I have a Sylvania SRD 4900 combo vcr/DVD player. There are led's
which light up when the power is turned on, but the drawers for the
vcr tape and for the DVD disk are totally inert. I suppose the power
supply is not working, but I need a circuit diagram and parts layout
to get anywhere with it. Probing with my voltmeter shows me some
places where there is 10 volts, but That's not helping me.

Using Google I can't find any place to get a circuit digram and parts
layout. Can someone help me?

Mel Levine

What gave you the idea that the power supply was not working?
Could it have been the leds that are lighting up when it is turned on?

What on screen display do you get on your tv set, try both rf and video
outs?
Do you get any on screen message when you push any buttons?

As for any circuit diagram, you probably are not going to be able to
find one. Sylvania vcrs and dvd players are all being marketed/made by
Funai or some other company. I would bet that the unit had an exchange
warranty only, no repair service available.

I would guess without any measurements made at all that the system
control and buttons would be the place to start any troubleshooting.

On 13 Dec 2005 16:20:35 -0800, "
wrote:

What gave you the idea that the power supply was not working?.....


Many thanks for your response to my question about the non-working
sylvania vcr/dvd combo machine.
May I try your patience by describing some more details?

Since both the vcr and the dvd sections are not working, it seemed to
me that the power supply is the culprit since it is common to both of
them. The power led works, but it's on all the time regardless of the
power switch setting. The two led's that show which of the vcr or dvd
sections is chosen also work. So I know that the switch selecting
between the vcr and the dvd sections works. None of the other
switches cause anything to happen that I can see. The dvd drawer
doesn't open when its switch is activated. It's impossible to insert
a vcr cassette since the cassette carrier is blocked by a finger that
I suppose is activated electrically.
When I connect the rf output to my tv, there is no on-screen display.
I haven't tried the video output yet. (My tv does not have a video-in
input, but I intend to try the video output by getting hold of a
modulator.)

Is it worth pursuing this?

Mel Levine

My suspect initially would be either a stuck or liquid damaged button,
or a mechanism that is out of alignment in the vcr.

Since you have a power indicator working, the power supply must be
operational at least in the 5VDC. As the DVD/VCR button changes the
selection, most of the power supply again should be working.

If you get the unit apart it is a simple matter to check the power
supply voltages. You should measure 5VDC at any of the buttons to
ground and around 12VDC usually going to the motor drive circuits (may
be 6VDC or 9VDC).

You will not be able to diagnose any kind of mechanism faults without
the service manual and you will likely not be happy with the price if
it even is available, call the number in the back of the owners manual
for the brand.

As the buttons do not seem to work, you have no way to activate the
tv/vcr button to turn on the output for channel 3 or 4.

Also before doing anything at all, make certain that the unit is not in
some kind of child lock out mode. Again reference the owners manual.
Most modern vcrs and tv sets have a child lock out mode.

I've not had any success with resurrecting my sylvania dvd/vcr machine
in spite of the excellent suggestions you gave me. It was kind of you
to take the time to offer me your help, and I think that if I were
smarter, you could have pulled me thru.

In any case I did learn a lot from what you wrote, and I am grateful
to you.

Mel Levine