Loosing Sync with Ossc and Pc Engine
- This topic has 25 replies, 5 voices, and was last updated November 16, 2022 at 9:16 AM by
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I had some rare occasions of picture dropout on my white pce which has an rgb amp that I contructed myself and has been serving me well all these years. Its based on an old schematic and its supposed to be specifficly designed for the pce. It has 4 amps, 3 for the rgb and a slightly different one for the sync and it is comprised of a transistor (each), resistors and capacitors. The pce is on an IFU-30 with a cdrom2 but I get the RGB from the PCE and the stereo sound from the two RCAs of the IFU.
In my case, using the default settings of the OSSC (v1.6, fw 0.9a) and 2x upscale, I would rarely get a dropout for a second and the picture would come back. When I say rarely I mean that you could complete a game (Dynastic hero which is long for example) and it would happen once or twice throughout.
Fidling with pre and post coast and increasing HSync tolerance didn’t solve it. Neither the Sync LPF which is by default at 2.5Mhz.
I noticed that when turning on the OSSC and after the PCE, the OSSC would lock at 60.28Hz. If after that I turned off the OSSC and then back on, it would lock on 60.05Hz or 59.98Hz (OSSC LCD screen). Others have reported these same frequencies when using a PCE with the OSSC.
There hasn’t been one time that I would get a picture dropout when the OSSC is locked at 59.98Hz (I haven’t tried at 60.05Hz yet but I suspect the case will be the same). I’m talking finishing Dracula X and Star Parodia and not having a single dropout.Also to mention that when my OSSC locks on a frequency, it doesn’t change on it’s own, its stable.
I suspect that the OSSC doesn’t detect the frequency of the sync signal correctly on console power up and this definitely seems to be responsible for even these rare dropouts.
I mean, I know the PCE doesn’t output 60.28Hz, thats for sure. It should be around 59.89Hz or 59.83Hz depending on the software (Voultar). It is known to fluctuate.One other thing that I noticed and please if someone knows please tell me… The LCD may show 60.28Hz (or what have you) but if I press “info” on the remote the window that appears on screen says “FPGA 59.82Hz” among other things. Should these two be different? Could the 59.82Hz be the output of the OSSC and not the input and thats why they differ?
Well yes but that isn’t a problem. My DUO and DUO-R start at 60.28Hz and stay there (there’s no re-sync to another frequency).
The white I have on the other hand, begins at 68.28 and later on it loses sync for a second and re syncs at 60.05Hz. And some times later on it does it again but resyncs on 60.05 again.
Well I redid the mod on this white yesterday…. placed the amp (4 channel) on another spot and not on the oscillator that was initially, and also taped the R G B and Sync signals from the cpu chip and not the expansion port that was initially.
Played for an hour yesterday and remained at the initial 60.28Hz. We will see….
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