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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
This type is usually dark gray and soft - about the consistency of a pencil
eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. Thanks! -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. |
#2
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
Sam Goldwasser wrote in
: This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. I think you need a tin of grey rubbery stuff remover. |
#3
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
I think you need a tin of grey rubbery stuff remover.
Go back to your TARDIS. |
#4
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
Lostgallifreyan writes:
Sam Goldwasser wrote in : This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. I think you need a tin of grey rubbery stuff remover. HeHeHe... Do you charge BIG BUCKs for that advice, huh? And, it probably rots internal organs..... -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/ |
#5
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
Sam Goldwasser wrote in message
... This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. Thanks! -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. I seem to remember using a 1/8 inch ball mill in a Dremmel for that sort of stuff, localised heat and tugging action hepled in removing from surfaces, .. But still time consuming and you have to know there is no little vital stuff buiried within it. -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#6
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
Sam Goldwasser wrote in
: Lostgallifreyan writes: Sam Goldwasser wrote in : This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. I think you need a tin of grey rubbery stuff remover. HeHeHe... Do you charge BIG BUCKs for that advice, huh? Oh yeah, I should, given what anything seems to cost the moment I need it... Here's some for free though. Try snagging a bit and burning it, melting it, putting it in chemicals, and comparing to some knowns. If it's silicone you're SOL but a lot of other stuff might be attacked while the rest of the parts sit looking as if they enjoy it because a lot of PCB washes are strong stuff and most parts are designed to resist a lot. If you find something that can edge its way between the stuff and the parts, you might be able to peel it off. And if it's based on actual rubber try ozone to perish it fast so it will crumble away. And, it probably rots internal organs..... And what did you think the grey goop was made of? Thpthpthp (That being my best Hannibal Lecter impersonation, feeble though it may be). |
#7
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
Lostgallifreyan wrote in
: And if it's based on actual rubber try ozone to perish it fast so it will crumble away. Likewise, strong shortwave UV might also help degrade it so it's easy to remove. |
#8
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
"William Sommerwerck" wrote in
: I think you need a tin of grey rubbery stuff remover. Go back to your TARDIS. I would but I don't think it will have me. |
#9
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
"N_Cook" writes:
Sam Goldwasser wrote in message ... This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. Thanks! -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ I seem to remember using a 1/8 inch ball mill in a Dremmel for that sort of stuff, localised heat and tugging action hepled in removing from surfaces, . But still time consuming and you have to know there is no little vital stuff buiried within it. I've been using the mechanical approach. It is tedious and risky as you note. But does work: http://repairfaq.cis.upenn.edu/Misc/vmi373p1.jpg However, some components were damaged (a graphics editing program can work wonders!) and for what I really want, it is trickier as the part being removed is a glass laser tube and much of the potting material is in a space 2 or 3 mm thick surrounding the tube, and running its entire length. Thanks! -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#10
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
De-Solv-It hardware stores
Eposolve, mcmaster carr is your friend. Steve |
#11
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
Sam Goldwasser wrote:
This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. Thanks! The best luck I've had is with simply picking the stuff off, you're right though that it's no fun. I suspect it would become brittle at some temperature, can you get your hands on some liquid nitrogen? If so, give it a soak and smack it with something, hoping the components within do not shatter as well. I'm curious to hear the results. |
#12
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
On Jun 21, 10:32*pm, James Sweet wrote:
Sam Goldwasser wrote: This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. *It can be removed laboriously with knives, picks, and elbow grease. *But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. *Both of these are of interest to me. *Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. * Thanks! The best luck I've had is with simply picking the stuff off, you're right though that it's no fun. I suspect it would become brittle at some temperature, can you get your hands on some liquid nitrogen? If so, give it a soak and smack it with something, hoping the components within do not shatter as well. I'm curious to hear the results. The rubbery tarry stuff that is used in older hene tube heads dissolves in dichloromethane (DCM) used in paint strippers, The silicone stuff is pretty impervious to all but mechanical attack. |
#13
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
Sam Goldwasser wrote in message
... "N_Cook" writes: Sam Goldwasser wrote in message ... This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. Thanks! -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ I seem to remember using a 1/8 inch ball mill in a Dremmel for that sort of stuff, localised heat and tugging action hepled in removing from surfaces, . But still time consuming and you have to know there is no little vital stuff buiried within it. I've been using the mechanical approach. It is tedious and risky as you note. But does work: http://repairfaq.cis.upenn.edu/Misc/vmi373p1.jpg However, some components were damaged (a graphics editing program can work wonders!) and for what I really want, it is trickier as the part being removed is a glass laser tube and much of the potting material is in a space 2 or 3 mm thick surrounding the tube, and running its entire length. Thanks! -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ What is the output level of the Cockcroft Walton circuit ? -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#14
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
heruursciences wrote:
The rubbery tarry stuff that is used in older hene tube heads dissolves in dichloromethane (DCM) used in paint strippers, The silicone stuff is pretty impervious to all but mechanical attack. FWIW There is a home decorating product called 'silicone eater' designed for removing sealant from hard surfaces by dissolving it a little. http://www.cglass.co.uk/everbuild-everflex-silicone-eater-pr-17657.html -- Adrian C |
#15
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
In sci.electronics.repair Sam Goldwasser wrote:
This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. This probably isn't much help but we used to use a chemical called Eccostrip 93 made by Emerson and Cuming (or cumming or cummings). I don't know if it's sold anymore, probably on every EPA hazard chemical list by now but I believe the main purpose of it was to attack something in the resin. It wasn't a miracle worker, but did it's job eventually. Generally you needed to apply it with a glass eyedropper to keep the area wet, then periodically using a acid brush, dust off the powder, reapply. As far as component damage, yeah, some carbon film resistors, the bodies would flake off but I don't remember anything else. Even ic's (chips) that I thought had some epoxy holding them together were no worse for wear even soaking in the stuff. -bruce |
#16
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
James Sweet writes:
Sam Goldwasser wrote: This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. Thanks! The best luck I've had is with simply picking the stuff off, you're right though that it's no fun. I suspect it would become brittle at some temperature, can you get your hands on some liquid nitrogen? If so, give it a soak and smack it with something, hoping the components within do not shatter as well. I'm curious to hear the results. That might work for the PCBs, though what will it do to the components? However, what I really need to remove it from are special HeNe laser tube assemblies. Not the common laser heads, but ones where the tube is totally surrounded by the stuff as well as in front and back. So, the tube will still be stuck inside surrounded by brittle hard stuff. Thanks for thinking about it! -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. |
#17
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
"N_Cook" writes:
Sam Goldwasser wrote in message ... "N_Cook" writes: Sam Goldwasser wrote in message ... This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. Thanks! -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ I seem to remember using a 1/8 inch ball mill in a Dremmel for that sort of stuff, localised heat and tugging action hepled in removing from surfaces, . But still time consuming and you have to know there is no little vital stuff buiried within it. I've been using the mechanical approach. It is tedious and risky as you note. But does work: http://repairfaq.cis.upenn.edu/Misc/vmi373p1.jpg However, some components were damaged (a graphics editing program can work wonders!) and for what I really want, it is trickier as the part being removed is a glass laser tube and much of the potting material is in a space 2 or 3 mm thick surrounding the tube, and running its entire length. Thanks! -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ What is the output level of the Cockcroft Walton circuit ? Greater than 10 kV but the current is very low since it only needs to drive an open circuit, then is bypassed once the main current flows. Nearly every HeNe laser power supply has a circuit like that. -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. |
#18
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
Whatever this stuf is, common sense suggests it was designed not to be
easily removed, especially by chemical means. Otherwise, there would be little point to it. |
#19
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
Bruce Esquibel writes:
In sci.electronics.repair Sam Goldwasser wrote: This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. This probably isn't much help but we used to use a chemical called Eccostrip 93 made by Emerson and Cuming (or cumming or cummings). I don't know if it's sold anymore, probably on every EPA hazard chemical list by now but I believe the main purpose of it was to attack something in the resin. It wasn't a miracle worker, but did it's job eventually. Generally you needed to apply it with a glass eyedropper to keep the area wet, then periodically using a acid brush, dust off the powder, reapply. As far as component damage, yeah, some carbon film resistors, the bodies would flake off but I don't remember anything else. Even ic's (chips) that I thought had some epoxy holding them together were no worse for wear even soaking in the stuff. Yeah, for the real application I have in mind, this is probably going to take about 1,423 years (give or take a century). The PCB was just an example. But where this is needed is to remove the stuff surrounding a glass laser tube - about 6 inches in length and a space of 2 or 3 mm between the tube and the cylinder it's in. Both the cylinder and tube need to come out undamaged. Thanks. -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. -bruce |
#20
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
On Sun, 21 Jun 2009 12:31:27 -0400, Sam Goldwasser
wrote: This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. Thanks! Go to a good hardware store, and see if they have silicone tub caulk remover. Try that and see if it works. |
#21
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
Sam Goldwasser wrote in message
... Bruce Esquibel writes: In sci.electronics.repair Sam Goldwasser wrote: This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. This probably isn't much help but we used to use a chemical called Eccostrip 93 made by Emerson and Cuming (or cumming or cummings). I don't know if it's sold anymore, probably on every EPA hazard chemical list by now but I believe the main purpose of it was to attack something in the resin. It wasn't a miracle worker, but did it's job eventually. Generally you needed to apply it with a glass eyedropper to keep the area wet, then periodically using a acid brush, dust off the powder, reapply. As far as component damage, yeah, some carbon film resistors, the bodies would flake off but I don't remember anything else. Even ic's (chips) that I thought had some epoxy holding them together were no worse for wear even soaking in the stuff. Yeah, for the real application I have in mind, this is probably going to take about 1,423 years (give or take a century). The PCB was just an example. But where this is needed is to remove the stuff surrounding a glass laser tube - about 6 inches in length and a space of 2 or 3 mm between the tube and the cylinder it's in. Both the cylinder and tube need to come out undamaged. Thanks. -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. -bruce Can you make a pilot hole with a thin steel rod, chisel ground at the end. Then pass through it one of those carbide covered wire saw , garotte type things, or even a coping saw blade, kept under tension. Would some scratch damage matter? If so then perhaps spaced , glued-on, guard rings along the blade -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#22
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
N_Cook wrote in message
... Sam Goldwasser wrote in message ... Bruce Esquibel writes: In sci.electronics.repair Sam Goldwasser wrote: This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. This probably isn't much help but we used to use a chemical called Eccostrip 93 made by Emerson and Cuming (or cumming or cummings). I don't know if it's sold anymore, probably on every EPA hazard chemical list by now but I believe the main purpose of it was to attack something in the resin. It wasn't a miracle worker, but did it's job eventually. Generally you needed to apply it with a glass eyedropper to keep the area wet, then periodically using a acid brush, dust off the powder, reapply. As far as component damage, yeah, some carbon film resistors, the bodies would flake off but I don't remember anything else. Even ic's (chips) that I thought had some epoxy holding them together were no worse for wear even soaking in the stuff. Yeah, for the real application I have in mind, this is probably going to take about 1,423 years (give or take a century). The PCB was just an example. But where this is needed is to remove the stuff surrounding a glass laser tube - about 6 inches in length and a space of 2 or 3 mm between the tube and the cylinder it's in. Both the cylinder and tube need to come out undamaged. Thanks. -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. -bruce Can you make a pilot hole with a thin steel rod, chisel ground at the end. Then pass through it one of those carbide covered wire saw , garotte type things, or even a coping saw blade, kept under tension. Would some scratch damage matter? If so then perhaps spaced , glued-on, guard rings along the blade -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ or after a pilot hole then a current carrying length of straightened heater element wire perhaps would work to cut around |
#23
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
On Mon, 22 Jun 2009 08:33:23 -0400, Sam Goldwasser
wrote: Bruce Esquibel writes: In sci.electronics.repair Sam Goldwasser wrote: This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. This probably isn't much help but we used to use a chemical called Eccostrip 93 made by Emerson and Cuming (or cumming or cummings). I don't know if it's sold anymore, probably on every EPA hazard chemical list by now but I believe the main purpose of it was to attack something in the resin. It wasn't a miracle worker, but did it's job eventually. Generally you needed to apply it with a glass eyedropper to keep the area wet, then periodically using a acid brush, dust off the powder, reapply. As far as component damage, yeah, some carbon film resistors, the bodies would flake off but I don't remember anything else. Even ic's (chips) that I thought had some epoxy holding them together were no worse for wear even soaking in the stuff. Yeah, for the real application I have in mind, this is probably going to take about 1,423 years (give or take a century). The PCB was just an example. But where this is needed is to remove the stuff surrounding a glass laser tube - about 6 inches in length and a space of 2 or 3 mm between the tube and the cylinder it's in. Both the cylinder and tube need to come out undamaged. Maybe one of the oscillating-face tools, like the Fein MultiMaster? http://www.fein.de/fein-multimaster/us/en/main/ There are flexible blades that might do the trick. Won't work (very well) to de-pot an SMT-stuffed PCB but might get you a long way towards getting the stuff off of the tube. http://www.fein.de/fein-multimaster/us/en/products/accessories_scraping.php -- Rich Webb Norfolk, VA |
#24
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
On 6/22/2009 7:16 AM Rich Webb spake thus:
Maybe one of the oscillating-face tools, like the Fein MultiMaster? http://www.fein.de/fein-multimaster/us/en/main/ Don't think so; those tools work on a principle that's the complete opposite of what is needed here. That is, they'll cut something hard but not damage something soft next to it, like the saws used for cutting off plaster casts that don't harm skin. They'll just jiggle the rubbery stuff without cutting it. How about careful use of a cutoff wheel in a Dremel or equivalent tool, to make slices in the rubbery stuff? [note post trimming] -- Found--the gene that causes belief in genetic determinism |
#25
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Removing rubbery potting compound
On Mon, 22 Jun 2009 10:42:46 -0700, David Nebenzahl
wrote: On 6/22/2009 7:16 AM Rich Webb spake thus: Maybe one of the oscillating-face tools, like the Fein MultiMaster? http://www.fein.de/fein-multimaster/us/en/main/ Don't think so; those tools work on a principle that's the complete opposite of what is needed here. That is, they'll cut something hard but not damage something soft next to it, like the saws used for cutting off plaster casts that don't harm skin. They'll just jiggle the rubbery stuff without cutting it. Roger that. However, from watching the infomercial it looks like the flexible, spatulate heads are used to separate stuff like caulk beads from porcelain bathtubs. The working face isn't toothed and might just do the trick in this app. I don't speak from personal experience, just what I've seen on the tube. But, since "He who dies with the most tools, wins!" I'll probably have to break down someday and get one. -- Rich Webb Norfolk, VA |
#26
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Removing rubbery potting compound
"William Sommerwerck" writes:
Whatever this stuf is, common sense suggests it was designed not to be easily removed, especially by chemical means. Otherwise, there would be little point to it. I think that's only true in some cases. Since this CAN be removed using just brute force, it's a lot easier to reverse engineer PCBs and such with it than, say, hard Epoxy. -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. |
#27
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Removing rubbery potting compound
"N_Cook" writes:
Sam Goldwasser wrote in message ... Bruce Esquibel writes: In sci.electronics.repair Sam Goldwasser wrote: This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. This probably isn't much help but we used to use a chemical called Eccostrip 93 made by Emerson and Cuming (or cumming or cummings). I don't know if it's sold anymore, probably on every EPA hazard chemical list by now but I believe the main purpose of it was to attack something in the resin. It wasn't a miracle worker, but did it's job eventually. Generally you needed to apply it with a glass eyedropper to keep the area wet, then periodically using a acid brush, dust off the powder, reapply. As far as component damage, yeah, some carbon film resistors, the bodies would flake off but I don't remember anything else. Even ic's (chips) that I thought had some epoxy holding them together were no worse for wear even soaking in the stuff. Yeah, for the real application I have in mind, this is probably going to take about 1,423 years (give or take a century). The PCB was just an example. But where this is needed is to remove the stuff surrounding a glass laser tube - about 6 inches in length and a space of 2 or 3 mm between the tube and the cylinder it's in. Both the cylinder and tube need to come out undamaged. Thanks. -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ -bruce Can you make a pilot hole with a thin steel rod, chisel ground at the end. Then pass through it one of those carbide covered wire saw , garotte type things, or even a coping saw blade, kept under tension. Would some scratch damage matter? If so then perhaps spaced , glued-on, guard rings along the blade That's sort of what I've been doing, and have been contemplating making a tool that is more matched to the job than the strips of aluminum and other random items I've been using. I'm coming to believe that any chemical approach will take to long, not to mention the mess and health issues. --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#28
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
Rich Webb writes:
On Mon, 22 Jun 2009 08:33:23 -0400, Sam Goldwasser wrote: Bruce Esquibel writes: In sci.electronics.repair Sam Goldwasser wrote: This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. This probably isn't much help but we used to use a chemical called Eccostrip 93 made by Emerson and Cuming (or cumming or cummings). I don't know if it's sold anymore, probably on every EPA hazard chemical list by now but I believe the main purpose of it was to attack something in the resin. It wasn't a miracle worker, but did it's job eventually. Generally you needed to apply it with a glass eyedropper to keep the area wet, then periodically using a acid brush, dust off the powder, reapply. As far as component damage, yeah, some carbon film resistors, the bodies would flake off but I don't remember anything else. Even ic's (chips) that I thought had some epoxy holding them together were no worse for wear even soaking in the stuff. Yeah, for the real application I have in mind, this is probably going to take about 1,423 years (give or take a century). The PCB was just an example. But where this is needed is to remove the stuff surrounding a glass laser tube - about 6 inches in length and a space of 2 or 3 mm between the tube and the cylinder it's in. Both the cylinder and tube need to come out undamaged. Maybe one of the oscillating-face tools, like the Fein MultiMaster? http://www.fein.de/fein-multimaster/us/en/main/ There are flexible blades that might do the trick. Won't work (very well) to de-pot an SMT-stuffed PCB but might get you a long way towards getting the stuff off of the tube. http://www.fein.de/fein-multimaster/us/en/products/accessories_scraping.php Could be. The only real problem is getting the tube out. Once it's out, getting the stuff off of it and the cylinder it was in is no problem, the adhesion is not very strong, just enough that you can't push the tube out without likely smashing it. Thanks! --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. |
#29
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
Sam Goldwasser wrote in
: The only real problem is getting the tube out. Once it's out, getting the stuff off of it and the cylinder it was in is no problem, the adhesion is not very strong, just enough that you can't push the tube out without likely smashing it. So do it the way a capacitor is removed from the PFN for the SSY-1. Use a fast cutting disk, or slow hacksaw, to cut the outer cylinder parallel to axis, peel it back enough to remove the innards, then peel the gunk off the internal cylinder (cap, or laser in this case). |
#30
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
"Sam Goldwasser" wrote in message ... This type is usually dark gray and soft - about the consistency of a pencil eraser, maybe a bit tougher. It can be removed laboriously with knives, picks, and elbow grease. But the question is whether there is some easier way to do this that would leave the underlying components undamaged. This stuff is used in a variety of places including PCBs and laser tube assemblies. Both of these are of interest to me. Modest heat has no effect including immersing in boiling water - it's not hot-melt glue. Thanks! If it is silicone based, you might try Varsol. It causes one part silicone to swell and get even more rubbery, so maybe it will behave similiarly on that stuff. It tends to be easier to remove in this state. Mike |
#31
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Removing rubbery potting compound
That might work for the PCBs, though what will it do to the components? However, what I really need to remove it from are special HeNe laser tube assemblies. Not the common laser heads, but ones where the tube is totally surrounded by the stuff as well as in front and back. So, the tube will still be stuck inside surrounded by brittle hard stuff. Thanks for thinking about it! That sounds like a real pain. If you can use a long drill to drill a tunnel parallel to the tube, you might be able to saw around the tube with some piano wire. |
#32
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Removing rubbery potting compound
Sam Goldwasser wrote:
"William Sommerwerck" writes: Whatever this stuf is, common sense suggests it was designed not to be easily removed, especially by chemical means. Otherwise, there would be little point to it. I think that's only true in some cases. Since this CAN be removed using just brute force, it's a lot easier to reverse engineer PCBs and such with it than, say, hard Epoxy. Even hard epoxy is no real matter when it comes to reverse engineering if you are willing to destroy the thing you are analyzing. I've found that it's quite brittle stuff, and applying pressure in the right places with a bench vise will usually cause it to crumble. Some components will get broken in the process but they can usually still be identified. |
#33
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Removing rubbery potting compound
Sam Goldwasser wrote in message
... Rich Webb writes: On Mon, 22 Jun 2009 08:33:23 -0400, Sam Goldwasser wrote: Bruce Esquibel writes: In sci.electronics.repair Sam Goldwasser Could be. The only real problem is getting the tube out. Once it's out, getting the stuff off of it and the cylinder it was in is no problem, the adhesion is not very strong, just enough that you can't push the tube out without likely smashing it. Thanks! --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. In that case would mounting a vacuum chamber around the outside give enough force for air pressure to shift it. Or compressed air around it with appropriate seal? With some nearby soft physical restraint of course for if it does move. -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#34
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Removing rubbery potting compound
On Mon, 22 Jun 2009 08:33:23 -0400 Sam Goldwasser
wrote in Message id: : The PCB was just an example. But where this is needed is to remove the stuff surrounding a glass laser tube - about 6 inches in length and a space of 2 or 3 mm between the tube and the cylinder it's in. Both the cylinder and tube need to come out undamaged. How about using a thin blade from a coping saw? Once you manage to slip it all the way through the length of the cylinder it should work fairly well. I don't think it'd damage the glass either. |
#35
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Removing rubbery potting compound
Lostgallifreyan writes:
Sam Goldwasser wrote in : The only real problem is getting the tube out. Once it's out, getting the stuff off of it and the cylinder it was in is no problem, the adhesion is not very strong, just enough that you can't push the tube out without likely smashing it. So do it the way a capacitor is removed from the PFN for the SSY-1. Use a fast cutting disk, or slow hacksaw, to cut the outer cylinder parallel to axis, peel it back enough to remove the innards, then peel the gunk off the internal cylinder (cap, or laser in this case). That's what someone else did, but the important part is really the cylinder. I'd like to get the tube out intact as well, but the solution of last resort is to simply smash the tubes. Yes, I know, that's going to upset the gods of dead lasers, but we'll see how the alternatives work out! Thanks! -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. |
#36
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Removing rubbery potting compound
JW writes:
On Mon, 22 Jun 2009 08:33:23 -0400 Sam Goldwasser wrote in Message id: : The PCB was just an example. But where this is needed is to remove the stuff surrounding a glass laser tube - about 6 inches in length and a space of 2 or 3 mm between the tube and the cylinder it's in. Both the cylinder and tube need to come out undamaged. How about using a thin blade from a coping saw? Once you manage to slip it all the way through the length of the cylinder it should work fairly well. I don't think it'd damage the glass either. Yeah, that's been my thinking as well. I don't like chemicals and anything that would get through several inches of the close-fitting cylinder would almost certainly be rather ansty. Whether a coping saw blade is optimal I don't know, but something that can be forced through and then fastened at both ends with enough "teeth" to be able to eat away at the rubber. Thanks! -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. |
#37
Posted to sci.electronics.repair,alt.lasers
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Removing rubbery potting compound
"James Sweet" wrote in message
... Sam Goldwasser wrote: "William Sommerwerck" writes: Whatever this stuf is, common sense suggests it was designed not to be easily removed, especially by chemical means. Otherwise, there would be little point to it. I think that's only true in some cases. Since this CAN be removed using just brute force, it's a lot easier to reverse engineer PCBs and such with it than, say, hard Epoxy. Even hard epoxy is no real matter when it comes to reverse engineering if you are willing to destroy the thing you are analyzing. I've found that it's quite brittle stuff, and applying pressure in the right places with a bench vise will usually cause it to crumble. Some components will get broken in the process but they can usually still be identified. Please note the adverb in my original post. |
#38
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Removing rubbery potting compound
Sam Goldwasser wrote:
Whether a coping saw blade is optimal I don't know, but something that can be forced through and then fastened at both ends with enough "teeth" to be able to eat away at the rubber. Thanks! I've lost track of how long the laser tube is. If you can thread dental floss along the length of the tube you can saw the tube out with the floss. |
#39
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Removing rubbery potting compound
JW wrote in message
... On Mon, 22 Jun 2009 08:33:23 -0400 Sam Goldwasser wrote in Message id: : The PCB was just an example. But where this is needed is to remove the stuff surrounding a glass laser tube - about 6 inches in length and a space of 2 or 3 mm between the tube and the cylinder it's in. Both the cylinder and tube need to come out undamaged. How about using a thin blade from a coping saw? Once you manage to slip it all the way through the length of the cylinder it should work fairly well. I don't think it'd damage the glass either. My coping saw blades are only 6 inches long, I doubt they come any longer as only intended for small light work. After drilling a pilot hole I would try one of these sort of wire saws http://www.ecamo.co.uk/product/webte...e-saw/265.html fed through and then bodge fixed in a 12 inch hacksaw frame for rigidity. Or straightened out bit of heater element wire -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#40
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Removing rubbery potting compound
Sam Goldwasser wrote:
JW writes: On Mon, 22 Jun 2009 08:33:23 -0400 Sam Goldwasser wrote in Message id: : The PCB was just an example. But where this is needed is to remove the stuff surrounding a glass laser tube - about 6 inches in length and a space of 2 or 3 mm between the tube and the cylinder it's in. Both the cylinder and tube need to come out undamaged. How about using a thin blade from a coping saw? Once you manage to slip it all the way through the length of the cylinder it should work fairly well. I don't think it'd damage the glass either. Yeah, that's been my thinking as well. I don't like chemicals and anything that would get through several inches of the close-fitting cylinder would almost certainly be rather ansty. Whether a coping saw blade is optimal I don't know, but something that can be forced through and then fastened at both ends with enough "teeth" to be able to eat away at the rubber. Might I suggest a flexible wire saw such as this one: http://www.vtarmynavy.com/commando-wire-saw.htm or this http://au.farnell.com/abrafile/25013...dles/dp/108078 Perhaps you could stretch the saw between two fixed vices having first threaded the tube over it, then work it back and forth while rotating it to cut throught the rubber compound. Ron(UK) |
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