CurtPalme.com Home Theater Forum

Nashou66 · Posted: Fri Mar 14, 2008 11:52 am Post subject:

1031 · Joined: 22 Mar 2006 Posts: 648 Location: Finland

[quote="Nashou66"]

Nashou66 · Posted: Fri Mar 14, 2008 1:22 pm Post subject:

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! Smile

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.

1031 · Joined: 22 Mar 2006 Posts: 648 Location: Finland

Nashou66 · Posted: Fri Mar 14, 2008 3:36 pm Post subject:

Ok everyone, thanks to 1031(Jarmo) for pointing out the current draw through those +/- 15 volt rails the inductors i had were to low an amprage only .44 and Jarmo scoped them to have peaks up 1.5 amps so I edited the post and also added a section on how to add same inductors to the +/- 24 volt rails.

pic of higher current inductors

I also Ordered caps for the three non-polars Jarmo mentiond and will try those once they come in.

https://www.mouser.com/Search/ProductDetail.aspx?R=UET2A101MHDvirtualkey64700000virtualkey647-UET2A101MHD

Athanasios

PaulB · Posted: Fri Mar 14, 2008 9:13 pm Post subject:

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

Nashou66 · Posted: Fri Mar 14, 2008 10:39 pm Post subject:

Paul, Yes you are correct with the trace cut and scratches. I got my part from Newark which I think has Farnbell as its UK distributor as I get some parts delived directly from them when i order through Newark here is the newark link. And if you notice the digikey has it listed as an obsolte item. These are very low DCR, it didnt even show any resistance whan i measured it on my multi meter.
Edit: correct part number and 4.6 amp rated...if it will fit on board

http://www.newark.com/63K3339/passives/product.us0?sku=BOURNS-JW-MILLER-1130-271K-RC

And this is the lower 1.6amp rated inductor

http://www.newark.com/63K3260/passives/product.us0?sku=BOURNS-JW-MILLER-1110-271K-RC

try Farnell also since its in the UK.

Athanasios

1031 · Joined: 22 Mar 2006 Posts: 648 Location: Finland

I measured those +-24v lines at 1080p50hz those take 1.1-1.4 amp. That current draw was mostly ac-amps, i measured those with fluke. That meter should be quite accurate also when measuring higher freq. So inductor for those lines should have also enough current capacity.. I say least 2amp.

Nashou66 · Posted: Sat Mar 15, 2008 11:57 am Post subject:

Thanks Jarmo, the ones i had lying around were 4.5 amps more than enough and they have almost no resistance. .03ohms. seem to be working fine after a few hours of use.

Athanasios

**Joust** · Posted: Sat Mar 15, 2008 1:28 pm Post subject:

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?

Nashou66 · Posted: Sat Mar 15, 2008 2:42 pm Post subject:

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:

Nashou66 · Posted: Sat Mar 15, 2008 9:49 pm Post subject:

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

PaulB · Posted: Sat Mar 15, 2008 10:39 pm Post subject:

What about this http://www.mouser.com/Search/ProductDetail.aspx?qs=slt62z1C2uqVfyJy8ykWkg%3d%3d ?

1120-271K-RC 270uh 2amps 0.81" diameter. 13 weeks backorder though.

Paul

Nashou66 · Posted: Sat Mar 15, 2008 11:15 pm Post subject:

Nashou66 · Posted: Sat Mar 15, 2008 11:32 pm Post subject:

I would still like to use the 1.6 amp rated one's since they are cheaper and Jarmo's measurement was max'd at 1.4 amps. Wish Jarmo was awake now to answer. Wink

Athanasios

tse · Joined: 03 May 2006 Posts: 1005 Location: Sweatbucket, Fl.

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

Nashou66 · Posted: Sun Mar 16, 2008 1:37 am Post subject:

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 Wink

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

**Joust** · Posted: Sun Mar 16, 2008 2:11 am Post subject:

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.

Nashou66 · Posted: Sun Mar 16, 2008 2:27 am Post subject:

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

**Joust** · Posted: Sun Mar 16, 2008 2:32 am Post subject:

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.