[SOLVED] No Sync after attempting 1.00 bodge wire on 1.6 hardware
- This topic has 11 replies, 2 voices, and was last updated August 9, 2025 at 3:18 AM by
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Hi there, looking for a sanity check or debugging steps I can take for updating to the latest firmware on an older OSSC model.
Haven’t used the OSSC in quite awhile, but I removed R35 and installed the bodge wire to the far leg on the video chip as described in the firmware v1.xx thread. I verified with a multimeter that the pins on the chip weren’t bridged and that the closer pad to R35 had connectivity.
After getting home (it really sucks but my soldering equipment is elsewhere), flashing firmware v1.12, and trying out NES lumacode I’m getting a solid No Sync message for the AV2 RGsB input. Not knowing if the OSSC update or the lumacode install was the issue, I hooked the VGA output from my Extron VGA switch to AV3 and tried some other sources (namely SNES via RGBS) and still got a no sync message. I’m forgetting what the OSSC supports but this would be TTL RGBS with sync on the HSync pin, which should be correct? EDIT: Also tried Dreamcast RGBHV for something more standard and still had the No Sync message.
Anyways, does this sound like it’s definitely a bad install of the bodge wire? I still get the test pattern and everything else seems to be working on the OSSC side, other than sync input processing.
Is there a test point further on from the R35 pad where I can check continuity between the video chip’s end pin and said test point? I exposed a bit of solder mask near R35 so maybe I managed to sever a trace or something???
Difficult to measure with no help from the silkscreen, but if the below pinout is correct (model number does differ slightly), then pin 126 is grounded. It was around the 2 on the U2 marking, and I counted in from both directions verifying other ground points as I went.
Well here’s something that might actually be helpful- that pin on U1 and the closer pad on R35 appear to be connected to ground. Is that expected or did I maybe hit a via near the pin on U1 or something? I’d assume if you just needed to ground the pin or pad there’d be a much closer connection point for the mod.
EDIT: Duh, open source project with gerbers available. Looks like the U1 pin is normally floating, and then after the bodge wire, should connect to pin 46 on the FPGA, IO_16 if that earlier diagram is right?
Still don’t know how I managed to ground it all- the R35 pad I guess is surrounded by ground plane, maybe I need to check if I scraped some soldermask off and managed to short to it???
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