HELP! Can't figure out TV/VCR Problems!!!!!

[sandy]

We've got a problem with our VCR that is about to drive us nutty! Our
motorhome has a TV/VCR compartment forward over the driver/passenger
seats. Cabinet is metal and you can see a jumble of TV cables and
other wires that appear to go to exterior lights. The TV, Amplified
antenna & VCR wires are all connect3d to a little black box
(Magnadyne); Power is from an inverter which we installed.

The TV works fine but the VCR has really annoying interference in the
way of wide rolling lines (composed of colored dots or thingies that
look like a line up of golf tees). When you take the VCR out of the
cabinet, it works fine. We've tried exchanging the VCR for another
and it still gets interferrence. We've tried expensive shielded
cables and it didn't help at all. We'd really, REALLY appreciate any
suggestions as to what the problem is and how we can fix it. We've
been pretending to fix it for over a week now and my husband is about
to drill holes in the dash and install the VCR there (and have cables
dangling from the dash to the overhead). Can you help!!!!!!!!!!?

Thanks!

Sandy

 

[Sofie]

Sandy:
An important experiment here: If you run the VCR and TV from the AC power
directly..... and do not use the Inverter (unplug it from the AC power).....
doe the VCR still have interference???

 

[sandy]

Sandy:
An important experiment here: If you run the VCR and TV from the AC power
directly..... and do not use the Inverter (unplug it from the AC power).....
doe the VCR still have interference???

Yes it does. I think we've tried everything and the only thing that
seems to take the lines away is taking the vcr out of the cabinet. We
had it sitting on the passenger seat & it worked fine. When I picked
it up and it even got close to the overhead cabinet, the lines start.
Any ideas?

Sandy

 

[b]

Sandy:
An important experiment here: If you run the VCR and TV from the AC power
directly..... and do not use the Inverter (unplug it from the AC power).....
doe the VCR still have interference???
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

The fact that this only happens when installed the cabinet suggests a
possible proximity problem of electro-magnetic interference.

try if poss. moving ther inverter further away, or the vcr away from
the TV?

check the grounds - does the cabinet (if metal parts) have any voltage
on it??
Ben

 

[Deke]

We've got a problem with our VCR that is about to drive us nutty! Our
motorhome has a TV/VCR compartment forward over the driver/passenger
seats. Cabinet is metal and you can see a jumble of TV cables and
other wires that appear to go to exterior lights. The TV, Amplified
antenna & VCR wires are all connect3d to a little black box
(Magnadyne); Power is from an inverter which we installed.

The TV works fine but the VCR has really annoying interference in the
way of wide rolling lines (composed of colored dots or thingies that
look like a line up of golf tees). When you take the VCR out of the
cabinet, it works fine. We've tried exchanging the VCR for another
and it still gets interferrence. We've tried expensive shielded
cables and it didn't help at all. We'd really, REALLY appreciate any
suggestions as to what the problem is and how we can fix it. We've
been pretending to fix it for over a week now and my husband is about
to drill holes in the dash and install the VCR there (and have cables
dangling from the dash to the overhead). Can you help!!!!!!!!!!?

Thanks!

Sandy

Radar detector?
CB radio?
If you have one, try a small AM transistor radio.
Tune to a blank spot, and move it around the front of the RV and see where
the noise gets loudest.
Old trick, but it might work.

 

[Deke]

Also, are there any 12V fans running in the area?
They're notoriously noisy, RF wise.

 

[Graham]

We've got a problem with our VCR that is about to drive us nutty! Our
motorhome has a TV/VCR compartment forward over the driver/passenger
seats. Cabinet is metal and you can see a jumble of TV cables and
other wires that appear to go to exterior lights. The TV, Amplified
antenna & VCR wires are all connect3d to a little black box
(Magnadyne); Power is from an inverter which we installed.

The TV works fine but the VCR has really annoying interference in the
way of wide rolling lines (composed of colored dots or thingies that
look like a line up of golf tees). When you take the VCR out of the
cabinet, it works fine. We've tried exchanging the VCR for another
and it still gets interferrence. We've tried expensive shielded
cables and it didn't help at all. We'd really, REALLY appreciate any
suggestions as to what the problem is and how we can fix it. We've
been pretending to fix it for over a week now and my husband is about
to drill holes in the dash and install the VCR there (and have cables
dangling from the dash to the overhead). Can you help!!!!!!!!!!?

Thanks!

Sandy

The problem is simple, strong dynamic magnetic field around the scan coils
and h-output transformer in TV being picked up by the video heads.

The solution-

1 physical separation (you have figured this)

2 shielding, try a VCR in a steel rather than plastic case or try putting
some sheet steel between TV & VCR

3 swap your TV for an LCD type (they do have there own interference issues
but not this type)


Good luck,

 

[sandy]

in TV being picked up by the video heads.

The solution-

1 physical separation (you have figured this)

2 shielding, try a VCR in a steel rather than plastic case or try putting
some sheet steel between TV & VCR

3 swap your TV for an LCD type (they do have there own interference issues
but not this type)


Good luck,

Thanks for the info...really appreciate it. We'll try shielding it
tomorrow. Also try switching the vcr for another one we have that is
mostly metal (still has plastic front). I feel a lot better...just
getting an idea of what the problem is. Thanks again.

Sandy

 

[sandy]

Also, are there any 12V fans running in the area?
They're notoriously noisy, RF wise.

We have 2 fans in front but seldom use them (never while stopped and
with TV and VCR on.) We also have a CB mounted on the "drink console"
on the "engine hump". It also wouldn't be on when TV and VCR are on.
This motorhome is a "new"(to us) '92 Winnebago....and we'd been
beginning to think it was haunted!

By the way, the inverter is mounted behind the driver's seat (not that
close to TV) and we snaked a long wire up to the TV cabinet and
installed a wall outlet on that end to plug the TV and VCR into.

Another thing I noticed is that the TV power cord has a piece of
electrical tape wrapped around it in one place. (TV came with RV).
Don't know if that might cause the problem or not and I haven't pulled
the tape off to see why it's there.

Sandy

 

[Mike Kennedy]

You could get a DVD player to solve this problem : )

 

[Yukio]

Not Quite the same Problem, but related.

Most motor homes use a 12 Volt Inverter powered Flourescent Light .These
inverters operate in the 15 Khz range ! (More efficient then 60 cycle)
I was surprised to find out my Infra Red Remote Controller was not working
properly (ya , I put in new batteries and tried it close up) but it would
not operate at any distance.

To make a long story short, I had to shield the IR sensor in my satelite
dish receiver, from the Flourescent Room light Fixture.

Under normal conditions flourescent Lighting is driven by 60 cycle power,
and I am reasonably sure that the sensor circuits ar well filtered to block
this 60/120 cycle light interference. (Hi-Pass filter circuit)

In the case of 12 Volt lighting, these tubes are driven by a ~15 Khz
inverter and will appear as a 15/30 Khz modulated light ( modulation
invisible to the Human eye). .

This modulated signal even though in the visible light range, will leak
through the IR sensor and block the detector from responding to the ~15/30
Khz IR signal from the Remote Controller. Reducing the strenght of the
interfereing
room light by placing a magazine on top of the satelite receiver and shading
the detector , eliminated the problem..

BTW I like the LCD TV idea, I suspect your TV is a Trinitron, eg SONY . I
recall a rumour 20 or 30 years back that it produced a strong signal around
100/200 Khz, , the switching frequency for the trinitron screen. this would
explain the 10~200 pips per line you see in the interference.

I also like the DVD idea , should not be bothered by Trinitron .

All of their Remote Controls will still be bothered by 12 Volt Flourescent
lamps however !

Yukio YANO

 

[sandy]

Here's what we did:

We finally decided to relocate the VCR to another cabinet farther away
from the tv. We first ran cables to it (from the Magadyne black box"
and tried it out. Picture was fine. So we went out & bought some
longer cables so we could run the cables unobtrusively from the new
cabinet to the TV cabinet. (they do run behind the TV). Hooked it up
and we STILL have the lines though not as bad (and we'll probably just
go with this for now as we're sick of trying to figure it out).

Another thing I tried was running the vcr WITHOUT the front TV being
turned on...and looking at the tv in the bedroom area. It still has
the lines so now I'm beginning to wonder if the (front) TV is the
culprit afterall.

We're still thinking about getting a satellite dish...so maybe when we
have that installed we can have somebody who knows what they're doing
look at it. But if you have anymore ideas, I'm hornery enough to
still want to solve this problem myself (with your help of course).

Sandy

 

[Wayne Tiffany]

What if the front TV is unplugged so there is no possibility of the power
supply still running in it? The other thought would then be that there is
something else running that is causing RF interference. Is the motorhome
engine running by chance?

WT

 

[sandy]

What if the front TV is unplugged so there is no possibility of the power
supply still running in it? The other thought would then be that there is
something else running that is causing RF interference. Is the motorhome
engine running by chance?

WT

Nope. Engine is not running. The ('92) motorhome is a "new" toy for
us and we're still learning about all it's gremmies. It has a switch
on the dash where you can turn off the battery power. As we put in a
2nd battery bank that is seperate from the RV's batteries and is
charged by 2 solar panels, I'm thinking of turning off the RV
batteries and seeing if that solves the problem.

Maybe it's just haunted!!!!!

Another thought....would running the cables near the TV have any
influence on anything? And another thought... When we tried
replacing the cables with shielded cables, we changed only the 3
cables that went to/from TV and vcr (and didn't change the wires that
we couldn't reach...like wires that run thru the roof from the
antenna. Would these cables have anything to do with anything?

Maybe we'll just name our "ghost" and learn to live with him!

Sandy

Sandy