Sony SLV-315 VCR Repair - Power on, tape loading fail, display flickers or blinks

Date: 5/2012

Problem:

This Sony SLV-315 VHS VCR is probably from 1992. It sat unused, plugged in for several years. One day, when I tried to use it, when attempting to insert a cassette, the cassette / tape loading mechanism does not load the cassette and rejects it immediately. The power light does not stay constant, clock blinks but other information on the display panel only flickers very briefly after pressing the power button. This was my first VCR repair and I had no past experience with such project.

Diagnosis:

With the cover open, when I power on the VCR, the video head drum spins very briefly and stops. When I insert a tape, while the tape loading mechanism pushes the tape back out before it is even one third way in, the LCD display very briefly flickers. Yet the unset digital clocks keep blinking as it normally would.

Since the motor of the tape loading mechanism seems to be working, even if the cassette is not accepted, you can see the gears moving in and out; and the video head drum spins, however slightly; in combination with the strange LCD behavior, the first place and most likely place to troubleshoot is the power supply that regulates the digital power output delivery various voltages to different circuits.

Repair:

I removed the power supply unit. After cleaning extensively using cotton swabs around the shell of the electrolytic capacitors, I was able to read their ratings. Visually, not one showed any obvious damage typical of electrolytic capacitors. Since they are two decades old, I decided to replace all except the main 400V capacitor. Generally, the high voltage capacitor does not need to be replaced, but the smaller filtering capacitors become bad more often. Sony used high quality Rubycon brand capacitors and they lasted a very long time compared to many of today’s electrolytic capacitors which last two to three years.

Result:

After the replacing all electrolytic capacitors and placing the power supply back into the VCR, at power on the video head drum spins normally for few seconds until coming to a gradual stop; the LCD display remains steady with information; and the tape loading mechanism accepts the cassette. While that fixed the initial problem, I discovered a new problem of the VCR not outputting video and not tracking video time during play. This is caused by a mechanical problem as I later discovered, in another article and video I show how to fix it.

Parts list::

Capacitor Identification	Voltage	Capacitance
C111	100V	1uf
C201	50V	100uf
C208	10V	2200uf
C202	16V	3300uf
C212	50V	100uf
C204	50V	1uf
C205	16V	1000uf
C206	16V	100uf
C207	16V	100uf
C213	6.3V	1000uf
C209	10V	100uf
C218	10V	100uf

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