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Nashou66
Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY
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Link Posted: Fri Mar 14, 2008 11:52 am Post subject: |
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Quote: | Athanasios. What is current rating of those inductors that you used?.
I tested yesterday that fcm takes about 0.2-0.8 amps, measured on just one rail, and it also take some "current spikes" so those inductors must have big enought to hadle that current. I think that inductor in that place must have current rating near 1,5-2amp min. |
Thanks Jarmo for taking those readings, I looked up the specs and i need to increase to a higer amp rating for those, can you also test the 24 volt rails too. I have some 270uh inductors that are 4 amp rated to use, the ones in the pics are only .44 amps!!! too low for that ! But i did watch Hitman last night with no problems, great looking movie since i think it was filmed in HD.
Thanks for your input and any more help and suggestions are deeply appreciated.
Post has been edited to state amp current draw.
Athanasios
_________________ Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan
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1031
Joined: 22 Mar 2006 Posts: 657 Location: Finland
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Nashou66
Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY
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Link Posted: Fri Mar 14, 2008 1:22 pm Post subject: |
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Thanks Jarmo! I will still add those beefier 270uh inductor on the 24 volt rails and replace my smaller 220uh indutors on the 15 volt rails. Thanks for the heads up on the current draw ,the 220uh are probably good for my CLM and VIM but the focus board and HDM(still looking at schematics) will most likley need a larger current draw capability, this is where a scope would come in handy.
Regarding the Big Pink plastic caps, Mcpheve said that they couple the dynamic focus, so I assume that a better cap will help stablize the current in that dynamic coil? Maybe you could swap out one of those caps before any others are changed on that board and put the scope on the out put to the dynamic coil and see which has a more stable current/pulse. Like said in the beggining of this thread I am not an EE nad any help we get for this thread will be of great help! I didnt do a long test after each part replacement so i cant tell if any one part replacment makes a difference but overall the focus board has much more stability after all mods are done as a whole. Like you said the 1000uf cap replacement I say made the biggest improvment, then the op amp replacement next. I did those changes first before i recieved the rest of the parts for all the other cap changes, the inductors i did while writting the post for the thread.
Quote: | But those 3 100uF bipolars can make some drifting, changing those could help little for more stable focusing. |
I thought you meant the 6 470uf i changed to 1000uf...but I was thinking fo changing those non polars with a higher lower esr cap but havnt looked around to find a replacement do you think a film cap would be better here?
Athanasios
_________________ Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan
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1031
Joined: 22 Mar 2006 Posts: 657 Location: Finland
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Nashou66
Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY
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PaulB
Joined: 26 Oct 2007 Posts: 359 Location: Bonnie (but rainy) Scotland
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Link Posted: Fri Mar 14, 2008 9:13 pm Post subject: |
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Hi Athanasios,
Just a clarification, the inductors, are they both 1110-270k ( http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=M6225-ND ) for attachment to the resistors and for attachment to the -/+ 24volt rails?
Also, the picture where you have scratched the 24volt trace, its looks like there are three scratches on the - (minus) 24volt trace, presumably this is two outer scratches on each trace for attaching the inductor and the middle scratch is actually cutting the trace?
Thanks,
Paul
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Nashou66
Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY
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1031
Joined: 22 Mar 2006 Posts: 657 Location: Finland
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Nashou66
Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY
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Joust
Joined: 05 May 2006 Posts: 2431 Location: Almonte, Ontario, Canada
TV/Projector: Marquee 8501LC
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Link Posted: Sat Mar 15, 2008 1:28 pm Post subject: |
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did you look at these lines with a scope?
How much noise is on them?
Where I'm going with this is do you need an inductor? or will a ferrite bead suffice?
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Nashou66
Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY
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Link Posted: Sat Mar 15, 2008 2:42 pm Post subject: |
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I don't have a scope but from my research and from comments in old posts on the AVS archives it was mentioned
that they added inductors to all the power rails on each board and some also do it to the main conector on the
mother board as well. I dont thing ferrite beads added to the apropriate wires, lets say the wires going to the
focus coils, will do as much as cleaning it up right at the source. Mike Parker was one of the people who I
read mentioning inductors but not sure which boards he uses them on. It wont hurt if thats what your asking, especially
if you use very low DCR inductors that wont impead electricity flow like the ones I use. Jarmo(1031) has a scope
and would be able to let us know more on this. I cant remeber if he and I talked about this off forum, but i think
we both agree indutors on all boards will do more good than harm.
I found the post where Mike parker comments on another member filtering the power rails
on the Upper mother board. Here is his reply:
Mike parker said from old AVS post:
Quote: | Actually this is the same method that I'm using on my modded boards. It's very obvious to anyone who has seen one of my modded VIM's.
The main board (UMB) idea sounds like a good idea. I'll like to know how that turns out.
__________________
mike parker |
So we know there is noise going through those rails probably throughout the entire marquee. You could try to clean it up at the power supplies but eventualy each board may create its own noise being trsnfered to other boards. So the Inductors will help catch and minimize noise that may be there. Also in the original post that Mike was commenting on the OP also was using a few caps as well on the mother board filtering. But that will come at a later times as I have not fully researched this.
Maybe when Jarmo gets some free time from his busy schedual he can scope each boards power rails for noise, including the mother board. What do you think Buddy?
Athanasios
_________________ Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan
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Nashou66
Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY
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Link Posted: Sat Mar 15, 2008 9:49 pm Post subject: |
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Guys I was just going over other possibilities for inductors and realized that Newark sent me the wrong inductors in a miss printed package. I was reviewing my orders and found thet the package shows the right part number but the parts were wrong. The big inductor in my pic is only a 27uh not a 270uh as my package states. Pauls post asking about the numbers on the inductors made me look at it again. the package states series 1130-271k-RC and my inductors are 1110-270k-RC. So I looked up that part , the ones I have, and they are the 27uh ones and smaller in diameter. the 270 series 1130 are 1.1 inch diameter!!!! that huge ! I am looking for at least a 2 amp version but that is the closet one. it should still fit but geeze! its alot bigger than the ones i have on there. if any one finds a inductor of either 220uh-270uh and of at least 2 amps or more post. the one in the 1110 271k rc is only 1.6 amps, Jarmo will this work or is it too low to be safe?
this is the huge fat one but high current
http://www.newark.com/63K3339/passives/product.us0?sku=BOURNS-JW-MILLER-1130-271K-RC
this is the 1.6 amp 270uh inductor.Same Physical size as one in pictures
http://www.newark.com/63K3260/passives/product.us0?sku=BOURNS-JW-MILLER-1110-271K-RC
Athanasios
_________________ Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan
One Smart Dog!!!
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PaulB
Joined: 26 Oct 2007 Posts: 359 Location: Bonnie (but rainy) Scotland
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Nashou66
Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY
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Nashou66
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tse
Joined: 03 May 2006 Posts: 1014 Location: Sweatbucket, Fl.
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Link Posted: Sun Mar 16, 2008 1:15 am Post subject: |
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Bigger value with inductors doesn't always mean better filter action. Every inductor also has capacitance between the windings that resonates with the inductance. These two values create what is called the Self Resonant Frequency or SRF. Frequencies higher than the SRF tend to bypass the inductor by travelling through the capacitance. So, if the freqency that you are trying to filter is 10 or 20MHz and the SRF of the inductor is 1.7MHz alot of the noise will not be reduced. Sometimes a smaller value with a higher SRF will work better. It all depends on what you are trying to filter.
Ferrite beads are usually spec'ed at 100MHz and present little impedance at lower frequencies. Once again it depends on what you are trying to filter.
Scott
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Nashou66
Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY
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Link Posted: Sun Mar 16, 2008 1:37 am Post subject: |
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Thanks Scott, this is why i need to get a scope! I was actually reading up on what values of inductors filter out what frequencies, and trying to grasp this whole concept of noise reduction/filtering. I was reading also that the de coupling capacitor in the circuit that inductor is on, also dictates what value you should use as not to increase that self resonant frequency. I still need to study this more, also thanks for you added input! we definitely could use some more guidance on this thread
this is what i was reading and have sort of grasped a little about de coupling and inductors.
http://www.williamson-labs.com/480_xmis.htm
Still looking up more....
Athansios
_________________ Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan
One Smart Dog!!!
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Joust
Joined: 05 May 2006 Posts: 2431 Location: Almonte, Ontario, Canada
TV/Projector: Marquee 8501LC
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Link Posted: Sun Mar 16, 2008 2:11 am Post subject: |
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the best thing to do to filter DC lines is to use a PI filter.
cap to ground - inductor in series - cap to ground.
the larger the values used the lower the frequency cutoff is.
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Nashou66
Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY
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Link Posted: Sun Mar 16, 2008 2:27 am Post subject: |
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You could also use different value inductors together in parallel right? I think the de coupling caps for that voltage rail(24) are the 100uf caps Jarmo mentioned earlier in the thread. there is a ground trace right next to the 24 volt rails where we could add those caps Joust mentions in the post above, not sure if its the right ground trace though there are a few all marked different. Any thought on this Joust and what value caps might be best... although I know it be best to know what frequencies we need to filter out to help decide the exact values.
Athansios
_________________ Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"Republicans believe every day is the Fourth of July, but the Democrats believe every day is April 15." --- President Reagan
One Smart Dog!!!
Marquee High Performance Bellows now shipping!!
Marquee Modifications and Performance Enhancement
Marquee C-element and Bellow removal
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Joust
Joined: 05 May 2006 Posts: 2431 Location: Almonte, Ontario, Canada
TV/Projector: Marquee 8501LC
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Link Posted: Sun Mar 16, 2008 2:32 am Post subject: |
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I'd use two in parallel. Put a large one to filter all frequencies down as close to DC as is practical. Also add a 0.1 ceramic cap. The reason for this is because some higher radio frequencies can slip by electrolytics.
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