Color Classic Inverted

[techknight]

You cant measure ohms while the machine is running! thats how you blow shit up. 

That thermistor should get warm. So that means current is flowing through the degaussing coil. Possibly. When you first plug power in while everything is cold and flip the switch you should hear that coil go DOOIINNKKK and out. itll be fast. 

With the machine on, and picture on screen. Unplug the degaussing coil and see if the colors jump or shift on the screen to a complete 180 of where they are now. 

If it does not, and the thermistor is getting really hot then you may have a shorted coil. 

Worst case scenario the aperture grille could have gotten knocked loose or shifted during shipping and thats permanent and cannot be fixed. 

Also, when the computer is off, as long as the mains is connected and the switch is on, that circuit is constantly getting power and it will stay on and stay hot IF there is no cut-out relay. I will have to check and see if there is one or not. I cannot remember. 

 

[just.in.time]

You cant measure ohms while the machine is running! thats how you blow shit up. 

I never knew this tidbit of information, good to know!

On the possibility of damage during shipping, that may be it.  The top right corner of the bezel got cracked from the edge of the crt diagonally up to the top right edge of the case, looking at it from the front.

As for unplugging the coil, it seems to have no change on the picture.

If we do come to the worst case scenario you mentioned, hopefully UPS shipping insurance will actually do something to help acquire repair parts :'( .  I held onto the boxes since they were so heavily crunched.  I was amazed that the 2nd Color Classic didn't smash the LC575 board in the box they were sharing.  Both bubble wrapped pretty well, but that box also took quite a beating  >

 

[CelGen]

I've only ever run across a loose aperture grille once before. It's pretty rare to happen as usually that much phyiscal trauma breaks the glass envelope or the inertia in the deflection yoke necks it instantly.

You can try putting one color classic up to the other and using its degaussing coil. Never done it that way but if the field is strong enough it will work. Another thing you can try is looking for an electronics repair shop. There's still a few of them left. At least one will have a degaussing coil.

In the end though if you're desperate, see what waving a magnet around in front of the tube does. I had a situation years ago where a stereo speaker magnetized a TV in random spots and I found twisting a magnet over the magnetized points could help clear it up. It's not a permanent fix but in the end nothing beats a proper degauss.

 

[techknight]

Depends. You can take a high load of G forces against the face, knock loose the shadow mask/aperture grille and not affect the CRT in any way. The front glass is much much thicker than the bell, or the neck. It depends on where the impact is. 

Sure, I will agree its rare, I have only seen a few cases, But it does exist. It would royally suck if yours met that fate

If your color "blob" is near the vicinity of the impact, then most likely that is the cause. 

Anyways right now this is all speculation. The only way to really make sure your tube is any good is if you unplug the factory degaussing coil, and purchase/find/borrow a manual degaussing coil and see if you can clear it up. Looking at the CRT Neck pictures, your purity and convergence rings are still right where they are supposed to be so we can rule that out.

Last ditch check: Make sure the yoke hasnt slid back on the neck, it will cause this symptom as well! But it would have affected the convergence as well but I dont see that. 

 

[just.in.time]

Techknight: Tried the ultimate experiment to see if it was the degaussing mechanism on the damaged CC.  I sat them next to each other, unplugged the good unit's degaussing coil from the analog board, and plugged the bad unit's degaussing coil into the good unit's analog board.  I left the good unit's degaussing cable unplugged during this test.  I let the computers run for one minute before shutting both back down.  Unfortunately, bad computer showed no change.  See attached photos:



With that test complete, I think it's safe to say that the degaussing circuitry on the analog board of the bad system is most likely functioning correctly and not the source of this problem.  Also worthy of note is that immediately after shutting down and unplugging both systems, the thermister cube's temperature felt the same.

Assuming that it is the actual degaussing coil around the display that went bad:  How does a length of wire stop working?  Isn't the coil just a run of coper wire?

How do I check the yoke?  Also, maybe it is a capacitor issue on the analog board?  I'm running out of ideas.

 

[techknight]

If the degaussing coil was bad, the thermistor wouldnt heat up. If it was shorted, the thermistor would heat up and stay hot about equally as to the good one. But it would heat up much faster. 

If you measure the ohms between both coils, they will be very close if not the same. 

Unfortunately, the further this goes, the darker it seems to take it. More and more looking like the CRT is bad. 

Since you have the 2 machines, swap the analog boards. 

 

[just.in.time]

Hi everyone.

Update on where we are at.  It's been a busy weekend with life stuff.  I got a hold of the seller and we compared photos of the unit before and after.  It definitely took a hard hit during shipping that cracked the outer bezel of the display, and I'm guessing potentially damaged the CRT as well.  I'll be contacting UPS today to see what the options are to get the unit repaired.

 

[techknight]

You cant repair it unless you can find another CRT. 

 

[just.in.time]

Yes, sourcing a new CRT may be tricky.  I submitted the claim to UPS, will see what they say.  Luckily I still had the packaging that it came in.  When I hear back I'll update here regardless of the outcome.

Thank you everyone for your input, suggestions, and help along the way of this battle to get regular color restored.

 

[just.in.time]

Does anyone know where the Display Service Utility can be located?  It is referenced in the service manual, but I can't seem to locate the software anywhere.

I found an old earthlink address that had the file listed, but the download appears to be broken.

In the garden, it doesn't appear to be there as a lone item.  Has anyone found it on a system disk there?

Thanks.

 

[Bunsen]

Try putting the link you found into the Wayback Machine at archive.org.  Sometimes you can get lucky and they've archived the download.

 

[just.in.time]

Sorry, I never replied back to this thread. It actually was in the garden.

 

[just.in.time]

Late update to what ended up happening to this CC.  I didn't want to do too much tinkering until after the shipping company paid out for the insurance.  After following the procedure, they did indeed pay out so that was nice  Still unfortunate that the world is now short one 10" Sony Trinitron CRT :-/  At least I got my money back though!

On to the machine.  I ended up pulling the analog board, doing the 640*480 mod (http://colourclassicfaq.com/general/vga.html).  It was very straight forward and doable, even with my beginner level soldering skills  Installed the modified analog board into the good Color Classic and it worked great (after some video adjustments).

At long last, I can definitely say that the CRT internals were damaged during shipping, most likely at the same instant the top right corner of the bezel was cracked. TechKnight, you were unfortunately right on the CRT taking irreversible damage