CurtPalme.com Home Theater Forum

deronmoped · Joined: 03 Nov 2006 Posts: 1154 Location: San Diego

New problem for me. Although, it seems there was always something amiss about this PJ. Initially, the PJ did not seem to hold memory and I was having the clamp setting problem recurring. I'm hoping these problems were related to the Dallas chip being close to twenty years old. And those problems seem to have gone away after I installed the new Dallas Chip.

Now what is happening is, when I first fire up the PJ, there is a unstable band (about one quarter of the screen) towards the top portion of the screen, flashing on and off, randomly. This goes on for a minute or two, then goes away. After that, no problems. I'm not sure if it's in the video input chain or elsewhere. I will have to try starting the PJ with no input and go to a internal pattern. I doubt if it's source related, I'm using input A RGBHV off my computer.

It seems odd, kinda like the PJ knows there is a problem and then fixes it, only having to do it all over again on the next start.

Any ideas on which part of the PJ could be causing this random, flashing, band.

CIR Engineering · Posted: Fri Aug 09, 2019 12:57 pm Post subject:

It's the DF board. You can send yours to me for repair if you want to keep your current geometry, convergence, and focus calibration intact, or you can buy a rebuilt one from me or possibly Curt.

Shoot me an email craigr@cir-engineering.com

craigr

CIR Engineering · Posted: Fri Aug 09, 2019 2:13 pm Post subject:

Actually, can you post a short video of the problem.

Do test with the internal patterns as well please.

craigr

deronmoped · Joined: 03 Nov 2006 Posts: 1154 Location: San Diego

Is the DF board the deflection board?

I will test the PJ's internal patterns and get back to you.

I will see if I can get a video too.

Also, I would like to see about getting some spare replacement boards. The ones that have been a problematic.

CIR Engineering · Posted: Fri Aug 09, 2019 6:13 pm Post subject:

Yes, that is the deflection board. It's easy to get to. Between the tubes, the only one with three wires coming out the top. It's a pretty frequent failure on G90's.

I've got all boards and even just listed YA boards:

http://www.curtpalme.com/forum/viewtopic.php?t=42137

Best,
craigr

deronmoped · Joined: 03 Nov 2006 Posts: 1154 Location: San Diego

OK, I checked again.

Did the same thing, on start up, a wide (1/4 the screen) band across the top portion of the screen that's a scrambled mess. The very upper portion of the screen and the lower portion of the screen, looks fine. This goes on for a minute or so and then is gone for good. This is on input A RGBHV showing my desktop of my computer. When I brought up the Menu, the Menu would be affected too.

Now the PJ started with a all white screen and did not show this problem and when I went into the internal patterns this problem did not show either. Would not the deflection board affect anything the PJ put on the screen?

CIR Engineering · Posted: Sun Aug 11, 2019 3:58 am Post subject:

Yeah, I doubt it’s the deflection board. Probably the YA or BA board. If you want to send them to me for testing let me know.

craigr

HaydnG90 · Joined: 22 May 2006 Posts: 1335

If you have access to a Moome card try a different Input, B or C.

deronmoped · Joined: 03 Nov 2006 Posts: 1154 Location: San Diego

I checked last night and I have the YA board with the good chip on it, 836AO1E, if that means anything towards this problem.

I'm going to try pulling the HDMI board and run the PJ to see if that could be affecting it. If that does nothing to change the problem, I will try the HDMI input off of that board.

I'm going to try to do as much as I can do on this end to isolate the problem, before I start sending boards out for testing. Visual inspection of the boards, check connections, clean, or whatever else anyone here suggests.

Is there anybody in the San Diego area with a G90?

Also, I have a G70, are any boards similar in that PJ I can swap around for testing?

I'm thinking of picking up a spare G90 or backup parts, if those are available.

HaydnG90 · Joined: 22 May 2006 Posts: 1335

Symptoms you're describing are not typical of IC421 issues. Problem lies elsewhere especially since you're lucky with the 'good' SN.

Unfortunately there aren't any boards that are interchangeable with the G70. Good call getting a parts mule G90. That was the only way I was able to get my G90 running when it's YA went bad 10 years ago. I sold the lenses and the ancillary input boards to help offset the $1500 I paid.

CIR Engineering · Posted: Sun Aug 11, 2019 11:35 pm Post subject:

Just so you know OSD's and test patterns are generated on the YA board and then inserted into the video signal on the BA board. All that aside, the YA board also controls insertion of said OSD's and test patterns.

All video that winds up displayed goes through the BA board and is timed there with the HVSync. I suspect there is something wrong with the HVsync circuit up stream from the test pattern / OSD insertion, or the control of the insertion. I strongly suspect that the problem has to do with the YA board calling for insertion and getting partially inserting garbage into the video during warm up. It could however be on the BA switching momentarily due to a bad IC and grabbing whatever noise might be coming down the pipe from the YA.

Do try using an HDMI board as that could provide a valuable data point. Also, pull your YA and BA boards out about an inch and then firmly reinsert them. Make sure the projector rocker switch is OFF! if the projector is on the ceiling, when you reinsert the YA board push on the black tabs on either end, but at the same time use a finger in the center of the YA board to slightly lift the cent up. The YA board flexes down a little and bows, and when that happens you will often get a poor connection in the sockets that will result in error code 11 or the projector running with retrace lines and an "over correction" message on the screen.

Another board that is a slight possibility is the BC board... I forget if RGBHV gets routed though that board or not, but I think it may. Both input card sockets have their video routed through that board. It's the small board just above the expansion card slots for inputs B/C. You may want to reseat that one as well. I have never seen this board go bad, but there are a number of mechanical relays on that board that pass video.

Keep us posted. I'm going to be working in Philly the next four days so probably won't be around again for a while.

craigr

deronmoped · Joined: 03 Nov 2006 Posts: 1154 Location: San Diego

Yeah, the distortion I'm getting looks like the horizontal sync is being affected.

A few years back, I picked up a G70 and the guy thru in a SS200 Sync Stabilizer, he said I might have use for it. I have been trying to find information on it. It's made by Extron. Not much on what problems it fixes. It says on the box that it strips the Sync and outputs a digitally restored Sync.

**AnalogRocks** · Posted: Fri Aug 23, 2019 11:37 pm Post subject:

deronmoped · Joined: 03 Nov 2006 Posts: 1154 Location: San Diego

I found this about The SS200. Digital displays — such as LCD,DLP™, and D-ILA®/LCoS — often have trouble with sync signals that have been altered through previous processing.

Also some Retro Gamers are having trouble with Sync on some displays.

I'm running thirty five foot RG6 cables for RGBHV. BNC connectors on both ends and a one foot BNC to VGA cable to hook to the computer. I guessing I should be OK with this setup. I have tested them several times for ohms and shorting. Maybe I should get my buddies Megger to test that too.

HaydnG90 · Joined: 22 May 2006 Posts: 1335

35' RGB cables are fine. More likely to have problems with signal over HDMI over extended runs, especially with poorer quality construction.

deronmoped · Joined: 03 Nov 2006 Posts: 1154 Location: San Diego

I tried reseating the BC board, no success there.

Well, anyways, the problem is consistent, almost as if it's supposed to be there. What looks like a H-sync problem across the top of the screen for about a minute. I bet if I timed it, it would be consistently long, too.

HaydnG90 · Joined: 22 May 2006 Posts: 1335

Seems reminiscent of a failing part thats out of spec. Eg a capacitor taking time to fully charge. Curious to know. Try turning the set off then on again before the min is up and after its settled down. Does that impact what you see on screen vs a cold start?

deronmoped · Joined: 03 Nov 2006 Posts: 1154 Location: San Diego

I think a better test, would be to turn the PJ off after the issue is gone (give the PJ twenty minutes to warm up) and see if it's there on a restart. Either way, it might tell us something.

Makes me wonder if these PJ's have internal regulators for SMPS voltages. Starts up with the wrong voltage and then corrects it.

Anyone know what switch S1 is for? It's on the BA board, next to the BNC input connections. I checked the manual, but could not find anything about it.

HaydnG90 · Joined: 22 May 2006 Posts: 1335

Nothing in the Theory of Operation. Maybe Craig knows. Try toggle it and see what happens

deronmoped · Joined: 03 Nov 2006 Posts: 1154 Location: San Diego

I tested the PJ by turning it on for a half hour and then did a restart after waiting a minute. I did not see the problem on restart. So something is happening on the initial start, not sure how long the PJ would have to be off to cause the problem on start.

I will try the HDMI input to see if that changes anything.