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HW mod the device to install a microsd holder

OP zooster

25th April 2012, 10:42 PM   |  #31  
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Ok guys, let's try to find a pic of the mainboard of a P7500. I'm quite confident there will be resistors and similar close to the microconnector of the simholder.
I've read the service manual of the P7500 and there are resistors pictured close to that connector.
25th April 2012, 11:55 PM   |  #32  
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Quote:
Originally Posted by zooster

Ok guys, let's try to find a pic of the mainboard of a P7500. I'm quite confident there will be resistors and similar close to the microconnector of the simholder.
I've read the service manual of the P7500 and there are resistors pictured close to that connector.

Well I do have the P7500 and want to help but I'm a little afraid of breaking my tab opening it. Is there a big risk of that?
I am use to do it to phones. I change lcd's and digitizers in my sparetime but have never opened a tablet.

Sent from my HTC One X using XDA
Last edited by tandfeen; 26th April 2012 at 10:22 AM.
26th April 2012, 12:19 AM   |  #33  
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There are many disassembly guide on internet, it's not much difficult...
26th April 2012, 12:46 AM   |  #34  
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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?

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26th April 2012, 01:21 AM   |  #35  
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Maybe... Who has a P7500 and wants to help the project giving it a try...
The sd holder is quite cheap.

btw I do suspect that all those sd holders on sale on ebay are the ones built for early orders by samsung and after they changed plans about sd slot someone is trying to sell them to gain something from "unuseful" spare parts.
Who knows, maybe they can support us, they have all the interest
Last edited by zooster; 26th April 2012 at 01:25 AM.
26th April 2012, 02:41 AM   |  #36  
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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>

Quote:
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.

Quote:
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.

Quote:
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.

Quote:
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.

Later,
Jason
26th April 2012, 07:29 PM   |  #37  
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We could also take a look at the mobo of a P7100. Just to see if by any chance they left some connector with resistor unused but ready for the usage...
27th April 2012, 12:43 AM   |  #38  
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Quote:
Originally Posted by jacampb2

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.

Jason

XDA is no longer worth my time.
Last edited by TimOster; 21st March 2013 at 09:59 PM.
27th April 2012, 02:01 AM   |  #39  
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Tim, that is exactly what I was talking about. The center pad is more than likely heat sink area like you say, but still no ideas on the package. I will try to spend a few minutes researching the package later tonight.

In other news, I did find a handful of pictures of the insides of the pre-release tab with SD card slot. You can find the article here: Clicky, I am not going to post copies of the pictures unless they give me permission. I emailed the site editor last night and asked if they had any higher resolution pictures they could provide, and if I could have permission to post their pictures here. I have yet to receive a reply, but you guys will be the first to know when I do. The area of interest in that particular tab is populated, but the pictures are poor enough quality that you can't really make much out except for being able to make a bit more educated guess as to which components are caps and which are resistors. Values are left to the imagination, and frankly, when you get bellow a 0805 package size for SMD resistors, sometimes you are left with components that are not labeled at all, so these pictures might be all the help we can get... Anyone have any of the fictional software from CSI that will sharpen those images into visibility

zooster, thanks for the PM, the link was dead (file missing) but if the service manual is out there, I will keep searching. If you have a copy saved, I am happy to give you my email address.

Thanks,
Jason
27th April 2012, 06:46 AM   |  #40  
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Hey guys. 2 things.

1. I'm getting a galaxy tab on the 28th, so i will be spying on you guys a lot more for the XDA Portal.

which brings me to

2. When this mod gets done, I'm so doing it and then writing the hell out of it

Just so you know, the Portal is keeping tabs on you...no pressure

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