Help diagnose my Intellivision

[boxpressed]

Here's a pic from my Intellivision (my backup, so no urgency) when I turn it on sometimes:

 

I say sometimes because other times it will boot up normally. And sometimes it will boot to the white screen above, and if I just let it sit, the screen will start flickering, more of the color bars will appear, and the normal boot screen will appear, allowing me to play the game as normal. Once I'm in the game, I can play without any problems.

 

I thought that something had to "warm up" first, so I left the unit plugged in overnight, and it worked the first time I fired it up the next day. But then I had it unplugged overnight, and it still worked the next day.

 

So this unit seems like an old car that needs some patience, but I also suspect impending component failure. I haven't opened up the unit yet since I don't know how to solder. Thanks for any advice if you've encountered anything like this before.

[vprette]

I remember those guys can help intv failures

give a try

http://osgservice.ca/

[+DZ-Jay]

Here's a pic from my Intellivision (my backup, so no urgency) when I turn it on sometimes:

 

I say sometimes because other times it will boot up normally. And sometimes it will boot to the white screen above, and if I just let it sit, the screen will start flickering, more of the color bars will appear, and the normal boot screen will appear, allowing me to play the game as normal. Once I'm in the game, I can play without any problems.

 

I thought that something had to "warm up" first, so I left the unit plugged in overnight, and it worked the first time I fired it up the next day. But then I had it unplugged overnight, and it still worked the next day.

 

So this unit seems like an old car that needs some patience, but I also suspect impending component failure. I haven't opened up the unit yet since I don't know how to solder. Thanks for any advice if you've encountered anything like this before.

 

Maybe it's haunted. Did you play Dracula recently? Try putting a crucifix on top before turning it on.

 

-dZ.

[IntellivisionGuy97]

Intersting... I've never seen anything like that...

[boxpressed]

In another thread on AA, I read that someone fixed a startup problem by holding down "Clear" and then pressing the Reset button. I tried it, and it worked! I still don't like the prognosis for my system, but at least I don't have to wait for it to warm up. Anyone know what Clear+Reset does? Or am I just imagining this?

 

Update: Screen started to geek out after the game started, so something is definitely wrong.

Edited October 20, 2011 by boxpressed

[FABombjoy]

Do games actually play when the screen looks like that? If so, my first suspect would be the AY-3-8915 chip (U10) and/or chip socket.

[boxpressed]

You can start a game, but the play screen is all garbled. I went ahead and opened up the unit last night to see if there was an easy fix (resocketing). But as many of you know, the RF shield is soldered on. With the screen garbled, I actually pressed down on the RF shield at a few points and got the screen to look normal. I'm not optimistic that I fixed anything, but it worked normally for the next few hours and then again this morning. A lot of fun to take a peek into a unit I was too afraid to open when I was a kid.

[RickR]

Sorry to drag up an old post, but did you ever find a solution for this? I have an intellivision that is doing something similar. I turn it on, and the title screen comes up, then the screen goes garbled after a few seconds. The game seems to play ok behind that garbled screen (I can hear the sounds). Thanks.

[RickR]

So a little more info if anyone can help me. I checked the AC voltages coming off the transformer, and they look fine. Then I checked the DC voltages on the output of the power board, and they look fine. So something on the main motherboard is causing this problem. Game turns on, then the screen garbles after a few seconds.

 

Thanks.

[boxpressed]

I'm sorry, but I wasn't able to find a fix for this problem. My solution was to buy a Sears model and an Intellivison II for cheap. I'll probably offer up this unit for free plus shipping costs soon.

[sqoon]

You both might try this trick:

 

Take the on/off switch cover off the console and spray liberal amounts of electronics part cleaner into the switch. Then flip the switch back and forth 5-10 times. Put the switch cover back on and try out the systems.

 

I had one that had a black screen, but you could still hear the game sounds playing in the background. This switch cleaning technique cured it.

[intvnut]

The first thing I'd suspect is that one or more chips are loose in their socket. The screen above shows that you didn't complete the EXEC's title screen drawing routine.

 

The complete lack of color is odd. Is that a black and white screen, or is that just the normal Intellivision grey and white (or black and grey) colors? You mention that games will play but they're garbled... do you get color in them?

 

I doubt it's a bad AY-3-8915 color processor. If that's bad, it'll mess up your colors but the rest of the system should be stable. It seems more likely that either the STIC chip isn't firmly in its socket, or one of the EXEC chips isn't.

 

On the Inty 1 mainboard I have sitting here, the GROM, STIC, PSG, System RAM, CPU, AY-3-8915 and both EXEC ROMs are all socketed. The Intellivision main board mounts with the components facing the floor, so perhaps a combination of thermal cycling and gravity have taken their toll.

 

You mentioned pushing on the shielding helped. Three of the chips (the STIC, System RAM and CPU) all have large heat sinks on them, so perhaps you pushed one of those back into its socket better.

Edited March 28, 2012 by intvnut

[+thegoldenband]

On the Inty 1 mainboard I have sitting here, the GROM, STIC, PSG, System RAM, CPU, AY-3-8915 and both EXEC ROMs are all socketed.

 

Huh, very interesting -- I didn't know that. That makes the prospect of Intellivision repair a lot more appealing.

 

BTW intvnut, have you ever looked into the cause of the overheating problem that some Intellivision I consoles have? I've got two consoles that both crash after a certain interval, and that interval gets shorter the longer they're on. (One lasts 10 minutes at first and goes down from there; the other is lucky to make 30 seconds.) Is there a particular component that's known to be the probable culprit?

[intvnut]

BTW intvnut, have you ever looked into the cause of the overheating problem that some Intellivision I consoles have? I've got two consoles that both crash after a certain interval, and that interval gets shorter the longer they're on. (One lasts 10 minutes at first and goes down from there; the other is lucky to make 30 seconds.) Is there a particular component that's known to be the probable culprit?

 

No, I haven't. The old GI parts are NMOS parts that tend to run on the hot side. It could be something as simple as "needs its chips reseated," or something else such as an aging capacitor.

 

For example, Chad Schell has a system I sold him that's losing its color, and it seems to be heat related. I warned him when I sold it to him that after leaving it on for 24 hours, the colors were "off". Letting it cool for a half hour or so restored normal colors. Now, it's far enough off that it shows up in black & white if at all, if I recall correctly. All that suggests to me a capacitor or something that's shifting the clock frequency as a function of temperature. Color shift and color loss are a sign of frequency drift on the colorburst. (Caps are the most likely culprit as I understand it, although I admit I'm repeating dogma here as opposed to having a deep understanding.)

 

Now, this does raise an interesting point. I just took a look at the Intellivision schematic: http://spatula-city....s/schematic.png

 

I had thought the system clock was hooked to the STIC, but actually the system crystal *is* connected to the AY-3-8915. (The circuit appears in the middle bottom area; look for the AY-3-8915 and the crystal X1, just above U14 and U15.) There's two capacitors attached to the crystal also--one fixed 20pF cap, and one variable 5pF to 50pF adjustable trimmer cap. If the AY-3-8915 *is* dodgy (or at least not socketed well), then who knows -- that could be causing system instability. The variable capacitor may have degraded also.

 

I am no electrical technician, so I really couldn't tell you what to do to fix it. I may have an EE degree, but that doesn't mean I have real world experience fixing these things, just a lot of experience experimenting in lab on a breadboard *mumblety* years ago. If you do open up one of these logic board assemblies and start to poke around, the crystal is the big "tower" next to where the power ribbon cable comes in. The trimmer cap for the crystal is the short, fat cylindrical component next to it with a much narrower slotted shaft sticking out the top. If you adjust the trimmer, I believe you should use something plastic to turn the shaft, to avoid skewing the capacitance. An orange peeler ought to work.

 

I've attached a picture that shows the crystal, the tunable cap, and an orange peeler. :-)

 

And remember, you can tune a capacitor, but you can't tune a fish.

Edited March 29, 2012 by intvnut

[intvnut]

BTW intvnut, have you ever looked into the cause of the overheating problem that some Intellivision I consoles have? I've got two consoles that both crash after a certain interval, and that interval gets shorter the longer they're on. (One lasts 10 minutes at first and goes down from there; the other is lucky to make 30 seconds.) Is there a particular component that's known to be the probable culprit?

 

Also, the problem may not even be on the logic board. It could be the power supply board. Without desoldering the logic board's sarcophagus, you should be able to check the voltages coming from the supply board when the unit is cold and behaving well, and when the unit is hot and misbehaving.

 

Of course, without an oscilloscope, what this won't show you is whether you're getting increasing amounts of noise or ripple on the supply lines. It could be that the voltage is fine on average (which is what a DC voltmeter will show you), but the caps are getting less and less able to filter the ripple from the rectifier. There are some large electrolytics on there that may not be filtering like they once did.

 

If you look at the schematic I linked above, you'll see that the +16v line goes to a pair of transistors that directly drive the clock into the CPU. IIRC, the +16v line is just rectified and filtered, but otherwise unregulated, and tends to run on the high side. (Memory fails me here, but I think mine all measured more like 18v - 19v.)

 

So, as you can imagine, there's plenty of ways for ripple from the power supply board to wreak havoc on the logic board.

 

Again, I'm no technician, so please understand any advice I offer at this level is just a shot in the dark. I do best when I can keep all the components fully digital. :-)

Edited March 29, 2012 by intvnut

[boxpressed]

You both might try this trick:

 

Take the on/off switch cover off the console and spray liberal amounts of electronics part cleaner into the switch. Then flip the switch back and forth 5-10 times. Put the switch cover back on and try out the systems.

 

I had one that had a black screen, but you could still hear the game sounds playing in the background. This switch cleaning technique cured it.

 

I did that, and everything worked for a while. (I'd started another thread around that time about the wonders of contact cleaner.) I suspect that you're right that the problem is with the power switch, but I don't have the inclination or the skills to clean it out properly.

 

The first thing I'd suspect is that one or more chips are loose in their socket. The screen above shows that you didn't complete the EXEC's title screen drawing routine.

 

The complete lack of color is odd. Is that a black and white screen, or is that just the normal Intellivision grey and white (or black and grey) colors? You mention that games will play but they're garbled... do you get color in them?

 

I think you're responding to my original post. Thanks for your detailed reply. The bars are actually dark green in color (against a white background). If I leave it like that, the normal start-up screen (with multicolored bars against a green background) usually appears within 5 minutes, and then I can play everything normally.

[sqoon]

Maybe Radio Shack sells similar switches and you could desolder the old one and solder a new one in place.