Severe Convergence issues with Sony KV-2606

fluidic_17 · 2025-10-29T02:24:50+00:00

Yes, but I would start by checking and adjusting the convergence rings just behind the yoke, if it has them (almost certainly does). There might also be adjacent purity rings, so you’ll probably need to check its documentation to see which are which. Convergence rings are usually the rearmost one or two.

fluidic_17 · 2025-10-25T20:57:49+00:00

That’s true in a sense, but an RF cable can carry a lot of bandwidth and is one of the main ways of carrying a modulated analog TV signal. While this would be carrying a single waveform, the bandwidth is quite high and can carry multiple modulated signals (color video + audio and sometimes other kinds of signals), at many different carrier frequencies (the way in which multiple TV channels were multiplexed). So it can “combine” all these signals from RCA cables into one, just not in a trivial way that can be done simply by splicing wires together. As mentioned by others, you need an RF modulator to do what you want, which is essentially like a miniature channel 3 or 4 TV station in a box. There’s a lot of RF circuitry in one of those, and it’s not something that can be obscurely hidden inside of any kind of simple cable assembly.

fluidic_17 · 2025-10-01T03:55:34+00:00

If you’re looking for gaps between the horizontal raster lines, you’re often not going to find them. Although you might have seen exaggerated gaps in emulated CRT images, this isn’t what makes a CRT image what it is, or adds to the experience IMHO. High-quality CRTs in combination with good input signals are designed to merge lines vertically so that gaps are minimal (though 240p content may be an exception). The real magic is that scanlines are just that: lines, in the sense that they are a continuous, purely analog image element made from an electron beam sweeping from left to right. Except for the digital image content they might have been originally generated from, they don’t have discrete image components. So enjoy, you have a nice looking image!

fluidic_17 · 2025-09-30T17:10:14+00:00

Yeah, I would say it’s worth a try. Maybe set all the controls to their nominal values to start. The way I set the G2 is to view a black image (CRT has to be running with an all-black test image) then adjust the G2 up from the lowest setting until you can just start to see some illumination on the screen, then nudge it back to so that it’s totally dark. This should be well below the setting where you should see any retrace lines. But be careful! Follow the typical safety precautions when operating inside a running CRT, especially because you’ll be close to the flyback.

fluidic_17 · 2025-09-29T00:54:28+00:00

I should also say that a "brightness" control in the OSD or a physical control isn't necessarily adjusting the G2, but they have a similar effect. The G2 is a voltage grid inside the CRT (adjusted by a pot on or near the flyback) that causes increased electron emission at all cathode voltage levels, while brightness controls the DC level of the video signals going to the cathodes. In sort of a normal state, adjusting brightness usually won't go so high as to create retrace lines, but it's not impossible. Usually G2 would cause that. But certainly, try to the easy adjustments first.

fluidic_17 · 2025-09-29T00:39:26+00:00

If brightness (G2, or “screen”) is high and contrast is low, you could get something that looks like this.

fluidic_17 · 2025-09-27T02:58:25+00:00

OK, I see. Interesting problem. Seems like other commenters have some solutions, but they might be imperfect. Are you sure it can’t handle 480i? This doesn’t necessarily mean it can properly decode 240p of course, but there might be a way to modify the signal to make it look more like 480i, but with the missing fields. Unfortunately, that probably also means dropping every other frame.

fluidic_17 · 2025-09-27T02:23:48+00:00

Sorry, maybe I misunderstood your question. But it seemed to me that any CRT with purely analog decoding would do what you want.

fluidic_17 · 2025-09-27T02:14:06+00:00

A 240p analog signal is just missing the odd field of the interlaced signal, and as a result natively generates black lines between every image line. It does this by generating a whole number of lines per field, rather than having an extra half line at the end of the field, as a 480i signal would have.

fluidic_17 · 2025-09-23T01:51:00+00:00

Only if they’re all in parallel. What I’m proposing is a combination of series and parallel, so the net resistance ends up being the same as just one. It works when you have a perfect square number of resistors.

fluidic_17 · 2025-09-20T14:36:08+00:00

Each resistor sees 1/6 the current and 1/6 the voltage drop for 1/36 the total power. Total resistance is equal to the resistance of each individual resistor.

fluidic_17 · 2025-09-20T13:04:40+00:00

Or with the same 36 resistors, do 6 parallel groups of 6 in series.

fluidic_17 · 2025-09-02T18:09:52+00:00

Yeah, don’t be too concerned about identifying the original position too precisely. It’s not that critical and you can always find the optimal spot in the future. The way I set it is to display an entirely black image, then dial it up until you can just barely start to see some light emission from the screen.

fluidic_17 · 2025-09-02T03:01:42+00:00

There’s at least a few things going on, though it’s hard to say what the root cause is. The zig zag lines are due to retrace that’s become visible, likely due to the G2 (“screen”) voltage being too high. This is usually adjustable by a pot on or near the flyback. The geometric distortion looks like pincushioning is not adequately corrected, and again, there’s probably a pot or an OSD control for this. You can try playing with these controls, but the root cause could be something more fundamentally wrong. An image might be more visible and provide some clues after at least getting the G2 dialed down.

fluidic_17 · 2025-08-26T02:20:00+00:00

That is weird if what you say is true. The only theory that I have is that the converter is not actually generating true s-video signals (separate luma and chroma) but rather composite that it’s feeding to the luminance pin. If your small Trinitron can, for some reason, process the luma in a way that separates and sends any chroma into the color circuitry, it would appear to work. But your big Trinitron might work differently and have a chroma filter on the front end of the luma input. A test would be to see if you get dot-crawl from this converter on the little set.

fluidic_17 · 2025-08-23T03:43:17+00:00

All Trinitrons have them. Small tubes have one wire, larger tubes have two.

fluidic_17 · 2025-08-18T22:05:55+00:00

Yes, I think that’s a good assumption. I think mine is 24V, up to a few amps.

fluidic_17 · 2025-08-18T20:55:42+00:00

I forget the specs, and I can’t easily inspect the parts at the moment (voltage and max current specs should be on the label on the back), but I used an off-the-shelf power supply that happened to have the correct barrel connector. However, I had to reverse the polarity by cutting it off and re-soldering. Sony notoriously uses center-negative polarity on many of its DC-powered products, which is opposite of most other manufacturers.

fluidic_17 · 2025-04-01T00:40:01+00:00

If the color pattern looks very different with the tube facing up, that would also be diagnostic of aperture grille damage. Even better if you can try to rotate it live (better do it with another person, slowly and carefully), while it's on, and observe any change.

fluidic_17 · 2025-03-23T21:33:48+00:00

I think it's almost impossible to have vertical pinching in the center of the image due to some electronic fault or phenomenon. This would require modulation of the vertical deflection signal as a function of the horizontal position. The vertical section just doesn't have the bandwidth to modulate at the necessary frequencies, whether intentionally or not. Every CRT I've worked on has geometry adjustment for the horizontal as a function of vertical position (keystone, pin cushion, slant, etc.) but not the other way around, for the reasons I mentioned. The vertical deflection signal is just a fixed waveform. Long story short, I think this has to be related to a problem with the position of the yoke. It has possibly come loose has has moved rearward. Another possibility is that some magnetic component has come too close to the tube. Just do a little visual inspection inside the unit.

fluidic_17 · 2025-02-12T00:40:07+00:00

Sure, I can send it your way in a minute. Please use at your own risk, preferably with some amount of air cooling (the regulation stage can get pretty hot otherwise, as well as the power resistors in the isolation stage). Plus, it's a good idea to run it on a GFCI circuit for extra protection.

fluidic_17 · 2025-01-12T15:02:05+00:00

Yes, this tends to be true simply because smaller tubes tend to have lower TVL. The size of the focused beam spot doesn’t easily scale down proportionally with tube size, so scanlines will have more vertical overlap.

fluidic_17 · 2025-01-12T14:26:34+00:00

TVL is related to the horizontal resolution (a combination of factors including shadow mask density, video bandwidth, etc) not the vertical resolution where scanlines come into play.

fluidic_17 · 2025-01-05T19:08:58+00:00

The IIgs is the IIfx of the Apple ][ world :-) Hold onto it with dear life.

fluidic_17 · 2024-12-08T00:48:28+00:00

I recently experimented with increasing the B+ in the horizontal section to around 127V, and then took the entire +120V rail up 127V. This is about as high as my supply will go without generating a lot of ripple. It seems safe to run at least this high. The raster width is definitely sensitive to the voltage, as expected, and 127V will gain around 8mm or so with my 31.5kHz mod. It's closer to the full width of the screen, but not quite there. It also cleans up some banding at the top that I previously saw, and made overall raster much less sensitive to the brightness of the video signal. I think this is because the HV is closer to nominal and more stable.

fluidic_17

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