[Q] Could a noob RGB mod a CRT?

Discussion in 'Modding and Hacking - Consoles and Electronics' started by syboxez, Jul 24, 2016.

  1. syboxez

    syboxez Active Member

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    By noob, I mean someone who only has experience modding consoles and not designing electronics. I just got a Panasonic TV that I would like to mod, and have no idea where to start. I know the very basics (disable OSD, splice in RGB and sync to RGB in on the jungle IC), but not much past that. I found the service manual, but I don't see a part number for the jungle IC, or RGB in, only RGB out.

    I also know basics on CRT safety, such as unplugging it and grounding under the anode cap. I'm assuming this is a hot chassis since it has no ground plug.

    My TV is the CT-2006SE with the FP360 chassis.

    If it turns out to be impossible, I would settle for a Y/C S-Video mod, since I see Y/C in on the jungle IC, which are both completely disconnected.

    I would also like to be able to use PAL signals. I see a 50/60Hz switch on IC451 which is grounded right now. If it was tied HIGH somehow, would it be PAL?

    So where do I start?
     

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    Last edited: Jul 24, 2016
  2. xLDKx NewYorker

    xLDKx NewYorker Member

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    Same TV here, wouldn't mind knowing this as well.
     
  3. LeHaM

    LeHaM Site Soldier

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    You know what.. The fact you are willing to learn means you are not a n00b.
     
  4. TriMesh

    TriMesh Site Supporter 2013-2017

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    I just had a quick look at the service manual you posted, and the OSD signal doesn't go through the video processing at all - it's being directly driven into the cathode amplifiers for the CRT. It's still possible, but it would mean building an inverting buffer with adjustable gain and offset, and it's hence probably not the best TV to use for your first attempt at this sort of stuff.

    In fact, this is not a hot chassis design, despite using an ungrounded power cord - if you look at the part of the schematic labelled "A board schematic, right portion" then you can see that the hot part of the circuit is enclosed in a dashed box and isolated from the rest of the circuit using a transformer, a relay and some safety rated caps. This doesn't mean it's not dangerous (all TVs are potentially dangerous!) - but it does mean that you don't have to worry about getting line voltage on the internal ground (and hence the grounds of your external connections).

    As for getting S-Video / Y/C working - that looks entirely possible,especially since some of the other TVs built using that basis chassis support it. If you look on page 8 there is a schematic for the CT-20D11E andCT-20D11DE models - and that has a Y/C input socket. You would need to add the load resistor (75R to ground) and the coupling components (10nF + 100R in series) for both Y and C, and it looks like pin 72 of IC001 needs to be pulled low to enable S-Video (originally done by a contact in the S-Video socket). It's very probable that the spaces for all these parts are already on the PCB. If just grounding pin 72 doesn't seem to do anything, then try replacing R044 (5K6 on pin 69 of IC001) with a 3K3 to make the MCU think that this is one of the models with the S-Video socket.

    As for 50/60Hz, you can try changing that signal, but I would personally not expect it to work - it's very likely that the main control chip has a lot of "60Hz" assumptions wired into it's code.
     
  5. syboxez

    syboxez Active Member

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    Well S-Video seems dead simple, so I'll try that first. Did someone ever build a prebuilt inverting buffer, maybe for arcade monitors?
     

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