CurtPalme.com Home Theater Forum

[dcmfx]

I have a new to me G70. Says 6600 hours on it but has only very minor wear on the tubes in a nice large flat patern. I have worked with projectors for years and this to replace my 1270 which replaced my 1020 of decades past. Overall the setup has gone well and as expected. Wow, there are lots more things to adjust on G series. My trouble is that once roughly setup, my whites seem fairly dim, and generally slightly greenish/blue. Kind of like watching through a Matrix color correction. But the odd thing is that the whites of the menu and the internal test patterns are nice and bright white. It this normal?

I have tried various inputs to see if it is the inputs. But they have been fine on my 1270.
Composite on IFB-1000 in switcher
Composite and Y/C on IFB-3000 in switcher
RGB on IFB-10 in switcher
Composite on G70
Composite on G70 with internal LineDoubler

All appear dim. Kind of like an internal gain limiter is on. I have tried with the two settings I could find turned on and off. I don't remember offhand what they are called, but I think one is AGB and the other is for linking multi g70s. Watching tv seems brighter sometimes and dimmer sometimes. Very disapointing.

Anybody know if menu's and internal paterns should be brighter than input signals? Any thoughts?

thanks
dan

[Curt Palme]

Try turning on/off the abg setting in the menus. Gains can be as high as 200 or so, there's a reference setting guide in the manual somewhere, if someone played with those.

A neck board or two could be bad, I've had one bad one affect all three colors. Press either the gain or bias control twice to see if you have 'hidden' G2 controls. THE older software did, the newer didn't.

The B board (RGB input board) could be bad.

That's all that jumps out at me right now. THe last one I had that was dim had a bad neckboard. Oh, and there's two types of neckboards, the heatsinks are either dull and larger than the shiny and thinner/smaller ones. You cannot mix and match those neckboards, at least not from what I've seen here. I have lots of spare parts for these sets. I'm sure your tubes are fine.

[Curt Palme]

Try turning on/off the abg setting in the menus. Gains can be as high as 200 or so, there's a reference setting guide in the manual somewhere, if someone played with those.

A neck board or two could be bad, I've had one bad one affect all three colors. Press either the gain or bias control twice to see if you have 'hidden' G2 controls. THE older software did, the newer didn't.

The B board (RGB input board) could be bad.

That's all that jumps out at me right now. THe last one I had that was dim had a bad neckboard. Oh, and there's two types of neckboards, the heatsinks are either dull and larger than the shiny and thinner/smaller ones. You cannot mix and match those neckboards, at least not from what I've seen here. I have lots of spare parts for these sets. I'm sure your tubes are fine.

[mike calcott]

Hi Curt, have you managed to post the B board to me yet?

[dcmfx]

Would a neck board give dim video but bright menu and internal test signals? The internal color bars are nice and bright.

I will play with the gains and biases tonight when I get home.

Otherwise it might be the B board if that is the input board. Possibly dimming the inputs but not the internal signals. Are those swappable between sets? Do inputs from the IFB-40 go through the B board?


thanks Curt!
dan

[stuffandpuff]

Dan,
I doubt there is anything wrong with your projector. Sounds like a your gray scale is off.. If whites are not white and have a blue, red green tint, it is almost always due to incorrect gain settings/interaction of the three colors. No way to get it perfect without expensive equipment but you should be able to get something passable by carefully adjusting the gain settings. Wear on the blue tube will effect your whites and requires a gain adjustment to compensate.

The default gain settings will not produce the desired effect ( in this case, the color white) because of the wear on the tubes (even slight wear) The problem is tubes do not wear evenly with respect to one another.
Pull up the full white test screen and fool around with the settings, You can always return them to their default settings if you make it worse. If whites are too green, this could mean your green is set too high or your blue too low etc.

If all three tubes are working properly then you have everything you need to get the color white. It's just a matter of correctly adjusting them. If it were something else, you would have a dimness/color issue across the board, not just on a white screen.

The difficult part is knowing whether to decrease one color or increase the others. As far as the whites in the menu, the menus are always brighter than the image. I don't have the answer as to why this is.

[AFryia]

Each input signal selects a memory block that selects a specific color temperture setting, I believe they are 4800 5600, 6500, 9600, and PRESET. check the color setting for the active memory block.

When I perform a grey scale calibration I'll select the PRESET color and monkey around with the GAIN/BIAS then transfer those to the 6500.

I leave PRESET tweaked for my HTPC and 6500 for everything else.

[dcmfx]

I played around with the Bias and G2 last night. It appears my new to me G70 is an early unit because it does G2.

Can someone tell me what exactly G2 is? Bias should be black level, right? So why a G2?

Setting G2 and Bias as per another topic, then Gain, I get a pretty good picture with brighter shows and the ABG on. With the ABG off, it varries massively per channel I am watching. Either way, it still looks "clipped" to me. Near whites shoved up to white. Near blacks too dark. If I see an add that is black screen with white text, the white text comes out about 50% brightness and 50% greenblue. But if I am watching a bright show, it looks farily good. If I watch a dark show like CSI, it is very dark in the mids. Seems very weird, but it varries with the overall screen average brightness. But much better with the ABG on.

thanks
dan

[ecrabb]

Dan, I think you're chasing your tail. G2, Bias, ABG, and the brightness control ALL interact with each other and in the end all effect the same change - the G2 voltage. Because it's screwed up already, and several of those controls interact, you're going to have to use the service manual and try to reset everything to default or proper values, then go from there.

One point of clarification... I think that on the early G70's, G2 is a "global" projector-wide setting independent of input... OTOH, bias, gain, brightness and contrast are all memory-based, and can change with different frequency inputs.

Read this thread for more on adjusting color:
https://www.curtpalme.com/forum_archived/viewtopic.php@t=4538.html

Now, if you're talking about whites specifically, then that's contrast and gain. What are your gain settings? What's your contrast setting? With color temp at 6500, B gain at 255, and the other two a little less than that (I don't remember the exact numbers, but let's say B255, G220, and R200), and contrast at 70-80, whites should be pretty white. If you can't get it there, then there's something else awry. If you can get a good white with the internal patterns, then I don't think there's anything physically wrong with the projector, but something amiss in one of the input/memory based settings.

You said, "If I see an add that is black screen with white text, the white text comes out about 50% brightness and 50% greenblue." That sounds like your red gain is too low. You also said, "Near blacks too dark," which sounds like G2 or bias are too low.

You're going to have to get systematic, and do some reading in the service manual to find out where those settings are supposed to be - otherwise, you'll keep going in circles. Also, has been mentioned, without a color meter, you'll never get it truly right (but you should be able to get it much better than it is).

SC

[dcmfx]

Ok. I will play with them more. I never knew what G2 was before. I never adjusted it on my 1020 or 1270. But both were brand new so were good from the factory. Even when I was a projector field tech, we never adjusted the G2 settings. If we couldn't get them to look good with the standard adjustments, we pulled them and brought them back to the shop and gave them to our repair techs. But my two partners were hacks and I was new to projectors. So what I knew at the time I learned from them. Also, I can't find the adjustment procedure specific for a G70 with early firmware. My copy of the manual, install manual, and repair manual don't say anything about it, probably being copies from later models. My web search found Curt's page:

http://www.curtpalme.com/ES_Tube_Projector_Gray_Scale_Adjustment1.shtm

So I will set my gain and bias to default and try G2 as per Curt's page.

thanks
dan

[dcmfx]

FIXED! Turns out it was not the gains/bias/G2 at all. Here's an odd one. My new to me G70 is replacing a 1270 that has been in for years doing a fairly nice job for what it is. I have a PC-1271 with IFB-3000 feeding it my composites. Since the 1270 does not do component, I had the RGB-Component switch on RGB and it worked fine for years and the 1270 had no troubles with the signal. I pulled the 1270 and put in the G70 and had really weird color/blacks/whites. I tried other inputs than the IFB-3000 and even tried direct composite to the G70. All seemed to have the same troubles. Possibly I didn't explore the other inputs enough with correct gain/bias/G2, but in the end, it turns out the G70 can not handle the RGB signal from an IFB-3000. I switched it to Component and all is well. I guess the G70 knows about the IFB-3000 and can recognize it. It showed the input signal as RGB on the menus, but seems it was treating the signal like it was component as to signal levels, which would account for what I was seeing. Shows like MASH looked pretty good, but overall they are bright greenish without much other color. Shows like CSI looked terrible, but it is dark and colorful. Problem solved! Thanks for the advise overall, I never knew about G2 and now can pay attention to it on my G70 and the 1270 which will be moved somewhere else in the house. Probably my shop
dan