1. MNiceGuy

    MNiceGuy Member
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    In fairness this is with only one GBA with one particular screen and cable. The 'interlacing' is subtle but it's enough that it would bother me if I used it a lot. I am going to try a Type-A cable along with the 'component removal' (outlined on pg.60 of the other big thread on the topic) to see if that gets me anywhere.

    The Type-B cable seems to be working for people so who knows. My understanding is that the GBA has that little potentiometer for a reason and I know I've used it to fine-tune the screens on both systems I've worked with so far.

    I have a new meter coming in today (yay!) so I have a perfect excuse to double check my statement about pin routing on the Type-B
     
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  2. malheur

    OP malheur Advanced Member
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    Thank you for sharing your experience. it seems i little late for reply, but anyway.

    for "B" cable interlace issue :

    a. "B" cable uses two (what so called) same fixed value resistor for making REVC. original VCOM volt will be bypass(it means internal pot no longer works).

    b. REVC must be "EXACT" middle volt of LCD working volt. i mean "EXACT" really exact.

    c. every single fixed value resistor cannot be exact. it has tolerance 1~5%. it is not exact 50,000 Ohm if its marked 50k Ohm. sometimes its 50,051.1 Ohm, sometimes it's 49,980.5 Ohm.

    d. therefore combination with a+b+c cannot be perfect. though if you have enough luck, you can't tell interlace line with such slight difference on your bare eye, but sometimes it sure exists.

    actually original post explains that part.

     
    Last edited by malheur, Sep 14, 2017
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  3. MNiceGuy

    MNiceGuy Member
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    Malheur,

    Thanks for the information. I completely agree with your assessment. I've had screens which need a very precise adjustment of the potentiometer to eliminate the interlace lines. It would seem the Type-B cable is good for people that don't want to solder/desolder but there is a risk that the non-adjustable REVC voltage could pose a problem.

    My findings so far suggest that a Type-A cable and a soldering iron is the way to go.

    Last night I changed my 40-pin/Type-B screen/Type-B cable back to a Type-A cable. I chose to eliminate certain motherboard components (as detailed in the other thread) rather than modify the ribbon. This is basically malheur's theory just executed a different way.

    Eliminating R16, R17, and C33 isolates the P2-VEE circuit (which feeds the important REVC voltage when using a Type B screen and Type A cable). By means of a small jumper, REVC from the GBA can then be fed to P2-VEE, giving the screen exactly what it needs. Malheur accomplished the same result but fed REVC directly to the ribbon.

    Eliminating C54 and Q3 isolates the GBA's potentiometer. This allows adjustability in the voltage supplied to the Type B screen's COM input. This is important because as mentioned having this voltage incorrect can result in low contrast, interlacing lines, etc. Malheur accomplished the same result by adding a potentiometer which tied directly into the ribbon.

    I should point out that doing the above work was fairly easy. Personally, I wouldn't have wanted this to be my first soldering experience but it's not especially difficult either.

    Now my 40-pin (B LCD/A cable) looks just as good as my 32-pin with the same screen. Given all the options on the table to make this GBA/Screen combination play nice with each other, the above gets my vote.
     
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  4. victorstk

    victorstk Member
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    how do i know if my lcd is white tab or brown tab?

    can someone post a picture?
     
  5. eldontyrell

    eldontyrell Member
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    Hi all!

    I tried the 40 pins Type-B ribbon with my white tab screen, and I still get a lot of ghosting.
    But I didn't unsoldered the 103 to GND connection. Could it be the reason ?
    Also, screen brightness is not very high, even though I connected P1 to DA1.

    Thanks for your comments / help,

    Stephane
     
  6. avocado

    avocado GBAtemp Regular
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    hi..

    I finished moding my GBA and it works. thanks again to malheur and gaggi for this super tutorial.
    the first time I turn up the GBA, it shows perfect picture.
    I did not need to adjust the variable resistor.

    I am just curious..has anyone compare the screen with NDS lite playing GBA games?
    I think GBA screen is not as bright as the screen of NDSlite.
    Is it because I did not adjust the resistor or it is the way it is?

    I have only one flashcard so cannot take a photo of them side by side.

    I hope you guys dont take me wrong, I am happy with the result but I just want to know if it can be any better...more bright maybe.
     
  7. eldontyrell

    eldontyrell Member
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    Hi all,

    This weekend I installed a backlit screen in my "32 pins GBA", and the result is perfect (and connected P1 to DA1) !
    No ghosting, pleasing picture.
    So the best solution is to source "32 pins GBA's", easiest solution.
    But these seem to be rare on the market. Out of 4 GBA's, only one is a 32 pins one (motherboard serial number beginning with "1").

    Stephane
     
  8. eldontyrell

    eldontyrell Member
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    Hi,

    I used a Type B ribbon connector in my 40 pins GBA and I still get a lot of ghosting (but I still have this 103 to GND wire, dunno if it's the reason).
    Also, as noticed by another user, connecting P1 to DA1 does not have any effects. Screen brightness is the same (too low for me). Strange.
    So for me the, the Type B connector is not the solution...
     
  9. malheur

    OP malheur Advanced Member
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    103 is actually CPU pin number marking. the pin you mentioned is P2-Vee. look the board closer.

    and of course, you have to remove P2-Vee to GND mod or any other mod about AGS-101 LCD, before do this method.

    P1 to DA1 for add more backlight brightness mod also working with this method.
     
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  10. MNiceGuy

    MNiceGuy Member
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    The DSLite definitely has better screens than the 101 but that is to be somewhat expected. The DSLite is newer, better tech. A properly-adjusted AGS-101 is not going to compete with the screens in a DSLite.

    If you really want to make the backlight of the AGS-101 brighter than the typical P1->DA1 solution you are going to have to find a voltage regulator like the one recently released by BennVenn. I have one on the way so I can't comment on it yet but supposedly it allows the 101 screen to go beyond the max brightness level of the SP. I'll report back once I have everything installed.

    When experimenting with modding, it's important not to mix elements of different approaches. The Type-B ribbon adapter is meant to attach a white-tab AGS-101 screen to a 40-pin GBA without any soldering needed (unless the user wishes to add P1->DA1 for extra brightness). I would remove the REV-103->GND jumper and see what happens.

    The problem I experienced with the Type-B cable is it removes the GBA's potentiometer from the circuit which makes screen adjustability impossible without additional work. I've read that some do not have any trouble but all six 101 mods I've done so far have needed potentiometer adjustment before the screen would perform properly. Boring detail found here.

    For white tab screens to 40-pin GBA, I have yet to find a better solution than using a Type-A cable and this method.
     
    Last edited by MNiceGuy, Nov 6, 2017
  11. eldontyrell

    eldontyrell Member
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    Hi !

    Last week I had the time to do some more tests.
    As I previously said, 103 to GND was still connected. I removed this wire and now everything is perfect !
    No more ghosting.
    I checked that the wire running from P1 to DA1 was still ok, and it was. Apparently brightness is a little bit lower for this screen, but I guess it should be ok in most situations, excepted outside.

    So now I can safely say that:
    - A 32 pins GBA with the matching 32 pins connector gives perfect results. In this case, it's still possible to use the pot to adjust the screen.
    - Same with a 40 pins GBA, with the Type B connector. Perfect results (to my eyes).
    But in this case, the pot cannot be used if I correctly understand, which is not a problem as the result suits me. But I had to adjust the pot in
    my modded 32 pins GBA.

    Regards,

    Stéphane
     
  12. MNiceGuy

    MNiceGuy Member
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    Glad you got it working!

    If you really want a brighter backlight, look here
     
  13. pasc

    pasc Newbie

    I've got a different "problem". One of my gba's has the apparantly got white edges on the backlit screen now.
    (Probably some strange pressure on the display).
    Oh well.
     
  14. malheur

    OP malheur Advanced Member
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    thats because it does not enough grounded the front housing. you have to cut the guideline. i saw someone even using soldering iron for melt that line surely.
     
  15. pasc

    pasc Newbie

    Sounds reasonable enough. Gotta try that.
     
  16. Nico128

    Nico128 Member
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    deleted
     
    Last edited by Nico128, Nov 20, 2017
  17. Swel_

    Swel_ Newbie
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    Hi all,

    I just want to strongly advise to use gaggi's method.
    Cutting into the cable comes with much risk Plus taking away parts makes them not use any power anymore.
    Cables with extra components on them makes it use more power.
    Just a little bridge wire on the cpu side and remove 5 parts (still need the ribbon cable to DA1 too).

    I did many like this, all came out perfect.

    To stop light bleeding from the edges I use some black tape. Works like a charm, just be careful to put it in the right place.
     
  18. gaggi

    gaggi Newbie
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    Actually, you don't have to do this anymore as there is a new version of the Adapter Cable which has an 50/50 Voltage divider Build in so it is just "plug an play".
    I think its called Type-B...
     
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  19. NPlayer

    NPlayer Newbie
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    Hi! I have a brown tab AGS 101 screen? Should I get a Type B 40 pin ribbon, the ones with resistors built in and without removing components from the GBA?


    My problem is that I made the component removal but I have some type of contrast problem. I tried with the rear pot but now I have some ghosting issues. I think that the problem is that it's not a white tabbed ags lcd, and the ribbon is somewhat rare. So I'm going to start over with another 40 pin that I have, that's why I ask about the new ribbon.


    Thank you for your help.
     
  20. Deleted User

    Deleted User Newbie

    Hi,

    I bought a new backlit LCD with white connector into my 40pin GBA I do not know if seller sent me the ribbon type B, so I was searching for another one just for sure (I do not want to wait for another a half of the month if he did not). As I was reading this I found a ribbon - I hope type B for my GBA. My question is, do you think this ribbon is authentic TypeB in the picture below? There are two resistors under the connector. I was searching only for theese. The price is about 1.26$, so I little bit doubt about quality. Seller said it is exactly the same as in the picture. Another seller with a price up to 5$ have the same picture - there is only a yellow tape on a connector. That is the only difference between them. Have some of you experience with something like this?
    Thanks in advance.
     

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