No Signal (possibly related to sync issues?) – SOLVED!

[Morpheus_79]

Hi there. I bought the barebone DIY kit, the audio addon and all parts some weeks ago and managed to assemble everything over the last week. Well… almost everything – i couldn’t get my hands on a IRM-V538 IR receiver, since by the time i bought everything there was no seller available with this part in its stock. But i did get everything else, assembled it, flashed the latest firmware with audio support via JTAG connector and… have now some problems getting the OSSC to work properly.

Without any input source connected i get a proper grey test pattern on my LG TV (42LM615S). But with my PAL SNES connected to the OSSC my TV simply tells me ‘no signal’ and just shows a black screen. Since it is a SuperCIC modded SNES i can switch between 50Hz and 60Hz output – but that won’t change anything at all.

Maybe my TV has some incompatibility issues with the OSSC… and that’s the only problem (i couldn’t rule that out, since i don’t have any other screen to test… yet). But there’s some sync related strange behavior with the OSSC too. I made some videos to show what i mean:

As those videos show: it doesn’t matter if my SNES outputs a 50Hz or 60Hz signal – i couldn’t convince the OSSC to get a stable sync to save my life. I tried different RGB cables… but: no change at all. I even tried to feed the RGB output of an old receiver and a DVD player to the OSSC – the results are the same: the LCD of the OSSC shows an occasional ‘NO SYNC’ and short flashes of different resolution/refresh rate values… and my TV continues to complain about ‘no signal’.

To make bad things worse: since the IRM-V538 is still missing i can’t use the remote control to access the menu. So i don’t know if any fine tuning of the settings may help. But shouldn’t get the OSSC a stable sync from (at least!) ONE of the tested video sources “out of the box”!?

Since at first there was a solder bridge on the pins 79 & 80 of the TVP7002, which prevented the OSSC from proper running, i’ve double checked every pin on every IC in hopes of finding something. But everything seems to be fine. So i’ve simply run out of ideas. Maybe someone reading this got one…

[BuckoA51]

Well the NTSC input is definitely being recognised wrong there, SNES should work out of the box and give you some kind of picture even on incompatible TVs.

[Morpheus_79]

Since the preview pic on the second video could be misleading -> for NTSC input most of the time it reads:

AV1: RGBS 262p
15.59kHz 59.53Hz

But now and then it goes bonkers and shows something like:

AV1: RGBS 532i
15.59kHz 58.63Hz

… or even:

AV1: RGBS 995i
15.59kHz 31.35Hz

But since there was a solder bridge: could this issue be related to a possibly damaged TVP7002?

[marqs]

Please try another console if possible to ensure connection between TVP7002 and FPGA is working. 532i/995i do not look right indeed – that might be due to a cable issue or a certain bug that will be fixed in next fw.

[Morpheus_79]

I don’t have another console. But i’ll try to connect my old pc with the OSSC. Sadly i don’t have a VGA cable at hand but i will get hold of one.

Hopefully it’ll work since i guess if it won’t, there may be an issue related to the TVP7002 or even the FPGA.

[Morpheus_79]

Update:
Today i checked all pins of every IC under the microscope at work… but didn’t find any suspicious solder joint. Still: . Back at home i connected the OSSC with an old laptop via VGA and did some testing. Sync is unstable but existing. For whatever reason an output of 1280×720 is recognized as 746p… and 1280×800 as 828p. Sadly it doesn’t change anything for the HDMI output: my tv still shows ‘no signal’. I even replaced VGA and HDMI cables with different ones – but that didn’t enhance anything at all.

Seems like i didn’t assemble an OSSC but just an expensive paper weight..

[marqs]

It sounds like FPGA is not getting sync signals from TVP7002, please check that HSYNC and VSYNC have connection between them (and scope the signals if possible). 746p and 828p are valid numbers since they include blanking lines.

[Morpheus_79]

Thanks for the clarification regarding the resolutions. I’ll test the connections of the HSYNC/VSYNC-OUT- and IN-Pins between both ICs tomorrow. Sadly i don’t own any scope to check for proper signals… but maybe i can borrow one from work.

[Morpheus_79]

I checked the connections: TVP7002/Pin23 -> EP4CE15E22/Pin91 & TVP7002/Pin24 -> EP4CE15E22/Pin90 are perfectly fine. I resoldered them nonetheless… but it didn’t change anything. I wasn’t able to get my hands on a scope… so i couldn’t check the signals. I would assume: either the TVP7002 is damaged spits out some corrupt sync signals or the FPGA does something wrong interpreting them?? But without scoping the signals between the digitizer IC and the FPGA no one can say for sure??? Am i right or am i wrong? Any suggestions for what else to test?

[marqs]

You can actually press info button on the remote to see the line count FPGA is processing (the number on main screen is read from TVP7002 status regs). Just to rule out rare compatibility issues, have you tried connecting it to any other display besides 42LM615S, e.g. a PC monitor?

[Morpheus_79]

I didn’t get the IRM-V538 IR receiver (yet) – so every function beyond the two-button-control isn’t possibly for me by now. But the receiver is on its way…

Sadly i don’t have any other device with HDMI/DVI input. I plan on buying a new display (as part of an new PC) in the near future… but until then only a retro PC with CRT monitor, a laptop, an old CRT TV and the aforementioned LG TV are available. But i’ll try to get my hands on an LCD with (at least) DVI input – maybe i can borrow one from my brother in law…

Btw… Peter (aka ‘borti4939′) offered me a spare TVP7002 and Cyclone IV he had lying around. It will be a pain in the ass to replace one of the ICs. But then again… if everything else fails (maybe if it’s just to rule ’em out)…

[Morpheus_79]

Now it gets really weird:

Yesterday the final missing part, the IR receiver, arrived. I soldered it into place, plugged my OSSC between SNES and tv and fired it up – just for the sake of it. I didn’t expect anything… but… it worked! For the first time!!! I just had to switch to AV1… the red led lit up briefly… but then it went off and only the green led stayed on… and i enjoyed a clear an vibrant picture with sound (so the audio addon board did work too). I switched my OSSC off and on again and everything continued to work as it should. So i tried to set up the remote and therefore tested a remote from my old Toshiba crt tv for its compatibility. I pressed a button, the green led blinked… and my OSSC immediately lost sync permanently and the screen of my LG tv went black.

Since i was unable to regain a stable sync signal, i set up the remote and decided to test the firmware update via sd card. I prepared the card with the v0.77_aud *.bin file and did the update. Everything went flawlessly, so i jumped through the OSSC menu til i saw the ‘Sync options’ and played around with them. Just when i thought it couldn’t get any stranger, i chose ‘Analog sync LPF’ -> ‘Off’… and got the picture back. But just for a couple of minutes. After that, the screen stayed black again. And i couldn’t get it to work to save my life. It was frustrating.

Today i tried again… but nothing changed. The red LED always stayed on and my tv reported ‘No signal’. I switched through different output and sync settings without any success. So i did reset them, restarted my OSSC… an it worked again! I tested 50Hz and 60Hz input from my SNES… 5x scaling and the the OSSC did its job perfectly:

But after 10 minutes or so it started to loose sync briefly.

And now it’s back to the ‘no sync at all’ point… and it drives me to despair since i don’t know where to look for the culprit. Is it a cold solder joint? But i resoldered R3 and every pin on all three ICs and checked everything under a microscope for shorts. I even replaced C13 (just because i got some strange capacity readings after desoldering and testing it). Should i resolder some more parts… ALL parts?? Could it be a broken TVP1002(?) or a defective FPGA??? At least there’s no compatibility issue with my tv – cause when it works, it works like a treat. But apart from that it’s like searching for the proverbial needle in the haystack…

[marqs]

Sounds like TVP7002 is either overheating or just has a weak connection to PCB. I’d also test with some other source just to make sure that your SNES e.g. doesn’t have flaky caps.

[Morpheus_79]

Could the solder bridge i had at first (between Pin79/VSYNC_B and Pin80/EXT_CLK) have damaged the TVP7002 (or any other component)?

I’ve replaced all caps inside my SNES some months ago… but… of course: you never know. Then again: it’s the same with the VGA input via my old laptop. The sync signal is unstable – even though AV3/VGA uses no Composite- but separate H- and V-sync lines and different input pins on the TVP7002.

I thought about a heat related problem too – even though i mounted a 14x14x7mm heat sink on the TVP while assembling the OSSC. For ruling it out yesterday i even placed a 120mm fan at the side of my OSSC… sadly with zero effect at all.

‘Borti4939′ was kind enough to send me a TVP7002 and an EP4CE15E22. But since it is a pain in the ass to desolder even one of ’em not to mention both, i’ll wait till tuesday… since a colleague from work wanted to borrow me an old scope he has. Sadly he didn’t know for sure if it’s in working condition. But if it is, i may be able to check the sync signals between the TVP and the FPGA and narrow the source of the problem down…

[Morpheus_79]

Since i still was unable to get a scope, i’ve replaced the TVP7002 with the one from ‘borti4939′… but the problem still remains.

Tomorrow i’ll replace the EP4CE15E22. If it doesn’t help too, i call it quits and see it as a successful attempt to build an expensive bookend.

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