Damaged Sony PVM repairable?

[Nam]

Bought a Sony HR Trinitron PVM-14M4E on ebay for a good price inc. delivery. I know, probably not the best idea to have a crt shipped but after a fair while looking I could not find one reasonably local to me. So I took a chance.

Anyway it turned up yesterday by courier in a parcel taped cardboard box with a layer of bubble wrap and some more cardboard taped over the screen and the rear inputs. I unwrapped it to find that the screen had been pushed back off it's mounts, away from the bezel and into the casing.

My first thoughts were it has to have been necked due to this damage. I took the back off and had a look inside. The tube was hanging loose and all four plastic fixing points had snapped, but could not see any obvious damage to the neck or neckboard. After repositioning the tube just about into place on the bezel, I connected a source and powered it up to see what it would do.

It powers up, has sync but seems to have lost red. The colours it displays are green, blue, yellow, cyan, purple. I've degaussed it now multiple times but no luck (degauss button and power off/on). However if I hold a magnet 6 to 10 inches above the screen it displays full colour and convergence looks to be ok. I know it's not recommended to hold a magnet near a crt but at this stage I thought it was knackered anyway.

Anyone know if there's a possible fix? Is it worth saving, trying to repair? I've read about degaussing wands being a possible fix for colour problems, but I don't know whether it's relevant in this case.

[22point8]

Yellow is red+green, magenta is red+blue, so there might be some hope.

[Nam]

Thanks. Like I say if you change the magnetic field by holding a magnet above the tube all looks fine, full RGB colour is displayed. So I don't think any of the guns are completely shot (if you'll pardon the pun )

I've even tried turning the pvm upside down and degaussing again but it does not correct the colour issues. Would be nice to get this up and running as it looks like it was a nice monitor before the courier decided to use it as a bowling ball. But to be fair the seller did not indicate on the box it had fragile contents. There again the issues may well have been present before it was shipped, although it was described as fully working.

All thoughts and a advice appreciated.

Cheers

[fagin]

Can you take a picture of what the image looks like? I suspect the shadowmask has been damaged, which means its ****ed.

[Nam]

Can you take a picture of what the image looks like? I suspect the shadowmask has been damaged, which means its ****ed.

Will do mate. Not at home now. Might be able to get it set up again and take some tomorrow. After doing a bit of reading up, I suspect your ****ing right.

Thanks for taking the time to reply.

[Nam]

Pics added. I don't know if you can make out from the photos but the lower left 3 inches or so on the monitor actually displays correct colour. No coincidence that this portion of the screen is just above the internal speaker.

[fagin]

I would suggest the shadowmask is mullered.

The fact that the tube had been pushed back off it's mounts, suggests it's had some heavy impact - this is what normally causes issues with the shadowmask.

I've never had a set with a damaged shadowmask, so don't know if the fact that holding a magnet above it temporarily resolving the issue means the SM is actually not at fault.

If you can hear the degauss fire up (the "twang") I would suggest the SM is the problem.

[Nam]

Yeah, it does the degauss sound when powered up or hitting the button.

It's a real sod this though. Because when temporarily changing the surrounding magnetic field the quality and vibrancy of the full RGB image is fantastic.

You don't think there'd be any chance that a degauss wand or purity adjustment could help? The anode lead was very close to one of the rings when I opened the casing.

[22point8]

As you have nothing to lose, try a factory reset:

Press menu.
Press Enter+Degauss.
Hold Blue Only until it says 'Factory', then press Blue Only again.

[fagin]

The factory reset has no bearing on type of issue. But as you say.... nothing to lose in reality.

[fagin]

You don't think there'd be any chance that a degauss wand or purity adjustment could help? The anode lead was very close to one of the rings when I opened the casing.

The shadowmask effectively filters the colours that are displayed. A magnetic field will bend the beams and in the case of a damaged shadowmask, enable a temporary alignment "fix"...... trying to do this across the whole tube will be impossible if the shadowmask is mullered over an area. Hence why it's unrepairable.

By all means try a wand... personally, if it's the shadowmask, you're wasting your time. You can always give it a go..... it won't make it any worse. You don't need a wand for this though, you can use something like a transformer..... there is a process you need to follow though, whether you use a wand or any other type of magnetic field.

[Nam]

By all means try a wand... personally, if it's the shadowmask, you're wasting your time.
.

Agreed, IF it's the shadowmask then that's the end of it. But of the handful of times I've seen shadowmask damage the colour distortion has been non-uniform, like a rainbow effect, some wave patterns affecting the portion of the screen where the mask has broken. Not like this where the image itself looks good across the entire screen, but with some portion of colour missing. Hence I hoped that it may not be so terminal.

Anyway thanks for your thoughts, much appreciated.

[fagin]

Valid point... I can see a moire effect on your screen shots and assumed that was the shadowmask damage.

Give a demag a go.... you won't lose anything in reality (OK perhaps a few quid if you have to buy one).

[Nam]

Valid point... I can see a moire effect on your screen shots and assumed that was the shadowmask damage.

Give a demag a go.... you won't lose anything in reality (OK perhaps a few quid if you have to buy one).

No moire at all, other than the f'd up colour the picture looks great. I'd be far less p'd off if the image was total crap to be honest. The moire is just the way the camera has captured the image refresh and probably made to look worse by resizing the photos for the forum.