one last dead system question

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?

Chris
If life seems jolly rotten
There's spmething you've forgotten
and thats to laugh and smile and dance and sing!

In article , 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. 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

In comp.sys.ibm.pc.hardware.misc Chris 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.

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

In comp.sys.ibm.pc.hardware.misc krw wrote:
In article , 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...

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.

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.

Let's put it this way, what have you got to lose?

A board, that is essentially fine?

Arno

In article ,
says...
In comp.sys.ibm.pc.hardware.misc krw wrote:
In article , 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.

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.

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.

Let's put it this way, what have you got to lose?

A board, that is essentially fine?

What a maroon!

--
Keith

In article ,
says...
In comp.sys.ibm.pc.hardware.misc Chris 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.

Bull****. Just heat a hunk of capacitor or resistor lead of
similar size and pass it through the hole.

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?

--
Keith

In comp.sys.ibm.pc.hardware.misc krw wrote:
In article ,
says...
In comp.sys.ibm.pc.hardware.misc krw wrote:
In article , 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. 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...

Arno

In comp.sys.ibm.pc.hardware.misc krw wrote:
In article ,
says...
In comp.sys.ibm.pc.hardware.misc Chris 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.

Bull****. 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...

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.

Arno

In article ,
says...
In comp.sys.ibm.pc.hardware.misc krw wrote:
In article ,
says...
In comp.sys.ibm.pc.hardware.misc krw wrote:
In article , 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.

Add one, and change.

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...

Do come back when you've knocked that pointy chip off your
shoulders. On second thought...

--
Keith

In article ,
says...
In comp.sys.ibm.pc.hardware.misc krw wrote:
In article ,
says...
In comp.sys.ibm.pc.hardware.misc Chris 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.

Bull****. 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...

Weren't you just talking about a technique that might work for a
has-been-drip-under-pressure, but an amateur better not try? LOL

It's a *lot* safer than a drill bit!

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
through hole at all! Sheesh!

--
Keith