Required Stability Fixes (Intellivision)
The Intellivision is pretty unique in that I have found certain steps and things to be required to make the console stable and to simply work.
Firstly, the console is insanely sensitive to digital noise, resistance on pins (dirt, grime or poor fitment) and has a bit of a messy reset circuit.
The below steps I have found almost a must on any Intellivision before even attempting any kind of repair or service.
Most steps would not make any difference on almost any other console, but honestly, they make a huge difference to the Intellivision. You would not believe it until you have seen it for yourself.
For all pre-socketed chips like the STIC, CPU and RAM, and any ICs you want to socket, you MUST replace them.
Do not leave the old sockets in, they are really old and poor quality, and even the slightly bit of dirt or a loose spring in them causes the system not to boot.
I have proven on a fully working system that boots 100% of the time, over and over, you can simply remove the CPU from its original socket, reinstall it and the system no longer boots. You need to them clean the socket, reinstall it several times until you get the perfect resistance-free fitment.
I have never known this on another console to be so sensitive to resistance on pins and fitment/sockets.
Also, when replacing the sockets use spring-loaded sockets, not turned pin sockets.
Use this kind:
īģŋNOT this kind:
I have personally witnessed and fixed Intellivision consoles where simply swapping a single stock socket for a turned pin socket prevents the console booting 9 times out of 10. Replacing that socket for a spring design makes it work 100% of the time.
Keeping in mind the main issue with the console is resistance on pins causing reflections, changes in voltage levels and noise, everywhere we can improve the quality of connections is vital.
Any IC that is in a socket, also give it a very good clean. Lightly polish the pins with sandpaper, clean with contact cleaner or IPA, and make sure the fitment into the socket is tight by bending the pins out a little if needed.
Make sure to clean the entire PCB with IPA to remove any dirt, dust or contaminants that can cause issues with the digital signals.
The reset circuit on the Intellivision is from the STIC.
The !RESET (pin 14) is pulled high to the 5.7V rail internally by the STIC.
This pin is connected through a non-polorized capacitor with the other side of that capacitor pulled to 5V and sunk to ground by the cartridge.
This capacitive coupling means the game (which keeps the !RESET line low almost always, and by default), will keep the capacitor grounded one side, and pulled to 5.7V the other side, resulting in a smooth rise out of reset.
Here is a capture without the capacitor installed (faded blue) and with it installed as normal (light blue).
The capacitor has two jobs:
- Prevent oscillation noise on the !RESET pin as it is coming out of reset on boot
- Allow the game to send a high to low pulse to pull the !RESET pin briefly low, resetting the STIC, effectively resetting the system.
If you have no capacitor installed you will get a noisy out of reset. This will then require manually pressing the RESET button to directly pull the !RESET pin low and allowing it to rise smoothly the second time.
Make sure to clean the cartridge slot with contact cleaner, sandpaper and IPA or any combination you feel of those techniques, with the goal to get the pins as clean as possible.
When using sandpaper use high grit and do not do many passes as this will polish off the gold plating. It is a last resort. Start with cotact cleaner and IPA.
If you see any light blue rust (from water damage) use warm vinegar and soak the connector in it.
Then perform the remaining cleaning steps.
Clean the game cartridge with a pencil eraser first to remove any physical dirt and grease, then contact cleaner and IPA to finish.
The ribbon sending power from the power board to the motherboard through a fairly flimsy flat copper wire ribbon, and a separate red 5.7V wire.
I like to replace these with a clean push-fit 6-pin connector made using Kynar wire and turned pin headers.
Not as vital, but still useful to do is replace the wire harness which is pretty poorly connector with glue, a metal brace, and bare copper on some wires, with two of the Atari 2600 Interboard Ribbons.
This gives the perfect length, a brand-new ribbon, and strong connection.
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