How fix lines on CRT from signal lead ?

They can fail.

You only get that if its got a break in the wire or at the connector.

Likely thats where the problem is.

They can, you dont see that with most CRTs.

Because its got the most wires in it.

Nope, most CRTs dont behave like that.

Not the design, the actual implementation of the cable/connector.

Yes, replace the cable and connector if you dont get that effect with a different CRT. If you do, its the video card.

Yeah, wont make any difference.

The problem is a physical break in the cable/connector.

Yeah, tho you can find that the break is actually in the connector itself, or even just a broken pin there.

Replace it with a 19" CRT.

Then buy a new one.

Or don't do anything at all.. ;)

You probably have corroded solder connections where that pc board hooks to the input cable. Very common in old crts. Sounds like you also have a flyback going bad. Time for new monitor.

johns

johns ha escrito:

Please explain how a bad flyback can cause the fault described by the original poster.

Picture size .. blooming .. is caused by high voltage changing. Generally when the solder joints start going, it occurs across all the power handling connections, and at the flyback. Also, the electrolytics tend to crap out and lose their capacitance .. even to dead shorts. I've been into lots of crts where all I did was touch up solder connections and replace electrolytics ... and the thing ran fine. Of course that did not fix the gassy crt which starts the picture to blur. TRUTH: I've had people come in and say "just make it work. I'll pay the cost. I like my crt". So, I clean it ... resolder a bunch of points .. replace horizontal output transistor ... replace flyback ... run tube through phosphor restore and degauss ... set flyback focus .. dark level ... remove and test all the big electrolytics, and replace a bunch of them ... replace the the transistor amps and current limit resistors on the crt board ... put it back together and clean the case and screen to nearly new ... and charge the lady 3 hours labor at $65 per hour plus parts .. and hope to heaven that the 90 day warranty holds :-)

johns

Sounds like a flyback problem, but it might just be a poor connection on the sync pulse line. Prodding should lead you to see where its most sensitive, and thus where the probelm is. Typically its cable ends or connectors.

The good news is this fault is likely non-fatal. Having retrace lines scattered over the screen doesnt exactly make it look better, but it means you can wait to see if it goes bad, and if it does find a monitor then.

NT

Yes, but you havent established that the real reason for the picture size changing is because the monitor is getting confused by the obvious glitches on the cable into changing the screen mode etc.

Oh bullshit. You only get bad joints where large components are soldered onto the pcb and they start to fail due to thermal cycling.

Utterly mangled all over again. Flybacks fail quite differently.

No evidence of that in the symptoms the OP mentioned.

Sure, but that doesnt appear to be the OP's problem given that its so sensitive to the video cable.

Irrelevant to what the OP's symptoms indicate.

Nope, doesnt explain the sensitivity to the video cable.

Rod Speed ha escrito:

That=B4s exactly what I thought. A bad flyback will not worsen or improve by "wiggling" the VGA cable of the monitor. In other words, if the fault dissapears by wiggling the VGA cable, that rules out the flyback and other components of the monitor.

johns ha escrito:

True, but high voltage changes can be caused by a number of other things, not just the flyback.

OK, but that can be solved by simply resoldering the faulty joints. No need to blame the flyback on that, or to replace it blindly.

Bad electrolytics in the PSU can be the origin of the high voltage changes.

I don=B4t understand why do you replace the CRT drivers and the HOT if they are OK. I can understand that part about replacing aged electrolytics, redoing any stressed solder joints and restoring the CRT... but why to replace transistors if they are ok?

I've never seen light-colored lines like that caused by a bad monitor cable, which usually causes the color to be funny all over the screen or change abruptly.

Buy? They're free.

How long can cleaning take? Almost every one I've found was very clean.

How does cleaning the inside make the image sharper? There are 1-2 focus adjustments inside, but it takes just seconds to adjust each one.

Wiggling the flyback can disturb the horizontal sync, which in turn disturbs the HV, which in turn affects the picture size.

The admission by the OP of being a troll, in plain sight, and nobody noticed!

Nothing to notice except you jumping at bogeymen.

sorry, I though it was obvious. Wiggling a thick fat cable will wiggle the main pcb slightly, which may disturb any poor connection anywhere on the board.

NT

snipped-for-privacy@care2.com wrote

Never ever could bullshit its way out of a wet paper bag.

Not if you only fiddle with the video card end it doesnt.

Pity the FBT isnt even on that board.

Because you are in there. It takes bench time $$$$ just to open the thing, and so you don't take chances on the HOT, flyback, power electrolytics, CRT board adjustments .. esp the driver transistors and current limit resistors. All of those points "heat cycle" badly, and the solder joints crack. That causes any movement of the video cable to wiggle those bad joints and glitch the picture in a million ways. A bench tech can't spend time diagnosing that stuff. I just shotgun all the potentially weak areas and run a bench test for about an hour to watch the video cycle. If it works ... start praying for 90 days. Otherwise .. MAD BOSS ... mad mad Boss ! Something else .. all those parts run about $30 total on the bill. Stupid not to replace them. More stupid is to repair the thing at all, but that is not my option, and some customers simply believe in maintaining their hardware.

johns

Wiggling the cable wiggles the entire monitor. What drives me crazy is to pick up the monitor and carry it back to the test bench, and have it run perfectly :-)

johns

johns ha escrito:

Just resoldering the transistors will suffice. No need to replace them blindly.

I agree, trying to repair a computer monitor from 1994 is a waste of money.