CurtPalme.com Home Theater Forum

[andy2000]

The point convergence board on my 9PG has developed an odd intermittent problem. It seems fine when cold, but after about an hour if the projector has to re-sync, it loads completely wrong values for the red and green point convergence. Attempting to adjust any point results in the entire screen changing wildly (although not randomly). Strangely, the blue is completely unaffected. Turning off point convergence restores a normal picture. I turned point on the next day, and it was fine until I changed sources after it had been on for an hour.

I suspect that there is a problem reading data from the EEPROM (maybe a bad address line that only affects the memory used for the red and green). That would explain why it works until it has to reload the point data.

I've already inspected the board for obvious problems (it has been recapped). I'm going to take one more look at it, but considering how hard it is to troubleshoot an intermittent problem on a very inaccessible board, I'd take a replacement if I could find one. Does anyone in the US have a board they could sell for a reasonable price? It doesn't have to be recapped.

Andy

[deronmoped]

I have a point board.

But my recommendation is to get the PJ set up correctly, point is not needed. And a lot of times, you will find it's your initial convergence set up that needs refinement.

I found using point, although it fixes one point of convergence, it messes up another point of convergence. More of a crutch then a fix.

[CasetheCorvetteman]

That is somewhat untrue, you wont get perfect linearity across the entire screen without using point. Its there to be used. It has no effect on the stability if if is used correctly.

If you set everything perfect as you can, then use green point to make it flawless, then line up red and blue followed by red and blue point, you will not have issues.

If you find that moving one point has an effect on other points, you have NOT set it up properly, and id say your phase is out. Moving one point moves only that point, it has no effect on the next point if phase is correctly set.

Pull the point board out, clean the terminals and put it back in. That might fix it if youre lucky.

[andy2000]

I'm only using the point convergence for minor touch ups after getting is as close as possible with the standard controls. I'm still using it with point disabled, but it's a little less perfect than I would like. It's a handy feature for a perfectionist.

[Curt Palme]

Nah, I've seen this before, it is a bad point board. I should have one as well if Deron's doesn't work for some reason.

[Curt Palme]

Nah, I've seen this before, it is a bad point board. I should have one as well if Deron's doesn't work for some reason.

[CasetheCorvetteman]

[deronmoped]

[CasetheCorvetteman]

If you have PHASE set as it should be, then POINT will only move the exact point youre on, moving the line between the two points either side of it, leaving those two points exactly where they were unless you go a huge amount. If you don't set the PHASE correctly, you will get exactly what you describe.

Who are you claiming is not using it and where are their images of 100% perfection? Here is mine:


That was set around 3 months prior to that pic being taken. POINT was used where required on all three colours to gain the best possible geometry. Solid as a rock, never ever drifted. Scanlines were straight as an arrow from top to bottom, no undue deviation anywhere on the entire screen. Colours all lined up pixel perfect from corner to corner. You wont get that without using some POINT.

Ive never had an issue with it on both the 9PG and again on the XG, in both instances it works exactly as I describe, and if yours is not, then you have not set something else correctly.

I don't use much of it, you shouldn't need to use much, but the fact remains there is no good reason not to use it, its there to be used for that very reason.

[deronmoped]

Over the years I have been on here and AVS, someone would usually chime in to recommend not using point.

The reasons for this, were several. If the PJ is properly set up, it's not needed. People were having problems with setting up point. The PJ did not have the board to begin with, no reason to track one down and buy it. The point board was failing, like Andy's board is.

Quite a few people using CRT PJ's are not up to speed on the fine details that involve getting a corner to corner pixel perfect convergence. Recommending that they not use point, will force them to go over and over their set up till they have found the problem that is causing the convergence to be off.

You probably even found that your using less point then when you first set up the PJ. First time around most people use a lot of point, after they have had the PJ for a while and the more they learn and the more they revisit their set up, they are able to get away with using less and less point. Anyone that has set up a PJ, no matter what type it is, finds that they learn how to get it more and more refined.

[CasetheCorvetteman]

Im not doubting or disagreeing with most of this, but point is there to be used.

In some situations, such as projecting onto a wall with a less than absolutely perfect surface using a PG Plain series that does not have line distortion adjustment, YOU WILL NEED POINT TO GET IT PERFECT. Its a fact. Curt even says so in his setup guide, im reasonably confident he knows what he is on about

If others are not proficient enough in their mechanical setups as well as initial electronic alignment, that is not the fault of point convergence. If people get themselves into trouble using point when they shouldnt, that is not the fault of point.

Im not sure if youre under the impression here that im saying nothing is super critical, you can fix it all with point, but im not. Everything is critical, if you want it perfect it has to be perfect every step of the way, but i will repeat it over and over, you wont get pixel perfect convergence in every setup to every corner without using point, ESPECIALLY if youre using a larger tube face area on an earlier PG.

[CasetheCorvetteman]

[Curt Palme]

you're both right. the point board is there for fine tuning. Normally a PG with a skilled setup tech won't need the point board, but at 20ish years old for most PG sets at this point, component drift is applicable, and even 10 years ago I had some PG sets that simply wouldn't converge properly no matter what I did until i added the point board.

As Doug said years ago, more than 4-5 point board clicks in any direction, and the basic setup isn't good enough.

Also, if you're lazy, the point board is a workaround from doing a good basic setup.

[Curt Palme]

you're both right. the point board is there for fine tuning. Normally a PG with a skilled setup tech won't need the point board, but at 20ish years old for most PG sets at this point, component drift is applicable, and even 10 years ago I had some PG sets that simply wouldn't converge properly no matter what I did until i added the point board.

As Doug said years ago, more than 4-5 point board clicks in any direction, and the basic setup isn't good enough.

Also, if you're lazy, the point board is a workaround from doing a good basic setup.

[CasetheCorvetteman]

[andy2000]

Re seating the connectors hasn't changed anything. I still plan to try a few basic things on the my board, but I don't want to spend days working on a board if I can replace it cheaply. While I'm in there, I wouldn't mind adding the composite video board if anyone has one.

I don't want to get into a debate about whether or not the point convergence feature is a good thing. I'm fairly sure it's not supposed to make the whole screen look crazy at random times. Even if I don't use it, I wold like to have a fully working 9PG (including the apparently controversial point convergence board)...

[CasetheCorvetteman]

Nothing controversial about it mate, and its actually been a long time since ive seen a post where someone has come along and said "get rid of it, it causes issues" which is garbage. It used to get said quite abit here. The people saying it sometime knew what they were on about and were assuming it was going to lead to lazyness and sloppy pre-alignment, the others were just repeating something someone else said and they thought it sounded plausable enough. Either way, to just remove it and live with less than perfect convergence would be plain stupid. May as well buy a Barco and be done with it

NEC always had the most comprehensive convergence systems for their time, and provided you set it up properly they are exceptionally stable for a very long time. Its great. Extremely fine adjustment and very easy to get perfect.

[hansilili]

Andy,

I had a quite similar issue recently (go search for the thread). Tried to recap the point board but made it worse - my fault. With some time gone by the problem escalated and finally the tubes stayed totally dark. After replacing all 4 boards all is now good again.

So if you look tor a replacement point board, better try to exchange all boards in the system cage.

[andy2000]

[CasetheCorvetteman]

No worries mate

[gjaky]

We have a similarly bad point convergence board here too. And we found that the EPROM content on the bad board is corrupted.. I know of a good working point board so we'll try to rewrite the EPROM with the good working on, and we'll see if that solves the problem.

[CasetheCorvetteman]

Keep us all posted Gábor