SONY TV model KV-32XBR96S---Bad color purity--help needed

CRT

The correct speakers for this TV or any speakers made to be on a TV would be magnetically shielded so that should not matter. The two main possibilities are a problem with the degaussing circuit or the set has been dropped and the shadow mask has shifted. You should first check and maybe resolder the degaussing thermistor. If the degaussing circuit seems to be working correctly then it's probably the CRT. One way to be sure is to disconnect the internal degaussing coil and manually degauss it from outside the set. If that doesn't work chances are it was dropped and the CRT is toast.

Just fixed a the same problem in a set the other day - bad PTC (Three-legged device near where the degauss coil connects to the board)

Pulled one of a SVGA monitor, and popped it in the set, and at the next powercycle it was sorted out.

Peter

On Mon, 31 Dec 2007 19:03:09 +0200, "Peter Kolbe" wrote: If the problem was the internal degauss I would expect that use of my external degausser would fix the display. It does not , but thanks for the suggestion. I am leaning toward a "bad" CRT for now but will try a few things more before salvaging parts.

If the CRT has not been damaged from a hard knock or a drop, most likely the thermosistor for the degausser has to be replaced. These are universally available from most electronics parts suppliers for TV service, or from the original manufacture parts department.

I doubt the purity alignment is out, unless someone messed with the magnet and yoke assembly. This is not something the average service tech would have an easy time to re-align unless he has had a lot of practice.

You can remove the old one, and get a manual degaussed coil from an electronics supplier. But, this is not a convenient way to use the TV set.

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Jerry G. ======

This TV was recently given to my grandson ... I am a while retired from servicing but still have my test gear. He expects me to fix it so I have a few queries to make that could speed this up.We have bought no manuals as of yet or had the back off.

The set was given to him minus the remote control and no speakers.

Appears to be working and has a nice bright focused picture except the color purity is terrible.

There are four knobs on each side of the case near to the front close to the CRT face. I am assuming that these are where the speakers would normally attach.

2/ The screen symptoms are a symmetrical wide rainbow from the center screen to the lower outside corners.

4/ I have no knowledge of the history of this set so I cannot determine if it has been dropped . Or worse somebody has been inside "fixing "

I am asking for opinions as to whether this set is fixable , If so we can invest in a service manual and a remote control.

Anybody help me out with this ? Thanks

Aperture is the correct spelling.

This appears to be what happened to my Sony. While degaussing the CRT with a bulk tape eraser, the eraser was accidentally shut off near the tube, which then developed a small area of permanent impurity.

ge

In 86 I started at Sony Broadcast and got a tour of the San Diego plant where tubes and TVs were manufactured and saw a guy whose job it was to hit the face of each tube on the suspended conveyor with a rubber mallet. Some years later we had run an external degaussing coil on a BVM1910 monitor and 'deformed' the aperture grill by apparently criss-crossing some of the strips. Since it was trashed, I smacked it wih a mallet like I saw in San Diego. After several serious hits, the strips untangled and worked normally again. BTW the replacement cost on that CRT was $2000.

This failure was _not_ broad blotches but localized disruptions of only a few stripes.

GG

Was that bashing done with power on to the tube ? This rubber hammer bashing technique is near the bottom on my" to do" list right before I take the CRT outside and use it for target practice (a safe distance of course). On the other hand I might just stick the set outside when the temperature is 22 degrees below zero just to see what happens (the little strips should maybe contract a bit ). Also been wondering about trying a vibrator.

Try unplugging the degaussing coil and then degaussing it. I've seen Sony sets where manual degaussing didn't help until the degaussing coil was unplugged from the defective degaussing circuit.

I've seen Trinitron CRTs with aperture grill wires that were stuck together and it looks like sharp vertical lines of incorrect purity, not large areas. I've only ever seen it on a computer monitor. I think the wires are too far apart for this to happen on a TV.

The aperture grill functions exactly the same way as a shadow mask. It's just a sheet of metal with thin slits cut in it. A shadow mask is made of similar metal, but has slots or holes instead of slits. Andy Cuffe

snipped-for-privacy@gmail.com

Sure with power on. How else would you know when to stop?. BTW they were NOT taps but pretty solid hits. Of course you want to be VERY SURE there are no metal shavings or grit in the mallet !!

The BVM 1910 had a hi resolution tube to show noise in a standard def signal, similar to a computer monitor but with SMPTE phosphors. Consumer TV tubes have much coarser aperture which hides HF noise and is easier to build and has P22 phosphors.

GG GG