Atari 400 Spectre Svideo mod with a twist.

[Skywise]

The 400 mod itself wasn't unusual, just a Spectre. (pulling off audio/video combining components to access raw audio)

I followed @flashjazzcat DIN mod to the rear of the power board which worked great. (Thanks Flash!)

What I did do different was not using dupont connectors but the unused/reused pins of the power board connector.

Pin 1 for composite, pin 8 for audio, and pins 19 and 20 for Chroma/Luma.

It left the 400 looking mostly stock inside for future work, just pull off the power board as per usual.

The video seems fine, no noise.

[+x=usr(1536)]

22 hours ago, Skywise said:

What I did do different was not using dupont connectors but the unused/reused pins of the power board connector.

Pin 1 for composite, pin 8 for audio, and pins 19 and 20 for Chroma/Luma.

That is an excellent idea   Do you happen to have photos?

 

While not a Spectre, I do have a couple of SCCCs arriving soon and would like to see what other options may exist for routing their signals.  FJC's video on the install in an 800 was a great pointer for that, but there are ideas kicking around in my head 

[flashjazzcat]

22 hours ago, Skywise said:

Pin 1 for composite, pin 8 for audio, and pins 19 and 20 for Chroma/Luma.

Excellent lateral thinking. Would like to see pics of this too.

[Skywise]

I just so happen to have taken a few pics.

Installed Spectre and the poor 4050 stuck to the bottom of the main board.

You can see the composite wire sneaking off to a removed inductor which connects to pin 1.

Power board wiring (not too neat just yet, I'll get there) and the DIN on the back of the power board against the heatsink.

BTW, I drilled the DIN holes using a PCBway printed DIN to Svideo adapter board, clamped to the power board and drilled what I needed with a Dremel.

And the wiring of the main board.

Luma is pin 20

Chroma is pin 19

Audio is pin 8

(in case someone decides we should standardize this hack

 

 

[_The Doctor__]

dead bug chip installation is a mainstay of retro engineering, and it's as a badge of honor! don't sweat it.

[flashjazzcat]

14 minutes ago, Skywise said:

I just so happen to have taken a few pics.

Excellent. I love this approach and will happily follow suit going forward.

 

14 minutes ago, Skywise said:

Installed Spectre and the poor 4050 stuck to the bottom of the main board.

Why is CD4050 attached at all? Is there some special requirement on the 400 board for the original chip to be there? Normally UAV and Spectre completely replace CD4050.

[Skywise]

Just now, flashjazzcat said:

Excellent. I love this approach and will happily follow suit going forward.

 

Why is CD4050 attached at all? Is there some special requirement on the 400 board for the original chip to be there? Normally UAV and Spectre completely replace CD4050.

A bit of the 4050 handles the reset of the system, it seems.  If it's not there, every few power cycles it won't start up.

Here's the article I followed: 

 

 

[flashjazzcat]

2 minutes ago, Skywise said:

A bit of the 4050 handles the reset of the system, it seems.  If it's not there, every few power cycles it won't start up.

Here's the article I followed: 

Thanks. I just scuttled off to my schematic collection after posting, wondering if something like this were the case. I've never installed UAV or Spectre into a 400 or 800 (only the SCCC or the architectural 400 A/V mod), so this is good info to have.