Sony BVM-20F1U Geometry Issues

[TerakRall]

Hi all...been lurking here for a little while and want to thank everyone who's posted about the Sony BVMs...made my decision to pick one up last week an easy one. I picked up a BVM-20F1U with about 35,000 hours of use time and have been trying unsuccessfully to tweak the geometry for hours and hours. I've included some pictures here...basically there is an "indent" of some kind on the left side that is most apparent when scrolling vertically - the image seems to stretch and distort around that point, then come out the other side ok. There's also some stretching in the lower right corner. I'm using an original SNES with a SCART cable and a SCART to RGBs connector from Retro Gaming Cables. The grid pattern is from my Wii running the 240p Test Suite via component and shows the same geometry issues. Those of you with lots of experience with these monitors...is there a simple tweak I'm missing or a series of steps I can follow to troubleshoot? I've been going with trial and error and have been unable to resolve these last lingering problems.

The thing looks freaking amazing on my RGB-modded NES and my SNES and I would love to resolve these annoying geometry issues if possible...thanks in advance for your help!

[Skips]

Dips like these are typically caused by failing capacitors (but not all the time). I would start with replacing all the capacitors on the deflection card. That is the card with the huge ass heat sink that goes down the entire length of the card. That is not a problem you will fix in the service menu.

Also id ask the person you got it from if they know if those 35,000 hours are on the electronics or the CRT itself. Sony replaced the CRT's in these monitors every 30,000 hours (of actual use the CRT received) as part of its maintenance cycle. If the CRT is in fact the original one 35,000 hours is a ton of time for it. That is of course assuming it was actually used most of those hours and not left on in standby mode. The hours of operation in the service menu counts standby hours.

[TerakRall]

Thanks for the reply...have been doing some quick research into soldering components on a board (something I have zero experience with)...I guess I will have to decide if it's worth taking the risk of damaging the deflection card or if I can just live with it. Is it a relatively easy procedure to replace any blown caps?

[TerakRall]

Have confirmed with the original owner that the CRT is the original (was not "re-gunned" in his words) but that the 35,000 hours includes a fair amount of standby time.

Will pull the deflection card and take pictures when I get home this afternoon.

[Skips]

Thanks for the reply...have been doing some quick research into soldering components on a board (something I have zero experience with)...I guess I will have to decide if it's worth taking the risk of damaging the deflection card or if I can just live with it. Is it a relatively easy procedure to replace any blown caps?

Caps will go bad without bursting. I believe the caps on these types of BVMs use surface mounted caps so they are slightly harder to replace if you have never done soldering of surface mounted components.

[TerakRall]

Ok...first off, here's a GIF of the grid scroll pattern showing the "dip":



Second, some pictures of the deflection board. I am admittedly a novice but everything looked pretty pristine to me...didn't see any burst caps, and only saw 2 that weren't at perfect 90 degree angles (in the upper right hand corner of the first picture and zoomed in on the second). Are there known, specific capacitors that are problematic or would it be a replacement of every single one (something that looks like a VERY daunting task)?

[Xan]

The issue you are talking about seems not that noticeable to be honest. Just about every CRT has some geometry imperfections and this isn't among the worst ones. Did you try shifting the image to the left a bit? All of your pictures appear rather greenish to me though, but I don't know if that's just due to the camera.

About the caps, I'd do all the through-hole electrolytic ones first since they are the easiest to replace. It's possible to measure ESR and capacitance but the cap needs to be desoldered first I believe. Would be interesting to see how these stack up after 35k hours. And yeah, these Japanese caps usually won't leak like CrapXon and other junk in cheap PC PSUs, but can still cause issues, even due to presumably improper design. There was a guide around for a common issue with M-series PVMs which suggested swapping out some caps with different value ones, though the site doesn't seem to be around anymore.

[TerakRall]

The issue you are talking about seems not that noticeable to be honest. Just about every CRT has some geometry imperfections and this isn't among the worst ones.

Yeah, that's kind of where my thinking is at as well...I've tried showing pictures of the problem to some friends and most of them haven't seen the problem. It's most apparent playing vertical-scrolling games like RPGs, but I think I could learn to live with it. The rest of the picture is just so fantastic. The colors in the pictures are more washed out than in person...I used the 240p test suite and color-calibrated using the blue-only mode and the SMPTE color bars.

[Ed Oscuro]

It's possible to measure ESR and capacitance but the cap needs to be desoldered first I believe.

Yes, because nearby traces and components provide excess capacitance. Might as well buy a new cap and solder it in if you're going to desolder them.
In some cases you can detect bad caps with other means, i.e. checking for shorts (really low resistance) or caps that have failed open, which shouldn't require desoldering. But this won't show whether the cap is really up to spec.

Isn't this something that could be fixed by tweaking the magnet positions?