General information

 

Job Number

 

0303-74

 

 

 

 

Equipment type

 

VCR

 

 

 

Maker + Model #

 

MultiTech VP-1700

 

 

 

Made in

 

Korea

 

 

 

 

 

 

 

 

 

 

Date in

 

Fri.28.Mar

2003

Date of repair

 

Sun.06.Apr

2003

Date out

 

Mon.06.Apr

2003

 

 

 

Comments

 

Phoned Mrs Rosso for her sister. VCR picked from her Mrs Rosso house, Hamrun

 

 

 

 

Symptoms observed

 

 

BAD

1

FF / REW very slow

 

 

 

 

2

Playback is weak and stops after 2-3 seconds

 

 

 

 

 

 

GOOD

1

Powers Up

 

 

 

 

2

Good Eject mechanism

 

 

 

 

 

 

 

 

Repair notes

 

Full repair description and observations

 

1

On opening the VCR, I noted that there where 3 belts which were quite loose. I changed them (bought them from G&E) and hoped for victory, but only FF and REW was improved, playback was still faulty,

 

 

2

On inspecting the fault closely, I noted that the capstan motor was very weak on playback, and was jerky (moving in small rapid steps, rather then smooth rotation).

 

 

3

I tried to find an equivalent circuit from RTV, which did not have. I tried the circuit of a Samsung VB900 (which Euras stated that it is an equivalent the MultiTech VP-1600) but it seamed not much similar.

 

 

4

I tried to find some fault in the Power Supply. It was quite ackward to remove the power supply board because it was well buried under the main circuit board and lots of wires in the way. The power supply seemed quite OK. It’s main components where:

·         3 x 3-pin IC (probably voltage regulators) attached with a large heat sink,

·         1 x  DB234 (14pin IC by Daewoo).

 

The voltages of the Ics and voltage output via a 9-pin cable to the main board are given in the ‘other notes section’ below.

 

I changed 6 electrolytic capacitors in the power supply, maybe they were supplying the playback voltage to the capstan motor. These were:

·         C807   47uF/16V

·         C808   47uF / 25V

·         C810     1uF / 50V

·         C811   47uF / 16V

·         C812  100uF / 25V

·         C813  100uF / 16V

 

This did not fixed the problem, playback still weak / unoperative.

 

 

5

I checked the voltages at the cable entering the capstan board. It was a blue wire at pin 1 which had variable voltages on REW, FF, and PLAY. On FF it was reading 10V, but on playback just 3.5 to 4.0V. I disconnected the cable and checked again playback voltage – it gave 7.5V this time. Hence it was obvious that the voltage was given correctly and there is some fault in the capstan board.

 

 

6

Then I read that it could be the electrolytic capacitor on the capstan board. This was a 47uF / 16V surface mount metallic cover, short capacitor. I replaced with a normal capacitor, but I placed it horizontal since it would not fit upright. The result was – SUCCESS … The playback came normal

 

 

7

On trying the video, the picture was just snow and little sound L ok no panic, just a little alcohol cleaning of the heads and playing a clean video tape and perfect picture + sound was produced by this video.

 

 

 

Repair summary

CAPSTAN MOTOR ELECTROLYTIC CAPACITOR

 

 

 

 

 

Precautions, fouls and advises

 

1

Maybe it would been a better decission if the capstan section would have been analysed first instead of pointing to the power supply.

 

 

 

 

 

Other measurements and technical comments

 

1

Power Supply Voltages:

 

a) IC DB234

Pin 1

6.3V

Pin  6

5.7V

Pin 11

0V

Pin 2

5.0V

Pin  7

12.7V

Pin 12

5.7V

Pin 3

5.0V

Pin  8

12.5V

Pin 13

5.0V

Pin 4

20V

Pin  9

5.6V

Pin 14

17.1V

Pin 5

5.7V

Pin 10

5.6V

 

 

 

b) 3 IC  on heat sink (Voltage Regulators ??

Q802

D2058

E

12.0V

B

12.6V

C

20.2V (Supply Voltage)

Q801

D1273

E

12.0V

B

12.5V

C

20.2V (Supply Voltage)

Q803

D1406

E

5.0V

B

5.7V

C

8.0V

 

c) Cable output voltages

Pin 1

  0.0V

Pin 4

0.34V

Pin  7

11.9V

Pin 2

12.5V

Pin 5

    0V

Pin  8

  5.0V

Pin 3

  5.0V

Pin 6

    0V

Pin  9

12.0V