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Thread: Fei Hao MD clone with HDMI out

  1. #1
    Road Rasher Genesis32XCD's Avatar
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    Default Fei Hao Mega Drive clone with HDMI out

    New version with 150 built-in games and stereo audio:
    http://www.sega-16.com/forum/showthr...l=1#post832869

    Original post:
    I bought this Fei Hao MD clone from Taobao (I also see it on Aliexpress):
    https://item.taobao.com/item.htm?spm...cket=19#detail
    https://item.taobao.com/item.htm?spm...cket=19#detail
    https://www.aliexpress.com/item/Newe...0-8fa9c531bd96

    It's a MD clone with HDMI output.




    Comes with two 2.4ghz RF wireless controllers, a wired 3-button controller with a screw-in stick, hdmi cable, composite cable, power adapter.



    Has a US/Japan region switch on the back.

    Compared to a real MD.

    Nothing much on the inside.






    Above: MD clone through HDMI to Framemeister.
    Below: real MD through RGB SCART to Framemeister.







    HDMI out has a more smoothed look to it. It outputs at 720p in 16:9. My tv can't force 16:9 into 4:3 so I hooked it up to the Framemeister to force it into 4:3
    The wireless controllers are actually good. It's RF so you don't need to aim it at the console.
    The cart slot has a strong grip on legit carts. It seems to be easier on bootleg carts.
    I don't have an Everdrive but it seems to work with it. You can see some reviews on Taobao where users uploaded some photos with Everdrive running.
    The sound is fairly accurate; it's not like those old horrible sounding Atgames clones. It's also very loud.
    However, the sound is only in mono. I tested all 3 (HDMI, composite, front headphone socket) and there is no stereo. What were they thinking?!
    Last edited by Genesis32XCD; 12-05-2018 at 12:35 AM.

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    Creator of the Mega Amp Raging in the Streets Ace's Avatar
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    TCT-6803... Guntz had posted about a portable Geneclone with this thing. I would think this clone is using a similar method of generating HDMI as the 8-Bit HD and RetroN HD Famiclones, i.e. a chipset with an LCD interface where the LCD interface is connected to some unknown chip to send the video out over HDMI. What's the chip on the A/V board? I can't read the markings.
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    AKA Mister Xiado Master of Shinobi Raijin Z's Avatar
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    Looks nice. Maybe perform a case swap with an actual Genesis, stencil on a Decepticon insignia, and make a proper MegaDrive Megatron? If the sound and compatibility with oddities like Virtua Racing are up to snuff, this could be a suitable replacement system for people looking to start a collection. Mix it with an Everdrive and High Frequency/MadCatz controllers, and you've got yourself a fully fake fun experience. Wait what?

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    Road Rasher Genesis32XCD's Avatar
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    Quote Originally Posted by Ace View Post
    TCT-6803... Guntz had posted about a portable Geneclone with this thing. I would think this clone is using a similar method of generating HDMI as the 8-Bit HD and RetroN HD Famiclones, i.e. a chipset with an LCD interface where the LCD interface is connected to some unknown chip to send the video out over HDMI. What's the chip on the A/V board? I can't read the markings.
    It's hard to make out, but it's "Ni GT208".



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    So then, that's the same chip used on the GamerzTek 8-Bit HD. I can never seem to find a datasheet on this thing. It might be a rebadged chip for all we know.

    Think you can get a better closeup of the main PCB? Specifically, get the bottom-left corner of the board. I believe the audio mixer is in that area.
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    Quote Originally Posted by Ace View Post
    So then, that's the same chip used on the GamerzTek 8-Bit HD. I can never seem to find a datasheet on this thing. It might be a rebadged chip for all we know.

    Think you can get a better closeup of the main PCB? Specifically, get the bottom-left corner of the board. I believe the audio mixer is in that area.


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    I can see several 10Kohm resistors in that mixer. That's wrong and will distort the sound. Also, having both FM and PSG mixed with 10Kohm resistors will result in major PSG/FM balance problems. This should be set up like the GOAC YM3438 variant of the original Mega Amp design, i.e. 39Kohm on the FM outs and 75Kohm on the PSG out. It also looks as if there is only one of the two headphone amps in the TCT-6803 in use, so if you want to get the audio right, you will likely need to wire up a Mega Amp 2.0 without the mono audio section to safely get the audio to sound right (I say "safely" as the pins on the TCT-6803 are very thin and tightly-spaced). You won't lose headphone output like this either as the TDA1308 has a built-in headphone driver. In fact, you'll get a better end result because the TDA1308 can handle much higher gain than the built-in audio amplifier of the TCT-6803 and a similar chip, the TCT-6801.

    The big question is whether or not the GT208 only has a single audio input. I will take a look at one of my 8-Bit HDs to confirm.

    Also, pay attention to all those missing components on the board. Those are part of a mixing circuit to generate Composite video from the GOAC's native S-Video output, but the parts are all completely missing. From my time with the 8-Bit HD Version 2 specifically, the GT208 appears to have a dedicated Composite output that shuts itself off if an HDMI cable is plugged into the HDMI output. Can you confirm this is the case?
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    Yep, I hooked it up through composite, then plugged in the HDMI cable and the composite video shut off.

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    Hedgehog-in-Training Hedgehog-in-TrainingWCPO Agent avlon's Avatar
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    Great thread. I love reading up on these types of things.

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    Well, I've come to find out a really ugly oversight with the GT208... it only has a single MONO audio input! I don't believe it's possible to get stereo audio over HDMI with this thing unless you can get an external device that can allow you to inject an analog or digital (via SPDIF or optical audio) audio source into the HDMI signal. This likely explains the total lack of stereo audio on the console.

    Also, I believe that 12MHz crystal is used as part of the audio ADC in the chip. Every HDMI clone I've come across uses a small cylindrical crystal (this clocks the entire chip) alongside a bigger 12MHz crystal that I believe is used to set the sample rate of the audio ADC, and that sample rate is 32KHz, a sample rate that not all TVs will accept (such as my Sony KV-30HS420 HD CRT - I get video with the two GamerzTek 8-Bit HD revisions, which use the same chip, but no sound on that particular TV). If you divide 12MHz by 32KHz, you will get an exact multiple of 375. Ideally, you'd want 48KHz sample rate, 44.1KHz worst-case scenario. If this crystal controls the audio ADC's sample rate, replacing the 12MHz crystal by an 18MHz crystal will give exactly 48KHz sample rate. I don't have an 18MHz crystal on-hand, but I could at least desolder the crystal off one of my consoles to test the theory. If the system still puts out video, but has no sound, that crystal likely clocks the ADC.

    EDIT: I think that theory can be tossed out the window. Removing the 12MHz crystal breaks the HDMI output just like removing the smaller cylindrical crystal. Bleh.
    Last edited by Ace; 07-09-2017 at 12:13 AM.
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  11. #11
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    Quote Originally Posted by Ace View Post
    TCT-6803... Guntz had posted about a portable Geneclone with this thing. I would think this clone is using a similar method of generating HDMI as the 8-Bit HD and RetroN HD Famiclones, i.e. a chipset with an LCD interface where the LCD interface is connected to some unknown chip to send the video out over HDMI. What's the chip on the A/V board? I can't read the markings.
    Do you see Ace? , this is what Joe was trying to tell you in the other thread. Basically same new/old NOAC/GOACS but attached to this new IC that outputs pseudo HDMI.

    I can almost swear I have seen the same chip in those cheap AV to HDMI converters.

    @Genesis32XCD , I know is wishful thinking but can this clone run SMS games (Everdrive or converter) ?.
    Last edited by Segaedge; 07-09-2017 at 12:27 AM.

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    Quote Originally Posted by Segaedge View Post
    Do you see Ace? , this is what Joe was trying to tell you in the other thread. Basically same new/old NOAC/GOACS but attached to this new IC that outputs pseudo HDMI.
    I don't need anybody to point this out to me. The VRTech NOAC datasheets told me everything already. However, if the TCT-6803 is using some sort of decoded Composite or S-Video signal to generate HDMI, shame on whoever designed this chip. That's just insanely retarded when the Genesis is natively RGB. It would seem that HDMI chip is taking in some form of RGB, but exactly what, I don't know. It's not taking the raw Composite output on the HDMI Famiclones, I can tell you that for sure.

    I believe the real answer as to what the GT208 takes in as a video signal lies within an HDMI Super NES/NES 2-in-1 that is commonly seen on AliExpress. We all know what kind of NOAC it's using, but being as the clone Super NES chipset used in every Super Famiclone outputs RGB right out of the PPU clone, if the GT208 is taking RGB, we'll see the RGB output of the Super NES side going into the GT208 (whether it's analog or digital, I can't say).

    I was hoping the GT208 would be a half-decent solution to test different clone chipsets for my own clone console designs, but it's looking highly questionable.
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  13. #13
    Outrunner Segaedge's Avatar
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    From what I've seen so far this IC can take more than one input, this includes anywhere from composite video to RGB.

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    Where have you seen this chip before? I'm interested in investigating it a little further, particularly if there's a way to get it to output at 4:3 aspect ratio. Hyperkin has a 4:3/16:9 switch on the RetroN HD, though I'm not sure if the chip used to output HDMI is the GT208 as I've seen the chip with generic markings and with said markings grinded off. It appears one pin on the chip allows for that, but as I said, I don't know if it's the same chip.
    HATES ATGAMES WITH A PASSION


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    (formerly known as 5233) Master of Shinobi Jeckidy's Avatar
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    Is this thing NTSC or PAL? I thought those standards died with digital HD technology, but I may be wrong. I am not sure if this is Taiwanese or Hong Kong made. The latter use PAL because Hong Kong was a british territory for a while and adopted the european standard in the early days of TV.

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