Job Number |
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0303-74 |
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Equipment type |
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VCR |
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Maker + Model # |
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MultiTech VP-1700 |
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Made in |
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Date in |
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Fri.28.Mar |
2003 |
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Date of repair |
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Sun.06.Apr |
2003 |
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Date out |
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Mon.06.Apr |
2003 |
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Comments |
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Phoned Mrs Rosso for her sister. VCR picked from her
Mrs Rosso house, Hamrun |
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BAD |
1 |
FF / REW very slow |
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2 |
Playback is weak and
stops after 2-3 seconds |
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GOOD |
1 |
Powers Up |
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2 |
Good Eject mechanism |
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Full repair description and observations |
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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, |
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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). |
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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. |
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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. |
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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. |
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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 |
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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. |
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Repair summary |
CAPSTAN MOTOR ELECTROLYTIC
CAPACITOR |
Precautions, fouls and advises |
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1 |
Maybe it would been a
better decission if the capstan section would have been analysed first
instead of pointing to the power supply. |
1 |
Power Supply Voltages: a) IC DB234 |
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Pin 1 |
6.3V |
Pin 6 |
5.7V |
Pin 11 |
0V |
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Pin 2 |
5.0V |
Pin 7 |
12.7V |
Pin 12 |
5.7V |
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Pin 3 |
5.0V |
Pin 8 |
12.5V |
Pin 13 |
5.0V |
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Pin 4 |
20V |
Pin 9 |
5.6V |
Pin 14 |
17.1V |
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Pin 5 |
5.7V |
Pin 10 |
5.6V |
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b) 3 IC on heat sink (Voltage
Regulators ?? |
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Q802 |
D2058 |
E |
12.0V |
B |
12.6V |
C |
20.2V (Supply Voltage) |
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Q801 |
D1273 |
E |
12.0V |
B |
12.5V |
C |
20.2V (Supply Voltage) |
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Q803 |
D1406 |
E |
5.0V |
B |
5.7V |
C |
8.0V |
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c) Cable output voltages |
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Pin 1 |
0.0V |
Pin 4 |
0.34V |
Pin 7 |
11.9V |
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Pin 2 |
12.5V |
Pin 5 |
0V |
Pin 8 |
5.0V |
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Pin 3 |
5.0V |
Pin 6 |
0V |
Pin 9 |
12.0V |
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