1 Jan
2015
1 Jan
'15
10:23 p.m.
Happy New Year, all!
Has anyone here gone through the process of reparing leaky NiCd damage
to an A4000 motherboard? I _thought_ I had removed the battery some
time ago but puttering around today, I cracked open the case to find
the battery still there and some damage around U891 (a 74F245) and
U850 (Bank 3 DIMM socket). I have washed off the residue but I may
have to pull a DIMM socket to get access to the vias under it.
I know the general process, but I'm curious if anyone has done this
specifically to an A4000 board and has any tips. As I said, I'm
probably going to have to pull the DIMM socket to get to all the
damage.
Barring success from running a dozen or so repair wires, would anyone
happen to have a lead on an A4000 motherboard? Everything else in the
machine should be good, the Daughter Card, the CPU card, etc...
It's my only A4000, so I'd like to get it back up and running, or
replace it if necessary.
Thanks for any tips,
-ethan
2 Jan
2 Jan
1:06 a.m.
well change all the Elertrolytics first. They are all toast.
clean it up really good, and try it. it might still work anyways.
Charles
MacCaps.com
ps:
make sure to change the caps on the cpu card as well.
I re-cap many of these for people.
On Jan 2, 2015, at 1:23 AM, Ethan Dicks <ethan.dicks at gmail.com> wrote:
Happy New Year, all!
Has anyone here gone through the process of reparing leaky NiCd damage
to an A4000 motherboard? I _thought_ I had removed the battery some
time ago but puttering around today, I cracked open the case to find
the battery still there and some damage around U891 (a 74F245) and
U850 (Bank 3 DIMM socket). I have washed off the residue but I may
have to pull a DIMM socket to get access to the vias under it.
I know the general process, but I'm curious if anyone has done this
specifically to an A4000 board and has any tips. As I said, I'm
probably going to have to pull the DIMM socket to get to all the
damage.
Barring success from running a dozen or so repair wires, would anyone
happen to have a lead on an A4000 motherboard? Everything else in the
machine should be good, the Daughter Card, the CPU card, etc...
It's my only A4000, so I'd like to get it back up and running, or
replace it if necessary.
Thanks for any tips,
-ethan
1:40 a.m.
On Fri, Jan 02, 2015 at 04:06:48AM -0500, Charles wrote:
[...]
make sure to change the caps on the cpu card as well.
I re-cap many of these for people.
Is this a specific known problem with the A3640 board, or just a prophylactic
fix-all for all machines of that age? It would perhaps explain the behaviour
I'm seeing.
1:43 a.m.
yes and yes :-)
make sure to read this? some of them are on there backwards from the factory.
http://amiga.serveftp.net/A3640_capacitor.html
On Jan 2, 2015, at 4:40 AM, Peter Corlett <abuse at cabal.org.uk> wrote:
On Fri, Jan 02, 2015 at 04:06:48AM -0500, Charles
wrote:
[...]
make sure to change the caps on the cpu card as
well.
I re-cap many of these for people.
Is this a specific known problem with the A3640 board, or just a prophylactic
fix-all for all machines of that age? It would perhaps explain the behaviour
I'm seeing.
2:31 a.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Peter
Corlett
Sent: 02 January 2015 09:40
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Repairing A4000 leaky NiCd damage?
On Fri, Jan 02, 2015 at 04:06:48AM -0500, Charles wrote:
[...]
prophylactic
make sure to change the caps on the cpu card as
well.
I re-cap many of these for people.
Is this a specific known problem with the A3640 board, or just a fix-all for all machines of that age? It would
perhaps explain the
behaviour
I'm seeing.
Electrolytic and Tantalum Capacitors seem to be problematic on machines of a
wide range of ages. Sometimes it is obvious they have failed as the caps
have domed tops.
Some times its not so obvious I would recommend a low-voltage ESR meter
that uses less than 0.6v so it doesn't turn on any diodes.
Dave
G4UGM
1:36 a.m.
On Fri, Jan 02, 2015 at 01:23:14AM -0500, Ethan Dicks wrote:
[...]
You didn't say what kind of A4000, but I'm assuming you are referring to the
Amiga, as this is a known problem.
I know the general process, but I'm curious if
anyone has done this
specifically to an A4000 board and has any tips. As I said, I'm probably
going to have to pull the DIMM socket to get to all the damage.
I've never had much luck with this kind of repair, but the A4000 repair always
sounded particularly difficult and liable to fail. Still, if you've got the
right tools and are patient and careful, you won't be worse off than if you
didn't bother at all.
Barring success from running a dozen or so repair
wires, would anyone happen
to have a lead on an A4000 motherboard? Everything else in the machine
should be good, the Daughter Card, the CPU card, etc...
I've got a surplus spare from a part-stripped carcass I bought back in 2001 to
try and clear a fault in my own A4000. However, a motherboard swap failed to
clear the fault I had. What this would imply is that both boards are OK since
the failure was sufficiently bizarre that it was unlikely that both would fail
identically, but since I've not conclusively seen either of them work for
nearly two decades, I wouldn't like to offer any sort of guarantee.
These boards also turn up on eBay in the USA, which might be a better bet. As
far as I can tell, the same boards were used in both NTSC and PAL machines and
a jumper configures the video standard. (I sometimes re-jumpered mine for NTSC
to reduce display flicker.)
2:39 a.m.
I've repaired many...I usually take off all the components of the affected
area, wash it with vinegar (!) to neutralize the electrolyte, wash again
with alchool or MEK (Metil-Etil-Ketone, cancerous and very dangerous
solvent) and rebuild the traces with very thin (awg 30) wire-wrap wire. It
always works (for me) :)
I've spent someday 6 hours to recover a board. In Brazil it is worth it!
good luck!
On Fri, Jan 2, 2015 at 7:36 AM, Peter Corlett <abuse at cabal.org.uk> wrote:
On Fri, Jan 02, 2015 at 01:23:14AM -0500, Ethan Dicks
wrote:
[...]
You didn't say what kind of A4000, but I'm assuming you are referring to
the
Amiga, as this is a known problem.
I know the general process, but I'm curious
if anyone has done this
specifically to an A4000 board and has any tips. As I said, I'm probably
going to have to pull the DIMM socket to get to all the damage.
I've never had much luck with this kind of repair, but the A4000 repair
always
sounded particularly difficult and liable to fail. Still, if you've got
the
right tools and are patient and careful, you won't be worse off than if you
didn't bother at all.
Barring success from running a dozen or so repair
wires, would anyone
happen
to have a lead on an A4000 motherboard?
Everything else in the machine
should be good, the Daughter Card, the CPU card, etc...
I've got a surplus spare from a part-stripped carcass I bought back in
2001 to
try and clear a fault in my own A4000. However, a motherboard swap failed
to
clear the fault I had. What this would imply is that both boards are OK
since
the failure was sufficiently bizarre that it was unlikely that both would
fail
identically, but since I've not conclusively seen either of them work for
nearly two decades, I wouldn't like to offer any sort of guarantee.
These boards also turn up on eBay in the USA, which might be a better
bet. As
far as I can tell, the same boards were used in both NTSC and PAL machines
and
a jumper configures the video standard. (I sometimes re-jumpered mine for
NTSC
to reduce display flicker.)
5:15 p.m.
On Fri, 2 Jan 2015, Alexandre Souza wrote:
On Fri, Jan 2, 2015 at 7:36 AM, Peter Corlett
<abuse at cabal.org.uk> wrote:
What is the purpose of using MEK (Methyl-Ethyl-Ketone) on a pc board? I
would be worried it could potentially damage the rubber end seals of
electrolytics or any styrene or ABS plastic encapsulated components.
On Fri, Jan 02, 2015 at 01:23:14AM -0500, Ethan
Dicks wrote:
[...]
You didn't say what kind of A4000, but I'm assuming you are referring
to the Amiga, as this is a known problem.
I've repaired many...I usually take off all the components of the
affected area, wash it with vinegar (!) to neutralize the electrolyte,
wash again with alchool or MEK (Metil-Etil-Ketone, cancerous and very
dangerous solvent) and rebuild the traces with very thin (awg 30)
wire-wrap wire. It always works (for me) :)
I've spent someday 6 hours to recover a board. In Brazil it is worth it! I know the general process, but I'm curious
if anyone has done this
specifically to an A4000 board and has any tips. As I said, I'm
probably going to have to pull the DIMM socket to get to all the
damage.
I've never had much luck with this kind of repair, but the A4000 repair
always sounded particularly difficult and liable to fail. Still, if
you've got the right tools and are patient and careful, you won't be
worse off than if you didn't bother at all. 
4:39 a.m.
On Fri, 2 Jan 2015, Ethan Dicks wrote:
Has anyone here gone through the process of reparing
leaky NiCd damage
to an A4000 motherboard? I _thought_ I had removed the battery some
time ago but puttering around today, I cracked open the case to find
the battery still there and some damage around U891 (a 74F245) and
U850 (Bank 3 DIMM socket). I have washed off the residue but I may
have to pull a DIMM socket to get access to the vias under it.
I know the general process, but I'm curious if anyone has done this
specifically to an A4000 board and has any tips. As I said, I'm
probably going to have to pull the DIMM socket to get to all the
damage.
Went through this entire process on my A4000 a couple of years back. In my
case there was damage to traces underneath several of the adjacent chips
and the clock chip was dead to boot. I would suggest soaking the board
overnight in dilute vinegar in addition to washing, since the alkaline
crud gets into via holes where washing won't dislodge it. If traces are
not already eaten, this may eliminate the need to remove the DIMM sockets.
I ended up removing all the chips in the immdiate vicinity of the battery
and piecing things back together with 30g wire. This did include
threading through a few of the vias. One random bit of advice: The
leaked crud tends to dissolve the solder mask on the circuit board and
makes hot-air reflow a bit touch and go. The solder will migrate
underneath the chip rather than flowing around the legs. After two
unsuccesful rounds with the reflow tool (shorted traces underneath) I
ended up hand-soldering the smaller parts.
At the time I did this work, the Ricoh clock chip was still available from
Amigakit in the UK. Unfortunately its function goes beyond simple
timekeeping. It has some involvement in the power-up sequence and the
system won't function with it. There may be a way to mod around this, but
I simply replaced the chip.
Steve
--
5:18 a.m.
the chip isn't hard to come by, Steve. You can find it on ebay.
On Fri, Jan 2, 2015 at 10:39 AM, Steven Hirsch <snhirsch at gmail.com> wrote:
On Fri, 2 Jan 2015, Ethan Dicks wrote:
Has anyone here gone through the process of reparing leaky NiCd damage
to an A4000 motherboard? I _thought_ I had
removed the battery some
time ago but puttering around today, I cracked open the case to find
the battery still there and some damage around U891 (a 74F245) and
U850 (Bank 3 DIMM socket). I have washed off the residue but I may
have to pull a DIMM socket to get access to the vias under it.
I know the general process, but I'm curious if anyone has done this
specifically to an A4000 board and has any tips. As I said, I'm
probably going to have to pull the DIMM socket to get to all the
damage.
Went through this entire process on my A4000 a couple of years back. In my
case there was damage to traces underneath several of the adjacent chips
and the clock chip was dead to boot. I would suggest soaking the board
overnight in dilute vinegar in addition to washing, since the alkaline crud
gets into via holes where washing won't dislodge it. If traces are not
already eaten, this may eliminate the need to remove the DIMM sockets.
I ended up removing all the chips in the immdiate vicinity of the battery
and piecing things back together with 30g wire. This did include threading
through a few of the vias. One random bit of advice: The leaked crud
tends to dissolve the solder mask on the circuit board and makes hot-air
reflow a bit touch and go. The solder will migrate underneath the chip
rather than flowing around the legs. After two unsuccesful rounds with the
reflow tool (shorted traces underneath) I ended up hand-soldering the
smaller parts.
At the time I did this work, the Ricoh clock chip was still available from
Amigakit in the UK. Unfortunately its function goes beyond simple
timekeeping. It has some involvement in the power-up sequence and the
system won't function with it. There may be a way to mod around this, but
I simply replaced the chip.
Steve
--
1:34 p.m.
Went through this entire process on my A4000 a couple of years back. In my
case there was damage to traces underneath several of the adjacent chips
and the clock chip was dead to boot. I would suggest soaking the board
overnight in dilute vinegar in addition to washing, since the alkaline
crud gets into via holes where washing won't dislodge it. If traces are
not already eaten, this may eliminate the need to remove the DIMM sockets.
I've often seen it suggested that acid or alkali contamination should be
neutralised somehow. In theory it seems like the thing to do but I've always
had doubts about how successfully this can be done and whether the cure might
do further damage on top of the original contamination.
In practice, I can't see how it would be possible to get the concentration of
neutralising agent even approximately right and how it would be possible to
cover all the contaminated areas and yet avoid getting it on non-contaminated
areas and maybe causing new damage there.
And then there's the wondering whether the resulting wet salts will do different
or worse damage than the original contamination before they are washed off
and whether they might be dangerous to people?
Unusally for this list, everyone seems to agree that it is the way to go
but it still seems a bit black art to me. Yet we have long and inconclusive
debates about retrobrite and the like where there are opionions on both sides
of the fence. I'm not saying I'd like to have a big debate about this, just
wondering if I'm missing something somewhere.
Regards,
Peter Coghlan.
2:38 p.m.
Unusally for this list, everyone seems to agree that
it is the way to go
but it still seems a bit black art to me. Yet we have long and
inconclusive
debates about retrobrite and the like where there are opionions on both
sides
of the fence. I'm not saying I'd like to have a big debate about this,
just
wondering if I'm missing something somewhere.
Dear Peter
I hate to "show credentials" but...
I'm an engineer with long experience in development and repair of
embbedded electronics systems, from simple household items to radar and
microwave communication systems. I've repaired boards way more complicated
(and fragile) than A4000 boards for years, and - of course - before applying
techniques unknown in fragile (and more expensive than a year's pay) boards,
I've studied the chemical and physical aspects of anything, since an error
could me cost lots and lots of money.
So, when I say something, it may even not be the more perfect method (so
it must be reproductible by people without acess to special chemicals and
tools) but **it works, because I tried and use it for years**. It isn't a
tip from a weekender.
Anyway, I can always be wrong, and I'm very happy to be confronted with
good knowledge and pratice. Anyone here, please, feel free to correct me.
But give me proof.
Very sorry to "show credentials", I don't want to be rude nor better
than anyone here in any way
Greetings from Brazil
Alexandre
2:43 p.m.
On Jan 2, 2015, at 1:34 PM, Peter Coghlan <cctalk at beyondthepale.ie> wrote:
In practice, I can't see how it would be possible
to get the concentration of
neutralising agent even approximately right and how it would be possible to
cover all the contaminated areas and yet avoid getting it on non-contaminated
areas and maybe causing new damage there.
And then there's the wondering whether the resulting wet salts will do different
or worse damage than the original contamination before they are washed off
and whether they might be dangerous to people?
The few times I have had to deal with this, I washed/cleaned with a relatively weak
acid/base solution. Household vinegar isn't all that acidic, and for a base I used a
teaspoon of baking soda in cup of water. After scrubbing things down with a soft brush to
remove the caked on crud, the key is to rinse everything thoroughly with lots of distilled
water. A Waterpik full of distilled water is very useful to flush out residue and
neutralizing solution from hard-to-reach places, and especially vias. Afterwards, put the
board under a fan to dry out. (You don't need to hit it with a hair dryer. A steady
continuous airflow is all that's required.)
So far I have rescued two cell phones, one Pentax SLR, and an expensive Fluke DVM using
this technique.
--lyndon
5:08 p.m.
On Fri, 2 Jan 2015, Peter Coghlan wrote:
I recently re-re-summarized the process over on the EEVBlog forums after
Dave Jones found his Apple Lisa badly damaged by the on-board batteries.
(I don't know if he will repair it, but I think it would make for a good
how-to video for this process should he decide to do it.)
I'm not sure how many times I've mentioned the process I use in
neutralizing the alkaline mess from leaking NiCd or alkaline batteries
(finding those old messages isn't easy with the archives down), but I know
lots of people have used this technique successfully.
"Basically, you clean the entire affected area (multiple boards in the
case of this Lisa) with white vinegar and scrub at it lightly with a
toothbrush (even get down into the card edge sockets, although they will
likely need to be replaced later). The NiCd material that leaks from the
batteries is highly alkaline, so the vinegar, being a mild acid, will
neutralize it. You then need to rinse the boards with lots of water in a
sink to make sure you flush out all the vinegar because any remaining
vinegar would also be mildly corrosive. Flushing with vinegar and
scrubbing away any buildup will stabilize the boards and stop further
corrosion. Simply cleaning with isopropyl won't neutralize the battery
mess and even if you clean off a lot of it, without neutralizing, the
boards will corrode up again."
"The next step, if you wanted to go a little further with cleaning, would
be to lightly scrub the corroded areas using a baking soda and water paste
with a toothbrush, followed by another water rinse. This will remove the
bulk of the surface corrosion on any exposed copper traces, component
leads, etc. and also helps neutralize any remaining vinegar."
"The cleaning/stabilization technique is very simple, but a little messy,
so you'll want to clean the boards in a sink. Some people claim you need
deionized water for this sort of thing, but I've been using tap water to
do this for decades and have yet to have any issues with it."
"As for the discoloration and tarnish under the solder mask, once the
board is neutralized with white vinegar, it shouldn't corrode further.
Unless there is already a break in a trace, those discolored spots are
best left alone."
http://www.eevblog.com/forum/blog/eevblog-696-apple-lisa-retro-computer-tea…
"I've repaired 100s of battery damaged boards and very rarely did I need
to scrape away the solder mask. The discolored spots are just
tarnish/oxidization of the surface of the copper trace just under the
solder mask. Tarnish under the solder mask is really more of just a
cosmetic blemish and will not affect the conductivity of the copper trace
itself. What seems to happen is that there are microscopic holes or weak
spots in the solder mask and when the batteries leak/vent, it tarnishes
the surface of the copper."
"Unless the solder mask is actually bubbling up and peeling or flaking off
the copper, messing with it will cause more harm than good. If the solder
mask is peeling, then that probably means the solder mask wasn't applied
well and battery electrolyte actually got in between the copper and solder
mask. In that case, the baking soda paste and toothbrush technique I
mentioned is likely to remove any loose solder mask anyway, so you
probably wouldn't have to scrape it."
http://www.eevblog.com/forum/blog/eevblog-696-apple-lisa-retro-computer-tea…
Went through
this entire process on my A4000 a couple of years back. In
my case there was damage to traces underneath several of the adjacent
chips and the clock chip was dead to boot. I would suggest soaking the
board overnight in dilute vinegar in addition to washing, since the
alkaline crud gets into via holes where washing won't dislodge it. If
traces are not already eaten, this may eliminate the need to remove the
DIMM sockets.
I've often seen it suggested that acid or alkali contamination should be
neutralised somehow. In theory it seems like the thing to do but I've
always had doubts about how successfully this can be done and whether
the cure might do further damage on top of the original contamination.
In practice, I can't see how it would be possible to get the
concentration of neutralising agent even approximately right and how it
would be possible to cover all the contaminated areas and yet avoid
getting it on non-contaminated areas and maybe causing new damage there.
And then there's the wondering whether the resulting wet salts will do
different or worse damage than the original contamination before they
are washed off and whether they might be dangerous to people?
Unusally for this list, everyone seems to agree that it is the way to go
but it still seems a bit black art to me. Yet we have long and
inconclusive debates about retrobrite and the like where there are
opionions on both sides of the fence. I'm not saying I'd like to have a
big debate about this, just wondering if I'm missing something
somewhere.
11 Feb
11 Feb
1:19 a.m.
On Fri, Jan 2, 2015 at 1:23 AM, Ethan Dicks <ethan.dicks at gmail.com> wrote:
Handy tip! No, none of my caps are on backwards. Yes, every single
one on the A3640 has leaked.
Thanks, all, for your input. I am going to take a stab at
refurb/repair, but in case the damage is too extensive, I'm willing to
entertain replacement down the road.
-ethan
Has anyone
here gone through the process of reparing leaky NiCd
damage to an A4000 motherboard?
make sure to read this? some of them are on there backwards from
the factory.
http://amiga.serveftp.net/A3640_capacitor.html
3366
days inactive
3406
days old
14 comments
9 participants
participants (9)
-
abuse＠cabal.org.uk -
alexandre.tabajara＠gmail.com -
cctalk＠beyondthepale.ie -
charles＠uniwho.com -
dave.g4ugm＠gmail.com -
ethan.dicks＠gmail.com -
lyndon＠orthanc.ca -
snhirsch＠gmail.com -
tothwolf＠concentric.net