noelleamelie
Deep Blooper
Posts: 18
Homebrew skills: Musician (Tracker, MML, MIDI)
Fave PCE Shooter: Soldier Blade
Fave PCE Platformer: Rondo of Blood
Fave PCE Game Overall: Rondo of Blood
Fave PCE RPG: Ys IV: Dawn of Ys
Currently Playing: AliceSoft RPGs
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Post by noelleamelie on Oct 25, 2020 17:26:12 GMT
Hi all! First, thanks to the admins for approving my acc - I had one on PCEFX years back before it shut down, and was surprised when I tried to get on this month and found it was gone!! So I'm glad to be here ^^ Second, the title of the post - I recently got a PC Engine Duo-R modded by doujindance on eBay this month. I know about his negative reputation up until about 2018, but I heard a lot of positive things since then and his mod work being better, so I bit the bullet as I couldn't find anywhere else to search for a unit to buy first. First impressions are the unit looks absolutely amazing and plays great on my JVC PVM, with exception to one issue: the sync. For whatever reason, there's a VERY small amount of jitter every so often - there's no particular intervals, sometimes I get it two minutes into playing, sometimes two hours, sometimes an hour, sometimes just never, and it usually goes away in under 5 minutes, sometimes in a minute. It looks like the image is shifting up and down by one or three scanlines - it's not really.... major, I'd say? But it's not subtle either. It's also only my PVM that seems to care, my iScan DVDO HD didn't seem care at all about the slight fluctuation - I didn't have it hooked up to a monitor but usually the front light goes out if it's struggling with a signal. I did try to diagnose it with it hooked up to a display last night, but after a half hour of literally no issues I just gave up and went to bed >_< I don't *think* it's the kind of sync my cable is using, I've used both the Sync on Composite and CSync 75 ohm modes of it and I had the same issue - didn't try TTL since I don't know if it's safe to use with my monitor. I think this issue is only with RGB, too, I left it on composite for a while and didn't see any issues (but I could have just missed it ><). Regardless I'm sure the console is fine, I've played through all of Rondo of Blood, most of Ys I, some HuCard games, and some other titles and had no problems besides the slight jitter. The audio is super clean too and sounds fantastic, and the video signal is probably one of the sharpest of any console I have. It's just that weird sync issue I cannot figure out for the life of me.... I did read someone fixed it a few years back by enabling the low pass filter on their system, but I haven't gotten my torx security bits yet so I can't try it myself. I would also try a different RGB cable but I don't really have the money for one, I sold a bunch of games to afford the PC Engine and I have to save the rest of my cash for moving out. Dropping $35 on a nice SCART RGB cable is out of the question for quite a while. I've uploaded a video here: you can see a very tiny jitter to the image. It looks more clearly like it's shifting up in real life, but the effect is still kinda there on camera. www.youtube.com/watch?v=9Har7my-Axk&feature=youtu.beThanks!
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Post by dshadoff on Oct 25, 2020 18:18:54 GMT
The video is marked private when I try to view it.
Does the jitter happen at particular places on particular games ? I've been discussing something like this in another discussion area, where setting a "composite output artifacting on/off" register actually changes the number of lines per frame between 262 and 263. This change would probably be more obvious on RGB than composite, if it is indeed the root cause.
But that register isn't normally turned on and off in the same game (with the exception of one or two)... so this is why I asked whether it happens at specific spots in specific games.
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noelleamelie
Deep Blooper
Posts: 18
Homebrew skills: Musician (Tracker, MML, MIDI)
Fave PCE Shooter: Soldier Blade
Fave PCE Platformer: Rondo of Blood
Fave PCE Game Overall: Rondo of Blood
Fave PCE RPG: Ys IV: Dawn of Ys
Currently Playing: AliceSoft RPGs
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Post by noelleamelie on Oct 25, 2020 18:33:33 GMT
Sorry about that, I set it to unlisted - YT marked my video as a 'draft' for some reason and kept it on private, no idea why.
It happens at random, the same spots in a game will get it sometimes and not at all.
EDIT: I got the torx kit coming tomorrow, so I'll see if I can get some time in that evening with the low pass on, and hopefully that solves it for good!
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noelleamelie
Deep Blooper
Posts: 18
Homebrew skills: Musician (Tracker, MML, MIDI)
Fave PCE Shooter: Soldier Blade
Fave PCE Platformer: Rondo of Blood
Fave PCE Game Overall: Rondo of Blood
Fave PCE RPG: Ys IV: Dawn of Ys
Currently Playing: AliceSoft RPGs
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Post by noelleamelie on Oct 26, 2020 20:14:40 GMT
Got it opened up, seemed like the LPF was already set on which is fine! I tried it with it set off and no dice, still has the tiny jitter on my PVM at random. I think it might just be the cable not being heavily shielded, so I'll see what I can do about buying a different one sometime. I'll post some pics of the board if I can soon but it looked pretty clean and well done inside.
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Post by dshadoff on Oct 26, 2020 23:18:42 GMT
What type of monitor re you sending the output to ? I also heard from SamIAm the other day that there is something a bit out-of-spec about the sync signal which is produced; most monitors aren't sensitive to it, but his was.
Maybe Sam can mention the specifics...
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samiam
Punkic Cyborg
Posts: 100
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Post by samiam on Oct 27, 2020 3:13:28 GMT
I'm afraid that I don't think that the imperfections that are naturally present in the PCE's sync signal are likely to be the cause of the vertical jitter you're seeing. For one thing, it's the horizontal domain that is potentially affected. For another, the imperfections shouldn't cause jitter, but rather a constant warping.
Without knowing the exact circuitry used in your mod, I can't say much else with confidence. What is the model number of your monitor? It's extremely likely to that the monitor is compatible with TTL sync, and if you can find a manual or spec sheet confirming that it is, I would try enabling it in order to rule out one possible culprit.
Even if you can't get confirmation, I would go ahead and enable it if I were you. It's almost inconceivable that a pro monitor wouldn't be able to handle TTL level sync on an EXT sync input. By the way, you have a terminator on that input, right?
If your mod uses a THS7374 amp, you really don't want to enable the low-pass filter on it unless you absolutely have to. It will cause slight distortion to your RGB signals.
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noelleamelie
Deep Blooper
Posts: 18
Homebrew skills: Musician (Tracker, MML, MIDI)
Fave PCE Shooter: Soldier Blade
Fave PCE Platformer: Rondo of Blood
Fave PCE Game Overall: Rondo of Blood
Fave PCE RPG: Ys IV: Dawn of Ys
Currently Playing: AliceSoft RPGs
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Post by noelleamelie on Oct 27, 2020 4:32:11 GMT
I have a JVC BM-H1300SU, which I've owned for about a year now and it handles pretty much every system just fine. With regards to termination, I think you can set terminators on with it but I always left them off since the image gets ridiculously dark with them - I have to really crank the contrast and brightness up to compensate. I did try that just for the heck of it and, didn't make a difference with the light jitter. I wasn't able to find any information on TTL sync, but I'm gonna guess it's fine since... well, it is a pro monitor like you said. I'll give it a shot and report back! I'm not really sure what amp it has, I can't read it off of my amp and it's hard to see on other photos of it. I do have some board pictures though imgur.com/a/Cdc6U7MNevertheless I've tuned the LPF off, thanks for the heads up! Edit: so I am not a very bright woman and have forgotten I've been using a cable at TTL level sync with my SFC for 10 months now with no issue, so I just set the PCE cable to that too. Hoping for the best!!
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samiam
Punkic Cyborg
Posts: 100
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Post by samiam on Oct 27, 2020 4:50:52 GMT
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samiam
Punkic Cyborg
Posts: 100
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Post by samiam on Oct 27, 2020 5:16:43 GMT
On the subject of terminators and contrast: It's entirely natural that terminating the video signals cuts the contrast (and brightness) down. In most video circuits, including the THS7374 design that your mod is based on, there is a 75 ohm resistor in series with the output of each RGB signal. When you terminate the signal line with 75 ohms, you create a voltage divider that cuts the signal amplitude in half. This will happen with virtually every source and every monitor that you do it with, and is the way it's supposed to be. Let me give you some hard numbers. When displaying a white screen, all three RGB signals are at 100% amplitude. At this level, the THS7374 is outputting each signal at 1.4 volts peak-to-peak in amplitude, but the 75 ohm resistor pairs cut this in half, to about 0.7 volts. This is what the monitor is expecting; it's the industry standard for video signal levels. What you do when you leave off the terminators is essentially to over-drive the signal going into the monitor. If it happens that you simply cannot get enough contrast out of your monitor with termination enabled, then it more-or-less means that the picture tube itself is run down and on its last legs. In that case, I'd say go ahead and leave them off. However, if you can enable termination and get the contrast satisfactorily high, then that is definitely what you should do. Your monitor inputs will be happier to deal with a standard-level signal, for one thing. For another, the reason why termination is used in the first place is to prevent signal reflections, which I can almost guarantee you'll see in certain scenes if continue to leave termination off.
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noelleamelie
Deep Blooper
Posts: 18
Homebrew skills: Musician (Tracker, MML, MIDI)
Fave PCE Shooter: Soldier Blade
Fave PCE Platformer: Rondo of Blood
Fave PCE Game Overall: Rondo of Blood
Fave PCE RPG: Ys IV: Dawn of Ys
Currently Playing: AliceSoft RPGs
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Post by noelleamelie on Oct 27, 2020 5:32:43 GMT
Yeah, the listing you linked is pretty much identical to what I have. I had to bridge certain points to put it in TTL mode.
I think I understand now - and I think my issue with the brightness is due to me using the outputs on it. Any time I have the RGB output connected (which duplicates the signal coming into the PVM exactly) it dims the image on my PVM, which is even worse with the terminators enabled. Enabling the terminators and not using the outputs results in a perfectly usable image with a lot of control over brightness, which is... well, frustrating, because I use that output to go to my iScan so my capture card can handle the signal. But I'm guessing my best option is to keep termination on at all times, and just increase the brightness/contrast and deal with a slightly dark picture with the RGB outs connected?
I would just grab something that can duplicate the signal but, I'm tight on cash right now so I'm stuck with this. :x
I'm sorry if I come off as really ignorant about any of this stuff by the way, I'm not really familiar with the details of things and what's best practice. I've kinda just gone for what was available and I heard was good quality - in the case of my PVM it was just a thrift shop find, same as my capture card and iScan. On a happier note it does seem like I'm having better luck with TTL than I am the other two sync types - I'll put some time in the games tomorrow when I'm not preoccupied but so far so good
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samiam
Punkic Cyborg
Posts: 100
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Post by samiam on Oct 27, 2020 7:25:55 GMT
Ah, I getcha. In that case, I think you can assume that the inputs of your iScan have 75 ohm termination of their own, in which case you definitely don't want to switch on termination at your monitor. I can't find schematics for this particular monitor, but if you look at the schematics for similar monitors, you'll see that the outputs don't exactly duplicate the signal from the inputs; they connect the lines directly. It's like one pipe going in and out of the system that the system itself just kind of eavesdrops on. Here is a shot of the schematic for one of my monitors. C11 and L11 are just there to filter noise. Signal comes in CM901 and goes out CM902, although you can just reverse those. i.imgur.com/oUeRYcO.jpg
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noelleamelie
Deep Blooper
Posts: 18
Homebrew skills: Musician (Tracker, MML, MIDI)
Fave PCE Shooter: Soldier Blade
Fave PCE Platformer: Rondo of Blood
Fave PCE Game Overall: Rondo of Blood
Fave PCE RPG: Ys IV: Dawn of Ys
Currently Playing: AliceSoft RPGs
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Post by noelleamelie on Oct 27, 2020 16:07:47 GMT
Got it, thanks! I’ll leave it off whenever I’m using my iScan then. And that’s interesting, thanks for the explanation of how that usually works By the way I played a bit this morning and no luck with termination on and TTL sync, still getting the random slight jitters. Happened after about 10 minutes and persisted for a minute then went away. I can’t think of it being anything but the cables but I don’t have access to any others, besides my HD Retrovision MD cables but those won’t work without an adapter. >_> This is the cable I currently have by the way: www.ebay.com/itm/Scart-RGB-Csync-user-settable-shielded-cable-for-PC-Engine-RGB-modded-console/193160634322?hash=item2cf9455fd2:g:pYEAAOSwxUJdpssgI did read (and this was back in Feb. 2019 so maybe it's changed) someone said his Saturn cable was good but not the best, and had some image noise in it on a PVM. So it is very possible it's just the cable it self not playing nice with my PVM, I guess?
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woodcan
Deep Blooper
Posts: 9
Fave PCE Shooter: Star Parodier
Fave PCE Platformer: Bonk's Adventure
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Post by woodcan on Feb 26, 2021 18:59:17 GMT
Did you happen to ever find resolution to your problem? I'm really interested in hearing. That said, I recently saw someone on twitter talking about a similar PVM issue with a PC Engine + SSD3 and I believe I recall RetroRGB even talking about how the PC Engine sync is somewhat non-standard and causes issues with some PVMs. You can find the part in the video here: youtu.be/KdSY0UlV69k?t=1583
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keithcourage
Punkic Cyborg
https://www.facebook.com/turbografxfan/
Posts: 231
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Post by keithcourage on Feb 27, 2021 12:09:25 GMT
Man, that's way too much for me to read through.
Are you by chance using a Scart switch of some sort? I've heard of some people having sync issues something when using certain scart switches. See what happens without one if you have not tried that yet.
Also, if this was already discussed somewhere in this thread then just ignore this suggestion.
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