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one last dead system question
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one last dead system question -
11-22-2006
, 10:37 AM
#2
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Thanks for the help so far, I am going to replace the caps with the lower rated caps (1200uf vs 1800uf). Somone posted that replacing caps on multi-layer boards was very difficult. The 3 caps that caps that need replacement go all the way through the board and are soldered on the back of the board. I am assuming that I can just de-solder the old caps are solder on the new caps without a hitch. My soldering skills are so-so, but I have soldered and desoldered chips from old boards before. For example, I replaced the bios chip from an Atari 7800 system board with a new bios chip to make a cart dumper. Any advise? Would this be beyond my skill level? |
alright. Remember that the cap leads are heavier and they are
connected directly to planes (a big heat sink) and will take more
heat. Too much though and bad things happen. I'd highly recommend
"solder wick" ( essentially tinned copper braid laced with flux) to
remove the caps and clean the pads.
Let's put it this way, what have you got to lose?
--
Keith
#3
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Thanks for the help so far, I am going to replace the caps with the lower rated caps (1200uf vs 1800uf). |
that. May blow up your CPU.
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Somone posted that replacing caps on multi-layer boards was very difficult. The 3 caps that caps that need replacement go all the way through the board and are soldered on the back of the board. I am assuming that I can just de-solder the old caps are solder on the new caps without a hitch. My soldering skills are so-so, but I have soldered and desoldered chips from old boards before. For example, I replaced the bios chip from an Atari 7800 system board with a new bios chip to make a cart dumper. Any advise? Would this be beyond my skill level? |
holes in-between, which can be very hard, except with the right equipment.
On thing you can do is drill them out. For this it is very important to
use a drill bit that is at leat 0.1mm (better 0.2mm) smaller in diameter
than the holes.
Best is to measure the leads of the old or new caps and make the drill bit
0.1mm thicker. If your drill bit is smaller than the holes and you drill
carefully (Dremel or the like on very slow setting), you will not damage
the copper much, since the tin solder is much softer. I have done this
several times sucessfully.
Arno
#4
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In article <r8r8m2p78fsgqefedlr85klh14m50gie36 (AT) 4ax (DOT) com>, christo9 @notalotofunwanted.aol.com says... Thanks for the help so far, I am going to replace the caps with the lower rated caps (1200uf vs 1800uf). Somone posted that replacing caps on multi-layer boards was very difficult. The 3 caps that caps that need replacement go all the way through the board and are soldered on the back of the board. I am assuming that I can just de-solder the old caps are solder on the new caps without a hitch. My soldering skills are so-so, but I have soldered and desoldered chips from old boards before. For example, I replaced the bios chip from an Atari 7800 system board with a new bios chip to make a cart dumper. Any advise? Would this be beyond my skill level? If you've desoldered a BIOS chip successfully you should be alright. Remember that the cap leads are heavier and they are connected directly to planes (a big heat sink) and will take more heat. |
have up to 7...
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Too much though and bad things happen. I'd highly recommend "solder wick" ( essentially tinned copper braid laced with flux) to remove the caps and clean the pads. |
soldering iron to 450C or so, and then you run a real risk
of damaging the board. I tried this with a professional vaccuum
desoldering station and it worked maybe one time out of three.
solder wick will not work at all.
Use additional solder to get clean contact between the soldering iron
and the board, melt the solder quickly and carefully lever the cap out
on that side. Repeat on the oder side. After all they only have two
leads, so this works. You will end up witk a clogged though hole, see
my other posting on how to deal with that.
Quote:
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Let's put it this way, what have you got to lose? |
Arno
#5
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In comp.sys.ibm.pc.hardware.misc krw <krw (AT) att (DOT) bizzzz> wrote: In article <r8r8m2p78fsgqefedlr85klh14m50gie36 (AT) 4ax (DOT) com>, christo9 @notalotofunwanted.aol.com says... Thanks for the help so far, I am going to replace the caps with the lower rated caps (1200uf vs 1800uf). Somone posted that replacing caps on multi-layer boards was very difficult. The 3 caps that caps that need replacement go all the way through the board and are soldered on the back of the board. I am assuming that I can just de-solder the old caps are solder on the new caps without a hitch. My soldering skills are so-so, but I have soldered and desoldered chips from old boards before. For example, I replaced the bios chip from an Atari 7800 system board with a new bios chip to make a cart dumper. Any advise? Would this be beyond my skill level? If you've desoldered a BIOS chip successfully you should be alright. Remember that the cap leads are heavier and they are connected directly to planes (a big heat sink) and will take more heat. And the Atari had dual or 3-layer PCB, while a modern mainboard can have up to 7... |
connected to one.
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Too much though and bad things happen. I'd highly recommend "solder wick" ( essentially tinned copper braid laced with flux) to remove the caps and clean the pads. Forget it. You will not get the caps desoldered, unless you set your soldering iron to 450C or so, and then you run a real risk of damaging the board. I tried this with a professional vaccuum desoldering station and it worked maybe one time out of three. solder wick will not work at all. |
this sort of thing a *LONG* time. Solder wick works.
Quote:
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Use additional solder to get clean contact between the soldering iron and the board, melt the solder quickly and carefully lever the cap out on that side. Repeat on the oder side. After all they only have two leads, so this works. You will end up witk a clogged though hole, see my other posting on how to deal with that. |
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Let's put it this way, what have you got to lose? A board, that is essentially fine? |
--
Keith
#6
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In comp.sys.ibm.pc.hardware.misc Chris <christo9 (AT) notalotofunwanted (DOT) aol.com> wrote: Thanks for the help so far, I am going to replace the caps with the lower rated caps (1200uf vs 1800uf). Good luck! I had a board going into oscillations when I tried that. May blow up your CPU. Somone posted that replacing caps on multi-layer boards was very difficult. The 3 caps that caps that need replacement go all the way through the board and are soldered on the back of the board. I am assuming that I can just de-solder the old caps are solder on the new caps without a hitch. My soldering skills are so-so, but I have soldered and desoldered chips from old boards before. For example, I replaced the bios chip from an Atari 7800 system board with a new bios chip to make a cart dumper. Any advise? Would this be beyond my skill level? De-soldering should work. Re-soldering also. The trick is clearing the holes in-between, which can be very hard, except with the right equipment. On thing you can do is drill them out. For this it is very important to use a drill bit that is at leat 0.1mm (better 0.2mm) smaller in diameter than the holes. |
similar size and pass it through the hole.
Quote:
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Best is to measure the leads of the old or new caps and make the drill bit 0.1mm thicker. If your drill bit is smaller than the holes and you drill carefully (Dremel or the like on very slow setting), you will not damage the copper much, since the tin solder is much softer. I have done this several times sucessfully. |
through hole?
--
Keith
#7
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In article <4sjd6tF106apcU2 (AT) mid (DOT) individual.net>, me (AT) privacy (DOT) net says... In comp.sys.ibm.pc.hardware.misc krw <krw (AT) att (DOT) bizzzz> wrote: In article <r8r8m2p78fsgqefedlr85klh14m50gie36 (AT) 4ax (DOT) com>, christo9 @notalotofunwanted.aol.com says... Thanks for the help so far, I am going to replace the caps with the lower rated caps (1200uf vs 1800uf). Somone posted that replacing caps on multi-layer boards was very difficult. The 3 caps that caps that need replacement go all the way through the board and are soldered on the back of the board. I am assuming that I can just de-solder the old caps are solder on the new caps without a hitch. My soldering skills are so-so, but I have soldered and desoldered chips from old boards before. For example, I replaced the bios chip from an Atari 7800 system board with a new bios chip to make a cart dumper. Any advise? Would this be beyond my skill level? If you've desoldered a BIOS chip successfully you should be alright. Remember that the cap leads are heavier and they are connected directly to planes (a big heat sink) and will take more heat. And the Atari had dual or 3-layer PCB, while a modern mainboard can have up to 7... The number of planes is irrelevant. Each lead of the cap is only connected to one. |
several layers. All I have seen were connected to at least two.
Quote:
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Too much though and bad things happen. I'd highly recommend "solder wick" ( essentially tinned copper braid laced with flux) to remove the caps and clean the pads. Forget it. You will not get the caps desoldered, unless you set your soldering iron to 450C or so, and then you run a real risk of damaging the board. I tried this with a professional vaccuum desoldering station and it worked maybe one time out of three. solder wick will not work at all. I'm so glad *you* are the font of all knowledge. I've been doing this sort of thing a *LONG* time. Solder wick works. |
work for you or me, but not for somebode with the soldering skills
of the OP. And it especially deos not work if you have a large copper
area on the upper side of the board around the trough-hole.
Quote:
|
Use additional solder to get clean contact between the soldering iron and the board, melt the solder quickly and carefully lever the cap out on that side. Repeat on the oder side. After all they only have two leads, so this works. You will end up witk a clogged though hole, see my other posting on how to deal with that. Doing that you're likely to lift the pads. Bad plan. |
to rip the leads out of the capacitor. But there is no need to
use excessive force. The trhoug-connections of power leads
are pretty sturdy in these boards.
Quote:
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Let's put it this way, what have you got to lose? A board, that is essentially fine? What a maroon! |
for any further discussion...
Arno
#8
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In article <4sjct2F106apcU1 (AT) mid (DOT) individual.net>, me (AT) privacy (DOT) net says... In comp.sys.ibm.pc.hardware.misc Chris <christo9 (AT) notalotofunwanted (DOT) aol.com> wrote: Thanks for the help so far, I am going to replace the caps with the lower rated caps (1200uf vs 1800uf). Good luck! I had a board going into oscillations when I tried that. May blow up your CPU. Somone posted that replacing caps on multi-layer boards was very difficult. The 3 caps that caps that need replacement go all the way through the board and are soldered on the back of the board. I am assuming that I can just de-solder the old caps are solder on the new caps without a hitch. My soldering skills are so-so, but I have soldered and desoldered chips from old boards before. For example, I replaced the bios chip from an Atari 7800 system board with a new bios chip to make a cart dumper. Any advise? Would this be beyond my skill level? De-soldering should work. Re-soldering also. The trick is clearing the holes in-between, which can be very hard, except with the right equipment. On thing you can do is drill them out. For this it is very important to use a drill bit that is at leat 0.1mm (better 0.2mm) smaller in diameter than the holes. Bullshit. Just heat a hunk of capacitor or resistor lead of similar size and pass it through the hole. |
Quote:
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Best is to measure the leads of the old or new caps and make the drill bit 0.1mm thicker. If your drill bit is smaller than the holes and you drill carefully (Dremel or the like on very slow setting), you will not damage the copper much, since the tin solder is much softer. I have done this several times sucessfully. Oh, this is a good idea! What happens when you destroy the plated- through hole? |
Arno
#9
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In comp.sys.ibm.pc.hardware.misc krw <krw (AT) att (DOT) bizzzz> wrote: In article <4sjd6tF106apcU2 (AT) mid (DOT) individual.net>, me (AT) privacy (DOT) net says... In comp.sys.ibm.pc.hardware.misc krw <krw (AT) att (DOT) bizzzz> wrote: In article <r8r8m2p78fsgqefedlr85klh14m50gie36 (AT) 4ax (DOT) com>, christo9 @notalotofunwanted.aol.com says... Thanks for the help so far, I am going to replace the caps with the lower rated caps (1200uf vs 1800uf). Somone posted that replacing caps on multi-layer boards was very difficult. The 3 caps that caps that need replacement go all the way through the board and are soldered on the back of the board. I am assuming that I can just de-solder the old caps are solder on the new caps without a hitch. My soldering skills are so-so, but I have soldered and desoldered chips from old boards before. For example, I replaced the bios chip from an Atari 7800 system board with a new bios chip to make a cart dumper. Any advise? Would this be beyond my skill level? If you've desoldered a BIOS chip successfully you should be alright. Remember that the cap leads are heavier and they are connected directly to planes (a big heat sink) and will take more heat. And the Atari had dual or 3-layer PCB, while a modern mainboard can have up to 7... The number of planes is irrelevant. Each lead of the cap is only connected to one. For the powrer parts that is untrue. They may be connected to several layers. All I have seen were connected to at least two. Too much though and bad things happen. I'd highly recommend "solder wick" ( essentially tinned copper braid laced with flux) to remove the caps and clean the pads. Forget it. You will not get the caps desoldered, unless you set your soldering iron to 450C or so, and then you run a real risk of damaging the board. I tried this with a professional vaccuum desoldering station and it worked maybe one time out of three. solder wick will not work at all. I'm so glad *you* are the font of all knowledge. I've been doing this sort of thing a *LONG* time. Solder wick works. I have been doing this for more than two decades. |
Quote:
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Solder wick may work for you or me, but not for somebode with the soldering skills of the OP. And it especially deos not work if you have a large copper area on the upper side of the board around the trough-hole. Use additional solder to get clean contact between the soldering iron and the board, melt the solder quickly and carefully lever the cap out on that side. Repeat on the oder side. After all they only have two leads, so this works. You will end up witk a clogged though hole, see my other posting on how to deal with that. Doing that you're likely to lift the pads. Bad plan. Very unlikely. Even with excessive force you are more likely to rip the leads out of the capacitor. But there is no need to use excessive force. The trhoug-connections of power leads are pretty sturdy in these boards. Let's put it this way, what have you got to lose? A board, that is essentially fine? What a maroon! And the same back to you. Seems to me you just disqualified yourself for any further discussion... |
shoulders. On second thought...
--
Keith
#10
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In comp.sys.ibm.pc.hardware.misc krw <krw (AT) att (DOT) bizzzz> wrote: In article <4sjct2F106apcU1 (AT) mid (DOT) individual.net>, me (AT) privacy (DOT) net says... In comp.sys.ibm.pc.hardware.misc Chris <christo9 (AT) notalotofunwanted (DOT) aol.com> wrote: Thanks for the help so far, I am going to replace the caps with the lower rated caps (1200uf vs 1800uf). Good luck! I had a board going into oscillations when I tried that. May blow up your CPU. Somone posted that replacing caps on multi-layer boards was very difficult. The 3 caps that caps that need replacement go all the way through the board and are soldered on the back of the board. I am assuming that I can just de-solder the old caps are solder on the new caps without a hitch. My soldering skills are so-so, but I have soldered and desoldered chips from old boards before. For example, I replaced the bios chip from an Atari 7800 system board with a new bios chip to make a cart dumper. Any advise? Would this be beyond my skill level? De-soldering should work. Re-soldering also. The trick is clearing the holes in-between, which can be very hard, except with the right equipment. On thing you can do is drill them out. For this it is very important to use a drill bit that is at leat 0.1mm (better 0.2mm) smaller in diameter than the holes. Bullshit. Just heat a hunk of capacitor or resistor lead of similar size and pass it through the hole. Good luck with that amateur-style technique... |
has-been-drip-under-pressure, but an amateur better not try? <LOL>
It's a *lot* safer than a drill bit!
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Best is to measure the leads of the old or new caps and make the drill bit 0.1mm thicker. If your drill bit is smaller than the holes and you drill carefully (Dremel or the like on very slow setting), you will not damage the copper much, since the tin solder is much softer. I have done this several times sucessfully. Oh, this is a good idea! What happens when you destroy the plated- through hole? You don't. Unless you are really clumsy. You don't because if your's smart you don't drill out a plated |
--
Keith
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