Ben_Larson Posted October 24, 2023 Share Posted October 24, 2023 Hey guys, Picked up my first ever Intellivision I at an antique mall recently ('antique' in air quotes maybe but that's another story... ). Unfortunately when it plugged it in, it would work fine for a few minutes and then glitch out and freeze. Or sometimes the screen would blank out completely. After doing some research, I determined it was probably either a bad RA-3-9600 RAM chip or bad STIC chip. So I bought a donor Intellivision II unit and started swapping parts - turned out it was the RAM chip. I couldn't help but notice when I was inside the Intellivision I, how badly designed it seems to be compared to the Intellivision II. There's a giant RF shield, plus the plastic tray on top of that, but most egregious of all (to me), the motherboard faces down instead of up. This seems like a great recipe for trapping heat considering circuit boards are usually made from insulating materials. Is it true that the Intellivision I fails more frequently than the Intellivision II? (if so I think I can see why) Did I just get unlucky or is it pretty common? Quote Link to comment Share on other sites More sharing options...
The Mr. Video Posted October 24, 2023 Share Posted October 24, 2023 I've had an Intellivision I for a few years now and, aside from it being picky about what TV it's plugged into, never dropped dead on me. I will say that the Intellivision has questionable design choices on both the hardware side and software side. Bad RAM chips seem to be a common problem with many old consoles and computers, but the Intellivision may have it slightly worse due to the board facing away from the controller tray where heat can easily escape. Quote Link to comment Share on other sites More sharing options...
Old Timey Retro Gamer Posted October 24, 2023 Share Posted October 24, 2023 I have always had the worst luck with the version 1 models. I have 3 of them that are dead. I've tried replacing components between them all, but they all do the same thing. Black screen when powered on. My Intellivision II is still kicking though... 1 Quote Link to comment Share on other sites More sharing options...
+Black_Tiger Posted October 24, 2023 Share Posted October 24, 2023 My family's Intellivision died bitd and my parents didn't know how to get it fixed. They ordered an Intv System III to replace it. Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted October 25, 2023 Share Posted October 25, 2023 Well I guess I'm on the opposite side of this. I've not had much luck getting Intellivision II consoles working that had issues, but have had much better luck getting model 1 units working again. A few things to keep in mind on the black screen issues.. yes, it can be a faulty IC, but I've also seen the twin 3906s that get crazy hot, also die causing issues. They are located near the CPU and easy to find. Just look for the scorched PCB under them and you will find them. I've also seen the black screen condition when the actual C2 variable cap is out of reading in spec which effects the clock frequency. Sometimes just turning it a very tiny bit and then back gets it working again. Consoles that work for a bit, then start to glitch and have issues can also be caused by the original voltage regulators on the power supply board not dissipating enough heat to the heat sinks and going into shutdown. So I always remove the old paste and repaste those too. 1 Quote Link to comment Share on other sites More sharing options...
walldog1 Posted October 25, 2023 Share Posted October 25, 2023 INTV 1's design is a bit backwards as Ben noticed and mentioned above. The Logic Board is sitting upside down when installed in the console. This puts the heatsinks on those IC Chips underneath the IC Chips. We all know that heat rises, and this causes the heatsink's actual purpose to be negated. I think that this is a big factor in those 3 IC Chips being prone to failing. I have actually installed a fan inside the INTV I consoles to help with heat removal from inside the Logic Board. No one has reported any issues with this set up to me yet. I know nothing about comparing failure rates between those models, I & II. Except that I have purchased enough broken INTV II's to think that the failure rates are similar. 1 Quote Link to comment Share on other sites More sharing options...
mthompson Posted October 25, 2023 Share Posted October 25, 2023 1 hour ago, walldog1 said: I have actually installed a fan inside the INTV I consoles to help with heat removal from inside the Logic Board. No one has reported any issues with this set up to me yet. Can you post a photo of your fan install, or provide a link if you've already posted that somewhere? Thanks! Quote Link to comment Share on other sites More sharing options...
walldog1 Posted October 25, 2023 Share Posted October 25, 2023 5 minutes ago, mthompson said: Can you post a photo of your fan install, or provide a link if you've already posted that somewhere? Thanks! This 12VDC Fan is a 10cfm. A 5cf fan does also work, but not as well from my perspective. But any cooling is helpful. There are 2 holes in the bottom of the console corner. The RF shielding case around the Logic Board also has holes in that location. I can feel the heat being pushed out the console top where the controllers are stored. Maybe I should not advertise here, but the INTV I pictured is up for sale... 2 1 Quote Link to comment Share on other sites More sharing options...
walldog1 Posted October 25, 2023 Share Posted October 25, 2023 2 hours ago, Black_Tiger said: My family's Intellivision died bitd and my parents didn't know how to get it fixed. That is too bad as there are a few of us who love (or hate) bringing these systems back to life. 1 Quote Link to comment Share on other sites More sharing options...
Ben_Larson Posted October 25, 2023 Author Share Posted October 25, 2023 12 hours ago, walldog1 said: This 12VDC Fan is a 10cfm. A 5cf fan does also work, but not as well from my perspective. But any cooling is helpful. There are 2 holes in the bottom of the console corner. The RF shielding case around the Logic Board also has holes in that location. I can feel the heat being pushed out the console top where the controllers are stored. Maybe I should not advertise here, but the INTV I pictured is up for sale... walldog you and I think alike. I ordered some very small 25mm case fans for this same purpose to experiment with (not a lot of room in the case so I went as small as possible). I installed one in the location you did, and the other one down near the switch. Mine are definitely not 10cfm though. Probably more like 2 each. But I also didn't reinstall the RF shield, so that probably helps... 1 Quote Link to comment Share on other sites More sharing options...
Walter Ives Posted February 18 Share Posted February 18 On 10/24/2023 at 5:41 PM, walldog1 said: The Logic Board is sitting upside down when installed in the console. This puts the heatsinks on those IC Chips underneath the IC Chips. We all know that heat rises, and this causes the heatsink's actual purpose to be negated. The primary actual purpose of the heat sinks in this geometry is to radiate infra-red photons to the heat shield. Those massless little boogers don't give a hoot about Earth's puny gravity, so for them the orientation of the logic board is irrelevant. There is also some conduction from the heat sinks to the air molecules that come into physical contact with them. Gravity isn't much of a factor there either, since those molecules are traveling on the order of 500 meters per second. That leaves convection. Pockets of hot air molecules won't convect away unless you give them someplace to convect to, and the RF shield would make that problematic even if the board were mounted right side up. The best geometry for inducing material internal convection currents is not to turn the unit upside down, but to tilt it on its end. WJI 1 Quote Link to comment Share on other sites More sharing options...
Walter Ives Posted February 18 Share Posted February 18 On 10/24/2023 at 5:41 PM, walldog1 said: I have actually installed a fan inside the INTV I consoles to help with heat removal from inside the Logic Board. Since you have taken the liberty of adding a fan, I take it that you are more concerned with keeping your unit operational rather than a pristine collector's item. You might be better served by ditching the RF shield. It's unlikely your neighbors will complain to the FCC about the snow on their TV sets. WJI 1 Quote Link to comment Share on other sites More sharing options...
Walter Ives Posted February 18 Share Posted February 18 On 10/24/2023 at 6:59 PM, walldog1 said: I can feel the heat being pushed out the console top where the controllers are stored. As a historical note, Mattel didn't have the option of ditching the shield and together they, GI and Sylvania considered the addition of exactly such a fan in early 1979. The FCC standards were more restrictive than they needed to be and were relaxed a few years later. That's why Intellivision II doesn't have an RF shield. Also, Master Components sold in (some) other countries didn't have RF shields. I don't know offhand which ones; it would have depended on the local rules. WJI 2 Quote Link to comment Share on other sites More sharing options...
walldog1 Posted February 19 Share Posted February 19 9 hours ago, Walter Ives said: The FCC standards were more restrictive than they needed to be and were relaxed a few years later. That's why Intellivision II doesn't have an RF shield. Also, Master Components sold in (some) other countries didn't have RF shields. I don't know offhand which ones; it would have depended on the local rules. WJI 9 hours ago, Walter Ives said: Thanks for sharing your in depth knowledge. I should have known that the shields in the INTV I were "government imposed", but yet I did not. Also, when I was studying electrical theory back in the 1970's, photons were certainly never part of the discussion. But I agree with all you stated. 9 hours ago, Walter Ives said: Since you have taken the liberty of adding a fan, I take it that you are more concerned with keeping your unit operational rather than a pristine collector's item. You might be better served by ditching the RF shield. It's unlikely your neighbors will complain to the FCC about the snow on their TV sets. They are still "pristine original condition" as the fan is held in place with Velcro and hot-glue. Oh, I suppose the 1mm hole I drilled in the PS PCB may have killed it's value.😁 1 Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted February 25 Share Posted February 25 Not sure how much change it makes, but on the 2609 models I've serviced, I typically don't reinstall the larger black rf shield. Makes it easier for the next guy to have to work on it and I would hope, help with the heat and convection. I also have been playing around with trying these out on the 2907A replacements I use over the original 3906 transistors. 2 Quote Link to comment Share on other sites More sharing options...
+Psycho Stormtrooper- Rog Posted February 25 Share Posted February 25 On 10/24/2023 at 8:59 PM, walldog1 said: This 12VDC Fan is a 10cfm. A 5cf fan does also work, but not as well from my perspective. But any cooling is helpful. There are 2 holes in the bottom of the console corner. The RF shielding case around the Logic Board also has holes in that location. I can feel the heat being pushed out the console top where the controllers are stored. Maybe I should not advertise here, but the INTV I pictured is up for sale... Can you also show us the hook-up points for the fan wiring Walldog? Ive been wanting to do this for a long time, but didnt want to mess up the wiring. Does it need any diodes, resistors, or capacitors? Quote Link to comment Share on other sites More sharing options...
walldog1 Posted February 26 Share Posted February 26 I just drew an "X" on the bottom of the DC PS PCB pictured below for the positive connection. This does not tap into any voltage going directly to the Logic Board. There is no need for any other electronic devices... although an inline fuse could be suggested. However, there are no other electrical protection features on an INTV anyways. Quote Link to comment Share on other sites More sharing options...
walldog1 Posted February 26 Share Posted February 26 22 hours ago, -^CrossBow^- said: I also have been playing around with trying these out on the 2907A replacements I use over the original 3906 transistors. That's cool. Literally I imagine. I remember talking about those in a post a couple of years back with you. Looks good! Quote Link to comment Share on other sites More sharing options...
+Psycho Stormtrooper- Rog Posted February 26 Share Posted February 26 31 minutes ago, walldog1 said: I just drew an "X" on the bottom of the DC PS PCB pictured below for the positive connection. This does not tap into any voltage going directly to the Logic Board. There is no need for any other electronic devices... although an inline fuse could be suggested. However, there are no other electrical protection features on an INTV anyways. Great. Thanks Quote Link to comment Share on other sites More sharing options...
Walter Ives Posted June 8 Share Posted June 8 On 2/18/2024 at 5:53 PM, walldog1 said: when I was studying electrical theory back in the 1970's, photons were certainly never part of the discussion. Sure they were, but in your thermodynamics courses, not your EE courses. Remember E=σT4 ? Stefan-Boltzmann black body radiation law was already a century old when you were in school. WJI Quote Link to comment Share on other sites More sharing options...
Walter Ives Posted June 8 Share Posted June 8 On 2/24/2024 at 8:14 PM, -^CrossBow^- said: I also have been playing around with trying these out on the 2907A replacements I use over the original 3906 transistors. All right, that's just cool. Are you using some kind of thermal paste to get a good contact between the transistors and your heat sinks? Because of the operating mode of the transistors in this particular circuit, I'd alternatively try installing two of them in parallel, preferably two from the same lot. By parallel I mean just piggy-back two transistors in each position—the power dissipation should divide about equally. If you have an oscilloscope, post before and after pictures of the wave forms. You can get a qualitative feel for whether you've reduced the heat dissipation by using a toothpick to place a drop of water on the plastic housing and timing how long it takes to evaporate. Be careful to not short out the leads. WJI 2 Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted June 8 Share Posted June 8 2 hours ago, Walter Ives said: All right, that's just cool. Are you using some kind of thermal paste to get a good contact between the transistors and your heat sinks? Because of the operating mode of the transistors in this particular circuit, I'd alternatively try installing two of them in parallel, preferably two from the same lot. By parallel I mean just piggy-back two transistors in each position—the power dissipation should divide about equally. If you have an oscilloscope, post before and after pictures of the wave forms. You can get a qualitative feel for whether you've reduced the heat dissipation by using a toothpick to place a drop of water on the plastic housing and timing how long it takes to evaporate. Be careful to not short out the leads. WJI Yes I have a 2 part thermal conductive epoxy that I mix up and use. Basically what I do is mix up a tiny bit of the epoxy as a little goes a long way here. I then coat the inside of the heatsink with it and then slide the transistor to where the bottom of the transistor is even with the bottom edge of the heatsink. Then I use some pliers to carefully crimp the heatsink around the transistor and then let them sit overnight to cure. The heatsinks are just aluminum so they will break and crack if you crimp them too quickly or too tight. I don't have a good way to measure the heat dissipation since the entire transistor is within the heatsink at that point and even what little of the top of the plastic package that you can see in the center usually a full coating of the thermal epoxy covering it. I will tell you that the heatsinks themselves get to blistering temps so the heat is transferring to the material at least. And I only chose to use 2907A because their specs appear to be a little better over the standard 3906 type and the cost difference is minimal. 1 Quote Link to comment Share on other sites More sharing options...
mthompson Posted Monday at 09:25 PM Share Posted Monday at 09:25 PM (edited) I know this is kind of an old post, but it seemed like the logical place for my question to keep all of this information together… I just acquired an Intellivision I in excellent working and cosmetic condition. Inside of it I found a small 5v 0.2A cooling fan mounted to blow air on the power board's two regulators. Although it's only 30mm square, it does seem to keep those components from getting as hot as I've seen them get. I've seen seen discussions about adding fans inside the case, but I don't remember seeing one about cooling down this area. 1. Is this a good idea? If so, I may add one to my other Intellivisions. 2. Is there a better way for it to get 5v instead of connecting to one leg of a regulator and a capacitor, or is this fine as-is? While I'm at it, I may as well ask about the brown shield. Some kind soul already detached it from the PCB, so I won't need to wrestle with it when I add composite video. Would keeping that shield in place help keep the composite picture clean, or am I better off tossing it out and putting a fan facing the underside of the board? Thanks. Edited Monday at 10:16 PM by mthompson Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted Monday at 10:00 PM Share Posted Monday at 10:00 PM Well, I've never installed fans into mine and it seems to have been working well with the small changes I have made. I will state that the +5v regulator gets far hotter than the +12v does so the fan in this case should be on the other side as that resistor and the +5v regulator are the hottest components on that board. The other hot component aside from the ICs and 3906s on the main board is the main transformer. It will get quite warm as well. Quote Link to comment Share on other sites More sharing options...
mthompson Posted Monday at 10:26 PM Share Posted Monday at 10:26 PM 23 minutes ago, -^CrossBow^- said: Well, I've never installed fans into mine and it seems to have been working well with the small changes I have made. I will state that the +5v regulator gets far hotter than the +12v does so the fan in this case should be on the other side as that resistor and the +5v regulator are the hottest components on that board. The other hot component aside from the ICs and 3906s on the main board is the main transformer. It will get quite warm as well. Thanks. I could certainly move it to the other side of the board and turn it around. Can you tell from my photo if that’s an original regulator installed horizontally? I’m wondering if someone replaced it. Quote Link to comment Share on other sites More sharing options...
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