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Discussion Starter · #1 ·
Hi all,


I have a low hour 9200 with good tubes. I have a chance to pick up a working 6200 with worn tubes for a good price.


I've had the 9200 for a little over a year. There has been a on-going problem with the 9200. In order to properly align the

horizontal keystone I have to have it set to +78. Once it reaches the 78 mark, I've always heard a slight "buzzing". If go beyond 78, the buzzing becomes louder, almost a clicking noise that appears to be coming from the HV power supply.


Just recently that buzzing is getting alot louder. If I back-off the horizontal keystone to +20 or it goes away.


I'm confident I have the projector properly set-up. All the other values are low. For example, vertical keystone +4, R-B statics +/- 5, and barely using point-convergence. The throw distance is exactly to NEC specs.


What can be causing the problem?


I've read post from Doug stating the power supplies are the same, tubes are not in the 6200/9200. Anything else compatible that could possibly fix the problem?


Thanks,

Kevin
 

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Kevin,

The 6200-9200 do use the same tube, but they dont interchange with the 6-9000 or 61-9100.


The keystone comes from the deflection board. We did note the noise in the Extra series at high keystone (but normal) values, If I remember right I think it was isolated to the power supply, I could be wrong on this but it was more of a oscillation noise or oscillation of the deflection yoke its self. One I solved by moving the focus yoke just a tad back from the deflection yoke, the noise on that one was just the vibration between the two coils. Doug


Use a small rubber hose (vacume hose works) and put one end to your ear and move the other end around until you find the source of the noise. Doug
 

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Quote:
Originally posted by Doug Baisey
Kevin,

The 6200-9200 do use the same tube, but they dont interchange with the 6-9000 or 61-9100.


The keystone comes from the deflection board. We did note the noise in the Extra series at high keystone (but normal) values, If I remember right I think it was isolated to the power supply, I could be wrong on this but it was more of a oscillation noise or oscillation of the deflection yoke its self. One I solved by moving the focus yoke just a tad back from the deflection yoke, the noise on that one was just the vibration between the two coils. Doug


Use a small rubber hose (vacume hose works) and put one end to your ear and move the other end around until you find the source of the noise. Doug


The old rubber hose engine trouble shotting trick:D


ts
 

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I think much of the 6200 is easily interchanged between it and the 9200, evne tubes. Whatever board controls horizontal scan may not be interchangeable as the 9200 scans higher than the 6200.
 

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Discussion Starter · #5 ·
Doug,


Using the hose trick to find the origin of the noise worked well, clever idea.


Projector is ceiling mounted. Above the front of the blue tube, slightly to the left facing the screen, there is a group of wires going up thru a hole. When I place the end of the hose into that hole, the noise is the loudest.


Thanks for the help,

Kevin


The only time I hear the noise is with the Keystone adjusted + not when -. I've gone thru and ramp up/down almost all other functions, no noise.
 

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kevinu,

That sounds like the power supply if the "hole" is above the blue lens.

Now you need to find out why its doing this, this could be the power supply or something putting a load on it. You could monitor the voltages (connected) at the 2 connectors that connect the power supply to the wire loom, this is located behind the front cover. This confirmed that the noise isnt the yokes vibrating. All voltages listed below are the (about values) and running a video signal. Doug


1A (1) 35V (H DEF)

1A (2) 7V (FOCUS)

1A (3) -7V (FOCUS

1A (4) 1.5V (H DEF CTL)

1A (6) -75V (VIDEO OUT)

1B (1) 110V (VIDEO OUT)

1B (3) 150V (HV)

1B (4) 60V (V DEF)

1B (5) 35V (CONV. etc)

1B (6) 15V

1B (7) -15V

1B (8) -35V (CONV. ect)

1B (11) 6.3V (CRT HEATER)

1B (13) 5V (DIGITAL)

1B (14) 5V (STAND BY)
 

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Discussion Starter · #7 ·
Doug,


Got the projector down and slid the power supply out. Using the hose trick again the noise is the loudest between the cluster of capacitors(C55-C56 area) and the SB02 board.


1A

Brown 94

Red 16

Orng -16

Yell 4

Black 0

Blue -77


1B0

Brown 110

Black 0

Yell 62

Black 0

Blue 16

Pink -16

Black 0


1B02

Brwn 6

Black 0

Orng 151

Black 0

Grn 36

Orng 5

Yel 5

Grey -36
 

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Hi ,

Was just thinking about bumping an old post of a similar problem. My 9200 makes the same noise, I believe its coming from transformer TO4. Sounds like a toy train transformer. It gets louder the more H-keystone I put in. Freqs stay the same just gets louder. As a matter of fact I mounted my pj lower so I could tilt it up (ceiling mounted) needing less H-keystone. I'm not very happy about it, but it's better then the buzz. I recorded a WAV. of the noise, if interested I can email it to you. From reading other posts it seems NEC has had some problems in the H-keystone area, not necessarily the buzzing but also a lack of adjustment, anybody have any input on this?

I talked to NEC and they don't sell just the transformer, they'll be happy to sell you a complete power supply for $1200.00. Doug can we get these transformers? You mentioned an excessive load on the circuit, what might be some of the causes?


Thanks

Myles
 

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Discussion Starter · #10 ·
Picked up the 6200 with worn green/blue tubes yesterday.

The various voltages measured the same as the 9200, +/- 1.

The 6200 H-keystone has more range of movement then the 9200. With the 6200 on the floor, roughly aligned, +47 corrected the H-keystone. But just like the 9200, once the value went above +75%, the power supply started buzzing.

So is there something wrong with 9200's Keystone circuit?

I also exchanged power supplies, same results.

The 6200 is very dusty inside, how should I clean it?

Where can I get a 6200/9200 service manual?


Kevin
 

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Hi Guys,

I wish I had an answer for you. I checked through all my notes and cant find anything as yet. I ran this through NEC a couple of days ago and couldnt get an answer, My quess is maybe some caps are breaking down or the TO4. I have a test chassis, Ill see what I can do to duplicate the problem as soon as I can. I took the c-drive out but have some coming in the next day or so.

One thing might help here, if you have a 6-9000 only can you give me the PWC number on the c-drive, its silk screened on the board.

We went to the PG 6-9200 series c-drives to replace these and they have a different hook up pattern. These seem to hold up better then the early ones but this might point me in the right direction. Then again it might not. Doug
 

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I did a little trouble shooting on this problem and I don't think it the TO4. I only get the noise when I have an external signal coming in. When I display the internal test pattern without an external signal (no rgbhv input) there is no noise from the transformer. But when I display the internal test patter with an external signal the transformer makes the noise. I disconnected the r,g,b, cables in different combinations the noise continued. In other words the transformer was under a load whether the crt's were powered up or not. Only when there was no h/v, v, signal input did the noise stop. I don't have the S-video card so I can't tell about that. I was sure hoping it was something to do with a crt, a little easier to trouble shoot.

Any suggestions??

Thanks

Myles
 

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Hi Doug, The load on the transformer is coming from the vertical sync circuit. Its seems independent of the crts. When I disconnect the vertical sync from my outside source (htpc) the buzzing stops and the picture starts rolling. I looked at the schematics to figure out what to try next and came to the quick conclusion I don't have a clue. Have any ideas?


Thanks Myles
 

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Myles,

It just means the HTPC doesnt use sync on green, thats normal. I didnt see that you were using a HTPC, sorry. Ill have to wait for the c-drives to come in to get the test chassis going.


Can you check the PA connector (deflection) at pin 2 and see where thats at using 31.5Khz or the 640x480 setting then also at video freq. This isnt really pointing to anything but wanted to see where that was set first.


What happens when you adjust keystone on the other axis at the same high settings? Doug
 

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Discussion Starter · #16 ·
Doug,


buzzing only occurs on + H-keystone.


I'm using a scaler. Is there any difference/benifit between sync on green vs comp?


Could I order a service manual from you?


Kevin
 

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kevinu,

If your using a scaler then your using sep sync unless you only have a 4 wire output (RGBH/V) comp. RGBHV is seperate sync and 5 wire. Some interfaces will change this to comp sync. A HD15 connector (monitor type) is seperate sync.

If you hit the info button it should read sep with all wires connected.


Service manuals are hard to come by and we are not suppose to sell these to non dealers, there are some out there but usually no one wants to sell them. I agree that after the warranty runs out that you should be able to buy these. If you do find one get the one for the extra series 6-9200 and also check that the suppliment is in it with the part numbers.


Im over my allotment for them. Doug
 

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Discussion Starter · #18 ·
Doug,


the scaler I have is selectable between green/sep sync. I'm using the sep sync. Just curious about the difference, or benifit if any.


Thanks for the tip about the suppliment in the manual.


Kevin
 
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