Menu

Tracking down a colour signal issue

Home Forums OSSC OSSC – DIY Kit support Tracking down a colour signal issue

This topic contains 12 replies, has 3 voices, and was last updated by  renegadeandy 5 months, 4 weeks ago.

Viewing 13 posts - 1 through 13 (of 13 total)
  • Author
    Posts
  • #17807

    renegadeandy
    Participant

    Hi,

    When I power on the board I get this screen on my TV (which I assume is a test screen)
    Test image
    When I connect the SNES via SCART to the OSSC, I get the following:

    SNES

    As you can see the image is very grainy, and the colouring is all off.

    This is what is showing on the OSSC screen when the SNES is connected and turned on:
    OSSC

    Any ideas what could be causing this?

    #17813

    renegadeandy
    Participant

    I found a bridge on the ITE chip, fixed that and now the test screen (or what I think is a test screen) shows:

    Black and white box

    And the game image looks as follows:

    Green snes!

    So — based on the update any thoughts?

    #17822

    Morpheus_79
    Participant

    Take a look if there’s no bridge on the HDMI connector and/or the TVS diode arrays (D6 & D7) too.

    #17823

    renegadeandy
    Participant

    The HDMI Connector is free from bridgeos.

    Where are the TVS Diode arrays?

    What am I expecting to see from this test screen? It would be useful to know so i can keep ‘fixing’ until I see it.

    #17824

    Morpheus_79
    Participant

    Your second test screen picture seems okay. There’s simply nothing more to see besides the grey rectangle and the black-to-white gradient:

    OSSC Grey Screen

    D6 and D7 are between the ITE and the HDMI connector:

    If you “only” took a look under a magnifying glas: i highly recommend measuring the continuity between adjacent pins of the HDMI connector too, since i had some cases where there was continuity (and a tinted and distorted picture) while there was no visible solder bridge – but after adding flux and reflowing the solder on all pins the problem (and continuity) was gone.

    #17834

    renegadeandy
    Participant

    Hi morpheus,

    Thanks for helping here 🙂

    Godo to know the test screen is good – that’s a good step forward.

    The picture you highlight here is of the V1.6 board but I am using the 1.5 board — This is the same area on my board, please see this image:

    closeup

    #17839

    Morpheus_79
    Participant

    The OSSC 1.5 does not have those TVS arrays.

    #17840

    renegadeandy
    Participant

    Ok – so what else should I be looking for? Can you see issues based upon that picture? I have reflowed the HDMI pins multiple times now.

    #17852

    Morpheus_79
    Participant

    Did you have those problems with every output mode (Line2X-5x)? If so: based on the greenish output I would still assume there’s a solder bridge somewhere on the output pins of the ITE – while not on the HDMI connector then maybe on the ITE itself. But maybe someone with more knowledge has a better idea.

    #17865

    renegadeandy
    Participant

    I don’t know how to change modes (I don’t have the remote control?) I do have a phone with an IR blaster if somebody made an app though!

    #17866

    Morpheus_79
    Participant

    Sadly without a remote the OSSCs usability is very limited. You should test all available remote controls in your house – maybe you have one laying around that’s compatible. Or you test some apps for your phones IR blaster with different remote control codes (the original remote uses a combination of Yamaha and Toshiba codes in 16bit NEC IR format… so you should start there: with codes for Toshiba and Yamaha devices – but the OSSCs remote compatibility goes beyond remotes just from devices of those companies). Just take a look at the green LED on your OSSC and if it flashes while pressing a button on some remote. If it does, you can configure your OSSC for that specific remote… like described here:

    http://junkerhq.net/xrgb/index.php?title=OSSC#Remote_control_setup

    #17872

    marqs
    Participant

    As your test pattern looks correct, the issue is most likely a floating input (G) pin on TVP7002 or on G-bus between TVP7002 and FPGA. If you have a VGA source you can connect to AV3, it might help pinpointing the problem.

    #18195

    renegadeandy
    Participant

    It was indeed something on the TVP, reflowed that several times – and now we are looking all good.

Viewing 13 posts - 1 through 13 (of 13 total)

You must be logged in to reply to this topic.