After going through a few forum posts, I think I’m going to start with replacing some of the capacitors and the 7805 5V voltage regulator on one of the Atari 2600s (the older one).
Physically the caps look fine but after who knows how long in storage, they probably need replacing anyway. There are three electrolytic capacitors, five mylar film (green chiclets) capacitors, two polystyrene capacitors and one ceramic disk capacitor I’m planning to replace.
I’ve replaced the video cord with an RCA-F adapter, so now the video signal will go through regular RG-6 coax right to the TV’s coax/cable input.
The power connector is a 3.5 mm tip-ring jack, which I’d like to replace as well with a more standard 2.1 mm barrel jack, but finding one with the right footprint is proving a bit difficult. That might be a second slightly more involved project.
Time to go shopping in my parts bins. I think I should have most of what I need already on hand.
On the bench are two Atari 2600 video game systems that were given to me by one of the members of the local Slack community I hang out in. They’d been sitting in storage for the past few decades and didn’t seem to be working so he asked if anyone wanted them before they went out to the dumpster. I, of course, said I’d take them.
They’re of two different vintages based on the serial numbers, and came with a number of controllers and cartridges. For having been in storage, they looked in decent shape, although the older one was obviously sitting out in the open more than the other newer one.
The older Atari 2600 system. SN 82227274
The 2600 isn’t too difficult to disassemble, and there’s already a pretty good Atari 2600 teardown on the iFixit site. This particular unit was made for Atari by Dimerco Electronic Corp in Taiwan and has serial number 82227274 according to the sticker on the back. I was able to brush off a lot of the dirt on this one, but it could still use a good cleaning.
Inside looked relatively clean with some tarnish and corrosion on the RF shield. No obvious issues with any of the components. From the silkscreen, this is a Rev 14 board.
Underneath the RF shield; MOS 6532 RIOT chip (top), MOS 6507 CPU (middle), TIA chip (bottom)
The RCA jack to the right is where the video signal goes out to the TV.
Initial testing of the two systems didn’t show anything on the screen. I ordered some RCA-F connector adapters (no idea these even existed until I started looking for them) to replace the RF modulator, and was able to get some images on the screen with one of the cartridges inserted. There was no response to any of the switches or controllers though, so more troubleshooting is going to be required.
It lives…sort of
I’ll need to do some more research on repairing and refurbishing these. I’ve found some potentially useful threads on the AtariAge Atari 2600 forum, so I’ll dig around there some more.
Starting to tackle some of the projects that have been stacking up on the workbench. First one up is a Heathkit GC-1092A digital clock (serial number 00433). This was part of a collection from KB4NNM (SK) that was donated to the club earlier this year that’s been sitting on the workbench waiting for me to have time to get to. Decode Systems has a very useful page on Heathkit clocks.
Heathkit GC-1092A digital clock
Aside from a bit of dust and a few scratches and scrapes on the case, it’s in pretty decent condition. The clock works well, although the numbers flicker sometimes, especially when handling the clock. Haven’t tested the alarm capabilities yet. Setting the clock and alarm is done with a bank of switches on the bottom of the clock. A helpful sticker shows how to set things with the switches.
Setting switches for the Heathkit GC-1092A clock
Removing 4 easily accessible screws from the bottom lets you take the top of the case off, revealing a fairly densely populated (for through-hole components anyway) circuit board and a big chunky transformer. Sitting in center stage is the brains of the operation, a MOSTEK MK5017AA clock chip (the white ceramic IC package in the center). There’s some corrosion on the heat spreader for the IC, but operation doesn’t seem to be affected.
Heathkit GC-1092A main circuit board and transformer
The underside of the board has two large filtering capacitors, and the setting switches and speaker are attached to the case below the board.
Below the main board of the Heathkit GC-1092A clock
The front panel contains the 3 2-digit 7-segment display units (Beckman SP-352). There are also a couple of 555 timer chips on the board, but I haven’t explored the schematic enough to know what they’re doing. Probably something related to the alarm function.
Heathkit GC-1092A display circuit board
I’ll need to do some more research and studying the schematic to see if I can figure out the display flickering problem. Closing this clock back up and putting it back on the pile for now.
Got out the last couple of evenings to get some photos of Comet NEOWISE before it goes away for the next ~6700 years.
The comet itself was pretty easy to spot. After about 9PM EDT, the sky was dark enough for me to see the brighter stars. Found the Big Dipper and looked down toward the horizon. I wasn’t able to see it with the naked eye where I was (too much light pollution), but it was pretty easy to capture with my camera using a 5s exposure.
Captured these (out of a bunch) with my 18-55 mm lens using a 5s exposure at 1600 ISO. My camera is pretty noisy at high ISO and there are a few artifacts, but the big dipper and the comet are pretty easy to see.
Comet NEOWISE and the Big Dipper 2020-07-18
Comet NEOWISE 2020-07-18
The next evening I went back out with my 18-200 mm lens to get a few more shots. Stayed with a 5s exposure and went with 800 ISO to reduce the noise a bit. These shots turned out a little better.
Comet NEOWISE and the Big Dipper 2020-07-19
Comet NEOWISE 2020-07-19
Zooming in at 200 mm gives a nice image of the comet and its tail.
Have a bunch of images that I took that I need to stack together, which should make for some pretty nice images. That will have to wait until later when I have more time.
Radiograph of my Galaxy S7. 80 kVp, 2.8 mAs, Canon Aero DR detector.
Galaxy S7 x-ray
The large rectangular gray block is the battery. Superimposed on the battery, the NFC and wireless charging coils are easily seen. Volume buttons are on the upper left side, and the power button is on the right side. The rear camera is the square object in the upper middle. The selfie camera is the white donut shaped object just above and to the right of the rear camera. There’s the micro-USB port at the bottom middle, and the headphone jack to the left of the USB port.
