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Adding composite out to TG16


RickR
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I decided to upgrade the AV out on my TG16 on the cheap.  From RF to composite. 

From ebay, I bought a simple cable with the standard yellow/white/red RCA connectors on one end and 4 pin connectors on the other.  Total shipped cost was $7.  The seller also provided a handy set of illustrated instructions. 

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Here is my TG-16 "Before":

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I used a piece of tape to secure the wire.  No matter where you place it, there's going to be a little "bowing" of the plastic cover.

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I fired up the TG-16, and it works beautifully

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And finally, for no good reason, a picture of my Vectrex.  I like to turn it on and make sure it still works whenever I'm upstairs.

1168532585_tg16avmod011.thumb.JPG.f2646056d0aff544bb622c23dbc8d559.JPG

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1 hour ago, Control Issues said:

I'm assuming it looks nicer than RF, how does it sound?  Do you have to turn the TV up more to hear it?  I was thinking I saw something about that somewhere...

The sound is fine.  It is a little quieter.  For RF, I have the TV volume set at level 15.  For composite, 20. 

 

 

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The mod you have done here is the exact same thing Hyperkin did with their AV adapter. this type of adapter is sending uncoupled AC voltage through the composite video input of the device.  That is a small safety issue. If you accidentally bridge composite video to ground, you can short out the transistor in the console.  While that’s not a common scenario, it’s something to take note of and is much less of a risk with a properly built circuit. Also, the DC offset without the buffer will make the receiving device burn more energy at the input.  Most devices should be well designed enough to tolerate that, but that’s not a risk I’m willing to take.  Since the damage (if there is any) would be done over a long period of time and shorten the lifespan of the console. People will respond with “I did this mod two years ago and my console is fine”.  That’s the same as saying “I’ve been smoking for 30 years and still alive”. Sound quality and volume level also take a hit and this mod tends to darken the overall image.  The OEM NEC Turbo Booster does composite properly with the proper components and circuitry. Composite video off of the expansion port is not suitable to interface directly to a TV. The “CVBS” you’re getting off of the expansion pin is a “muxxed”, unattenuated version of composite video which interleaves the luma, chroma, and sub-carrier signals into one, codified signal. This muxxing is done outside of the DAC. But that doesn’t make it TV friendly. Everything in the 2nd schematic represents what’s in every PC-E console (minus the portables) – Pins 26, 35, and 40 are chroma, colorburst, and luma outputs. These are weighted, mixed and staged, all the way to R11 where they’re muxed into a single, codified signal & output 2 the exp. 
The The 1st schematic shows the final staging amplifier that is required to properly drive the muxxed, composite video to a proper amplitude with PROPER impedance control and proper DC rejection. The 2nd schematic is the muxxed, unattenuated version of composite video you acheive with this type of modification. 

m07343_pkg_product_1.jpg

VoultarHyperkinTG16Composite3.png

VoultarHyperkinTG16Composite2.png

Edited by intellicolecovisonary
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Well thank you for that info.  The good news is that it takes about 30 seconds to undo and put the RF back, which is what I'll do.  That circuit looks easy enough to breadboard, but I'm not sure it's worth the effort. 

I didn't initially like the RF on TG-16 because it uses a screw-in adapter instead of just an RF cable, which required me to unscrew the adapter on my TV (it was a PITA for a lazy dude like me).  But I have an RF switchbox now, so it should be no issue.

 

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Could do what I did with my TG-16. Wasn't the 'cheap' option no..but it was the easiest and gives me all the outputs I would need.

I bought a DB grafix booster from Castlemania to stick off the back of my TG-16 to provide me with RGB, s-video, and composite + audio. 

https://castlemaniagames.com/collections/turbo-grafx-16/products/dbgrafx-booster-ttp

See what I'm up to over at the Ivory Tower Collections: http://www.youtube.com/ivorytowercollections

 

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6 hours ago, RickR said:

Well thank you for that info.  The good news is that it takes about 30 seconds to undo and put the RF back, which is what I'll do.  That circuit looks easy enough to breadboard, but I'm not sure it's worth the effort. 

I didn't initially like the RF on TG-16 because it uses a screw-in adapter instead of just an RF cable, which required me to unscrew the adapter on my TV (it was a PITA for a lazy dude like me).  But I have an RF switchbox now, so it should be no issue.

 

I don't use the OEM screw-in adapter, I use an RCA to F Adapter and a Single Digital S/PDIF RCA Cable plugged into the TG-16. The RF signal I get with this set up is sharp and colorful.

Edited by intellicolecovisonary
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51 minutes ago, CrossBow said:

Could do what I did with my TG-16. Wasn't the 'cheap' option no..but it was the easiest and gives me all the outputs I would need.

I bought a DB grafix booster from Castlemania to stick off the back of my TG-16 to provide me with RGB, s-video, and composite + audio. 

https://castlemaniagames.com/collections/turbo-grafx-16/products/dbgrafx-booster-ttp

That looks very similar to what a NEC Turbo Booster is designed to do and $69 is a reasonably price for that technology. The fact that you've tested and approved it gives me confidence. If my TG-16 RF signal didn't look so sweet on the CRT it is hooked up to, I would buy a DB grafix booster in a heartbeat. 

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