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Bad connection on tv

Panasonic 17" color tv, mnfgr'd 1987. Standard design, layout near as I can tell.

Dog bumps tv stand, pic is still viewable, but goes snowy and has pulsing waves across screen.

If I fiddle the power cord where it enters the box or bang on side of box I can get the proper pic back, if only for a second or 2.

I'm not particularly skilled at electronics, but if I could get proper access to where the cord connects to the power supply, I could likely solder the connection or some-such. Access looks kinda problematical: it's right under the nasty ol' CRT. The one that stores (what?) 20k volts?

I know, I know. The unit is truly jurassic, and the new LCD's etc are priced down a bunch. But it's stereo and it's connected to my jurassic stereo audio system. And I don't think enough of what they broadcast to spend any $ on it unless I have no choice.

Any ideas on how to approach it? Just workbench it and start disassembling stuff? Cautions other than about the 20kv "gun" at the back of the CRT? Etc, etc.

Thx, Puddin'

"Law Without Equity Is No Law At All. It Is A Form Of Jungle Rule."

Reply to
Puddin' Man
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On 9/5/2009 5:36 PM Puddin' Man spake thus:

To begin with, you could probably do with a little high-voltage precautionary education before you seriously zap yourself.

The high voltage isn't at the "gun" (actually the tube socket) at the back of the CRT: it's at the anode, which surrounds the tube and has a high-voltage lead connecting it to the rest of the set. This acts as a giant capacitor which can store a lethal charge.

Others here will tell you more. But learn up about HV first.

--
Found--the gene that causes belief in genetic determinism
Reply to
David Nebenzahl

You're likely right to suspect a poor connection somewhere, possibly a soldered joint that's cracked or similar.

It's almost certainly not the power cord connection, though, simply because a poor connection there would generally cause the set to intermittently turn itself off or not turn on, rather than cause snow. Snow suggests something is amiss in the RF or perhaps video circuitry.

The first place I'd look is the RF or video input connection (on the outside of the TV)--perhaps the connection is loose or corroded, or the cable is breaking near the connector.

If that's not it, then it's some internal connection or solder joint in the set. Positively do some research and reading up on how to safely work around in a TV before thinking about opening it up. Besides the high voltage for the CRT, there's high voltages in the power supply circuitry and the danger of implosion. If you have any doubts, you'd probably be better off taking it to a repair shop, assuming the set is otherwise worth spending money on (i.e. the picture, when the set is working properly, is bright and sharp and clear and generally well behaved).

--
Andrew Erickson

"He is no fool who gives what he cannot keep to gain that which he cannot
lose."  -- Jim Elliot
Reply to
Andrew Erickson

Then you shouldn't even consider delving inside the set.

Reply to
Meat Plow

The video input is about 1" from the power cord. The power cord seemed to be -very- sensitive to the condition, the vid. input less so, but after firmly re-seating the vid. input, the problem seems to have disappeared. So it was either the video input as you said or it's an intermittent problem that's likely to be a real headache down the road.

Much Thanks, P

"Law Without Equity Is No Law At All. It Is A Form Of Jungle Rule."

Reply to
Puddin' Man

More than likely there is a broken /intermittant connection, or the circuit board itself, or some other component(s) have been damaged.

Considering the age of the set, I would not want to put any serious money in to this servicing this set.

Jerry G.

Reply to
Jerry G.

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