Compaq SLT/286 Tear Down and RTC Real Time Clock Battery Fix

A good while back, I picked up a somewhat crusty Compaq SLT/286 “portable” with an azerty keyboard for $20. The owner sold it saying that the laptop wouldn’t fire up, the power supply just blinked a green LED, and that was it. I was just happy to add a 286 to my collection, and for the of fun trying to bring it back to life!

Well, today I found a folder on my phone with all the pictures I took, a) so that I could put the damn thing back together, and b) for that big long article I was going to write about the fix process. (haha)

Instead, here’s a 65 image pictorial, with some random comments, an RTC battery repair, and some useful SLT related links.

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.

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.