 (Tracking error). Use the following oscilloscope settings:

Channel 1: Probe x10, 100mV and 5ms/div (if the oscilloscope is faster than 20MHz turn on the bandwidth limiter for the channel). Adjust the oscilloscope channel ground so the tracking error signal is centred vertically on the display.

Put the player in the following condition:

  • Service mode
  • Play mode
  • Tracking servo loop open
  • Tilt servo 10:off

Play the test disc.  Press the DISPLAY key to show the current frame number on screen.  Open the tracking servo.

Using the SCAN FWD control, position the pick-up to around frame 20,000 of the test disc.

The pick-up will tend to move towards the centre of the disc during adjustment (due to the pressure on the pick-up from the screwdriver). To prevent this engage the plunger to prevent the pick-up from moving during adjustment.

Insert a flat bladed screw driver into the grating adjustment hole ensuring that the blade of the screwdriver is horizontal to the player. The adjustment changes the angle of the two metal points (shown in the following picture above and below the red line) which are pivoting from the right-side of the red line in the picture. You can adjust them counter-clockwise (which moves both points upwards) or clockwise (which moves both points downwards). The total adjustment in either direction is less than half a turn.

Grating adjustment screw

Note: It seems the length of the screwdriver, the width of the handle and the width of the tip are all really important for this adjustment. The wrong size will either not fit in the player, not fit in the aperture for the adjustment or not correctly turn the adjustment screw. After some experimentation I found that a 2.4-2.5mm X 50mm flat-bladed precision driver was the best choice. It’s also a good idea to mark the shaft of the screwdriver so you can see when the tip is flat. Please see the following photograph that shows the correct angle of insertion for the screwdriver:

Laser grating adjustment – with the screwdriver in place

Note: If you are having problems getting the screwdriver in the right place, or the adjustments seem to be getting you no where; then the two adjustment points are probably rotated either too high or two low (and no amount of screwdriver wiggling is going to get them centre again). The best thing to do is to flip over the player, remove the FTSB module and then unscrew the five mounting screws around the optical assembly (unplug the brushless motor driver board first). Now remove the entire assembly so you can get a good view of the adjustment point – now carefully centre the two metal points with the screwdriver. Reassemble the player and try the adjustment again (you’ll find it a lot easier once you know the initial position of the adjustment screw).

The first adjustment is to find the point that gives the ‘smoothest’ signal (i.e. the signal with least amplitude possible) – this is called the ‘on track position’. See the following oscilloscope trace:

On-track position

Once the adjustment is in the on track position, move the adjustment screw counter-clockwise very slowly. The amplitude of the tracking error signal will gradually become larger. Set the adjustment screw into the position where the tracking error signal amplitude is as large as possible as shown in the following oscilloscope trace:

Maximum amplitude

The original service manual states that you must switch to focus balance ‘1’ (using the [MULTI REV] key or [x3 REV] on the RMC12010) and adjust VR6 until the focus tracking amplitude is maximum, however the the RMC12010 does not switch the focus mode setting; after testing, the CU-V113A remote is the only verified remote that performs this function. The required calibration point for the focus balance is dependent on this setting:

  • VR7 sets the focus balance when focus balance 0 is selected
  • VR6 sets the focus balance when focus balance 1 is selected

Set the focus balance to it’s maximum peak-to-peak value using VR6. Once adjustment is complete, change the ‘focus balance’ in the service menu to ‘0’. Release the plunger, close the tracking servo and make sure the picture displayed on the screen is normal.  Note: When performing this test the picture displayed was not ‘normal’.  This was corrected (as a temporary setting) by adjusting VR7 (whilst in play-back) until the picture was as stable as possible.  There is no mention in the original service manual about what to do if the picture isn’t normal.

Tracking balance adjustment procedure

Note: The original service manual recommends raising the LaserDisc player vertically before performing this adjustment (however, testing shows there isn’t a noticeable difference in the result).  If the player cannot play the disc when vertical the advice is to start playing the disc whilst horizontal and then slowly lift the player so the left-hand side of the player is upright; then perform the adjustment.

Ensure that the oscilloscope ground is central on the display. Start the test disc playing in service mode (with tracking closed). At around frame 115, open the tracking and adjust VR2 so that the positive and negative peaks of the wave are as equal as possible as shown in the following oscilloscope trace:

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