Atari 2600 progress

After replacing the voltage regulators and several capacitors on the Atari 2600s, one of them is back in operation!

Pac-Man on the Atari 2600
Pac-Man on the Atari 2600

Out of the 18 cartridges I have, half of them worked (were playable) when I plugged them in. The others just gave me squiggly lines or just a black screen. Not sure if it’s an issue with the cartridges or the cartridge slot.

Still lots of work to do on the consoles. The other console only got a quick check with a couple cartridges, so I’m not sure if it’s working yet. The switches on both of them are a bit finicky so I’ll probably have to take them out for cleaning/refurb. I don’t think any of them will need to be replaced though. The cartridge slot seemed a bit touchy too, but looking into that will be a bit more work I think.

After that I’ll tackle the controllers. There are a few of them to work on. I’ve got 5 Atari and 5 third party joysticks plus a pair of paddles. The one joystick I tried mostly worked, although it wasn’t very responsive when pushing the stick in the down direction.

Atari 2600 refurb plan

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.

Project: Atari 2600 Repair/Restoration

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 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.

Atari 2600 main board
Atari 2600 main board

Underneath the RF shield are the brains of the system: the MOS 6532 RAM-I/O-Timer (RIOT) chip just below the cartridge connector, the MOS 6507 CPU, and the Atari television interface adapter (TIA) chip at the bottom.

Underneath the RF shield; MOS 6532 RIOT chip (top), MOS 6507 CPU (middle), TIA chip (bottom)
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.

Atari game on the television
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.

Project: Heathkit GC-1092A digital clock

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
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
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
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
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
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.

Beacon teardown

At the AAPM 2018 annual meeting, attendees received a BLE (Bluetooth Low Energy) beacon that was used to track attendance at sessions for continuing education and SAM (Self Assessment Module) credits.

Little blue beacon
Little blue beacon
Little blue beacon
Little blue beacon

The website stamped on the beacon redirects to a company called Gimbal where you can purchase the beacons for $5 each or get a whole case of 1650 for the same unit price.  They also provide web based software for managing the beacons.  The manual for the beacon contains some specs, instructions for using the beacon with the Gimbal software, and links to API docs for creating apps to use with the beacon.

The beacon opens pretty easily using a quarter.  Most of the beacon’s innards are taken up by a CR2032 coin cell that powers a tiny little circuit board underneath a plastic cover.

Beacon innards
Beacon innards

A bit of careful prying to release the cover (also held down by a couple dabs of adhesive) reveals the circuit board.  Three contact pads presumably for testing/programming are easily visible.

Beacon innards
Beacon innards
Beacon innards
Beacon innards
Beacon PCB
Beacon PCB

Not much identifying info on the little IC at the heart of the beacon.
4348695
2500D0A
2AJ
P36V G4

Guessing the first number would be a product identifier with the next line (2500D0A) maybe being a date code.  Google led me to a reasonably informative post about the beacons.

Seems to be a fairly simple device and beacons in general might be something fun and interesting to get into.