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Member Since 14 Jan 2013
OFFLINE Last Active Jan 23 2019 5:32 PM

#4144692 Need help repairing an Intellivision

Posted by HunterZero on Sun Oct 28, 2018 6:51 PM

If you don't have a replacement, you could swap the two RAM chips over (socket them after desoldering and removing them) and see if the graphics problem changes.


You could also check the logic gate on the chip select logic chip for the two GRAM chips. Most commonly this is driven by U17, a 74LS86 quad logic chip, using an XOR gate on pins 11/12/13 (output/intput/+5v). Chip select input comes from ADDR8 bit line, pin 14 on U5 (GROM), and other address lines and ENABLE and READ/WRITE comes from the same chip, so you could try swapping that chip too. And check both GRAM chips are getting a solid 5V at pin 22 (inspect 0.1uf caps C7 and C18).

#4129279 INTV 1 overheating?

Posted by HunterZero on Sun Oct 7, 2018 10:47 PM

FWIW, I tried to swap the high voltage part of the PSU with another unit from a broken console, but it didn't fix anything. Perhaps there were resistors on the main board that caused all the heat without breaking completely. Even one of the Swedish importers late into the Intellivision's lifespan was aware of this overheating problem and mused about perhaps the main board was placed upside down, which of course is technically impossible but at least they knew it was a major problem for them right before they switched to selling the much more reliable Nintendo Entertainment System.


There are no high voltage parts in the Intellivision power supply board. The transformer is the only HV part, it steps down the mains AC to 18V AC with 9V AC center tap. The power supply board rectifies these AC inputs into DC and regulates to the needed DC voltages, smoothed by two large power capacitors. The voltage regulators on the power supply board have heatsinks, and can get rather warm. I replace these with modern parts on my units, applying new thermal compound. From the outside, you can feel the area of the casing over these regulators gets warm.


The RAM and STIC and CPU all run reasonably warm and do come with heatsinks as a result. They are enclosed within RF shielding in most consoles, so it's possible that heat can accumulate and one of these ICs overheating caused the lockups over time. Active cooling with an external fan or an active cooling mod wouldn't be a bad idea for extended play.


- J

#4121193 INTV 1 overheating?

Posted by HunterZero on Tue Sep 25, 2018 10:21 PM

The old 7805 and 7812 voltage regulators are worth checking and replacing with newer parts too. These can get quite warm.


- J

#4053435 Picture scrambling problem

Posted by HunterZero on Wed Jun 20, 2018 6:32 PM

Could be a dirty IC socket causing intermittent connection issues on a data line pin on the STIC chip. Cleaning and resocketing the STIC would probably fix it. Could also be an issue with the reliability of the "blue jumper wire" connector.


If it's working now, I wouldn't touch it unless it does it again. You might find that bumping the console could cause the issue to reoccur, which could imply there's a bad connection or cracked/dry solder joint somewhere.


- J

#4046900 Dragon's Lair - Homebrew

Posted by HunterZero on Mon Jun 11, 2018 7:14 PM

It reminds me of Marble Madness, another very popular arcade game which relied on graphics and great physics simulations and controls. When ported to 8-bit micros, it seems like a weird isometric version of Pac-Man, and it was mostly awkward to play.


Did you play Marble Madness on the Amiga computer with the mouse? It was a very good conversion, pretty close to arcade perfect.


If the Intellivision had an RS-232 serial port, it could conceivably be used to emulate the original game board and run a port of the original code (the game board was based around a Z80A, and AY-3-8910 sound chip), and interface with a serial laserdisc player.

#4030631 Advice needed on repairing a motherboard

Posted by HunterZero on Sat May 19, 2018 11:08 AM

I could be wrong but I don't think gram can cause this problem, so I'd replace the logic gate chips before gram.

Yes and no... A bad GRAM issue could result in the system running with graphics corruption in custom background cards and/or sprites.

However all the RAM and ROM ICs in the Intellivision are on a common bus, so it's possible a short in the GRAM could halt the whole system.

Do any of the RAM or logic chips get hot to touch? Eg U11, U17? Or U13 U14 U15 U16? (4 5 6 7 8 9 on your diagram!)

#4030510 Advice needed on repairing a motherboard

Posted by HunterZero on Sat May 19, 2018 6:49 AM

Troubleshooting and repairing these things is a game itself. Fixing one is highly satisfying. Learning new skills is fun too.

Replacing old capacitors is not a bad idea but there should be a way to test them as well as the transistors to rule them out as the problem here. Would an Intellivision show some graphics even with bad scratch ram or bad gram?


The polarised electrolytic capacitors in these things are typically a limited life device, they can degrade with age to a point where they are out of tolerance and cause problems. Intellivisions are more than 30 to nearly 40 years old. You need a capacitance and ESR meter to check them accurately (some multimeters check capacitance, but not ESR). These are expensive, relative to the capacitors themselves which are dirt cheap. For this reason it's quite common to do preventative maintenance on old electrolytics and "shotgun" replace them, as they are cheap (except for the larger ones on the power supply) and easy to replace. That said, the SHOEI branded capacitors that are standard on most Intellivision main boards are quite good quality, and stand up well to age.


The transistors can easily be checked out of circuit with a multimeter or cheap Chinese component tester, but again the cost of the parts is so small that they are easy and cheap enough to just replace.


Logic chips are harder to troubleshoot, they require information about the pinout of the part, knowledge of the overall circuit schematic and corrrect operation of the IC being tested, and specialised equipment to test, such as at the very least a logic probe, preferably an oscilloscope, or best of all a logic analyzer. These aren't tools a hobbyist typically has in his arsenal, although a logic probe is quite cheap, and there are inexpensive (if less than optimal) options these days even for oscilloscopes. Even the Intellivision service manual recommends just swapping logic chips with known good ones to test them, as doing this is often more reliable and faster than setting up and testing with any of the IC analysis tools.


For example, checking for clock pulse at pins 37 and 38 of the CPU will verify transistors Q1 and Q2 are good.


A certain amount of experience shows what the common faults are with the Intellivision logic board. From experience (ignoring the ribbon cable, power supply/transformer or cartridge slot connectors), the RA-3-9600 RAM is the most common failure, then the STIC chip, then the transistors Q1/Q2, the sound generator chip and CP1610.


Edit - does the logic board still do the same thing with no controllers connected?


- J

#4029677 Advice needed on repairing a motherboard

Posted by HunterZero on Thu May 17, 2018 7:42 PM

Is the board pictured the actual faulty board?


Certainly one or both of those transistors Q1/Q2 could be bad. Cheap to replace, may as well just shotgun them. It's possible to check a transistor out of circuit using a multimeter with continuity check, or you can get one of those cheap component tester boards from China that do a reasonable job (check eBay).


Check the sockets for the RAM, STIC and CPU chips are good. Easy to check with a multimeter. No need to remove the chips, just touch one probe lead to the top of the leg, and the other probe lead to the other side of the board, or follow the trace to some easy to get at location. Check the cartridge port has no faulty pins as well.


A logic probe or oscilloscope will help to diagnose faulty logic chips, and check clocks/crystals. You can check to see if any data/signal/clock legs that should be pulsing are stuck, and trace back through the circuit diagram until you find the source. Multimeter can verify that chips are getting correct power on voltage lines.


The fact it flashes says that the video system is running, so it's possibly a component issue around the CPU, or its bus lines to Scratch RAM/Exec ROM. Eg, it could be the U12 scratchpad RAM, which you've marked "3", but I haven't seen one of those go bad before (first time for everything?).


Otherwise you are going to have to start checking the diodes and non-polarised capacitors on the board.


- James

#3972345 Does anyone have a source for new disc inlays?

Posted by HunterZero on Sun Feb 25, 2018 8:53 PM

I successfully restored a peeling disc controller by removing the old clear plastic layer and the adhesive with a bit of WD40 and some isopropyl alcohol, and applying new clear book cover plastic. Not perfect, but a lot better than it was.



#3968200 Power Ribbon Cable Replacement

Posted by HunterZero on Tue Feb 20, 2018 9:11 PM

These part numbers should work. The brand is Multicomp, MC34 series, but any other similar spec brand should work too.


90 degree header: http://au.element14....54 mm connector

Straight header: http://au.element14....54 mm connector

Plug: http://au.element14....54 mm connector

Crimp pins: http://au.element14....multicomp 2218t


I scored the bits I used from eBay.

#3966507 List of Intellivision games with boss battles?

Posted by HunterZero on Sun Feb 18, 2018 11:40 PM

Strictly speaking, while Swords & Serpents has a 'boss', there isn't a battle...


- J

#3956524 Only for European or Australian Collectors!

Posted by HunterZero on Thu Feb 8, 2018 8:18 AM

Please put this Aussie down for one copy please!


- James

#3873922 Intellivision newby; some questions ...

Posted by HunterZero on Sun Oct 22, 2017 6:14 PM

Does spinning the disc change the location where the disc gets stuck?


Best idea is probably to take the controller apart, check for broken pieces or spilled sticky drink, and give the plastic parts a good clean. Check the mylar insert with conductive printing for damage/wear. If you clean the mylar contacts, give them a gentle clean with a damp cloth or small amount of isopropyl alcohol (be very careful as you could damage the printed material on the mylar).


Ensure that the disc spring and the white plastic washer are intact and correctly assembled. If the disc movement isn't smooth, use a non-conductive dry lube like white graphitic BN where the disc pivots in the back housing.

#3845099 Best way to repair a broken Inty I controller?

Posted by HunterZero on Sun Sep 10, 2017 7:43 PM

I really appreciate the responses! I'll try cleaning the controller first. If that doesn't work, I'll search for an Intellivision Flashback and buy the adapter.


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

#3822185 Does Intellivision use Sprites

Posted by HunterZero on Sun Aug 6, 2017 7:04 PM

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