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Nashou66
Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY
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1031
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Nashou66
Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY
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Nashou66
Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY
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Link Posted: Tue Apr 08, 2008 1:47 am Post subject: |
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Update to my focus board problem, after I tested a 220uf color wheel inductor, DO NOT USE THEM !!!! Only use low DCR inductors of lower than .5 just to be safe.
After many e-mails with tse we finally found out that, even though it is very strange, that all 9 mosfet's Q113-115,Q213-215,Q313-315 went bad.
I am ordering new ones and will report back once they are in and working. Hopefully nothing else went bad that shorted out those mosfet's .
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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AnalogRocks Forum Moderator
Joined: 08 Mar 2006 Posts: 26690 Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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Link Posted: Tue Apr 08, 2008 4:08 am Post subject: |
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Nashou66 wrote: | Update to my focus board problem, after I tested a 220uf color wheel inductor, DO NOT USE THEM !!!! Only use low DCR inductors of lower than .5 just to be safe.
After many e-mails with tse we finally found out that, even though it is very strange, that all 9 mosfet's Q113-115,Q213-215,Q313-315 went bad.
I am ordering new ones and will report back once they are in and working. Hopefully nothing else went bad that shorted out those mosfet's .
Athanasios |
Awww that sucks, I hate defective part's. ( finger's crossed here )
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Nashou66
Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY
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Link Posted: Tue Apr 08, 2008 4:13 am Post subject: |
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AnalogRocks wrote: | Nashou66 wrote: | Update to my focus board problem, after I tested a 220uf color wheel inductor, DO NOT USE THEM !!!! Only use low DCR inductors of lower than .5 just to be safe.
After many e-mails with tse we finally found out that, even though it is very strange, that all 9 mosfet's Q113-115,Q213-215,Q313-315 went bad.
I am ordering new ones and will report back once they are in and working. Hopefully nothing else went bad that shorted out those mosfet's .
Athanasios |
Awww that sucks, I hate defective part's. ( finger's crossed here ) |
Me too, i really don't need to fix the board as i can get another one cheap, but part of the fun is learning how it all works and trouble shooting. Also the satisfaction of being able to solve and fix a problem is priceless.
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: Tue Apr 08, 2008 11:56 am Post subject: |
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1031 wrote: | Nashou66 wrote: | Hopefully nothing else went bad that shorted out those mosfet's .
Athanasios |
There is four 2 ohm resistors (on each channel) focus current goes through those.Check those also. R163-R166 (red channel).
-Jarmo |
Good call Jarmo ! It makes sense, I altered the 24 volt rail and each channel go to their own separate grounds that those 4 resistors are directly in series with. So if there was a surge in current it could have taken out those resistors, I should also check the three diodes in that circuit as well. Will do that today.
Follow up Those 4 2ohm resitors seem ok they all read about 1.6 ohms not enough to make a huge difference. Diodes seem ok as well.
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: Fri Apr 11, 2008 2:08 am Post subject: |
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Wooo hoooo!!!! Put in the new IRF520 mosfet's and all is well again!!! And I actually see a better focus control now...I think some were starting go, red is super tight and green is much better than before, and the blue which had the worst problem with left and right side focus is good again too. Thanks to TSE who walked me through using a scope to see the waveforms coming from the CLM and VDM to pinpoint were the problem was. I felt like he kinda knew what was wrong but was playing the roll of Mr Miagi and I was Danielson wax on wax off! Now that I have this under my belt i will move onto the next segment whick will be the VNB's , I still have some things to test so it might be a week before i start.
once again thanks scott for your help.
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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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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Link Posted: Mon Apr 14, 2008 7:55 pm Post subject: |
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Hi Paul I really don't think its necessary to change them out unless you are having a hard time focusing the left or right sides well ,or if you notice very little change while adjusting them .
I actually used the ones that have the Ultra low drain on source value:
http://www.newark.com/jsp/search/productdetail.jsp?SKU=63J7307
Watched about 5 movies since installing them and no problems so far, but i think any would do since they are new parts. I am not really sure if these parts wear much over time as to make a difference , I think the only reason i saw a difference was that maybe i had a few that were already bad as they switch in and out the caps for different frequencies and the frequency i used may not have been affected.
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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Nashou66
Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY
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Link Posted: Tue Apr 15, 2008 12:29 am Post subject: VNB Mod: Stage 1 |
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Back again and moving on to the neck board. I'll start with the Ceramic resistor upgrade originally posted by Jeaong-lee.
This is Stage 1
Pics of New and oder VNB's:
New Board
Old Board with metal can transitors
First we are going to change out the carbon comp resistors
and replace them with better ceramic resistors , Ohmites
being the favorite brand.
R76 100kohm 1 or 2 watt and R81 10Kohm of the same wattage.
R76 and R81
Pre bend the new resistor as shown
Make sure you remove all the solder using desoldering braid as a desoldering iron will not
have room with the heat sink still in place. I do not recommend trying to remove it either
as you may snap the transistors that are bolted to the heat sink.
Sliding resistor in place
Now solder in place from underside of VNB
R76 underside and R81 empty holes waiting to be filled
New resistors in place
Make sure you put the correct resistor in the right location !!!!!!
Next there are two more of those noisy carbon comp resitors, both are 33 ohm and we'll be replacing them with Ohmites of 1 or 2 watt value R23 and R27
33 ohm resistor location
These have the desoldering braid being used underneath, I remove as much solder as I can
and then use the tip of the Iron to push on the pin and then try wiggle the resistor out
with a plier . Be careful not to pull the solder hole out, I did it once not fun !!!
One of the ends of resistor 27 has to be heated from up top and then pulled out.
Location of resistor pins underneath, the two to the middle left closest to
the heat sink are the verticle resistor and only one pin of R27(right side
Also near heat sink)is accessible from here.
Lifting Resistor 27
Bend R23 as the previous two resistors and bend R27 as shown here:
And solder them into place. Also add heat shrink cover over
R23
Now we will upgrade the two caps C1 and C10. these are 22uf 100v which i changed to 22uf 160v 105c
Some up the capacitance to 33uf or higher, I have not tried it but may and will report back.
Old cap
getting under the heat sink is hard but can be done to remove the solder if you have trouble
cut the old cap off then use your desolder Iron or braid to remove the remaining pin and
solder, I like to try to keep all my old parts
I bend the lead of the cap so i can solder on end from the top then put
the other end in to hole and solder that from underneath.
Installing new cap
Board with new resistors and caps
Stage 2 coming next
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!!!
Marquee High Performance Bellows now shipping!!
Marquee Modifications and Performance Enhancement
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Last edited by Nashou66 on Wed Nov 10, 2010 8:17 pm; edited 1 time in total
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Nashou66
Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY
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Link Posted: Wed Apr 16, 2008 11:31 pm Post subject: VNB Chip Mod |
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Stage 2 VNB Chip mod.
For this stage i definitely suggest you have magnifying light of some sort. I got mine form
Joan Fabrics, its used for sewing and has a neat little tray that rotates around the base
were I keep parts
These are the two chips being put in A Burr Brown OPA2134 or a TLE2072 (either
one will work although i think the OPA2134 has better noise figure) and the
op amp Intersil's EL5166. This has an 800Mhz rating at a gain of
2 compared to the CLC449's 500Mhz. it also has a lower input voltage noise
rating. Some have said that looking at the current noise the CLC449 is better but they
took that reading at 1Mhz where the EL5166 were taken at the NTSC test of 3.58Mhz.
I think the higher bandwidth reading would show more noise, I am not sure what the
figure would be for the CLC449 at the same frequency but its probably not any better.
It also has a higher slew rate and Another reason I like this chip is that it is a direct drop
in, with no resistor changes like some of the more finicky super high slew rate chips.
Like the THS3201 I tried to use but had a hard time tameing , not saying it cant be done
but i just dont have the know how or patience at this time. Not to say i wont continue to
try as one other member here has had success it just seems like too much trouble for
what its worth. The EL5166 is nice and simple and for me it works.
Chips to be installed
We'll start with U4 the MC3402 chip
U4 chip location
You need to use the soldering braid again Using the tip of the iron push down on the braid
at each pin for it to suck up as much solder as possible out of the through hole. I make
two passes just to make sure.
Solder removed notice clear holes
Then from the underside i use a small flat head screw driver
to "snap" the pins loose.
Snapping pins loose
Then slowly and gently use the flathead driver to pry chip free.
If it does not want to move go back with the braid again and
snap the pins free. If you are able to get one side loose raise that out and then
from under the chip you can use the driver to snap the pins from up top by
pushing against the pin away from the side of the hole, you'll hear it "snap" .
Pry chip loose
Now put in new chip and solder, thats it one chip down one to go !!!!!
Now the small El5166, the video op amps are hard to get out because you don't want to
damage the pads they solder to. Pin 1 and 8 are No Connection pins and I almost always end up
taking the pad off with the chip. They are not put on very well to the PCB.
CLC449 location
Once agin make two passes with the desoldering braid. you will be able to see the edges of
the pins when its all removed and not much solder will move to the braid.
this is the hard part. I use the tip of an Exacto knive since it has a very fine point.
I put the tip under one of the pins and use the pin next to it as a pivot point
and pry the pin off the pad it should "snap" to the side a bit. if you have trouble
with any of the pins use the desolder braid again, you might find that just touching
it will move the chip off the pads.
Solder and chip removed
Now solder in the new EL5166
You'll need to hold it down while touching the tip of the iron to each
pin(they are pre tined a little bit) this will hold them in place while you
add solder to finish their mounting.
you can stop here or add the de coupling caps that are recommended in the data sheet.
I knew you would add them ! these are C29 and C30
(NOTE:if you dont add them and see anything wrong I'd add them)
Here we need 4.7 uf 50 volt tantalums C case would be ideal i only had D case size.
You could us radial tants if you cant find the SMT tants. I get mine
on e-bay you get more and a lot cheaper too.
D sized cap, I added the solder first because of its larger size
covers the solder pads, and caps in place
Well we are not done yet, Across those two caps we add a 100pf mica cap, i got a crap load
on ebay (silver mica)
I almost forgot!!! Add two more of those mica caps across C21 and C46 and C2
this is from McPherve's suggestion on the AVS archives, you can also replace C2(100nf) with a better film cap I haven't done it yet but will then add a 100pf across C2 as well
Thats it for now not sure when i'll have time for the next instalment.
Have fun!!
Athanasios Hatzinerantzis
_________________ 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
Last edited by Nashou66 on Wed Nov 10, 2010 8:46 pm; edited 2 times in total
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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: Thu Apr 17, 2008 12:22 am Post subject: |
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Athanasios
good write up.
Your chip removal methods can use a little improvement though. the through hole is ok but you should stress that if you do not enough solder removed when you start the prying and "snapping" it loose, you could end up pulling the plated through hole out of the board. On a multilayer board this is very bad. These boards are made well so its much harder to do this kind of damage. on cheap boards, it can be quite easy.
On the surface mount chip, try this...
Flow a LOT more solder on the pins on one side. Lay your soldering iron across all pins and pry up that side about 1mm. Then suck/wick out the solder. once one side pins are free. repeat the flow heat procedure on the other side and simple pick off the chip. Then wick teh pads clean. I guarantee this process will never lift a pad as long as you don't transfer too much heat to the board. I use my iron set to 800deg.
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Nashou66
Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY
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Link Posted: Thu Apr 17, 2008 2:00 am Post subject: |
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Thanks Joust , I think i mentioned in one of my earlier post with the resistor mods that i did pull out a though hole once and it wasn't fun, I was able to actually put it back in but ti took a long time to do so. With the SMT chip removal , I tried that method but was never able to master it, The way I do it takes a bit longer but i can do it very quickly now less that 3 minutes for an 8 pin chip. the key is to deflow the all the solder to the braid till no more flows to it, then each pin just pops off, actually they pop over to one side as I never pull up on the pins. Those pads that are of no use are the ones that usually come off. I was re attaching them to the board with some super glue but decided it really wasn't needed. I just like to have the board still look nice and neat after my mods.
Oh and one thing i for got to mention is to clean the boards before and after with denatured alcohol. flux and resin are left after the work and cleaning before helps the solder flow easier.
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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Joust
Joined: 05 May 2006 Posts: 2431 Location: Almonte, Ontario, Canada
TV/Projector: Marquee 8501LC
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Link Posted: Thu Apr 17, 2008 2:31 am Post subject: |
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with my method an 8pin chip removal takes 3 seconds per side.
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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: Thu Apr 17, 2008 3:02 am Post subject: |
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Sorry bud,
I wasn't trying to put you down.
I re-read my post and it seems a little snotty.
You are doing a great job.
I just noticed a couple pads came off and Know that is from too much heat transfer to the board.
I wish I had a video camera and could record me doing a SMT chip the way I described.
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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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Link Posted: Thu Apr 17, 2008 5:11 am Post subject: |
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Funny! I just got those El5166 chips yesterday, quick testing showed that works pretty well, without any resistor changes.
I order those el5166 chips as samples-> went weeks->nothing, so then i asked at Farnell Finland and they said that those are coming to stock, so i ordered those-> after two days i got those free samples and same chips from farnell
Nashou, you use 100pF mica cap for highfreq decoupling, i foundet that wiht least three caps parallel makes better job
So for Vnbīs trye something like that -> 4,7uF tanf + 100nF(that is in there allready) +22nF then that 100Pf mica
And remember that smallest cap should be close to op-amp supply pins, so that 100pF mica works better if you can put it closer to op-amp maybe parallel to those original 100nF caps
Here is good article-> http://electronicdesign.com/Articles/Index.cfm?AD=1&ArticleID=1478&pg=3
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Last edited by 1031 on Thu Apr 17, 2008 7:17 am; edited 1 time in total
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