Does anyone here have a contact at Samsung? Maybe they would be willing to divulge the details of the circuit. After all we whom are willing to solder on our tabs are guaranteed to be such a slim minority that it can't possibly hurt their profit margins. I don't have the first idea who to start with, or even what department to try to reach out to.
<RANT>In all actuality, this particular design/production scenario really pisses me off. I know that in the long run, scrapping the SD card read saved them a lot of money, BUT, my guess is that the reason behind scrapping the slot was not cutting production cost. I think it was much more likely that when the decision was made to release a few version with various amounts of internal storage, and they saw that scrapping removable storage allowed them to push the more expensive tabs with more internal storage. After all, why would I buy a 32g tab for $100-$150 more, when I can drop a $30 card in the 16g tab and get more storage? Have any of you questioned why the USB OTG devices are so damned bulky? How about why the dock connector for them is on the bottom of the tab in nearly the worst position possible? I have, I want to say it was planned inconvenience, but I think more than likely it was not intentional, however, they have made no effort to respond to complaints of users and made the OTG more useful. Have you actually seen a tab with the official USB adapter and a thumb drive? Even upside down it is ridiculous. Even the Chinese OTG dongle on a cable is better than the official, and it still isn't by much. -- sorry, I had to get that off my chest... </RANT>
Originally Posted by zooster
Anyway I noticed that the empty pads close to the microconnector of sd holder you soldered are very similar to the ones close to the microconnector of simholder.
I saw that too, and it might be useful information. However, from the info I can find, SIM cards are 1 bit serial data and have a Vcc of 5Vdc. SD cards are compatible with 1 bit and 4 bit serial data (as well as SPI being optional), and have a Vcc of ~2.7-3.6Vdc. So, we can see with some certainty that you cannot just plug the SD reader into the SIM reader circuit. If you did, I think it is likely that you will see hardware damage to the SD card. At most, the 10 pin connector pinout for the SIM might be drastically different, reversing Vcc and ground, or applying voltage to the data or clock lines. Anyhow, without a lot of verification, I would not just try it out. At the very least, the higher voltage might destroy the card. I have found some evidence that the SD cards can take 5Vdc, but that was not within their specification.
Originally Posted by TimOster
would be to Ohm out the connector (for the ribbon) pins to each of the pads. You can see how the one in the upper left is connected to ground, and the ones oriented horizontally to the right of them all have one side to ground also.
Yes, and this is my plan once I have a few days off work to mess with it again. The layout of the pads and the traces we can seems it might be RC networks and possibly some voltage dividers. I am somewhat stumped on what that five pad device might be on the right hand side. I don't even know that I have come across that package before.
Originally Posted by zooster
I've read the service manual of the P7500 and there are resistors pictured close to that connector.
Any chance of getting a copy of this service manual? PM me if possible.
Originally Posted by johho
Small question, is the sim holder usb too? Maybee its possible to connect the sd reader to the sim reader port and see whats happening? It seems they have the same connectors?
There is really no reason to assume any of these devices utilize USB. There is nothing at all to prevent the serial data from being read directly. As to swapping them and seeing what happens, I would advise against it. There are several components in here that have the same connector and would not even be remotely similar to the same device.
Long winded again, sorry.