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No reel rotation
The most common fault with older 950s is lack of reel torque. This can
result in the machine shutting down in playback/recored or the tape
not being would back into the cassette housing after eject.
The best cure for this is to replace the reel chassis. However, because
of changes during production you may find that some other bits, such as
springs, may need replacing as well.
Sony also made available a
'motor mod kit' which consists of a .02mm thick piece of plastic which
can be fitted in the worn bearing. Alternatively a small ball bearing
can be fitted but this may require the rotor to be filed down to ensure the
correct gap between rotor and stator coils.
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Audio level controls not operating
Check that the audio monitor is set to Auto. The VU meters only show
the Hi-Fi sound level in this mode.
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Failure of the VU meters
The audio level meters (2 lines of green and red LEDs on the front of the unit) can fail on some segments.
Failure can be either a defective LED
or a faulty drive IC. It is recommended to test the LEDs first
before suspecting the drive unit. Because of the way this unit
is constructed though, it is easier to replace the whole unit (if you can).
With a little effort though, it is possible to repair the LEDs:
- Open the white plastic bar casing by cutting the melted-legs at the back of the PCB and
carefully pull out of the PCB.
- Gently scrape all of the burned LED and take extra caution not to break the PCB tracks.
- Get a new set of Surface Mount Device LED, usually obatainable from Cellural Phone parts supplier.
- Solder each one of them in place.
- Check if there's no short circuit of the new soldered component.
- Assemble all parts then your VU meter is ready to give a show!
A number of units have been repaired using this method.
VU meter circuit board
Our thanks go to Baggio Rusli for suppying this fix
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Picture dropout due to static buildup
Static can build up between the cassette and the upper drum which will
result in what looks like excessive drop out on the tape. Sony fitted
a small piece of plastic which connects between the cassette housing and
the drum. Remove the lid and have a look if your machine has one fitted.
The diagram to the left shows the location of the plastic sheet to
discharge the static build-up.
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Conversion for additional-AV/S-VIDEO-IN through scart socket
The "SIMUL" switch on the front of the 950 can be converted to
allow for an additional input. With the current version, the recorder must be
receiving a television channel through the tuner.
How to perform the upgrade.
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Transport freezes
The deck uses a small DC motor to move the mechanism between different
operating modes. A dead spot can develop on the motor which will
cause it to stick which results in the machine freezing. While it is possible
to clean the brushes / armature of the motor fitting a replacement is
a better option if you can find one. The motor also performs the
threading / unthreading action but due to the longer action of this mode
it rarely ceases during threading.
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No head drum rotation
You may find that the head drum fails to rotate. This
is due to a problem with the Hall effect device on the
head drum motor which is secured by a blob of glue which
tends to become conductive especially if it absorbs
moisture. The best remedy is to remove the glue from
the device. To do this first remove the rotor from
the bottom of the drum by undoing the lock-nut.
Sometimes, however, it is enough to wait for the
damp to dry out.
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Intermittent audio on line input
The phono connectors are prone to intermittent failure and this can produce
a low level or distorted audio input. The connectors come as a moulded unit
and so the best
remedy fot this fault is to replace the entire unit. Many Sony VHS machines,
such as the SLV-353, use the same connector.
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Linear audio not erasing
Sometimes the linear audio on the 950 fails to erase. This is sometimes is
accompanied by patterning moving down the screen for about the first 10 seconds
of a new recording. This implies that the full erase head has failed. The head
itself though rarely fails with the usual cause being the transformer (T901)
powering it. The part number for this is 1-433-275-00.
Bias oscillator circuit
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| Fault | Solution |
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Line tearing - visible on playback | Line tearing can be seen on playback. ie a handful of lines in the middle of the picture appear right shifted slightly.
Sony has produced the following mod for this fault.
You will need:
1 x 4.7uh
1 x 22pF
1 x 33uh
1. Connect the 4.7uh o R772 (not C803 side) (RP31 board)
2. Connect other side to 22pF.
3. Connect other side of 22pF to ground.
4. connect 33uh in parallel with R807 YC-40 board) |
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Tape fails to eject | The sled has become completely jammed. Check the right hand side of the sled (or skate as Sony called it). This can jam because of a spring loaded roller breaking the plastic runner rail. Pushing this down as the tape was ejecting will allow the the mechanism to stay in its rail.
Unfortunately, the plastic rail is part of the "Inner Frame Assembly" (X-3697-606-1) and is no longer available. If you are able to find a replacement, it will probably be a big job to replace as the assembly is a structural part of the VCR, running right down the centre. |
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linear audio erase t901 failure | This part is no longer available but is used in the sl-f30. I have never heard of it failing in the f30, so if you can get the top tuner board out of an f30, the transformer is located in the uppermost can on the tuner board. simply desolder it and replace the faulty one in the 950 (again located on the tuner board) paying attention to the pinouts. I repaired one of my 3 950s in this way and was completely successful. |
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intermittent bw recording through av though rf fine | I found this was due to dust buildup on the internal side of the av connections to the pcb. simply use compressed air to blow out of the vcr. |
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