BVM 1911 help

[Aer Fixus]

So, I got a BVM-1911 today. I paid a fairly large amount for it (especially considering I should have expected some other issues) and I also knew I couldn't get returns on it. Fixing it is my only option (aside from reselling it for less than I paid). Soldering is not a problem. Diagnosing things isn't that big of an issue for me (although I don't have a proper transistor tester), but there are a LOT of boards in this thing and if I can get an idea of where to start, that would be amazing and would save me tons of time.

It has a couple issues that I'd like to solve. If I don't get a solid answer, I'm probably just going to recap the whole thing, however many caps that is (it's got to be close to 200) and however long it takes. To me, all these problems sound capacitor related in some manner. I'd love it to just be a cold solder joint, though.

Issue #1: On powering on, the screen turns blue and has diagonal lines in it. Almost exactly like this image (not my image. I couldn't get a good image of my set when it was doing it)
http://i41.tinypic.com/29fczlk.jpg
http://www.overclockers.com.au/wiki/TV_ ... _Diagnosis says it might be a faulty drive transistor, although mine is only temporary (only about a second, then it fades into the proper image that should be displayed), which makes me think that a faulty caps is letting too much power through (or too little) and causing it to share symptoms of a bad transistor or IC.

Issue #2: The overload light comes on when I turn the unit on, but almost immediately goes away. My suspicions again of a bad capacitor (or multiples). There could also be a bad voltage regulator somewhere. The boards are decently hard to get to when all together in the monitor, so testing any I find might be an issue.

Issue #3: Convergence. I purchased the system knowing the convergence was off. I thought that maybe I'd just be able to fix that with the knobs in the tray. However, this is as far as I've gotten after a few hours of tinkering back and forth. It's fairly consistent vertically, but otherwise, it's no where near good enough. On the left the convergence is off (red left). In the left of the middle, the convergence is fine. In the middle, the convergence is off in the opposite direction (red, right). Then good again, then bad again (red on the left). The knobs on the unit don't go far enough for me to adjust it any better. Adding more (or less) resistance to the knobs might solve my convergence problem, but this unit's problems certainly stem from something, so just tacking on resistors isn't satisfactory for me. Although it would look good, there would still be something wrong.
http://i.imgur.com/J0DgZL0.jpg

Issue #4: Screeching. This isn't the 15/16khz whine, this is lower but yet still high pitched. And it changes pitch, too (and at random and not really all that much). After the monitor warms up, it doesn't make this noise. (once again, the problem solving itself after warming up is a typical capacitor thing in my experience, but I don't work with CRTs that often. It's usually game systems, receivers and flat panel displays.)

Thanks a ton,
Aer

[Xan]

That's a really tough one you have there; not sure the purchase was worth it if you knew it had issues, especially if you paid a lot. Another issue for the list seems to be a slightly slanted picture to the left from what I can tell, possibly due to the yoke having been shifted if it was shipped. Artemio's 240p suite has a grid pattern which makes this easier to diagnose. Hope you have the service manual for it?

Have you tried reducing brightness to see if it affects those diagonal lines on powering on? Wrongly adjusted G2/screen voltage seems to be a common cause of this on many monitors (if recapping doesn't fix it), although in your case they aren't permanent though...

Haven't heard about whine pitch changes at random, though I do have a monitor which changes pitch depending on input.

[22point8]

Issue 1 looks like screen volts (G2) is too high.

Here is a service manual http://1drv.ms/1GwfwpV its for the BVM 2010P/PD/PM/PMD but should be close enough.

[Aer Fixus]

Honestly, it probably wasn't worth what I paid. However, I did know it was a gamble. I purchased it from a seller who clearly had no clue what they were doing so I assumed from the pictures that the convergence adjustments were just off. It was also the only thing described as being bad. On the other hand, I like projects, so if I can actually fix it, it would be another learning experience for me to add to my fairly long list of "mistakes" that ended up turning out fine.

I did notice some components that looked slightly scorched (but not at the traces). I'll be replacing those for sure. There were also some caps that almost certainly got very hot just because of their location. Whether or not these caps were rated for very high temps, I didn't check. I couldn't see any popped or leaking ones, but they could still be dried out.

The tilted image is partly my fault. That's after messing with the image for a while. When it was "good enough" for testing and trying to improve the convergence, I didn't touch it anymore. The calibration was off when I got it, so I'll check and see if the yoke is shifted any. Would that effect convergence as well? Also note, the vertical convergence is basically-spot on, so whatever effected the convergence only effected the horizontal convergence.

Also, if I'm reading this right, this unit only has 4348 hours on it? or is that the build number for the software revision? I'll check that number after messing with it a bit more and see if it goes up. http://i.imgur.com/ppxSLBV.jpg

Issue 1 looks like screen volts (G2) is too high.

Here is a service manual http://1drv.ms/1GwfwpV its for the BVM 2010P/PD/PM/PMD but should be close enough.

I'll definitely look into that. I'm sifting through the manual, now.

Thanks for the help so far!

Edit: the screeching seems to be influenced slightly by what I do with the unit. Over time, tt screeches no matter what then goes away, but if I swap to 480i, it starts faster. Swapping inputs can cause it to change pitch, but not always. Every time it eventually goes away.

This might be a bad (or failing) inductor. I'll look more into it after I solve the other issues and if it still exists. I'd prefer not to have to deal with that right now as I don't have to proper equipment to test for a bad one (unless it's something obvious, like burn marks or cracked solder joints).

[Xan]

I'm surprised even seeing a OSD on this monitor, I was pretty sure PVMs from the same time frame (late 80s/early 90s?) didn't have that.

About the rotation, could well be that it was delivered with that flaw and you just didn't notice it until making your adjustments, particularily v-pos can make it more or less noticeable.

[Aer Fixus]

This model is from 1993.

A few more notes on the monitor that I remembered. When I got it, the right side of the screen was discolored. I adjusted the knob on the neck and it fixed it. It also shifted the screen over to the left, so I readjusted that using the horizontal offset. I also adjusted the knob on the high voltage block to help with the discoloration and fine tune the convergence so I could get it as close as I did. They have the old positions painted on, so I can reset them if need be (or if someone tells me that it's actually harming something).

And I think the rotation is just a trapezoidal adjustment*. Even if the yoke did shift, if it stays in place from now on, would it be bad to adjust settings around it as I've been doing, or should I try shifting it back into place? That might have happened before I purchased it, too. It was VERY well packed. And it was oriented face down (with plenty of padding and instructions to keep it oriented that way).

Is the G2 on page 56 the one I'm looking for (I assume so). I'm just skimming for now. It's late and I'll read it more in-depth in a couple days when things are less hectic.

The manual refers to the convergence yoke that effects the vertical convergence, not horizontal convergence, I'll keep looking for an adjustment that effects the spread of the horizontal convergence. That's the only thing I need to fix to make it look perfect, the other issues aside (and the trap adjustment). Reading about CRTs is pretty interesting and kind of fun. Another reason for my boss to call me nerdy . A lot of adjustments require an oscilloscope, then I remembered my local maker space is getting one in soon-ish, the only problem is transport (I'll figure that out later).

*maybe it is rotated... Looking at it harder, the sides are slightly off as well, although that could still be pin adjustments to fix that. I'll still look at the yoke when I get the chance.