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Retro_Game_Lover96

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Posts posted by Retro_Game_Lover96

  4. Posted

    1 hour ago, Falonn said:

    Nice work.  That output looks great.

     

    Can you confirm whether the audio still works on the machine?  I haven't been following the thread closely, but last I saw, the audio subsystem relied on a clock output from the '9918A that isn't there on the '9928A.

    The audio works on my TI while it is connected from the audio pin from the original connector to the 8 pin din mini connector’s pins 1 & 2 because the TI has a mono sound just like the ColecoVision’s.

    • Like 1

  5. Posted

    3 hours ago, ChildOfCv said:

    One correction is that the red and blue lines represent jumpers to the DIN connector.  The red line is what you'll find in 9918-based TI's, and the blue line is where a jumper is connected to send component video to the DIN connector.  Changing the jumper lengths is unnecessary.  Only the yellow and green lines need to be resistors.

    Alright

  6. Posted · Edited by Retro_Game_Lover96

    How to add RGB on TI99/4A?

    Requirement tools/parts:

    A working TI99/4A Computer

    TMS-RGB Mod Board (Assembled)

    8 Pin Mini Din Female connector

    8 Pin Mini Din Connector Board from OSHPark (Optional)

    8 Pin Mini Din Scart RGB Cable

    3x 560 Ohm Resistors

    1x TMS9928A Chip

    Some wires

    A Phillips Head Screwdriver

    A decent Soldering Iron

    Some Soldering Wires

    Desoldering Braid, Pump, or Hakko Desoldering Gun (If you want to do no-cut method)

    An OSSC, a Framemeister, a PVM RGB Monitor, or any Scart adapter (Required for RGB)

     

    Step 1: Unscrew all of the screws from the bottom of the TI99/4A and then carefully open it.

    Step 2: Unplug the power supply from the motherboard and unscrew all of the screws from the motherboard. And don't forget to take off the cartridge connector and take out the RF Shield, as well as the keyboard connector!

    Step 3: After you open the RF shield from the motherboard, you will see the TMS9918A Chip, so you need to remove it. If it is socketed, it is very easy to remove it. Then, replace it with the TMS9928A Chip.

    Step 4: You need to solder the TMS RGB Board onto the bottom of the VDP Chip like this:

    F439F11B-0C40-48DD-B4E9-2C201CD3DD70.jpeg

    And solder the wires to the chip:

    0F089C84-B350-48B6-8204-081684F78421.jpeg

    And don't forget to feed the wire for the audio which is Pin 3 of the TI's Video connector.

    Step 5: Solder the three 560 Ohm resistors to those places like those:

    Screen Shot 2020-08-25 at 6.02.32 PM.png

    Step 6: If you want to do no-cut method, simply desolder the original video connector off from the board and feed all of the wires to the 8 pin mini din connector.

    Step 7: Test is to make sure it works before putting the TI back together. (If it works, then move on. But, if it doesn't work, check your work and try again.) Make sure you mount the RGB connector!

    Step 8: Carefully put the console back together, and then enjoy!

    • Like 3

  9. Posted · Edited by Retro_Game_Lover96

    On 8/30/2020 at 12:33 PM, Tantan said:

    From what i see you, you need to move the black wire connected to the POT to middle of the pot, not one side.   I see you have 3 wires going to your pot, and that is not correct. 

     

    Pins 9 and 5 are the paddle pins for Paddle 1 and Paddle 2.    the POT needs to go between pin 7 (positive)  to Pin 9 (paddle 1) or pin 5 (paddle 2).   If your black wire is the plus, then it should be connected to the middle of the pot not one side.  Also make sure your POT is 1 mega ohm.

    My pot is 1 Mega ohm. Also, I will try to move the black wire to the middle of the pot to see it works.

    https://www.ebay.com/itm/Radio-Shack-271-0211-1M-Ohm-Linear-Taper-Potentiometer-500VDC-5W-New-2710211/274437732275?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

  12. Posted

    2 hours ago, Tursi said:

    I got color out of a 9928 in a 4A console without jumper changes, but it looks like I DID have the resistors in there (using a component to VGA adapter)! The colors were not /correct/, but they were present ;). 

     

    image.thumb.png.9d9b68787213da4b545dd64ddec24425.png

     

    Not sure why the picture is so bad, probably hiding the awful soldering job. ;)

     

    You asked if checking for shorts was going to work - you got something to lose by trying? ;) Even experts sometimes short the pins by accident. 

     

     

    How fascinating?

  15. Posted

    38 minutes ago, Nathan Strum said:

    Unplug the mod. Plug the TIA back into the 2600, and test the system using RF out. If it works, the TIA is fine and the issue is with the RGB mod or how it's installed. If the TIA is fine, go through the mod and check every connection with a multimeter for continuity, and make sure there are no shorts.

    Before I did the RGB mod, the TIA chip is fine while it originally has a composite mod.

  20. Posted

    7 hours ago, Tursi said:

    I didn't see the details on your post in the Coleco forum - now I understand how it's attached. You're going to need to cut some traces.

     

    The three video pins on the 9928 are 35 (B-Y), 36 (Y) and 38 (R-Y). On the 9918, these pins are CPUCLK (38), Composite Video (36) and Ext VDP (35). (I erroneously stated in the other thread that one of them was tied to reset, different issue, not related to this).

     

    Anyway, I don't have a console handy to check, but I believe one or both of pins 35 and 38 are connected to something. CPUCLK /is/ used on the 99/4 but not the 4A, so I'm not 100% certain. The 4 schematic says that 35 is not terminated to anything and I do believe that is correct on the 4A as well, so I'd focus first on pin 38.

     

    Of course, after checking your wiring for shorts as suggested above - the 'Y' signal is your black and white picture. If that's shorting to the other pins, you'd also get that. ;)

     

    Are you sure this’ll work?

  22. Posted

    2 hours ago, Falonn said:

    It would be easy to just leave those three 9928A pins disconnected from the rest of the original circuit board by leaving them bent up or by cutting a trace on the board or something like that, except there is one key requirement laid out in the datasheet: they require a small "load circuit".

    Are you sure it will work?

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