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mp20748
Joined: 12 Sep 2006
Posts: 5689
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Posted: Tue Jul 13, 2010 11:36 am Post subject: |
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Some of the boards are getting older and would become more difficult to easily desolder regardless of what you use.
If either Vertical or Convergence boards have the dual one (1 - 1.2) ohm resistors they are the upgraded or later version, and would not need the resistors replaced at all.
The earlier version boards had the single 1 ohm resistors, with the upgrade, the resistance amount would then be half (0.5 ohm) of the one ohm value in the earlier design.
The resistors I recommended were 0.47 ohm 1/2 watt, which are NOT higher in wattage nor different in resistance value from the manufacturers upgraded value. The actual only difference is with the dual stock resistors the wattage doubles to 1 watt total.
So the manufacturer fixed the stability problem themselves by doubling the resistors. In doing that, they changed both resistance and wattage in those circuits.
Plus, and this would be the the main reason to leave the resistors alone and not be so apt to change them, would be the FUSIBLE value they provide to the circuit. Not all resistors would add this value, therefore it's not a good idea to randomly swap in resistors, especially based on cost and boutique rating.
One other thing to consider if dealing with acute bouts of Tweak-itis...
The resistors mentioned here are current sensitive (Current Limiting Resistors), and whenever you're dealing with both vertical and convergence circuits/stages and their stability, it's very important that all contacts, connections be soldered close to the original design as possible, to make sure there's proper resistance and current flow to each of the three channels as equal as possible -- there's a reason why some of the board traces are wider than others.
Again, if the boards have the dual resistors already, leave it alone - it's already upgraded!
| stefuel wrote: |
I haven't used seporate flux since I was in grade school which was before many of you were born  |
We're getting old Chip..
The only time these days to use separate Flux is when/if soldering copper pipes.
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Tue Jul 13, 2010 3:05 pm Post subject: |
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| mp20748 wrote: |
So the manufacturer fixed the stability problem themselves by doubling the resistors. In doing that, they changed both resistance and wattage in those circuits.
Plus, and this would be the the main reason to leave the resistors alone and not be so apt to change them, would be the FUSIBLE value they provide to the circuit. Not all resistors would add this value, therefore it's not a good idea to randomly swap in resistors, especially based on cost and boutique rating.
One other thing to consider if dealing with acute bouts of Tweak-itis...
The resistors mentioned here are current sensitive (Current Limiting Resistors), and whenever you're dealing with both vertical and convergence circuits/stages and their stability, it's very important that all contacts, connections be soldered close to the original design as possible, to make sure there's proper resistance and current flow to each of the three channels as equal as possible -- there's a reason why some of the board traces are wider than others.
Again, if the boards have the dual resistors already, leave it alone - it's already upgraded!
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There, just thought I'd help. 
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dvh99
Joined: 25 Dec 2009
Posts: 2158
Location: nederland
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| Posted: Tue Jul 13, 2010 3:12 pm Post subject: |
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talking from my own experience here, i didnt have stable convergence and after i changed those parallel 1ohm resistors with bigger sized 1% 1/2w my convergence is so stable that i havent touched it in 1/2 yr.
i used fusibles and kept the design the same by using 12*2*parallel 1ohm 1/2w.
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Tue Jul 13, 2010 3:57 pm Post subject: |
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| dvh99 wrote: | simplest way to desolder.
1 clean the entire board with alcohol let dry for 10 mins.
2 put flux on the pads that hold the components to desolder.
3 apply a little bit of fresh solder to the pads.
4 heat the pad and pull out the component gently to 1 side and then the other side.
5 use a simple vacuum pump (with a spring) and clean out the holes.
when done clean the entire board again with alcohol and wait 10 mins.
put the components in apply flux and solder.
1st put solder between the tip of the soldering pin and the wire of the component and once it flow apply the solder to the wire opposite of the soldering pin and hold a few seconds to let the solder flow through.
succes guaranteed.
and of course clean the entire board again. |
IMO this is really good advice. It's time consuming ot be sure but it practically gaurantees an undamaged board when your done. No.3 is especially important, from my experience the solder on these boards is very often Gray and dull looking, which means it won't liquify or transfer heat like fresh solder will.
It seems counter intuitive to add solder when your trying to De-solder but it's very important.
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Jeremy112
Joined: 28 Sep 2006
Posts: 2649
Location: Fond du Lac, WI
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| Posted: Tue Jul 13, 2010 6:08 pm Post subject: |
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Have none of you heard of Desoldering braid? Takes the old solder right out in an instant, no solder sucker can compete. Ill bet my life on that.
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Tue Jul 13, 2010 6:18 pm Post subject: |
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| Jeremy112 wrote: | Have none of you heard of Desoldering braid? Takes the old solder right out in an instant, no solder sucker can compete. Ill bet my life on that.
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I buy braid in 100 foot rolls but we were talking about removing the old part first. After that, cleaning the hole out with braid works great ............
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Jeremy112
Joined: 28 Sep 2006
Posts: 2649
Location: Fond du Lac, WI
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| Posted: Tue Jul 13, 2010 6:22 pm Post subject: |
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I have to say I've never used anything but braid, and always had 100% success in cleaning out the old holes without damaging the board in any way. the techniques described in this thread are ones I've not used (or needed to).
My opinions come from 10 years of experience in repairing Receivers, LCD monitors, and TV's...
perhaps im out of date
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cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
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| Posted: Wed Jul 14, 2010 12:34 am Post subject: |
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Good braid works great except when dealing with small holes and large ground planes.
What I like to do when the solder just can't be cleaned out of the hole no matter what you try, is to use a miniature hand drill (crank style,
not electric) with a tiny drill bit, and gently drill through the solder. The bit is substantially smaller than the hole, so as not to damage
the sides of the plated-through hole.
Then reapply the soldering iron and fresh wick. This way you get it all out.
CJ
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CZ Eddie
Joined: 23 Mar 2006
Posts: 1601
Location: Austin, TX
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| Posted: Wed Jul 14, 2010 12:53 am Post subject: |
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I've never been able to master the braid. Sometimes I can get the solder to soak up into it and sometimes the solder just ignores it. What's the trick?
Picked up a desoldering bulb at ratshack. Freakin $5 for $0.10 of plastic. I hate radio shack anymore. They didn't have the good solder poppers either.
Also paid $5 for a single small battery for my ESR tester. 
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Wed Jul 14, 2010 2:22 am Post subject: |
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| CZ Eddie wrote: | I've never been able to master the braid. Sometimes I can get the solder to soak up into it and sometimes the solder just ignores it. What's the trick?
Picked up a desoldering bulb at ratshack. Freakin $5 for $0.10 of plastic. |
you can't use the rat-shack braid either, it's flux free and only good for use as a ground-strap
I've tried a few and the chem-wik is my fave, works awesome.
Last edited by draganm on Wed Jul 14, 2010 2:25 am; edited 1 time in total
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JustGreg
Joined: 07 Mar 2006
Posts: 3098
Location: Kenosha, WI
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| Posted: Wed Jul 14, 2010 2:25 am Post subject: |
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| Nashou66 wrote: | here is the solder sucker I use:
For the braid I dip it in flux heat it up and the heat the solder , that helps it flow into the braid more.
Also do not tighten the braid push it together or bunch it up so the braids open up.
Athanasios |
I found that leaving the wick tight for initial desoldering works well (for me) and gets around the leads very well. If you push it against itself to open it up the wick doesn't act like a heatsink as much and the iron tip goes through the strands and puts more heat on the board than I like. I expand the wick width (say that three times fast!) to clean up after the component is out.
I also found that for stubborn holes (where wicking it from either side doesn't unplug the center) that a cut off component lead held in hemostats while heating it bores right through the solder without having to use mechanical means. That was before I got a good solder sucker iron like the one Nash and others use.
Funny rookie mistake using a solder sucker iron for the first time...never depress the bulb while over the board!! I spattered that crap all over the thing and spent an hour finding it all, and then got the willies when first powering it up.
draganm...100ft rolls of wick!! Wow...that has to cost a couple bucks. Hell, a 6ft dispenser at our local electronic parts outlet is $3.95!
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"Is it ignorance or apathy? Hey, I don't know and I don't care!" --Jimmy Buffett
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Wed Jul 14, 2010 2:27 am Post subject: |
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| JustGreg wrote: | | draganm...100ft rolls of wick!! Wow...that has to cost a couple bucks. Hell, a 6ft dispenser at our local electronic parts outlet is $3.95! |
I bought 2 x 100 foot rolls on closeout from MCM for like $12. each. Should last me a while especially with summer being so sloooowwwww
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CZ Eddie
Joined: 23 Mar 2006
Posts: 1601
Location: Austin, TX
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| Posted: Wed Jul 14, 2010 2:33 am Post subject: |
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Good tips.
I've always gotten my soldering stuff from the shack. Maybe that's why I've never gotten the hang of the braid. Didn't know to look for the flux style, if they have any.
No soldering for me tonight. I mowed front & back yard & worked out. Too tired.
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Spanky Ham
Joined: 22 Mar 2006
Posts: 5643
Location: Comedy Central
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| Posted: Wed Jul 14, 2010 3:29 am Post subject: |
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| CZ Eddie wrote: | Good tips.
I've always gotten my soldering stuff from the shack. Maybe that's why I've never gotten the hang of the braid. Didn't know to look for the flux style, if they have any.
No soldering for me tonight. I mowed front & back yard & worked out. Too tired. |
Wimp!
I just got almost back from SA. I was thinking of giving you a buzz as I went up to Schlitterbahn on Saturday. I figured it was to late of notice.
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CZ Eddie
Joined: 23 Mar 2006
Posts: 1601
Location: Austin, TX
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| Posted: Wed Jul 14, 2010 3:45 am Post subject: |
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Shoulda.... the best steakhouse in Texas is just two miles from my house!
Saltgrass -mmmh good steak. And one of the best BBQ places is across the street from it, where I coincidentally got some BBQ brisquette extra moist just this evening!!
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Spanky Ham
Joined: 22 Mar 2006
Posts: 5643
Location: Comedy Central
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| Posted: Wed Jul 14, 2010 3:56 am Post subject: |
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Stoppppppppppppp! I am already mouth watering for some Bill Miller.
If my cousins stay on me enough and I keep getting tired of Miami, then I may have to make the move. I saw where Texas was the best state for business by CNBC.
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Sparky015
Joined: 12 May 2009
Posts: 1185
Location: Cleveland / Akron, OH
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| Posted: Wed Jul 14, 2010 11:31 am Post subject: |
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| CZ Eddie wrote: | Shoulda.... the best steakhouse in Texas is just two miles from my house!
Saltgrass -mmmh good steak. And one of the best BBQ places is across the street from it, where I coincidentally got some BBQ brisquette extra moist just this evening!! |
Rudy's? When I traveled to Round Rock a lot, I always hit that place up for lunch. Great BBQ!
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CZ Eddie
Joined: 23 Mar 2006
Posts: 1601
Location: Austin, TX
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| Posted: Wed Jul 14, 2010 11:59 am Post subject: ~ |
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| Spanky Ham wrote: | Stoppppppppppppp! I am already mouth watering for some Bill Miller.
If my cousins stay on me enough and I keep getting tired of Miami, then I may have to make the move. I saw where Texas was the best state for business by CNBC. |
My little suburb of Round Rock is ranked the #2 fastest growing small city in America.
No state tax, just like FLA. House insurance is waaay cheaper, but our taxes are pretty high. ~$3k/annual on my starter house.
If you like sports, live entertainment, good people & tailgaters, Austin/Round Rock is the place to be.
Sparky, what brought you to RR?
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Sparky015
Joined: 12 May 2009
Posts: 1185
Location: Cleveland / Akron, OH
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| Posted: Wed Jul 14, 2010 2:18 pm Post subject: |
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We bought a company in RR back in 03. I traveled a lot to RR from 03 to about 07. After that things were moved from RR to either Ohio or Houston. I loved going there though. Lots to do around RR, and then Austin is fun too. The County Line resturant is awesome as well. I don't like Houston all that much, but I would certainly move to the Austin area.
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