What's currently the best RGB mod for the PC Engine?

Discussion in 'Modding and Hacking - Consoles and Electronics' started by FireAza, Apr 17, 2013.

  1. FireAza

    FireAza Shake! Shake!

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    Okay guys, I'm currently buying the parts for this mod, but I'm getting stuck on the mini-DIN connector. Searching "9 pin mini din" on eBay isn't getting me any hits. However, I am getting hits for "9 pin DIN", with ITEMS LIKE THIS. This one certainly looks like a mini-DIN connector (the pins are arranged like one anyway), but the fact it doesn't specify it's a mini-DIN worries me a bit. Any clues fellas?

    Also, are 22uF non-polorized capactors uncommon or something? I'm finding 0.22uF, but not any 22uF.
     
    Last edited: Apr 25, 2013
  2. Bad_Ad84

    Bad_Ad84 The Tick

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    Last edited: Apr 25, 2013
  3. FireAza

    FireAza Shake! Shake!

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    Thanks, I'll buy that one then!

    Sure, POLARIZED 22uF caps are common, but I need a non-polarized one for the THS7314 don't I?

    For the SOIC-8 adapter, THIS IS WHAT I NEED right?
     
    Last edited: Apr 25, 2013
  4. Bad_Ad84

    Bad_Ad84 The Tick

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    soic adapter - yes.
    the cap - 22uf seems really high value.... I have only ever used a 100nf (0.1uf) for decoupling. Will have a look at the datasheet later.
     
  5. FireAza

    FireAza Shake! Shake!

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    ApolloBoy said that's what he used:

    I've been able to find some Tantalum capacitors in 22uF, but these are polarized aren't they?

    For the THS7314, THIS is what I need right? It says "DR" on the end, so I'm not sure if that means anything.
     
    Last edited: Apr 25, 2013
  6. Bad_Ad84

    Bad_Ad84 The Tick

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    Amp yes, thats fine.

    I am not sure if Apolloboy has typoed it and its supposed to be 0.22uf (220nf) - as I said, 22uf seems high
     
  7. FireAza

    FireAza Shake! Shake!

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    His diagram shows a 22u non-polarized cap, so I don't think it's a typo...
     
  8. Bad_Ad84

    Bad_Ad84 The Tick

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    The diagram is still wrong, as I just checked the datasheet and its a polarised 22uf cap. It also says you should keep the 0.1uf (polarised too in the datasheet - but it really shouldnt make any difference either way). So I would put both as it says to do in the datasheet.

    [​IMG]
     
    Last edited: Apr 25, 2013
  9. FireAza

    FireAza Shake! Shake!

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    His diagram is wrong? That's a bit of a worry, is anything else wrong in it? :eek:

    Okay, so I need a polarized 22uF capacitor, but for the 0.1uF, can I use a non-polarized ceramic capacitor instead? I've already got one of those on order, so I'd like to use it if possible.
     
  10. Bad_Ad84

    Bad_Ad84 The Tick

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    yeah, it shouldnt make any difference.
     
  11. FireAza

    FireAza Shake! Shake!

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    Cool, thanks!

    Uh, in reference to my other question, is there anything else wrong with the diagram Apolloboy posted?
     
  12. Bad_Ad84

    Bad_Ad84 The Tick

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    No, all seems to be within acceptable values according to the datasheet.

    They do recommend you put a 0.1uf cap with the 220uf on the output - but its not a requirement, just recommended.
     
  13. FireAza

    FireAza Shake! Shake!

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    Well, I've already got some ordered, so why not?

    Okay, here's the new design with the two capacitors on the THS7314, does it all look good?
    [​IMG]
     
    Last edited: Apr 25, 2013
  14. Bad_Ad84

    Bad_Ad84 The Tick

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    the 0.1uf on the output would be on the 220uf, but in parallel. But like I said, its not a requirement apparently.

    But yes, caps look fine.
     
  15. FireAza

    FireAza Shake! Shake!

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    Ah, so you mean having the 0.1uF wired one after the other instead of soldering them both to the same solder points? I guess installation will be tricky since I'm trying to solder three wires to the same solder point. Hmm, what if I soldered the 0.1uF to the legs of the 22uF and soldered the 22uF directly to the appropriate legs of the THS7314? Would that work?
     
  16. Bad_Ad84

    Bad_Ad84 The Tick

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    Twice you have misread 220uf as 22uf.

    The 22uf and 0.1uf part is fine. I am talking about the ones on the OUTPUT which are 220uf (which I have said twice now).
     
  17. FireAza

    FireAza Shake! Shake!

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    Sorry! I thought we we're been talking about the two capacitors on the THS7314 the whole time! Ah, I see, you suggested adding a 1.0uF capacitor to the 220uF capacitors, so I just attach them to either before or after the 220s? Sure are a lot of 0.1uF capacitors in this amp, lucky I ordered 30 of the damned things! :p
     
  18. Bad_Ad84

    Bad_Ad84 The Tick

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    not before or after, in parallel. Like how you had to do the 22uf and 0.1uf caps.
     
  19. micro

    micro Member

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    I've created a forum account just to post a reply :)


    I'm the one who has drawn the schematic Apolloboy posted:

    [​IMG]
    [​IMG]
    (source: http://nfggames.com/forum2/index.php?topic=4822.0)



    It gives me this picture quality, I like it :)

    [​IMG]
    [​IMG]


    I wanted to make clear that it's perfectly fine to use a non-polarized 22 uF capacitor. The datasheet doesn't say it has to be a polarized cap.


    @fireaza: Your drawing really lokes like a big mess :wink-new: Is it really easier for you to work with such a drawing?

    It seems your audio caps are wrong, the negative side should point to the mini-DIN jack, or does it?

    Also your SOIC -> DIP adapter picture is wrong, it should be rotated by 180°. Pin 1 of the THS7314 is connected to the square-shaped pad and that pad should be in the upper-left corner.



    I'd also like to discuss the value of the three pull-up resistors. IIRC Calpis mentioned in another THS7314-thread that the datasheet recommends using 5.1 MOhm resistors when using a 5 V supply. But wasn't that just an example by TI to get the same 0.68 V DC bias point that has been calculated in the example before? (0.68 V DC bias point -> mid-rail output when using 3.3 power supply)
    I don't know much about the actual waveform of the RGB video signal. But when the amplitude is 0.7 Vpp then isn't it possible that the THS7314's input voltage can dip into the negative range? (even more if the built-in 800 kOhm pull-down resistor got a tolerance of 20%)
    In the gamesx thread viletim recommended to set the DC bias point to about 1 V which sounds more safe to me. What do you guys think?

    (This is a terrible 1st post, I know... ;P)
     
  20. FireAza

    FireAza Shake! Shake!

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    Ah, I getcha, I'll solder a 0.1uF to the legs of the 220uFs then, thanks!

    Hmmm, this thing's starting to become pretty bulky now, what would you suggest to keep it all tidy and not loosely flopping around inside the PC Engine? Maybe solder everything to some of that "breadboard" stuff?
     
    Last edited: Apr 25, 2013

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