HunterZero

Q1 and Q2 are the two 2N3906 PNP transistors; again, cheap part to replace.

That looks suspicious. The chip U11 is a HD7407P logic gate, you should be getting 5V at pin 14. I assume it is, since the output on pin 4 is pulsing. Logically, it's just a buffer, I would guess it's to ensure that the voltage of theta 2 is at the correct 5V value, the voltage of the clock signal may drop off a bit of passed through multiple chips. The input on pin 1 should match the output on pin 2. Pin 1 input comes from pin 11 on the STIC, as you say. No harm to try replacing the logic gate chip U11, it's an inexpensive easy to get part. - J

Hmm the clock input pins theta-1 38 and theta-2 37 on the CPU should pulse corresponding to outputs at pins 10 and 11 on the STIC respectively. Theta-2 also clocks the SRAM theta-2 on pin 8. So the SRAM could indeed be faulty, and affecting the theta-2 clock. You should be seeing the 1.79545 clock on pin 8 of the SRAM. It's feasible that the CPU/STIC system has crashed/halted, due to a damaged SRAM, causing the weird locked state. The SRAM uses 12V for Vdd on line 10, make sure that is correct before swapping in the new SRAM. I have a hunch that Intellivision SRAM chips are prone to damage from power surges... Good luck with the new SRAM! - J

Do you have a pic of the mod? Does the console still have an RF output that you can test with? There may be an issue with a decoupling cap that was intended to be used as a sound filter cap, or some other short in the mod. - J

By process of elimination, the RA-3-9600 SRAM does seem the most likely candidate. Does the screen flash when you press reset? I am guessing it does. An oscilloscope or logic probe or logic analyzer will confirm if the CPU is pulsing/running, and the rest of the logic is getting a clock, or if data buses are pulsing. Probing the SRAM will quickly show if it's working or not. Apart from the SRAM RA-3-9600, other things I can suggest: 1. Check the 12V jumper line, and the small caps/diodes around the STIC and SRAM. Eg, STIC locality: C9/CR7 (pin 20), C26 (NP) (pin 14), C11 (pin 40). SRAM locality: C15/CR6, C19 2. Check the 2 2N3906 transistors that drive the CPU. 3. Make sure you're getting the right power at the CPU, RAM, STIC. SRAM: Pin 9 +5V, pin 11 -3V, pin 10 +12V STIC: Pin 20 +5V, pin 40 -3V, pin 14 is reset line so will respond to reset key (I think resetting pulls this low), CLK in is 15 - J

Did you help him out? You're a fine gentleman if you did. Yes the conductive material on that mylar insert looks to have been worn through. I'd be interested to see if conductive pen could fix it. - J

Be VERY careful if you open the controller to attempt to clean the mylar. The printed traces are very fragile, and rubbing too hard with isopropyl alcohol can take sections of the traces off the mylar. More than likely, the left-right area of the traces are worn on the mylar inset, and replacing it will be the best option. The hand controllers are very easy to disassemble, just 4 screws on the back of each, but when you take the front off be careful to note which way everything goes back together, including how the mylar is folded. I tried conductive pen to attempt to repair traces on an Atari Lynx mylar controller insert, but had no luck. Anyone actually tried this on an Intellivision mylar insert with positive result? - J

So did you sort everything out and get the mod working? Please post a pic of your main board if you can.

Reference diagram for IC locations. Note this is for a model 2609, but all the main chips are in the same location.

For reference, here is the motherboard that came out of the model 3668 Intellivision that I modded, with close up of the PAL video D to A section, and the XTAL2 that was replaced. Note that this revision does not have a daughterboard, instead it uses a LM1886N video matrix digital to analogue converter, and LM1889N video modulator.

So you removed the AY-3-8914 sound chip, and put an NTSC AY-3-8900-1 STIC where the sound chip was? In some Intellivisions the AY-3-8914 sound chip is soldered in, in others it's socketed. When reversing the changes, did you socket the sound chip? The symptoms you are reporting definitely indicate a bad sound chip unfortunately, but double check any soldering work that you did. You need to be very conservative with heat and be careful of static discharge when working with ICs. This mod ONLY requires soldering to replace the 4.00MHz crystal. What model Intellivision? Do you have a pic of your logic board?

Yes, the oscilloscope will show you if the volts are held at 5V or 0V, or pulsing between. A digital 'scope with a memory can 'pause' the waveforms so you can read the data on the lines. - J

A logic probe connects to 5V and ground reference points, and you can then probe chip data legs/lines in 5V logic circuits for activity. The pen will then tell you if that line is held high, low or pulsing. An oscilloscope can do the same thing, but can display the pulses on the data line.

You should be using 60/40 tin-lead solder (it's easiest to work with), and a soldering iron suitable for electronics work. Ideally a temperature controlled one, so you can boost the heat when needed. If you have a temp controlled station, I find around 300-310 degrees C works for most general work, boosting the temp up a bit for ground planes. When desoldering: 1. Tin the tip of your iron (melt some solder on it and wipe on the wet sponge pad or use a wire wool cleaner), the tip should be bright silver 2. Optionally add flux to the joint (you can buy flux pens cheaply at the electronics store, it will last you ages) 3. Heat the joint with your iron and add new solder to the joint to help the old solder melt and flow 4. Use a desoldering pump or braid to wick away the old solder 5. Clean the pad using isopropyl alcohol and cotton tip For a good solder joint... 1. Optionally apply some liquid flux to the pad being soldered 2. Heat the joint with the tinned soldering iron for a few seconds FIRST, then apply solder to the joint (NOT the iron!). The solder may not form a nice cone initially, keep the heat on it and it should flow into the correct shape and stick when it reaches the right temperature. The solder should flow easily into the joint when it's hot enough, almost instantly in most cases. If the solder doesn't appear to stick after several seconds of direct heat, either your iron isn't hot enough (check if you are soldering a ground plane connection), or the surface being soldered is not clean enough. 3. Clean away any leftover flux with isopropyl alcohol The pads on the regulators are not very large, so be careful not to feed too much solder in. If you do, you can always wick or suck some solder away and retry. Be careful not to lift the pads. If the pads lift it's not the end of the world, you can work around it. Note pads that are connected to large trace areas eg ground planes can require more heat. If the solder is not sticking, then either the pads are dirty, or you didn't use enough flux, or you used not enough heat. Ripping the ribbon cable - Ugh, not ideal, these are so fragile and fall apart so easily. Try taping it to keep it together but check continuity is good. Someone on here did have some new old stock ribbon cables, but you can replace the 5 pin connectors with 2.54mm 5 pin connectors and some ribbon wire. Eg:

Indeed it looks like an address line between the STIC and GROM is stuck high (0x00 background card is displaying as 0x80). All the sprites and custom background cards look to be displaying fine. Clean the cartridge slot and look for bent pins. On the motherboard, look for obvious shorts or visually defective components. Check the continuity between the STIC/GRAM chips and the RA-3-9503 GROM chip, reseat and clean the GROM, and if that fails the next step is to use a logic probe to check which data pin is stuck on U7/U8/STIC/GROM (not oscillating). Check that the 74LS86N logic gate at U17 is working correctly too. - J

The different region/TV standard Intellivisions should all have different model numbers. Eg, the Australian PAL 50Hz Intellivision 1's are model 3668, while the USA 60Hz NTSC is 2609. Your SECAM model is model number 5156. Within each model, there may be multiple revisions (or local mods) of the same board. - J

Yes, the STIC chip allows for 8 moving objects (MOB), the same thing as sprites. Each MOB can be 8x8 or 8x16, and can be single height (pixel height is 1/2 a background pixel) or double height (pixel height is the same as a background pixel). Pixels in MOBs are always the same width as the background pixels. I believe that each sprite is a single colour 1-plane bitmap, which means each pixel can be on or off, ie, either a single sprite colour, or see-through so the background will be shown. You can make moving objects with more than one colour by overlapping multiple sprites in the same position with different colours. The Intellivision can redisplay the same sprites on different scan lines going down the screen with some clever programming to give the illusion of even more objects, a trick known as multiplexing, but this tends to cause sprite flicker. As far as I know, the Intellivision would not easily be able to do software sprites, due to the background card method of accessing the display. - J

In addition to all the different brandings/model numbers, there were several revisions of the Intellivision main logic boards too. Some mainboards are green, some are light tan. - J

You might have a bad/dry/cracked solder joint on the 12V regulator. You could try reflowing the solder on the regulators as a quick fix. But I would definitely replace the voltage regulators by the sounds of it. Don't forget to use a small blob of heatsink compound between the backs of the regulators and the heatsink. When you reflow or resolder the regulators, remove any existing solder and use isopropyl alcohol to clean away any ancient flux so you can make sure the pads are as clean as possible when you apply fresh solder. - J

The static in the audio will very likely just be the volume control dial on the Intellivoice. Clean with deoxit and spin the dial up and down a few times. Adjust the volume so the voices are a similar volume to the rest of the game sounds. As for the freezing/black screening, your power supply board may not be providing enough power under load. Have you cleaned the cartridge slot, power connectors and power switch with deoxit? Check the voltage on the 5V and 12V lines under load. If the voltage on the 5V is dipping too low, it could explain the black screens and crashes. Are either or both of the voltage regulators on the power board getting very hot? If you don't have another power board to swap in to try, a shotgun approach would be to replace the electrolytic caps and the 7805 and 7812 voltage regulators on the power supply board. The regulators should be quite cheap, the 2200uF 25V and 10000uF 16V/25V parts will be a little bit pricier for quality parts (Nichicon, etc). But since these parts are now more than 30 years old, replacing them is probably a good idea. The 7805 5V regulator is probably a good place to start. - J

My PAL 3668 unit gives the standard olive green-brown colour for the title screen background, the same as the NTSC version. I did notice that Thunder Castle when played on a USA unit has a black title screen background, while the PAL Intellivision displays the the default olive colour. However when I changed one of my units to a PAL60 unit, the background changed to black, so this appears to be game timing related, not to do with colour circuitry. There look to be three trim pots on the daughter board on top. I'm pretty sure that is the colour board that generates the video signal. Have you tried the adjusters on this top board? Maybe a previous owner twiddled those pots? Can you get a better detailed pic of the front and the back of the daughterboard that's on top? That would be the colour board. Especially useful would be chip numbers. Or better yet if someone has a schematic...

The INTV System III that I have does not have an RF shield. If they were all this way then overheating would have been somewhat less of an issue.

It's technically the same as they Intellivision 1. After the Intellivision II, INTV corp returned to the original design for the INTV System III. But they are a few years newer, and made from newer batches of GI parts, so might be a little more reliable. One of the units I have that worked all the way with no repairs needed is an INTV System III. - J

I believe that the red connector in this case is the 5-pin AC input connector from the transformer. You can try cleaning that connector with deoxit and see if that helps. Make sure that the pins are making proper contact inside the connector. Sometimes the 2-pin STIC wire can be a red connector too, that can come loose and need attention as well. The junk on the capacitors is indeed glue used to hold the larger capacitors in place. If this glue has disintegrated over time, there may be some stress on the solder joints that requires reflowing. The brown gunk on the solder side of the board is leftover flux from manufacturing. Isopropyl alcohol will get rid of it. I had one power board that had particularly bad flux residue, it's good practice to remove it. As a matter of course for two of my main Intellivision units, I replaced the three electrolytic caps and both the 7805 and 7812 voltage regulators on the power supply board. The SHOEI branded electrolytic caps are generally very good quality but they are over 30 years old now. Replacing these parts fixed a black rolling bar picture issue on one of my units. Your picture looks pretty good - The black shadows looks like it could be some RF interference or fine tuning. Have you tried the unit with an old CRT? Try a better shielded coaxial cable? Manually fine tuned the analogue signal a hair? A certain amount of artifacting (shadows and colour bleed to the immediate left of contrast areas) is normal. - James

I always really liked the disc controller. The number keypad was just OK after getting used to it. I kinda like the bubble top feel. The biggest problem is the side buttons, they are just too small and too stiff for rapid repeated presses. They make games like Nova Blast very difficult, almost impossible to play. I get the feeling that the game designers mostly shared these opinions, as most games use only occasional side button or keypad presses rather than rapid presses. Where rapid shooting is needed, they sometimes came up with ways around it, eg the gave you autofire in Astrosmash.