- Joined
- May 25, 2020
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I am looking for any technical advice to assess if I might be on the right track in my troubleshooting of this problem.
I have disassembled the keyboard and conducted a thorough cleaning.
I have checked and cleaned all connectors coming off of the keyboard.
I have spotted something suspicious, but I don't have the electronics tools nor expertise to make an absolute diagnoses.
Here is some more info and I've attached a series of photos to support my findings thus far.
So, the basic symptom is that all E and A# keys above middle C are dead, but all others on the keyboard work fine.
I had a hard time finding detailed technical information about the P95 keyboard, but I did run across a comment on the internet that acknowledged the shortcomings of the P95 Service Manual, but indicated the P85 Service Manual was way better and the internals between the two models are virtually identical. So, I’ve based my research on the P85 Service Manual.
After studying the schematic diagrams of the various printed circuit boards and identifying the pathways for impulses sent by the E and A# keys, I discovered that all E and A# impulses follow the same pathway to the connector coming off of the boards where the key contacts exist. There are three of these boards, for simplicity, the left board, the middle board and the right board. The problem keys are exclusively to the right of the outgoing connector of the middle board. The pathways assessment tells me that if some E & A# are working but others are not, then the problem is not in the connector coming off of the middle board. Also, the middle board and right board are joined through a connector and the dead keys exist on both boards. So, it is not a problem exclusively with the right board. So, I excluded a problem with the connector between the middle and right boards. I deduced that it is a pathway issue on the middle board and began looking closely at the middle board.
I’ve attached a series of photos showing the keyboard with center keys removed to expose the middle board. I have annotated the photos with circles and arrows to focus on an anomaly that might be the problem, but I don’t have equipment nor expertise to confirm my suspicion. The photos ‘drill down’ to the spot in question.
The first photo shows the whole keyboard and I’ve red-bracketed the middle board in question with an arrow pointing to the area of suspicion. The other photos are really just showing more and more detail.
In the second photo you can just begin to make out a small circular stain on the printed circuit board (circled) just to the right of the outgoing connector. Subsequent photos show more detail of this area. It looks like a single drip of something landed in that spot. And, I suspect what ever it was had corrosive properties and over time it ate into the circuit board pathways affecting the E and A# keys. All such keys to the right of that spot are dead, but all of them to the left work.
In images 0030 and 0035, you can see that three of the pathways show a copper appearance, which to me suggests corrosion has been at play. The last two images, 0040 and 0050, are of the underneath side of the board in the area where the spot is present on the top. Both suggest a liquid came through the small hole in the board and then dried up.
All of this is just my suspicion and it would be great if it could be confirmed by an electronics person, but in any event I think this is not repairable.
I have done some shopping on the internet to a replacement for the middle circuit board. It is only about 30 USD, but here is the rub. International shipping costs 95 USD and the merchant will only accept a wire transfer in payment, which is another 30 USD and Mexican Customs will open the package and see it is electronics and charge another 600 to 1000 pesos duty. So, a 30 dollar part ends up being close to 200 delivered. And, I’m not even sure this is in fact the problem. If I’m lucky enough to be able to find a replacement part that is already in Mexico, I will buy it. But, if I could get some expert advice that, based on the symptoms and my assessment that the middle board replacement seems very reasonable, I could have the part delivered to someone in the USA who could bring it to me on their next trip south.
Any advice is appreciated!
I have disassembled the keyboard and conducted a thorough cleaning.
I have checked and cleaned all connectors coming off of the keyboard.
I have spotted something suspicious, but I don't have the electronics tools nor expertise to make an absolute diagnoses.
Here is some more info and I've attached a series of photos to support my findings thus far.
So, the basic symptom is that all E and A# keys above middle C are dead, but all others on the keyboard work fine.
I had a hard time finding detailed technical information about the P95 keyboard, but I did run across a comment on the internet that acknowledged the shortcomings of the P95 Service Manual, but indicated the P85 Service Manual was way better and the internals between the two models are virtually identical. So, I’ve based my research on the P85 Service Manual.
After studying the schematic diagrams of the various printed circuit boards and identifying the pathways for impulses sent by the E and A# keys, I discovered that all E and A# impulses follow the same pathway to the connector coming off of the boards where the key contacts exist. There are three of these boards, for simplicity, the left board, the middle board and the right board. The problem keys are exclusively to the right of the outgoing connector of the middle board. The pathways assessment tells me that if some E & A# are working but others are not, then the problem is not in the connector coming off of the middle board. Also, the middle board and right board are joined through a connector and the dead keys exist on both boards. So, it is not a problem exclusively with the right board. So, I excluded a problem with the connector between the middle and right boards. I deduced that it is a pathway issue on the middle board and began looking closely at the middle board.
I’ve attached a series of photos showing the keyboard with center keys removed to expose the middle board. I have annotated the photos with circles and arrows to focus on an anomaly that might be the problem, but I don’t have equipment nor expertise to confirm my suspicion. The photos ‘drill down’ to the spot in question.
The first photo shows the whole keyboard and I’ve red-bracketed the middle board in question with an arrow pointing to the area of suspicion. The other photos are really just showing more and more detail.
In the second photo you can just begin to make out a small circular stain on the printed circuit board (circled) just to the right of the outgoing connector. Subsequent photos show more detail of this area. It looks like a single drip of something landed in that spot. And, I suspect what ever it was had corrosive properties and over time it ate into the circuit board pathways affecting the E and A# keys. All such keys to the right of that spot are dead, but all of them to the left work.
In images 0030 and 0035, you can see that three of the pathways show a copper appearance, which to me suggests corrosion has been at play. The last two images, 0040 and 0050, are of the underneath side of the board in the area where the spot is present on the top. Both suggest a liquid came through the small hole in the board and then dried up.
All of this is just my suspicion and it would be great if it could be confirmed by an electronics person, but in any event I think this is not repairable.
I have done some shopping on the internet to a replacement for the middle circuit board. It is only about 30 USD, but here is the rub. International shipping costs 95 USD and the merchant will only accept a wire transfer in payment, which is another 30 USD and Mexican Customs will open the package and see it is electronics and charge another 600 to 1000 pesos duty. So, a 30 dollar part ends up being close to 200 delivered. And, I’m not even sure this is in fact the problem. If I’m lucky enough to be able to find a replacement part that is already in Mexico, I will buy it. But, if I could get some expert advice that, based on the symptoms and my assessment that the middle board replacement seems very reasonable, I could have the part delivered to someone in the USA who could bring it to me on their next trip south.
Any advice is appreciated!
