Re: [volt-nuts] volt-nuts Digest, Vol 7, Issue 9
Alan, if it's possible to just leave the hole in the board, that may be the best solution overall. BTW, Nichicon has always had a very good reputation for quality electrolytics, as have the Japanese suppliers in general. The 2001 is certainly worth the effort to repair. I had a similar problem with a PCB in a Fluke 732A DC Reference. An epoxy coated Ta cap burned up and took a lot of the board with it and then a resistor burned as a result and took more board. I scraped and dug away the carbon and left the board as is -- of course this was not a multi-layer board. Most instruments don't need the sealer protection once in a lab in relatively dry, warm air where they'll be used for a long time. I wouldn't be sure that using the automotive epoxy would be a good idea...
Dick Moore
On Mar 17, 2010, at 5:00 AM, volt-nuts-request@febo.com wrote:
Message: 6
Date: Wed, 17 Mar 2010 11:20:37 -0000
From: "Alan Scrimgeour" scrimgap@blueyonder.co.uk
Subject: Re: [volt-nuts] Keithley 2001 Multimeter Fault - Update
To: jfor@quik.com, "Discussion of precise voltage measurement"
volt-nuts@febo.com
Message-ID: AE27F40615CE4CA08494C3AD153F4414@AlanPC
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Perhaps only the copper was 'etched', but I can imagine even epoxy being
attacked by hot electrolysis taking place right next to it. Electrolysis
could produce some very active compounds, depending on the electrolyte (and,
I'm not sure, but in such close proximity to the electrodes there may also
be some extremely reactive short lived species, or is that just Sci-Fi?).
But by some mechanism the upper layer of glass fiber in the board was
visible before I started digging it away.
The excavation is progressing with care. In the centre the damage has gone
right through the board to virtually the other side. Presumably air cooling
stopped or slowed the progress of the damage actually through the very last
layers of the board. It appears that once the hot electrolysis had begun to
damage the pcb it carbonised and in that conductive state, drew current and
generated yet more heat leading to a chain reaction in the form of a growing
carbonised region.
I've just had to cut a wide buried copper track in order to be able to
remove the carbonised pcb beneath it, which is disconcerting, but it will
just need soldering, or replacing with a piece of wire. I'm more worried
about what to use as a 'filling' in this cavity. I said I'd use epoxy resin,
but the usual stuff is damaged by soldering temperatures. I have some 'Auto
Weld' which says it's resistant to a constant 300C and should do. Once I
fill that hole back I'll never get it out again, so I'd better fix it
properly!
I'd like to add that I'm feeling pretty angry about those electrolytic
capacitors. They are sheer vandalism! Time for some companies heads to bow
down and appologise! Those unstable low dropout regulators are another
annoying self destruct mechanism too!!!
Alan
Depends on the curing chemistry.
Some epoxies release amines during the curing process.
Amines attack copper.
Bruce
Dick Moore wrote:
Alan, if it's possible to just leave the hole in the board, that may be the best solution overall. BTW, Nichicon has always had a very good reputation for quality electrolytics, as have the Japanese suppliers in general. The 2001 is certainly worth the effort to repair. I had a similar problem with a PCB in a Fluke 732A DC Reference. An epoxy coated Ta cap burned up and took a lot of the board with it and then a resistor burned as a result and took more board. I scraped and dug away the carbon and left the board as is -- of course this was not a multi-layer board. Most instruments don't need the sealer protection once in a lab in relatively dry, warm air where they'll be used for a long time. I wouldn't be sure that using the automotive epoxy would be a good idea...
Dick Moore
On Mar 17, 2010, at 5:00 AM, volt-nuts-request@febo.com wrote:
Message: 6
Date: Wed, 17 Mar 2010 11:20:37 -0000
From: "Alan Scrimgeour"scrimgap@blueyonder.co.uk
Subject: Re: [volt-nuts] Keithley 2001 Multimeter Fault - Update
To:jfor@quik.com, "Discussion of precise voltage measurement"
volt-nuts@febo.com
Message-ID:AE27F40615CE4CA08494C3AD153F4414@AlanPC
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Perhaps only the copper was 'etched', but I can imagine even epoxy being
attacked by hot electrolysis taking place right next to it. Electrolysis
could produce some very active compounds, depending on the electrolyte (and,
I'm not sure, but in such close proximity to the electrodes there may also
be some extremely reactive short lived species, or is that just Sci-Fi?).
But by some mechanism the upper layer of glass fiber in the board was
visible before I started digging it away.
The excavation is progressing with care. In the centre the damage has gone
right through the board to virtually the other side. Presumably air cooling
stopped or slowed the progress of the damage actually through the very last
layers of the board. It appears that once the hot electrolysis had begun to
damage the pcb it carbonised and in that conductive state, drew current and
generated yet more heat leading to a chain reaction in the form of a growing
carbonised region.
I've just had to cut a wide buried copper track in order to be able to
remove the carbonised pcb beneath it, which is disconcerting, but it will
just need soldering, or replacing with a piece of wire. I'm more worried
about what to use as a 'filling' in this cavity. I said I'd use epoxy resin,
but the usual stuff is damaged by soldering temperatures. I have some 'Auto
Weld' which says it's resistant to a constant 300C and should do. Once I
fill that hole back I'll never get it out again, so I'd better fix it
properly!
I'd like to add that I'm feeling pretty angry about those electrolytic
capacitors. They are sheer vandalism! Time for some companies heads to bow
down and appologise! Those unstable low dropout regulators are another
annoying self destruct mechanism too!!!
Alan
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
The epoxy I use for repais on circuit boards is completely clear two-part
without any fillers from HySol. Do not use the 5 minute setting stuff
either. You want something that takes several hours to set up. That's much
better stuff.
-John
==============
[snip] I wouldn't be sure
that using the automotive epoxy would be a good idea...
Dick Moore
On Mar 17, 2010, at 5:00 AM, volt-nuts-request@febo.com wrote:
Message: 6
Date: Wed, 17 Mar 2010 11:20:37 -0000
From: "Alan Scrimgeour" scrimgap@blueyonder.co.uk
Subject: Re: [volt-nuts] Keithley 2001 Multimeter Fault - Update
To: jfor@quik.com, "Discussion of precise voltage measurement"
volt-nuts@febo.com
Message-ID: AE27F40615CE4CA08494C3AD153F4414@AlanPC
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Perhaps only the copper was 'etched', but I can imagine even epoxy being
attacked by hot electrolysis taking place right next to it. Electrolysis
could produce some very active compounds, depending on the electrolyte
(and,
I'm not sure, but in such close proximity to the electrodes there may
also
be some extremely reactive short lived species, or is that just
Sci-Fi?).
But by some mechanism the upper layer of glass fiber in the board was
visible before I started digging it away.
The excavation is progressing with care. In the centre the damage has
gone
right through the board to virtually the other side. Presumably air
cooling
stopped or slowed the progress of the damage actually through the very
last
layers of the board. It appears that once the hot electrolysis had
begun to
damage the pcb it carbonised and in that conductive state, drew current
and
generated yet more heat leading to a chain reaction in the form of a
growing
carbonised region.
I've just had to cut a wide buried copper track in order to be able to
remove the carbonised pcb beneath it, which is disconcerting, but it
will
just need soldering, or replacing with a piece of wire. I'm more worried
about what to use as a 'filling' in this cavity. I said I'd use epoxy
resin,
but the usual stuff is damaged by soldering temperatures. I have some
'Auto
Weld' which says it's resistant to a constant 300C and should do. Once I
fill that hole back I'll never get it out again, so I'd better fix it
properly!
I'd like to add that I'm feeling pretty angry about those electrolytic
capacitors. They are sheer vandalism! Time for some companies heads to
bow
down and appologise! Those unstable low dropout regulators are another
annoying self destruct mechanism too!!!
Alan
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
I replaced the three tracks I had to cut with relatively sturdy wire, but I
might use just a little epoxy to anchor things in place where movement might
eventually cause stressed tracks to crack. What I'll avoid is epoxy bridging
any adjacent conductors so there's no chance of it causing leakage problems
if it eventually deteriorates.
Alan
----- Original Message -----
From: "Dick Moore" richiem@hughes.net
To: volt-nuts@febo.com
Sent: Wednesday, March 17, 2010 7:14 PM
Subject: Re: [volt-nuts] volt-nuts Digest, Vol 7, Issue 9
Alan, if it's possible to just leave the hole in the board, that may be
the best solution overall. BTW, Nichicon has always had a very good
reputation for quality electrolytics, as have the Japanese suppliers in
general. The 2001 is certainly worth the effort to repair. I had a similar
problem with a PCB in a Fluke 732A DC Reference. An epoxy coated Ta cap
burned up and took a lot of the board with it and then a resistor burned
as a result and took more board. I scraped and dug away the carbon and
left the board as is -- of course this was not a multi-layer board. Most
instruments don't need the sealer protection once in a lab in relatively
dry, warm air where they'll be used for a long time. I wouldn't be sure
that using the automotive epoxy would be a good idea...
Dick Moore
On Mar 17, 2010, at 5:00 AM, volt-nuts-request@febo.com wrote:
Message: 6
Date: Wed, 17 Mar 2010 11:20:37 -0000
From: "Alan Scrimgeour" scrimgap@blueyonder.co.uk
Subject: Re: [volt-nuts] Keithley 2001 Multimeter Fault - Update
To: jfor@quik.com, "Discussion of precise voltage measurement"
volt-nuts@febo.com
Message-ID: AE27F40615CE4CA08494C3AD153F4414@AlanPC
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Perhaps only the copper was 'etched', but I can imagine even epoxy being
attacked by hot electrolysis taking place right next to it. Electrolysis
could produce some very active compounds, depending on the electrolyte
(and,
I'm not sure, but in such close proximity to the electrodes there may
also
be some extremely reactive short lived species, or is that just Sci-Fi?).
But by some mechanism the upper layer of glass fiber in the board was
visible before I started digging it away.
The excavation is progressing with care. In the centre the damage has
gone
right through the board to virtually the other side. Presumably air
cooling
stopped or slowed the progress of the damage actually through the very
last
layers of the board. It appears that once the hot electrolysis had begun
to
damage the pcb it carbonised and in that conductive state, drew current
and
generated yet more heat leading to a chain reaction in the form of a
growing
carbonised region.
I've just had to cut a wide buried copper track in order to be able to
remove the carbonised pcb beneath it, which is disconcerting, but it will
just need soldering, or replacing with a piece of wire. I'm more worried
about what to use as a 'filling' in this cavity. I said I'd use epoxy
resin,
but the usual stuff is damaged by soldering temperatures. I have some
'Auto
Weld' which says it's resistant to a constant 300C and should do. Once I
fill that hole back I'll never get it out again, so I'd better fix it
properly!
I'd like to add that I'm feeling pretty angry about those electrolytic
capacitors. They are sheer vandalism! Time for some companies heads to
bow
down and appologise! Those unstable low dropout regulators are another
annoying self destruct mechanism too!!!
Alan
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
Hopefully not the stuff they make the board out of!
Alan
----- Original Message -----
From: "Bruce Griffiths" bruce.griffiths@xtra.co.nz
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Sent: Wednesday, March 17, 2010 7:31 PM
Subject: Re: [volt-nuts] volt-nuts Digest, Vol 7, Issue 9
Depends on the curing chemistry.
Some epoxies release amines during the curing process.
Amines attack copper.
Bruce
One of the things I like about slow setting epoxy is that heat not only
speeds up the cure but improves the bond too. I'm so conditioned to expect
every gain to come at a price that this really surprised me when I first
heard about it.
Alan
----- Original Message -----
From: "J. Forster" jfor@quik.com
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Sent: Wednesday, March 17, 2010 8:19 PM
Subject: Re: [volt-nuts] volt-nuts Digest, Vol 7, Issue 9
The epoxy I use for repais on circuit boards is completely clear two-part
without any fillers from HySol. Do not use the 5 minute setting stuff
either. You want something that takes several hours to set up. That's much
better stuff.
-John
==============
[snip] I wouldn't be sure
that using the automotive epoxy would be a good idea...
Dick Moore
On Mar 17, 2010, at 5:00 AM, volt-nuts-request@febo.com wrote:
Message: 6
Date: Wed, 17 Mar 2010 11:20:37 -0000
From: "Alan Scrimgeour" scrimgap@blueyonder.co.uk
Subject: Re: [volt-nuts] Keithley 2001 Multimeter Fault - Update
To: jfor@quik.com, "Discussion of precise voltage measurement"
volt-nuts@febo.com
Message-ID: AE27F40615CE4CA08494C3AD153F4414@AlanPC
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Perhaps only the copper was 'etched', but I can imagine even epoxy being
attacked by hot electrolysis taking place right next to it. Electrolysis
could produce some very active compounds, depending on the electrolyte
(and,
I'm not sure, but in such close proximity to the electrodes there may
also
be some extremely reactive short lived species, or is that just
Sci-Fi?).
But by some mechanism the upper layer of glass fiber in the board was
visible before I started digging it away.
The excavation is progressing with care. In the centre the damage has
gone
right through the board to virtually the other side. Presumably air
cooling
stopped or slowed the progress of the damage actually through the very
last
layers of the board. It appears that once the hot electrolysis had
begun to
damage the pcb it carbonised and in that conductive state, drew current
and
generated yet more heat leading to a chain reaction in the form of a
growing
carbonised region.
I've just had to cut a wide buried copper track in order to be able to
remove the carbonised pcb beneath it, which is disconcerting, but it
will
just need soldering, or replacing with a piece of wire. I'm more worried
about what to use as a 'filling' in this cavity. I said I'd use epoxy
resin,
but the usual stuff is damaged by soldering temperatures. I have some
'Auto
Weld' which says it's resistant to a constant 300C and should do. Once I
fill that hole back I'll never get it out again, so I'd better fix it
properly!
I'd like to add that I'm feeling pretty angry about those electrolytic
capacitors. They are sheer vandalism! Time for some companies heads to
bow
down and appologise! Those unstable low dropout regulators are another
annoying self destruct mechanism too!!!
Alan
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
I use almost nothing else but the clear. The HySol (Dexter now, I think)
is really good stuff. In the refrigerator it keeps for many years too.
-John
==============
One of the things I like about slow setting epoxy is that heat not only
speeds up the cure but improves the bond too. I'm so conditioned to expect
every gain to come at a price that this really surprised me when I first
heard about it.
Alan
----- Original Message -----
From: "J. Forster" jfor@quik.com
To: "Discussion of precise voltage measurement" volt-nuts@febo.com
Sent: Wednesday, March 17, 2010 8:19 PM
Subject: Re: [volt-nuts] volt-nuts Digest, Vol 7, Issue 9
The epoxy I use for repais on circuit boards is completely clear
two-part
without any fillers from HySol. Do not use the 5 minute setting stuff
either. You want something that takes several hours to set up. That's
much
better stuff.
-John
==============
[snip] I wouldn't be sure
that using the automotive epoxy would be a good idea...
Dick Moore
On Mar 17, 2010, at 5:00 AM, volt-nuts-request@febo.com wrote:
Message: 6
Date: Wed, 17 Mar 2010 11:20:37 -0000
From: "Alan Scrimgeour" scrimgap@blueyonder.co.uk
Subject: Re: [volt-nuts] Keithley 2001 Multimeter Fault - Update
To: jfor@quik.com, "Discussion of precise voltage measurement"
volt-nuts@febo.com
Message-ID: AE27F40615CE4CA08494C3AD153F4414@AlanPC
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
Perhaps only the copper was 'etched', but I can imagine even epoxy
being
attacked by hot electrolysis taking place right next to it.
Electrolysis
could produce some very active compounds, depending on the electrolyte
(and,
I'm not sure, but in such close proximity to the electrodes there may
also
be some extremely reactive short lived species, or is that just
Sci-Fi?).
But by some mechanism the upper layer of glass fiber in the board was
visible before I started digging it away.
The excavation is progressing with care. In the centre the damage has
gone
right through the board to virtually the other side. Presumably air
cooling
stopped or slowed the progress of the damage actually through the very
last
layers of the board. It appears that once the hot electrolysis had
begun to
damage the pcb it carbonised and in that conductive state, drew
current
and
generated yet more heat leading to a chain reaction in the form of a
growing
carbonised region.
I've just had to cut a wide buried copper track in order to be able to
remove the carbonised pcb beneath it, which is disconcerting, but it
will
just need soldering, or replacing with a piece of wire. I'm more
worried
about what to use as a 'filling' in this cavity. I said I'd use epoxy
resin,
but the usual stuff is damaged by soldering temperatures. I have some
'Auto
Weld' which says it's resistant to a constant 300C and should do. Once
I
fill that hole back I'll never get it out again, so I'd better fix it
properly!
I'd like to add that I'm feeling pretty angry about those electrolytic
capacitors. They are sheer vandalism! Time for some companies heads to
bow
down and appologise! Those unstable low dropout regulators are another
annoying self destruct mechanism too!!!
Alan
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To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
volt-nuts mailing list -- volt-nuts@febo.com
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and follow the instructions there.