XR-4890 - Sony Car Audio Service Manual (repair manual). Page 13

– 13 –

1. Clean the following parts with a denatured-alcohol-moistened

swab:

playback head

pinch roller

rubber belt

capstan

idlers

2. Demagnetize the playback head with a head demagnetizer.
3. Do not use a magnetized screwdriver for the adjustments.
4. After the adjustments, apply suitable locking compound to the

parts adjusted.

5. The adjustments should be performed with the power supply

voltage unless otherwise noted.

•

Mode

Tension Meter

Meter Reading

Forward

CQ-403A

more than 90 g

(more than 3.18 oz)

Reverse

CQ-403R

more than 90 g

(more than 3.18 oz)

•

Mode

Torque Meter

Meter Reading

Forward

CQ-102C

30 - 65 g•cm

(0.42 - 0.90 oz•inch)

Forward

CQ-102C

0.5 - 4.5g•cm

Back Tension

(0.01 - 0.06 oz•inch)

Reverse

CQ-102RC

30 - 65 g•cm

(0.42 - 0.90 oz•inch)

Reverse

CA-102RC

0.5 - 4.5g•cm

Back Tension

(0.01 - 0.06 oz•inch)

FF, REW

CQ-201B

60 - 200 g•cm

(0.83 - 2.78 oz•inch)

This set have the test mode function. In the test mode, FM Auto
Scan/Stop Level and MW Auto Scan/Stop Level adjustments can
be performed easier than it in ordinary procedure.

<Set the Test Mode>
1. Set the “OFF” mode.
2. Push the preset 

[4]

 button.

3. Push the preset 

[5]

 button.

4. Press the preset 

[1]

 button for more than two seconds.

5. Then the display indicates all lights, the test mode is set.

<Release the Test mode>
1. Push the 

[OFF]

 button.

Procedure:
1. Put the set into the FWD PB mode.

See the adjustment location from on page 16 for the
adjustment.

0 dB= 0.775 V

2. Adjust adjustment resistor for inside capastan motor so that  the

reading on the speed checker or frequency counter becomes in
specification.

Speed checker

Frequency counter

–1.5 to +2.5%

2,955 to 3,075Hz

Specification: Constant speed
Adjustment Location: See page 16.

+

–

test tape
WS-48A
(3 kHz, 0 dB)

speed checker

or

frequency counter

10 k

Ω

 

set

LINE OUT