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Post by gregstv on Mar 23, 2016 22:07:44 GMT -5
Added some caps to the rails on the HFA1100 amps on the switcher, + and -5V. I put them across the .1's. Some of the later boards had a 47uf on the +5 volt line at each chip. I added a 100uf to each rail on each chip. Also changed the switching transistor to a BFR92 on port 3. I will get some pictures and post them. I am using a MOOME internal card on port 3. I have reduced the visible snow quite a lot, but I can still see it if I look into the lens. More work to do as time allows. I have ordered some high quality caps to try in place of the 4.7uf (C217,317,417)coupling caps on the RGB driver board.
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Post by Casethecorvetteman on Mar 23, 2016 22:53:43 GMT -5
Do you notice it gets any sharper?
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Post by gregstv on May 21, 2016 2:30:38 GMT -5
I have been playing with the neck boards today. I found that adding a 2.2uf ceramic cap to the plus and minus rail on the OPA688 amp reduced even more noise. I did the blue first and looking into the lens the noise is now almost gone. If you check the Burr Brown OPA688 datasheet these caps are recommended to be fitted in parallel with the.1 cap. Barco fitted the .1 but not the 2.2uf. I also made up back shields for them. I will post some pictures later. Burr Brown recommended filtering diagram attached.  |
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Post by gregstv on May 28, 2016 0:35:56 GMT -5
Pictures of the shields I made for the neck board. The picture is very clean. I did the shields after adding the 2.2uf caps to the OPA688. The caps made the biggest difference.   |
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Post by Casethecorvetteman on May 28, 2016 9:52:56 GMT -5
Did the shields help further?
I have two sets of neck boards here, i might through a set your way when i send the switcher and RGB boards down if thats ok.
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Post by gregstv on May 29, 2016 1:02:11 GMT -5
Did the shields help further? I have two sets of neck boards here, i might through a set your way when i send the switcher and RGB boards down if thats ok. No Problem, I will recap them as well if you haven't done them. |
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Post by Casethecorvetteman on May 29, 2016 2:58:00 GMT -5
Nah mate i havent had time the past few weeks to touch anything. Been quite bogged down of late.
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