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Post by Deleted on Aug 21, 2015 8:37:08 GMT -5
The doubled mosfets on the output help in heat disspiation (at higher scanrates) in a cine9/cinemax this is a lesser issue, the general build up is the same for both versions. I see no big difference between the original and the suggested diode replacement, only just the case differs, however increasing those 10pF capacitors to 22pF and the 10R -> 100R will stabilize more the amplifier. Can the problems that Decibel sees be explained by an oscillating convergence amp? What I know about oscillation is that it increases power consumption hence heating of the resistors and it make the output swing? If we could be reasonable sure that oscillation is the problem than perhaps measuring and replacing certain components like the 10pF could solve it? |
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Post by gjaky on Aug 21, 2015 9:04:44 GMT -5
There are different extents of oscillation, maybe the circuit is only on the verge of oscillation, that can appear like what Domenico experiences. Now if I am right he unplugged the convergence coils and the picture remained calm, so it is quite sure the noise comes from that part. Otherwise the controls seems to be working -at least he didn't say they don't work- so basic functions appear to be working on all circuits which rule out major parts failing. Now, with a replacement convergence board he could decide if the noise is coming from the "signal generator" or the output amplifier induces it, but further /closer examination would need an oscilloscope.
I think he should replace the 10pF caps right away, since they are cheap and he has nothing to loose with them.
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Post by Decibel on Aug 21, 2015 9:23:04 GMT -5
The pictures remain calm and ultra stable when disconnect the convergence coils or when remove SW2 jumper.
I replaced the capacitors from 10r to 100r (12 pieces, four for each color) but I have not solved. Of course I have not solder the resistors 100r where there are diodes.
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Post by gjaky on Aug 21, 2015 9:48:44 GMT -5
The pictures remain calm and ultra stable when disconnect the convergence coils or when remove SW2 jumper. I replaced the capacitors from 10r to 100r (12 pieces, four for each color) but I have not solved. Of course I have not solder the resistors 100r where there are diodes. There are capacitors with different values in the newes design, might worth a try. |
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Post by mastertech on Aug 21, 2015 12:02:39 GMT -5
I have to run out for the day but here are a few things you can try.
Leaving the jumpers and stuff installed try disconnecting the wire harnesses from the controller and see if the image stabilizes.
Also check the output voltage of the 2 regulators, I200 and I201 on the convergence board. + and - 12v.
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Post by Decibel on Aug 21, 2015 13:06:51 GMT -5
Tried. I disconnected the two connectors between convergence and controller boards.
Grids super stable.
Check voltages from I200 and I201= +/- 12v present.
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Post by mastertech on Aug 21, 2015 16:36:06 GMT -5
Try reconnecting just one harness and look at test grid. Then disconnect that one and reconnect the other one and look at test grid to see if there is a difference.
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Post by Decibel on Aug 21, 2015 17:05:15 GMT -5
The flicker remain with connector J571. No flicker with J572.
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Post by mastertech on Aug 21, 2015 18:46:18 GMT -5
Just to verify, you have tried a different controller, correct?
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Post by Decibel on Aug 22, 2015 2:42:32 GMT -5
Just to verify, you have tried a different controller, correct? The answer to your question, Mastertech is NO ... because I'm an idiot  When I mounted the controller spare have not looked grids and I immediately put the original controller. I was sure that the original controller was working perfectly. But I was wrong! With the controller spare the flicker totally disappears!
it is therefore clear that there is a failure to the original controller.  The fact that I can solve with a spare part is good news but I'd like to repair the original controller. Unfortunately, the problems are not end. This thread will never end  I realized that not works the adjustments of top and down bow and keystone. Work in pre-correction bow and keystone of the sides, but not in normal operation. They do not work with both controllers. |
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Post by Deleted on Aug 22, 2015 5:10:04 GMT -5
Good news! The number of parts on the controller to the convergence are very few so I think you should be able to find the broken resistor or capacitor. This thread is long but a good lesson in trouble shooting a 909  |
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Post by Deleted on Aug 22, 2015 5:31:52 GMT -5
The flicker remain with connector J571. No flicker with J572. So I am thinking J571 is the problem that makes BV or RV or GV likely candidates I think. Here is the part for BV. I would check R82 and C92?  |
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Post by Decibel on Aug 22, 2015 6:20:55 GMT -5
The flicker remain with connector J571. No flicker with J572. So I am thinking J571 is the problem that makes BV or RV or GV likely candidates I think. Here is the part for BV. I would check R82 and C92? Tomorrow I'll check these components. |
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Post by Deleted on Aug 22, 2015 7:09:06 GMT -5
If I understand well that bow and keystone do not work you should try another vertical deflection module if available. Perhaps your Barco was a spare parts machine |
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Post by Decibel on Aug 22, 2015 9:01:49 GMT -5
If I understand well that bow and keystone do not work you should try another vertical deflection module if available. Perhaps your Barco was a spare parts machine As I wrote in the previous post, during testing I noticed a spark from the rear side of the vertical board. Perhaps at that moment broke something. I replaced the smd cap that was burned but perhaps not enough. I also wrote to have another vertical board with part number R7628085 that looks identical to R7631415. The diagram of R7631415 describes the small differences between the two boards. I'll try to make these changes and I'll post the result. |
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