Test Mode; Electrical Check - Sony D-NE240 Service Manual

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In the test mode, this set can check the microcomputer version and
liquid crystal display.
1) Short SL803 (TEST) on the MAIN board with a solder bridge.
Then, turn on the power.
2) Microcomputer version is displayed on the liquid crystal
display, and the liquid crystal display is all lighted.
3) Tuen off the power and open the solder bridge on SL803
(TEST) on the MAIN board.
Note: Remove the solders completely. Remaining could be shorted with
the chassis, etc.
– MAIN Board (Conductor Side) –
SL803
(TEST)
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D-NE240/NE241/NE241CK
SECTION 4

TEST MODE

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The CD section adjustments are done automatically in this set. In
case of operation check, confirm that focus bias.
Precautions for Cheack
1. Perform check in the order given.
2. Use YEDS-18 disc (Part No.: 3-702-101-01) unless otherwise
indicated.
3. Power supply voltage requirement: DC4.5 C in DC IN jack.
HOLD switch: OFF
Connecting and Checking Location:
– MAIN Board (Conductor Side) –
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SECTION 5
ELECTRICAL ADJUSTMENTS
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Focus Bias Check
Condition:
• Hold the set in horizonal state.
Connection:
(J401)
MAIN board TP604 (RF)
Procedure:
1. Connect the oscilloscope to the test point TP604 (RF) on the
MAIN board.
2. Set a disc. (YEDS-18)
3. Push the
4. Check the oscilloscope waveform is as shown below.
A good eye pattern means that the diamond shape (◊) in the
center of the waveform can be clearly distinguished.
TP604 (RF)
RF Signal reference Waveform (Eye Pattern)
VOLT/DIV: 500 mV (With the 10:1 probe in use)
TIME/DIV: 500 ns
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To watch the eye pattem, set the oscilloscope to AC range and
increase the vertical sensitivity of the oscilloscope for easy
watching.
5. Stop revolving of the disc motor by pressing the
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D-NE240/NE241/NE241CK
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oscilloscope
(AC range)
+
–
button.
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RF level
1.1 to 1.5 Vp-p
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button.
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