Need help after recap my CC with successfuly boot start chime- CRT show scattering smal and big black spots patches.

[MACTRO]

Hi, my latest collection cc has run thru clean,visual & multimeter check and recapped both Logic and analog board.
Moment of truth powerup successfully with happy chime, CRT show mouse cursor and icon D0?
Except it has horizontal line, big and small scary black spots patches scatterting all over.
My googling all over show no info about this CRT condition. Is my cc doom beyond further repair.
Need help on this.
Thanks

 

[AwkwardPotato]

For the horizontal lines: since the analog board has been recapped, you will need to redo most of the picture/geometry adjustments. Apple's own service guides explained how to do this step-by-step, go to the "Adjustments" section in the Color Classic guide. The lines on your machine will most likely be resolved by the G2/sub-contrast controls. If a section of the guide calls for using a light meter, adjust the control until the picture looks "about right." Ignore any section about yoke adjustment unless strictly necessary. As always, please take all necessary precautions around high voltage.

For the black spots: that is truly bizarre. Make sure the degaussing coil is plugged into the analog board. If it already is, you may need to purchase a degaussing wand to see if that clears up the spots. Hopefully someone else with more experience can chime in here

 

[MACTRO]

Hi, my latest collection cc has run thru clean,visual & multimeter check and recapped both Logic and analog board.
Moment of truth powerup successfully with happy chime, CRT show mouse cursor and icon D0?
Except it has horizontal line, big and small scary black spots patches scatterting all over.
My googling all over show no info about this CRT condition. Is my cc doom beyond further repair.
Need help on this.
Thanks

 

[cheesestraws]

Those black spots are absolutely weird. Never seen that before. It's like someone shot the screen with a shotgun loaded with magnetite or something. You can try degaussing the screen but personally if I saw that on a CRT I'd be feeling rather glum about its future prospects

 

[MACTRO]

I'd tried knocking the screen with a rubber mallet hoping to knock some dust or particles that may have stuck on the inner screen. Nice try all dots doesn't buckle. Spots seem to say burn mark rather that blocking debris.
Arcing and humming was heard too during my 1st powerup, Today, power up again without casing in the dark, traced the arcing noise from tube neck. Humming from highvoltage flyer. tweaking G2/Sub is only win that contrast better but horz.line remain.
Seem very challenging.

 

[AwkwardPotato]

Take the neckboard off the back of the CRT and see if you can remove the shielding. Make absolutely sure there's no debris/crud/burn marks anywhere on the neck board, especially around the CRT socket. Also check around the base/pins of the tube itself. You may want to use a multimeter to check for shorts between pins on the neckboard socket or pins on the tube.

EDIT: Did the screen look like that before the analog board was recapped? It would be a good idea to check the analog board for cracked solder joints, fairly common when the board has been handled a lot (like it is during recapping). Pay close attention to the area around the flyback transformer. If you can hear arcing coming from the neck of the tube, and the neckboard turns out to be fine, the tube may be shorted internally (or perhaps the focus/G2 block in the flyback is bad).

 

[MACTRO]

Neckboard appear clean both inside/outside, resolder broken solder joint from shieldcase to neck board No schematic or tube pin knowledge to test shorts, 3 pins on tube beep in cont' test do appear related after tracing visually into the narrow glass tube. Attempt remove yoke for cleaning seeing from youtube that look easy, not successful to pull yoke out, run thru board again for any bad soldering, Using back 3 big caps that I did not re-cap 2x5600uf 10v &1x`330uf 400 WV,tested good, tested RF11 390 ohm that look dirty and it's good. Coudn't get low profile 3300UF 16V Short Fat cap, replaced with normal tall Cap. I don't think that is an issue.

Assuming AB did power up normally and show icon D0?, LB/AB should be in good state.
From tell tale sign continue arcing in tube neck and humming flyback.
Like you mentioned, it will be either flyback or tube.
I would narrow down a bad flyback, will the arcing in tube neck damage the CRT or it is also shorted?

Thanks

 

[AwkwardPotato]

Attempt remove yoke for cleaning seeing from youtube that look easy, not successful to pull yoke out

The fact that you get full deflection on the screen suggests that the yoke is good. Avoid moving it unnecessarily on these displays, otherwise you might throw off the convergence/geometry.

Assuming AB did power up normally and show icon D0?, LB/AB should be in good state.

The logic board may be fine but the monitor side of the analog board isn't necessarily OK. Either there's a problem on the analog board that'll need further troubleshooting, or the tube is just damaged. Seeing the spots on your display, I would start thinking about finding a parts Color Classic to salvage both the tube and the analog board from...

The lines on your screen are vaguely reminiscent of what would happen if the focus and G2 were shorted together. Would you be able to take photos of the component-side of the neck board and the solder-side of the analog board?

 

[MACTRO]

I'd sweep thru video side re-checking all caps,diode,resistor hoping to find shorted/bad cap but MM read them good. Con't replaced with new caps since I'd bought them. Replaced TDA8145 too. Re-check and re-check. Power up and tweak focus/contrast. Lines are gone, spots and sparks remain..... .sign. Only win to see at least screen is decent now with spark & spots. Neckboard seem to be clean and already check solder. Also notice spots can shift, glow or shrink. CRT shouldn't be burnt. Assume AB is good if you agree, it is between flyer or CRT. Flyer seem working since it able gave High V. but humming noise seem loud, Is that normal to be humming this way?

View attachment VID-20220916-WA0003.mp4View attachment VID-20220916-WA0002.mp4

 

[AwkwardPotato]

Glad to see that you fixed the lines. The humming from the flyback is definitely not normal. The arcing is most likely due to a bad flyback or bad focus/G2 network on the analog board, although it could still be a bad tube.

What I would do first: try setting up the Color Classic somewhere else in your home, and see if that clears up the spots and the green bottom-right corner (in case there's magnetic interference where you're using it right now). If that doesn't work, find a degaussing wand and see if that improves the picture.

Chances are, you'll need to find another analog board. They're not easy to get hold of, but getting a new flyback by itself is near impossible. Try using a degaussing wand first, though, to make sure the tube isn't permanently damaged, otherwise you'd be wasting money on the new analog board. You might even find it cheaper and easier to buy an entire parts machine, especially if the tube turns out to be the problem.

 

[MACTRO]

Appreciate the walk this far and apology for silience. Mystic path was the plan for this cc except CRT failing me. My 575 happend to arrive for attempt AB/Flyer swop test. Was a double whammy to received badly shipment handling. Impact was so great 14" CRT glass neck broke, neck pin broke.case crumble..etc. Only left good was AB/LB/Ram/Vram/KB/Mse. Was very heartache and disappointed moment to consider stopping. eBay was my saver..long story short...Was force to walk Kay Koba sacred path and converted succesfuly, harddisk booted to 0s7.1 after quick HD fix with , earphone rubber cusion. Thanks to K.KB detail step. all good except bad CRT. Tested 575 AB/Flyer CRT con't arcing & spots. Swopped CC flyer, no diff. but cc flyer was quieter. CRT is likely issue. Read about CRT leak can casue arcing, had apply super glue and blue tac along the neck cap, pin & any possible gap for sealing.....It works...arcing almost only once before 15 min gap initially instead wild, but now is not consistant..may seal leak again. Now left with only spots and lower corner bluish. Shifted location but no change, location is not issue. my degauser should arrive likely tomorrow. Anyway, will hunt for another CRT to fully complete this baby. Hopefully good CRT

 

[techknight]

the CRT is junk.

the arcing you see in the back of the neck are pieces of metal debris from the remnants of the aperture grille that fell apart in the front of the CRT, that are what those spots are, metal debris caught between the phosphor and the aperture grille.

It would have taken a very strong wallop for that to happen.

Replace the CRT...

 

[MACTRO]

Able to sustain with no arcing after adding more super glue and blue tac at neck cap and pin. Spots and lower Blue zone remain even degausse.
Really bad CRT.
CRT replacement plan on d way...Hopefully shipment handling don't fail me again....