Unusual zapper failure mechanism

[N_Cook]

Plasticizer or something leaching out of the flexible membrane, at the
edge, dissolving the green pcb lacquer coating and etching lines into
the pcb traces. The one that failed was actually at this line through a
test pad circle, rather than just the width of a trace

 

[N_Cook]

On 17/07/2013 15:20, Jeroni Paul wrote:

N_Cook wrote:
Plasticizer or something leaching out of the flexible membrane, at the edge, dissolving the green pcb lacquer coating and etching lines into the pcb traces. The one that failed was actually at this line through a test pad circle, rather than just the width of a trace


The plastic membrane seems to leave this oil slowly. I have so far not seen any secondary effect caused by this oil, it appears to be non conductive, non corrosive and it allows the contact of conductive pads without problems. When I have to repair a remote I clean this oil but after some time of use it forms again near the most used buttons.

The conductive black rubber sooner or later wears out. Cleaning the surface sometimes works but not for long. Time ago I used conductive paint but it does not last either. I found it difficult to paste conductive foil, it can fall easily and keep the button permanently pressed.
So for a lasting repair I use a needle to create a small hole across the rubber under the conductive surface, it is surprisingly easy to puncture. Then I run a very fine copper wire through this hole and bend the ends so they lay on the failing conductive pad. It lasts forever and works great.

It naybe an abrasive process. Although the buttons nearest this edge are
never used, perhaps the membrane does move each time of usage. The
"etched" line is very precisely along the line of the edge of the
membrane. No drink ever spilt on it, very hot environmentally at the
moment, maybe connected with the failure

 

[Jeroni Paul]

N_Cook wrote:

Plasticizer or something leaching out of the flexible membrane, at the edge, dissolving the green pcb lacquer coating and etching lines into the pcb traces. The one that failed was actually at this line through a test pad circle, rather than just the width of a trace

The plastic membrane seems to leave this oil slowly. I have so far not seen any secondary effect caused by this oil, it appears to be non conductive, non corrosive and it allows the contact of conductive pads without problems.. When I have to repair a remote I clean this oil but after some time of use it forms again near the most used buttons.

The conductive black rubber sooner or later wears out. Cleaning the surface sometimes works but not for long. Time ago I used conductive paint but it does not last either. I found it difficult to paste conductive foil, it can fall easily and keep the button permanently pressed.
So for a lasting repair I use a needle to create a small hole across the rubber under the conductive surface, it is surprisingly easy to puncture. Then I run a very fine copper wire through this hole and bend the ends so they lay on the failing conductive pad. It lasts forever and works great.

 

[N_Cook]

On 17/07/2013 15:20, Jeroni Paul wrote:

N_Cook wrote:
Plasticizer or something leaching out of the flexible membrane, at the edge, dissolving the green pcb lacquer coating and etching lines into the pcb traces. The one that failed was actually at this line through a test pad circle, rather than just the width of a trace


The plastic membrane seems to leave this oil slowly. I have so far not seen any secondary effect caused by this oil, it appears to be non conductive, non corrosive and it allows the contact of conductive pads without problems. When I have to repair a remote I clean this oil but after some time of use it forms again near the most used buttons.

The conductive black rubber sooner or later wears out. Cleaning the surface sometimes works but not for long. Time ago I used conductive paint but it does not last either. I found it difficult to paste conductive foil, it can fall easily and keep the button permanently pressed.
So for a lasting repair I use a needle to create a small hole across the rubber under the conductive surface, it is surprisingly easy to puncture. Then I run a very fine copper wire through this hole and bend the ends so they lay on the failing conductive pad. It lasts forever and works great.

Next time with a pad failure I'll try your "sewing" a loop of copper
wire through the pad. Concerned about local pressure of the wire cutting
into the pcb conductive traces I would flatten the pad part of the wire
in some pliers with a washer "depth-stop"

 

[Jeroni Paul]

N_Cook wrote:

Next time with a pad failure I'll try your "sewing" a loop of copper wire through the pad. Concerned about local pressure of the wire cutting into the pcb conductive traces I would flatten the pad part of the wire in some pliers with a washer "depth-stop"

Before you flatten test the button by placing the rubber exactly the same position as assembled. Sometimes slight adjustments are necessary to the wire bending or position to match the PCB traces. Some cheap remotes do not perfectly align conductive pads and board traces, so placing the wire centered does not always work.

Anyway if the wire is fine enough the rubber accomodates it easily.