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Foam conductor problems
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I've added some pictures under "3561A repair" to document a problem with my SA. All the electronics check out after replacing some parts but some of the buttons and most of the LEDs were not working on the front panel. After opening the front panel I found that this conductive foam seems to be the culprit. I've repaired LCD displays by cleaning conductive foam but the conductors in this foam seem very small. I cleaned it up with some ISO-alcohol and some of the LEDs started working but some of the key pads quit working. I cleaned it a second time and the same results. Some other buttons are working but some still not. The LED problem is solely the problem of the conductive foam but the keys could also be the conductive pads on the rubber keys. I've measured the resistance on most of the pads and they are about 50 ohms except for some that are 200 ohms and greater (up to about 480 ohms). I'm not sure what the max resistance can be and still make the key function. My solution first is to just solder the two boards with a connection harness to eliminate the conductive foam but I'm not sure how to fix the rubber key problem. I have some conductive paint but the resistance is still high, around 150 ohms. Does anyone have any success repairing this kind of problem?
Gary |
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Conductive foam:? I have found the torque on the mounting screws needs to be
near perfectly?equal for these to work. Lots of trial and error :-) As for the switch contacts, I have found it is a good idea to wash?with distilled water?after the soaking in alcohol for a couple of hours, After this, they need to dry overnight before re-installing. They will not work right away! BTW recently I have found placing wet things on top of my de-humidifier, where the really dry air comes out speeds up?the process. Best Luck Karl ________________________________ From: Gary <GEMCCLUNG@...> To: hp_agilent_equipment@... Sent: Fri, December 28, 2012 10:19:59 PM Subject: [hp_agilent_equipment] Foam conductor problems ? I've added some pictures under "3561A repair" to document a problem with my SA. All the electronics check out after replacing some parts but some of the buttons and most of the LEDs were not working on the front panel. After opening the front panel I found that this conductive foam seems to be the culprit. I've repaired LCD displays by cleaning conductive foam but the conductors in this foam seem very small. I cleaned it up with some ISO-alcohol and some of the LEDs started working but some of the key pads quit working. I cleaned it a second time and the same results. Some other buttons are working but some still not. The LED problem is solely the problem of the conductive foam but the keys could also be the conductive pads on the rubber keys. I've measured the resistance on most of the pads and they are about 50 ohms except for some that are 200 ohms and greater (up to about 480 ohms). I'm not sure what the max resistance can be and still make the key function. My solution first is to just solder the two boards with a connection harness to eliminate the conductive foam but I'm not sure how to fix the rubber key problem. I have some conductive paint but the resistance is still high, around 150 ohms. Does anyone have any success repairing this kind of problem? Gary [Non-text portions of this message have been removed] |
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Thanks for the advice Karl; I'll give it a try.
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Gary --- In hp_agilent_equipment@..., Karl Schmeer <shire03@...> wrote:
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I Can't remember where, but I've seen repair kits for kits for those types of keyboard switches.
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Bill HIgdon --- In hp_agilent_equipment@..., "Gary" <GEMCCLUNG@...> wrote:
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I found this doing a search -->
; 5 <; 15> Has anyone ever used this stuff? I'm still not sure if my pads are defective. I want to make sure the conductive foam is working properly before I get crazy with fixes. All the LEDs and keypads go through the conductive foam which is the weak link in the design. Gary --- In hp_agilent_equipment@..., "William" wrote: types of keyboard switches. Bill HIgdonwith my SA. All the electronics check out after replacing some parts but some of the buttons and most of the LEDs were not working on the front panel. After opening the front panel I found that this conductive foam seems to be the culprit. I've repaired LCD displays by cleaning conductive foam but the conductors in this foam seem very small. I cleaned it up with some ISO-alcohol and some of the LEDs started working but some of the key pads quit working. I cleaned it a second time and the same results. Some other buttons are working but some still not. The LED problem is solely the problem of the conductive foam but the keys could also be the conductive pads on the rubber keys. I've measured the resistance on most of the pads and they are about 50 ohms except for some that are 200 ohms and greater (up to about 480 ohms). I'm not sure what the max resistance can be and still make the key function. My solution first is to just solder the two boards with a connection harness to eliminate the conductive foam but I'm not sure how to fix the rubber key problem. I have some conductive paint but the resistance is still high, around 150 ohms. Does anyone have any success repairing this kind of problem?
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Interesting stuff. ?I have not used it but I too would like to know how it works, and how it dries, for a totally different use. ?
How black is it when it is dry? ?I am curious if it would make a good absorptive coating for calorimeter-based optical power detection. Dan p.s. realize my interest is Off-Topic so happy to take any replies not related to the original post off-line. ?Thx. ________________________________ From: Gary <GEMCCLUNG@...> To: hp_agilent_equipment@... Sent: Saturday, December 29, 2012 2:26 PM Subject: [hp_agilent_equipment] Re: Foam conductor problems ? I found this doing a search --> <> Has anyone ever used this stuff? I'm still not sure if my pads are defective. I want to make sure the conductive foam is working properly before I get crazy with fixes. All the LEDs and keypads go through the conductive foam which is the weak link in the design. Gary --- In hp_agilent_equipment@..., "William" wrote: types of keyboard switches. Bill HIgdonwith my SA. All the electronics check out after replacing some parts but some of the buttons and most of the LEDs were not working on the front panel. After opening the front panel I found that this conductive foam seems to be the culprit. I've repaired LCD displays by cleaning conductive foam but the conductors in this foam seem very small. I cleaned it up with some ISO-alcohol and some of the LEDs started working but some of the key pads quit working. I cleaned it a second time and the same results. Some other buttons are working but some still not. The LED problem is solely the problem of the conductive foam but the keys could also be the conductive pads on the rubber keys. I've measured the resistance on most of the pads and they are about 50 ohms except for some that are 200 ohms and greater (up to about 480 ohms). I'm not sure what the max resistance can be and still make the key function. My solution first is to just solder the two boards with a connection harness to eliminate the conductive foam but I'm not sure how to fix the rubber key problem. I have some conductive paint but the resistance is still high, around 150 ohms. Does anyone have any success repairing this kind of problem? [Non-text portions of this message have been removed] [Non-text portions of this message have been removed] |
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Here's another product -->
<> but a bit more pricy! Gary --- In hp_agilent_equipment@..., Daniel Koller wrote: know how it works, and how it dries, for a totally different use. ? good absorptive coating for calorimeter-based optical power detection. related to the original post off-line. ? Thx. ; 5 properly before I get crazy with fixes. All the LEDs and keypads go throughthe conductive foam which is the weak link in the design.wrote: problem with my SA. All the electronics check out after replacing some partsconductive foam seems to be the culprit. I've repaired LCD displays by cleaningworking but some of the key pads quit working. I cleaned it a second time andhow to fix the rubber key problem. I have some conductive paint but thesuccess repairing this kind of problem?[Non-text portions of this message have been removed] [Non-text portions of this message have been removed] |
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Philip Souza
I have used a product from Anders Products called Wire Glue. Not an inspiring name, but works very well. It is non conductive until it cures. Very low resistance and dries to a dark neutral grey color. Interesting to watch the conductivity change during last part of cure process. Price around $10 US.
Phil From: Gary Sent: Saturday, December 29, 2012 12:33 PM To: hp_agilent_equipment@... Subject: [hp_agilent_equipment] Re: Foam conductor problems Here's another product --> <> but a bit more pricy! Gary --- In hp_agilent_equipment@..., Daniel Koller wrote: know how it works, and how it dries, for a totally different use. ? good absorptive coating for calorimeter-based optical power detection. related to the original post off-line. ? Thx. ; 5 properly before I get crazy with fixes. All the LEDs and keypads go throughthe conductive foam which is the weak link in the design.wrote: problem with my SA. All the electronics check out after replacing some partsconductive foam seems to be the culprit. I've repaired LCD displays by cleaningworking but some of the key pads quit working. I cleaned it a second time andhow to fix the rubber key problem. I have some conductive paint but thesuccess repairing this kind of problem?[Non-text portions of this message have been removed] [Non-text portions of this message have been removed] |
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It seems that for about $11 it would be worth buying some and
experimenting with it. Dave On 12/29/2012 12:38 PM, Daniel Koller wrote:
[Non-text portions of this message have been removed] |
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After taking these boards apart many times the results were always the same, either one or more LEDs and one or more buttons were not working. Every time it was a different set of buttons or LEDs. So I decided to take out the conductive foam and make my own mechanical connection using molex connectors and a right angle header. Now all the buttons and LEDs are working perfectly. Pictures of my mod are documented under "3561A repair"
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Gary --- In hp_agilent_equipment@..., "Gary" wrote:
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My two Advantest TR5823H did not work because of bad conductive foam in the pushbutton switches. I opened all of the switches and put a dab of conductive stuff sold to repair rear window defrosters in cars. It has been several years now and there is no sign of the problem returning. I hope I am referring to the same kind of conductive foam switches, I have not been following this thread.
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Peter. ----- Original Message -----
From: Gary To: hp_agilent_equipment@... Sent: Friday, January 18, 2013 8:50 PM Subject: [hp_agilent_equipment] Re: Foam conductor problems After taking these boards apart many times the results were always the same, either one or more LEDs and one or more buttons were not working. Every time it was a different set of buttons or LEDs. So I decided to take out the conductive foam and make my own mechanical connection using molex connectors and a right angle header. Now all the buttons and LEDs are working perfectly. Pictures of my mod are documented under "3561A repair" Gary --- In hp_agilent_equipment@..., "Gary" wrote: > > Thanks for the advice Karl; I'll give it a try. > > Gary > > --- In hp_agilent_equipment@..., Karl Schmeer wrote: > > > > Conductive foam:? I have found the torque on the mounting screws needs to be > > near perfectly? equal for these to work. Lots of trial and error :-) > > > > As for the switch contacts, I have found it is a good idea to wash? with > > distilled water? after the soaking in alcohol for a couple of hours, After this, > > they need to dry overnight before re-installing. They will not work right away! > > BTW recently I have found placing wet things on top of my de-humidifier, where > > the really dry air comes out speeds up? the process. > > > > Best Luck > > > > Karl > > > > > > > > ________________________________ > > From: Gary > > To: hp_agilent_equipment@... > > Sent: Fri, December 28, 2012 10:19:59 PM > > Subject: [hp_agilent_equipment] Foam conductor problems > > > > ? > > I've added some pictures under "3561A repair" to document a problem with my SA. > > All the electronics check out after replacing some parts but some of the buttons > > and most of the LEDs were not working on the front panel. After opening the > > front panel I found that this conductive foam seems to be the culprit. I've > > repaired LCD displays by cleaning conductive foam but the conductors in this > > foam seem very small. I cleaned it up with some ISO-alcohol and some of the LEDs > > started working but some of the key pads quit working. I cleaned it a second > > time and the same results. Some other buttons are working but some still not. > > The LED problem is solely the problem of the conductive foam but the keys could > > also be the conductive pads on the rubber keys. I've measured the resistance on > > most of the pads and they are about 50 ohms except for some that are 200 ohms > > and greater (up to about 480 ohms). I'm not sure what the max resistance can be > > and still make the key function. My solution first is to just solder the two > > boards with a connection harness to eliminate the conductive foam but I'm not > > sure how to fix the rubber key problem. I have some conductive paint but the > > resistance is still high, around 150 ohms. Does anyone have any success > > repairing this kind of problem? > > > > Gary > > > > > > > > > > [Non-text portions of this message have been removed] > > > [Non-text portions of this message have been removed] |
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On Sat, Jan 19, 2013 at 8:05 AM, Peter Bunge <bunge@...> wrote:
My two Advantest TR5823H did not work because of bad conductive foam in the pushbutton switches. I opened all of the switches and put a dab of conductive stuff sold to repair rear window defrosters in cars. It has been several years now and there is no sign of the problem returning. I hope I am referring to the same kind of conductive foam switches, I have not been following this thread.No, he is referring to a type of interboard connector which consists of stiff wires embedded in elastomer. It's in the same family as zebra strips, but works for higher current applications. |
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Dr. David Kirkby
On 01/19/13 04:48 PM, David DiGiacomo wrote:
No, he is referring to a type of interboard connector which consistsDoes it have to be conductive throughout the volume, or would surface conductivity do? There are plenty of companies selling conductive plastics. was my first hit with Google, but there are tons more. -- Dr. David Kirkby Ph.D C.Eng MIET |
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On Sat, Jan 19, 2013 at 3:46 PM, Dr. David Kirkby
<david.kirkby@...> wrote: Neither, it's a nonconductive elastomer with wires embedded to provideNo, he is referring to a type of interboard connector which consistsDoes it have to be conductive throughout the volume, or would surface conductivity along one axis only. I don't remember who made it. Anyway, the OP was saying that it's so unreliable that he replaced it with a hard connector, so he's not looking for a source. |
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