Monitor Swap Questions

skforty

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I just picked up a couple 19'' monitors from goodwill. One is a cr-31 with vert ohm 15.9 and horiz ohm 3.7. According to http://www.junknet.net/donor-tvs the sharp xm-1801 is a cr31 with 15 and 2. How close do the values have to be to perform a tube swap without swapping yokes? Or do they have to be perfect? Thanks in advance!
 
That's probably close enough, but I have yet to find one of the "close enoughs" that gives a perfect image geometrically. Usually there is a little bit of keystoning or pincushioning going on that won't adjust out. Sometimes it's so minor you can live with it. Sometimes it's just enough that it bugs you a little.

I had one that was damn close for a K4600 swap, but off just enough to bother me. I swapped on the actual 4600 yoke and it got better...
 
So i ended swapping several tubes, including the one i mentioned above. It was pointless of course, i knew that going in, since the monitor is for my red tent, there is no way a 19'' would fit. But it did look pretty damn good. Couldnt adjust the Horizontal out enough to fill the screen though (stupid coils). Actually the best results i got for the night came from a current-ish (2004) toshiba flat screen CRT 20'' that was almost DEAD on H&V wise. i put it inside my single monitor playchoice that had came stock with the zenith tubed k7000. After adjusting screen, it looked AMAZING (Forget mounting with normal frame though). But just like you said modessitt, the geometry was a tiny bit off, and in this case it, it had crossed the "bugged me too much" line. Fast moving horizontal or vertical movements (See EVERY nes game...) had a bit of a curve that popped when scrolling.

I'm just going to give up on the toshiba tube swap, but my question is, what can be done about the geometery? In this case, yoke swap wouldnt work. Is it the direct value delta in ohms that causes this? Would adding resistors to match the desired levels fix it (ive seen tubes with resistors on the yoke)? Playing with the rings? Service MAgnets? In this case, the chassis doesnt seem to offer any pin/trap adjustments.

Thanks for the advice. After staying up way too late, and swapping 5 different tubes on 5 different monitors...modessitt was spot on with his assessment. Using the "close enoughs" are great for people who have games on routes or for people who arent as picky. But for my games im trying to get PERFECT, gotta find a direct match i guess...
 
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