Posted inElectronics & Retro Gaming

Commodore 64 RF to Composite Video Mod

When I got my C64, it did not come with a power supply or video cable. A friend loaned me a power supply, but I had to wait weeks for my video cable to arrive from eBay. In the meantime, I was struggling for a way to get video, until I found this page shows the pinouts for the C64 AV connector. Helpfully, pin 4 on this connector is a composite out signal! So I made this quick video mod to get composite video through the RCA RF jack on the back of the C64 while I waited for my AV cable to arrive.

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Posted inAstronomy Astrophotography

M51 The Whirlpool Galaxy

https://flic.kr/p/2qVgJvU


I pushed my FSQ to f/8 with the Extender-Q 1.6x for this one. I was my first attempt with this setup because I was having a lot of tracking issues with my G11. I was getting an average RMS of 1.5″ and peaks of 4″. Not great at f/8! After a full clean and relube, lots of fiddling, and adjustment of the worms (boy, was that part frustrating), I now have it down to an RMS of (mostly) just under 0.5″ and peaks of 1.5″….

My first try at processing this came out with a lot of noise, bad color balance, and bad background gradients because I seem to have messed up my flats. This version was a re-process with no flats, which still produced some strong gradients, but they were much easier to filter out in PixInsight. I’m pretty happy with the color and detail now, and I am really impressed with the Extender-Q and the performance of the FSQ at f/8. Next (if I ever see good weather again) I’m going to try for M81/M82 with this setup.

I have a post that shows the internals and disassembly of this camera and filter wheel here:
https://www.astroturtle.com/2025/12/sbig-st-8300m/

  • Taken from a Bortle 5 suburban backyard.
  • Takahashi FSQ-106EDX4 at f/8 with the Extender-Q 1.6x.
  • SBIG ST-8300M at 1×1 binning, with the FW5-8300 5 position filter wheel.
  • IDAS LPS-D3 36mm unmounted filter for luminance and Astronomik Deep-Sky 36mm unmounted RGB filters.
  • Losmady G11 Gemini 2, guided with a piggybacked AstroTech 65EDQ and an Orion StarShoot autoguider.
  • Software included PHD2 for guiding, Sequence Generator Pro for acquisition, and PixInsight for image processing.
  • 90 x 120s luminance integrations (IDAS LPS-D3)
  • 90 x 120s each red, green, and blue filters

Total exposure time of 12 hours.

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Posted inElectronics & Retro Gaming

Commodore 64 Black Screen Repair

Commodore 64 motherboard Assy No. 250407
Commodore 64 motherboard model 250407

While I wait for parts for my recalcitrant ZX Spectrum, I turned my attention to a sick Commodore 64 bread bin model 250407 that I picked up from a friend. As with the ZX, at first this C64 didn’t boot at all. (no video, no power led… nothing) And once that was fixed, it only booted to a black screen.

At least this C64 does not look like it had any work done internally. The soldering on the bottom looks factory, and there’s no messy flux residues. Both the SID and VIC chips are socketed, but I think this generation all came this way.

I have a loaned power supply for this board, which is a dodgy original outputting 10.6VAC on the 9VAC line, and +5.2V on the 5V DC line. Not great, not terrible, and it’s definitely going to be replaced with a modern version down the line. For now, and for testing, it will do…

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Posted inAstronomy Astrophotography

M42 The Orion Nebula

https://flic.kr/p/2qNqRRw

I’m pretty amazed how nice this one came out. I started the image really late in the season so by 9pm I would already be doing a meridian flip. Plus weather and mount issues (tracking on the west side), made this one a challenge.

I have a post that shows the internals and disassembly of this camera and filter wheel here:
https://www.astroturtle.com/2025/12/sbig-st-8300m/

  • Taken from a Bortle 5 suburban back yard.
  • Takahashi FSQ-106EDX4 at f/3.6 with the CR Reducer 0.73x.
  • SBIG ST-8300M at 1×1 binning, with the FW5-8300 5 position filter wheel. (The halos around brighter stars are due to the camera)
  • IDAS LPS-D3 36mm unmounted filter for luminance and Astronomik Deep-Sky 36mm unmounted RGB filters.
  • Losmady G11 Gemini 2, guided with a piggybacked AstroTech 65EDQ and an Orion StarShoot autoguider.
  • Software included PHD2 for guiding, Sequence Generator Pro for acquisition, and PixInsight for image processing.
  • 70 x 300s luminance integrations (IDAS LPS-D3)
  • 70 x 300s each red, green and blue filters

Total exposure time of just over 23 hours

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