Seems to be lately that I'm getting in more and more Intellivision consoles that all arrive with the same similar condition. Basically what most might call a black screen when powering on the console but it is more like a dark grey screen with a few lines along the bottom of the screen of even lighter grey. Pressing the reset button does produce a full black screen that will flicker and come back to the same dark grey screen or sometimes it might do something different like an all fuscia colored screen or yellow for instance.

In all cases, it basically means that some IC chip or component in the chain of the IC logic has failed and the Intellivision isn't able to boot up properly as a result. You can pretty accurately simulate the effect by simply powering on the console with out a cartridge. Same thing will happen when you pull one of the main ICs out of the console.

But how to troubleshoot it and fix it? Well, honestly the service manual for the model II actually has a decent flowchart but even that still doesn't quite cover everything. So I wanted to share my experience on what I now basically do whenever I encounter this condition:

- First is to absolutely verify that all the voltages are present to the main logic board. The service manual will have you test the voltages on the power supply board internally sure, but you can have a bad connection on the ribbon cable to the main board causing voltage to not make it to the main board properly.

- If the voltages check out, then the first actual component to swap out is usually the STIC IC chip (Standard Television Interface Chip). It is one of the several large 40pin ICs that exists in both model 1 and model 2 consoles. Near as I can tell their aren't any differences between the ICs of those two models with the exception that the STIC on the model 1 has a heatsink attached and the model 2s don't. But they can be swapped interchangeably. Although the heatsink on the model 1 STIC will prevent the top case from closing properly on the model 2 console. So you have to be sure the chip is bad as you have to solder it directly to the board for it to all fit.

- If that fails, then I usually will try and swap out the CPU IC next. Although honestly the CPU seems to be a tank in the Intellivision. 

- Next up on the model 1 consoles is to look at replacing the pair of 3906 transistors that stand up off the board in the area just above where the CPU sits. Can't really miss it as they get so hot that the board is usually discolored around their solder points. But again, as they get really hot, they do burn out.

- From here I then grab my frequency counter and verify that I have a proper master clock signal all the way to the cartridge port using Pin 10 to test that signal. Though rare, I have had a crystal that was bad in one and a bad variable capacitor C2 in another that I found by checking the master clock frequency.

- From here it gets much less straight forward and will require having to break out an O'scope to start looking for various signal waveforms as per the service manual to try and help isolate which component might be at fault. 

Now in not so common fixes I've done to correct for this same issue.. or corrupted graphics.

The cartridge port...yeap. The games themselves complete some of the signals in the logic so if a game isn't present or the port has bad connections and isn't making good contact with the game cartridge, you will get the same black screen (dark grey) screen condition

And I've also had the Hi and Lo graphics rams cause a similar issue although in the cases of those chips going bad, the games will usually load up but look like they are missing sprite data in a way that looks like how NES games look with a bad 72-pin connector where the you have lines of missing graphics or corruption on the screen. Depending on the when the Intellivison was made, it might have a pair of 3539 ICs located in the upper left of the main board with the orientation of the cartridge slot on the center right. They are labeled U7 and U8 on both model 1 and model 2 consoles. At some point a main board design was made and they might have a pair of 2114 ICs there instead. All of the model 2 units have 2114s for the Hi and Lo video RAM and it is located in the lower left portion of the main board on the model 2. 

So... there you go. A few things to check out in the case of a black screen non-working Intellivision console. I will say that while more complex in components and IC chips, the model 1 units seem to be a bit more robust in regards to operational use vs the model 2. However, the model 2 cleaned up the power delivery quite a bit and tend to usually have a better RF output while being a little simpler on the inside component wise.

View the full article