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The PVM-2730QM thread (H-STAT issue, colour bleed, convergence and more!)


buttersoft

Question

This thread started about a single issue, but is devolving into a more general thread about PVM-2730's, so I changed the title. These are basically the same as the KX27HG1 and KX27HG2 sets (powersupplies are swappable but may not be identical) along with the Japanese Profeel sets that look the same. They are close cousins of the US PVM-2530's and possibly the PVM-2550's. Different revisions have S-Video, and the US versions have a DB25 plug instead of SCART. The Japanese sets may use JP21. The service manual for the 2530 shows it to be a bit different inside, with a ton of tiny extra circuit boards and different layout. Still a lot of commonalities though, but it will pay to note these differences and check the schematics before touching anything.

 

Hi all,

 

I have a KX27HG1 (same thing as a PVM-2730) with a CRT fault. It powers up when cold, and then after twenty minutes, or even longer if it's freezing in the garage, there's a click (normally) and the screen shuts down. The picture folds in like the screen has been powered down, but the rest of the set still works - indicator lights, sound, etc. If I power-cycle, the tube powers up again for maybe a second, and then goes down. If I wait 10-20 seconds and power up again, the picture comes up for a few seconds, but the colours are bleeding sideways, particularly red. Then the CRT loses power again.

 

There's definitely a buzzing sound the whole time the picture is up, and it's not as stable as it should be at 240p, and the brightness flickers slightly. There's a click sometimes as it powers down that might be coming from the HVT/flyback, or might be something nearby.

 

Also, the "Screen" adjustment, on the neckboard of this set, doesn't seem to do a lot, mostly just messes with colour gain, but no huge brightness adjust or retrace lines appearing.

 

I just recapped the electroyltics in the power supply, and the same thing still happens. Any ideas where to go next? I've found replacement flybacks online, I think, but I'm not 100% on that being the problem.

 

Help greatly appreciated!

Edited by buttersoft
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I don't believe these sets have any linearity adjustments. There are two more horizontal geometry options than the service manual lists though, but they're like shifted h-pins, and if you're lucky there's a parallelogram adjustment too. No vertical geometry tweaks apart from size,center though.

 

In my travels I've recapped the complete set of D boards, and it doesn't seem to help much with either geometry or convergence - as in, it's not a magic fix.

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I don't believe these sets have any linearity adjustments. There are two more horizontal geometry options than the service manual lists though, but they're like shifted h-pins, and if you're lucky there's a parallelogram adjustment too. No vertical geometry tweaks apart from size,center though.

 

In my travels I've recapped the complete set of D boards, and it doesn't seem to help much with either geometry or convergence - as in, it's not a magic fix.

 

Hmm, ok cause mine has pots on the yoke board that influence h-linearity.

 

Theyre all different and its a pain in the arse trying to figure out what can be done without being there and seeing what is available on that particular set.

 

I replaced all capacitors in a Sony CRT projector once, and despite the age of the set it made no difference what so ever. I found majority of them to be good quality such as Elna, and still well within spec.

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GOOD NEWS!! I have resolved both the vertical collapse and the loss of colours (esp blue).

 

To review earlier work, I changed R702, C766 and C704 on the neckboard © to address the colours issue. However, I was sick with some terrible stomach bug and, in my fevered state, I managed to put C766 in the wrong way around. Unawares, I turned on the monitor, heard a faint sucking sound, and got the vertical collapse.

 

I spent quite some time, many hours, poking around to try and identify the cause of the vertical collapse, but wasn't having much luck beyond noting that there was voltage at "VM IN" and no voltage at "VM OUT" or for nearby transistors.

 

So I decided to leverage my communications and Thai skills, and asked around in the local "big town" at the best electrical shop I knew. Turns out that there is a good electrician/TV guy (Wisadu) just a couple of doors down! I brokered an introduction and Wisadu and I became friends quickly. A couple of days later I loaded my naked Sony PVM2730QM onto the passenger seat of my ute, fastened the seatbelt and took it for an hour's drive into town.

 

After discussing the Sony's issues and history, Wisadu was able to track down the issue within an hour or so. When I had the cap in wrong, it caused a tiny protection resistor (R1572, 1.2R 1/4 watt) on the main D board, near the medium-sized transformer (T1513, outputting the 40v), to blow (thus protecting more sensitive/expensive stuff). Wisadu changed the resistor and, most amazingly of all, didn't even accept any payment.

 

Watching/helping Wisadu identify the problem was a pleasure in itself, he was so calm the whole time and located the problem without even a circuit diagram etc! I certainly learned a lot. However, I don't think he would have identified the colours issues with R702 etc, as when I described that problem to him he initially assumed it was the CRT colour guns starting to wear out (cathodes oxidising, blues go first). I assured him that was not the case (based on the experiences y'all have related to me here, and R702 being bad).

 

So, between the brains of all of us (and especially @buttersoft) we have collectively solved my Sony's problems. I'm very happy, I've got my blues back! Now I need to go write a song entitled "Baby, I've got the blues!"

 

I'm indulging you with some success pics. R1572 is on the big D board. Time Pilot is a good test image (1st stage of Time Pilot has a light blue background that disappears with the R702 breakdown). That Wonder Boy pic is a good one for colour purity (which is slightly out in top-left and centre-right, screen needs a good degauss with a wand).

 

All looks great, even better than before, but I've noted that minor geometry problems have moved. This isn't very surprising. Top-right looks good now, but was a tiny bit out before. Now the left side seems to have some slight pincushioning problem, (might be nothing, or possibly there is a dodgy cap somewhere). All this is adjustable of course. I will need to go over the RGB cutoffs and geometry again.

 

D_R1572.JPGSonyGood3.JPGSonyGood2.JPGSonyGood1.JPG

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Wow, that's awesome. This is another valuable piece of information going forward.

 

Gratifying to hear i trumped Wisadu on the colour bleeds, but i'm sure he'd have gotten there faster than i did. I thought it might be the tube aging myself, for a bit. And i certainly would have taken a shitload longer than he did to find the blown protection resistor, if i ever got there!

 

Great post, and glad to hear you got things sorted :)

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I thought it might be the tube aging myself, for a bit. :)

 

At first I thought that most likely as well. Yet as we can see, the CRT guns look as strong as ever.

 

10-12 years ago I refused an identical Sony PVM with "dead blue gun" for cheap (he still wanted $50). Now I think it was probably just R702 dying, could have missed a good deal for a good monitor. Ah well :D

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So I've still been working on geometry and convergence issues on my set, and I'm at a bit of an impasse.

 

First, to confirm, there is no Horizontal Linearity pot on this set, as mentioned may be a possibility above. I did resolve that apparent effect with some other adjustments (mainly horizontal shifting/convergence adjustments).

 

Here's my current issue. The top corners have very bad geometry. The PIN Phase and PIN Amp don't get anywhere close to correcting it. They go in the correct direction (it's arced inward, and adjusting them brings them in the right direction), but at their max setting I'm still looking at like 1-2CM difference between the top + on the grid and a few below it.

 

This is a crude sketch of what I'm left with, with the T.PIN (Top PIN setting) set to the very max. If the T.PIN allowed further adjustment I could correct this.

 

Grid.png

 

My questions are this:

 

- How can convergence strips and magnets be utilized on a frame such as this? This monitor has such a large metal cage that working near the yoke seems near impossible no matter how careful you are, yet my set does have 4-5 convergence strips stuck to the tube under the yoke (placed there by past service I'm sure), that I'd like to remove/replace/adjust. Can this be disassembled easily in a fashion where the set can still be running and calibrated? Anyone with experience with this?

 

- Second, does the fact that the PIN settings on the pots seem to be making only slight adjustments to the corners indicate perhaps that there are components (Caps or otherwise) that replacing may help?

 

I'm at a point with this monitor where the picture, while bright, clear, and beautiful, is only "passable" in the department of where I'd consider it acceptable for use. The top corners are so pulled in that playing virtually any game causes a noticeable affect in motion that is very hard to unsee. I need to decide if I'm going to to a full teardown and recap (which I've done with consumer and 14" PVM before, but never a set of this size), or if I'll decide to drive about 4-5 hours away to a very reputable service center for a full refurbishment.

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The main deflection board is the D board. D2 is the convergence board and D3 the geometry board. I've recapped two D2 boards, one time made a nice, if small, positive difference, the other time did nothing. I've also recapped a single D3 board while troubleshooting something else. I noticed no change, but i wasn't trying to fix anything geometry-related. I would say give it a go, there's less than 10 electrolytic caps on the D3 board, so it won't cost much to replace them. Also, check the pots are actually changing value correctly against the service manual when you dial them, and check for cold solder joints. You could also recap the D2 board. And then maybe the main D board as well, but doing so made little if any change to geometry for me. Again, i wasn't having a problem with geometry beforehand, so wasn't really looking.

 

The B, K, D and D2 boards will all fold out so you can work with a bit more room. They're all hinged. You do need to loosen all the cables first. After that, you just have to be delicate :)

 

Remember that convergence strips are for convergence, and the disc magnets are normally used for purity correction though they may affect convergence as well if placed close enough to the yoke. Neither is good for correcting geometry. If the convergence is good and the colours are fine, i'd leave the yoke and the rings alone for the time being.

 

EDIT: the thought occurs that you might be approaching things wrong. Put up a grid pattern like the 240p suite one. Then using the controls on the D3 board only, you're aiming for a rectangle first, with straight sides, even if that rectangle isn't the exact size of the screen. Once you have the straight-sided rectangle, or as close as you can get, you adjust the size and position via the pots on the main D board, using a thin screwdriver to reach through the holes on the outside of the board. This might be a little too obvious to have mentioned, and i apologise for that.

 

There is a page in the service manual with a shaded diagram that shows which board is which :)

 

EDIT2: Ok,i was at work and couldn't see the sketch before. I reckon you've already done everything in the right order as regards the adjustments you have, so next would be trying a recap on the D3 board. After that it might be time to check some voltages as described in the service manual, then at all the connectors on the back of the main D board, remembering that a lot of them are over 100VDC. Make sure you have a multimeter that's not going to fry at 1kV. Most newer ones will just shut off, but you never know.

Edited by buttersoft
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The main deflection board is the D board. D2 is the convergence board and D3 the geometry board. I've recapped two D2 boards, one time made a nice, if small, positive difference, the other time did nothing. I've also recapped a single D3 board while troubleshooting something else. I noticed no change, but i wasn't trying to fix anything geometry-related. I would say give it a go, there's less than 10 electrolytic caps on the D3 board, so it won't cost much to replace them. Also, check the pots are actually changing value correctly against the service manual when you dial them, and check for cold solder joints. You could also recap the D2 board. And then maybe the main D board as well, but doing so made little if any change to geometry for me. Again, i wasn't having a problem with geometry beforehand, so wasn't really looking.

 

The B, K, D and D2 boards will all fold out so you can work with a bit more room. They're all hinged. You do need to loosen all the cables first. After that, you just have to be delicate :)

 

Remember that convergence strips are for convergence, and the disc magnets are normally used for purity correction though they may affect convergence as well if placed close enough to the yoke. Neither is good for correcting geometry. If the convergence is good and the colours are fine, i'd leave the yoke and the rings alone for the time being.

 

EDIT: the thought occurs that you might be approaching things wrong. Put up a grid pattern like the 240p suite one. Then using the controls on the D3 board only, you're aiming for a rectangle first, with straight sides, even if that rectangle isn't the exact size of the screen. Once you have the straight-sided rectangle, or as close as you can get, you adjust the size and position via the pots on the main D board, using a thin screwdriver to reach through the holes on the outside of the board. This might be a little too obvious to have mentioned, and i apologise for that.

 

There is a page in the service manual with a shaded diagram that shows which board is which :)

 

EDIT2: Ok,i was at work and couldn't see the sketch before. I reckon you've already done everything in the right order as regards the adjustments you have, so next would be trying a recap on the D3 board. After that it might be time to check some voltages as described in the service manual, then at all the connectors on the back of the main D board, remembering that a lot of them are over 100VDC. Make sure you have a multimeter that's not going to fry at 1kV. Most newer ones will just shut off, but you never know.

 

Great info, thank you. I was completely unaware these boards were on hinges, but that makes much more sense. I should clarify, I do also have some slight convergence issues at the top corners which is why I mentioned working with the yoke. That's unrelated to my geometry issue up there.

 

Yes, I've been using the primary D board for adjustments (I see it referred to as the D board, not D3 in the manual, but perhaps different for the 2530 I have), it's as far as I can tell the only one that has anything related to geometry adjustment.

 

I was actually unaware of the D2 you mentioned, I think maybe the first step I may need to do is investigate this, because according to the service manual there are a few interesting pots there that are worth looking at. H.Tilt, Corner Bow, etc. I do have a very slight Horiztonal tilt, so that could correct another problem while i'm at it.

 

I think my next steps are probably going to happen in this order:

 

- Investigate D2

- Recap D (D3 as you called it)

- Re-adjust and test voltages.

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Jeebus, I'm really on the hook now. I would go with Soyl's advice first, then try mine :)

 

I have the service manual for the 2530. I had presumed it was the same as the 2730, where in fact there are differences. A lot of differences. There is no D3 board in the 2530, it seems, though there are like 10 extra tiny boards that probably aren't any help now. I think all your geometry controls are going to be on the main D board for that set. Sorry to mislead you there.

 

The main D board isn't small, so you may want to test voltage first, then think about recapping. You might also take a detailed look at the schematics as see about changing a few specific caps near to the Top-pin adjustment, if that's the one not going far enough.

 

The D2 board adjustments are all for convergence, not geometry. There is no rotation option on this set at all. H-tilt skews red sideways at the top, but not blue or green, or something like that. Make sure you photo the position of all the pots before you start, as a general rule. The three sets i have all have the convergence issues in the corners. I recapped two D2 boards, one time it helped, one did not.

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Ah yes, our 2530/2730s share a lot in common but apparently the layout of the boards isn't one of them.

 

Thanks Soyl for the suggestion. Just out of curiosity, what are the role of these diodes that lead you to believe they are worth checking? Do they specifically affect the t.pin adjustment, or just that group of potentiometers in general?

 

And to be honest, I don't believe I've ever checked a diode in circuit, can it be done accurately? If not, these are only a few dollars a piece, would probably just be worth replacing them to begin with if I have to take them out anyway.

 

Looking at the D board it appears grouped into specific sections based on what the components control, I think if I get into recapping I'll begin here, as this is where all of the corner options reside. I'm looking at about 20 or so caps to replace if I do this first, and a handful of diodes:

 

d-pin.png

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The diodes work as switches for the top and bottom pincushion corrections. They are MC931. Each one has two diodes in series. If you desolder them the test will be more reliable and you can also swap them and see if the issue goes to the bottom. They're very easy to test so I wouldn't blindly replace them and I wouldn't replace any electrolytic cap before getting the issue sorted.

 

https://datasheetspdf.com/pdf-file/1307097/Mitsubishi/MC931/1

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I don't have this monitor. I do have a 27" of the same time (KV-DX27TA) that has the dynamic convergence adjustments (H tilt, Y cross, Y bow etc.). When I take it out of the garage where it currently is I'll have to check how well they work but even the manual says that if the dynamic convergence is not sufficiently adjusted after the steps, repeat the steps :D as if they were aware that they don't work that great.
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lol. And no rush at all. I need help to move these sets by myself, so if you get to this sometime down the track i'd still be keen to hear your findings :)

 

I've been able to get things close enough on these sets without doing more than changing the angle of the yoke and using the pots on the D2 board, but maybe it's time to jump in and set one up from scratch.

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The diodes work as switches for the top and bottom pincushion corrections. They are MC931. Each one has two diodes in series. If you desolder them the test will be more reliable and you can also swap them and see if the issue goes to the bottom. They're very easy to test so I wouldn't blindly replace them and I wouldn't replace any electrolytic cap before getting the issue sorted.

 

Want to emphasise Soyl's comments there about not charging in and changing electrolytics willy-nilly.

 

Easiest thing is to test them with an ESR meter in-circuit (no need to de-solder). An ESR meter will catch about 99.9% of dodgy electro caps this way. If you don't have an ESR meter, then you can test capacitance with better multimeters (and even some cheap ones) BUT you'll need to remove the capacitors from the circuit to test them.

 

For example, when I was fixing my Sony 2730 earlier, there were 8 electro caps on the neckboard ©. I tested them all in-circuit with my ESR meter (Dick Smith/Bob Parker design, K7214) and found 2 seemed dodgy. Pulled them out and confirmed their dodginess with a multimeter (one was very dried-out, but this only visible after removal from board).

 

The obvious advantage of doing things like this is that I only had to change 2 electro caps instead of 8. The other caps are still perfectly good. In retail-speak, this means I "saved" about 6 caps (75% discount!), and that is from just 1 neckboard. Imagine how many caps I could "save" from re-capping the rest of the monitor in the same way. Speaking of which, I might just go and do that soon. As you can tell, I am very fond of my ESR meter.

 

As you probably know, Dick Smith is not the same company it once was. They certainly don't make ESR meter kits anymore (probably 20 years since they did). By an amazing coincidence, I just happen to have a few of the kits (K7214, ESR MkII meter) still in original plastic-wrap) in my shed, probably the last ones anywhere (let me know if you want one at a reasonable price).

 

Otherwise, the same Bob Parker design ESR meter is also available as the Anatek Blue ESR meter,

https://www.flippers.com/BlueEsr.html You can also find it on ebay (but beware of cheap Chinese fakery, look for the real thing). There are other meters that can do the same thing, but they will cost a lot more.

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Want to emphasise Soyl's comments there about not charging in and changing electrolytics willy-nilly.

 

Certainly, not a great method usually, in this case as I don't have a way to test in circuit and they only cost $2 each, replacing would take an equal amount of work. But I'll plan on swapping these to test first as recommended above.

 

Easiest thing is to test them with an ESR meter in-circuit (no need to de-solder)....

 

An ESR meter is something I've looked at needing for a while, but I've avoided because I haven't been familiar with the quality models to use. I see a lot of $10-20 options on Amazon and eBay that are clearly junk and can't be used in circuit. And then a lot of extremely expensive options.

 

The kits you referenced look reasonable (about $80USD for the kit to assemble the Blue ESR Kit). As I'm in the U.S. and you're in Australia the ones you have probably wouldn't be as cost effective to ship over here. I think I'll look into getting one of these kits soon and have that resource available to me.

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Yeah, caps are cheap and most even a lot less than $2 each. "Shotgun" replacement of cheaper suspect components is fine so long as you enjoy de/re-soldering a lot and have a good iron.

 

$US80 for the Anatek Blue ESR is pretty cheap for the work it'll save you. These days, in the second half of my life, I value my time and frustration levels at least as much as money. It's also good for finding cold solder points and testing batteries.

 

BTW I'm an Aussie but in Thailand ATM. But yeah, international registered post costs a bit.

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There is a flip side to this, and while ive not done this in a TV set ive done a few very high end CRT projectors top to bottom, and there is no question the stability of the sets improved in MOST cases, especially with Barco projectors.

 

Not that Barco used crap capacitors, but the Panasonic FCs and FRs are obviously better than what they did use.

 

I have no clue why they wouldnt use "the best" and take a "no compromise" aproach with a CRT projector that when first available here was around $118,500 AUD, but obviously there was many places where they used a $0.30c cap instead of a $1 cap, and overall set stability ( and in at least two cases, reliability ) suffered.

 

Ive have 2 of these Barco 9" monsters here and ive done all capacitors in both with the same results, so its not just a one-off fluke.

 

Sony consumer grade sets didnt typically suffer bad capacitors, but improvements can be made, simular could be said for Panasonic.

 

NEC were absolutely plagued with bad capacitors in the early to mid 90s, ive seen zero hour new old stock NEC 9PG CRT projectors dead out of the crate just because their Nichicon caps start leaking with age, but worse yet they destroy the boards at the same time. A lot of domestic consumer grade NECs suffered the same issues, just on a lesser scale.

 

The amount of dead LG and Samdung LCD and plasma sets i repaired back around 8-10 years ago was nothing short of a JOKE. They almost always had capacitors installed that were not up to the task, and often not a high enough voltage rating to cope with life. Its one thing to have them leak after 15 years, but there was no excuse for that shit, its nothing short of pathetic.

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@neo-geo_man, yeah I hear you, many cheap monitors would def benefit from a complete re-cap within 5-10 years. Crap caps are a major failure point and definitely a problem esp with some brands, not just monitors. For example, often power supplies crap out with bad caps.

 

Like you say, some original caps are just not good enough so often a good idea to replace with something higher rated for voltage, temp etc. Even so, many caps are perfectly OK, no need to change them out. Some caps get stressed out, some are just fine. ESR meter just makes it all a lot easier. Would be especially handy when doing a bunch of the same monitors like those Barcos as you'd work out where the stress points are.

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Unfortunately my refurbish/repair job on the PVM2530 is going to have to wait a while to resume. It's below freezing here and my good workbench is in the garage, so I'm working on building a repair station inside the house that I can use. To be continued...
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Unfortunately my refurbish/repair job on the PVM2530 is going to have to wait a while to resume. It's below freezing here and my good workbench is in the garage, so I'm working on building a repair station inside the house that I can use. To be continued...

 

Lol, i have the same prob here in Tasmania. I can't work in the garage when it's below about 5 degrees in there. I have some space inside, but can't use heavy tools :)

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The diodes work as switches for the top and bottom pincushion corrections. They are MC931. Each one has two diodes in series. If you desolder them the test will be more reliable and you can also swap them and see if the issue goes to the bottom. They're very easy to test so I wouldn't blindly replace them and I wouldn't replace any electrolytic cap before getting the issue sorted.

 

https://datasheetspdf.com/pdf-file/1307097/Mitsubishi/MC931/1

 

So Spring is here in the U.S. which means I can get back into working on my PVM 2530 now that weather is nicer in my workspace.

 

I'm looking at really devoting some time to this set in the next few weeks, and want to prepare and have a few of these diodes extra on hand in case I find they are going bad. The problem is I can't seem to track down a suitable replacement for these, or source for the originals.

 

I'm not familiar with double/switching diodes like this where they have three contacts. (This looks more like a transistor to me). If I knew what they were typically called, I could compare newer diodes with the original datasheet provided above and find a good replacement to have some on hand.

 

Anyone able to point me in the right direction and where I might order a few more of these MC931 diodes, or something compatible?

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