Intellivision II with black screen

[reverendshoebox]

Hey, all.

 

I'm trying to fix a friend's INTV II.  He claims it worked fine (though occasionally required cartridge repositioning) and then stopped.

 

I powered it on, and I get a black screen with a bit of snow.  The reset button DOES cause the screen to flash, and if I wiggle the cartridge around, I get a slight difference in the display...but nothing good.

 

Initially I suspected bad solder joins in the cartridge slot, so I reflowed all of that...no dice.

 

Taking it apart, I see a ribbon connecting the main board to the TOP of the power supply board where the test points should be - so clearly that's been messed with before.  

 

Following the troubleshooting guide in the service manual from Console5, I checked the power adapter and verified it was in the right range -  but I got 3.8VAC between TP1 and TP2, which should apparently be 16-20VAC.

 

The guide then suggests checking the jack, the trace between J1 and the power board, C38, C39, and F1.

 

The jack is good, the fuse is good. I don't see any obvious issues with the trace, though I'm honestly not sure what I'm looking for, and I not only can't locate C38 or C39 but I don't see a reference to them in the parts list.  

 

Barring an issue with the trace or the seemingly-nonexistent capacitors, the suggestion is to replace the power supply board.

 

Any thoughts on anything else I can try, or where these capacitors might be?

 

Thanks!

 

Tim

[+-^CrossBow^-]

Actually that looks like factory solder work to me on the ribbon interconnect cable. 

 

[majors]

Multiple times when troubleshooting consoles, the wall wart power supplies will read correct voltage when plugged into the wall by themselves, but under load (plugged into powered on console) will fail. I'll see voltage drop or just not enough amps. Before going too deep, can you make sure the INTV power supply works on a known working II? 

[reverendshoebox]

Thanks for the response.  Yes, the power supply works on my INTV II.

 

Tim

 

[+-^CrossBow^-]

18 hours ago, reverendshoebox said:

Thanks for the response.  Yes, the power supply works on my INTV II.

 

Tim

 

Well there are a lot of different passives that could go bad on the PSU board internally, but I would think that issue could likely be the transformer itself or the voltage regulator that is riveted to the heatsink. BTW, you can also use a 5200 power supply to power them as well. The DC from the 5200 supply will just bypass the rectification needed from the AC supply and go on through the rest of the voltage regulation. I've used a 5200 PSU on mine for years because with the normal AC supply the transformer on the Intv will have a noticed hum to it while I don't hear that when using a DC supply.

 

[reverendshoebox]

Hey, thanks for the suggestions!  I think I have an extra 7805 so I can try replacing that...any idea how I can determine whether that or the transformer  is the likely culprit? And what type of transformer would I need if that's what I need to replace?

 

Tim

[+-^CrossBow^-]

To check the VR you would need to probe the input voltage on pin 1 to make sure you have like 9v or so going to it and it should be providing the +5v on the output pin 3. I hope it isn't the regulator as Mattel riveted them to the heatsink making them more challenging to remove than they need to be.

 

 

[reverendshoebox]

Nope, it's 18V on pins 1 and 3.

 

I desoldered the voltage regulator and the other thing mounted to the heatsink (apologies, honestly not sure what this is and can't find a schematic) and twisted the two legs of the heatsink to line up with the holes in the PCB, but the heatsink absolutely won't come off the board! Is there some trick to this?

 

And assuming I'm able to get that out...as far as the riveted voltage regulator (WHY?!?) do I have to drill it out?  Or is there a less messy option?

 

Thanks again for the help!

 

Tim

[+-^CrossBow^-]

Have to drill out that regulator I'm afraid. the 18v in might be normal, I've not checked mine to know but you shouldn't be getting that on the output side I wouldn't think? The other component is a thermistor I believe.

 

[ChildOfCv]

It may sound stupid, but sometimes the simple things catch you.  If my intv has the wrong channel selected, the TV will see nothing but a pattern of white spaghetti.  Did you make sure you have the right channel?

[reverendshoebox]

So, the thing on the INTV2 PSU that looks like a voltage regulator is actually a power amp driver (the specific model number is X44C758 - I found an equivalent online in the form of the NTE377.

 

Stupidly, however, I hooked up the 7805 before figuring this out (I either read somewhere or more possibly inferred from something I read somewhere that this was a safe replacement, and just jumped into it) aaaand now I need a new fuse as well.  

 

Any suggestions for a proper fuse replacement?  And anything else I should order for this thing as long as I'm getting parts, in case replacing the X44C758 isn't the right thing?

 

I'll be bashing my head against the wall and berating myself for the rest of the evening.

 

Thanks,

Tim

[+-^CrossBow^-]

On 2/25/2023 at 11:24 PM, reverendshoebox said:

So, the thing on the INTV2 PSU that looks like a voltage regulator is actually a power amp driver (the specific model number is X44C758 - I found an equivalent online in the form of the NTE377.

 

Stupidly, however, I hooked up the 7805 before figuring this out (I either read somewhere or more possibly inferred from something I read somewhere that this was a safe replacement, and just jumped into it) aaaand now I need a new fuse as well.  

 

Any suggestions for a proper fuse replacement?  And anything else I should order for this thing as long as I'm getting parts, in case replacing the X44C758 isn't the right thing?

 

I'll be bashing my head against the wall and berating myself for the rest of the evening.

 

Thanks,

Tim

Odd...there is even a 7805 mentioned in the parts listing for the Intellivision II. But it doesn't state specifically where. Then again the service manual aside from advising where to check the power, just states the power supply board as a single replaceable part and doesn't go into the breakdown of it.

 

I've actually been using Pico fuses like what is used on the SegaCD for the Intellivision IIs that either have a blown fuse or for whatever reason, the factory just soldered a jumper lead in place of the fuse.

 

And...it looks like Console5 has now got an actual PICO replacement for the Intellivision II consoles:

 

https://console5.com/store/fuse-125v-2a-pico-for-mattel-intellivision-ii-2.html

 

[+-^CrossBow^-]

@reverendshoebox well, I will be watching your progress on this as I've now also received a InTV II console that powers on but just gives a grey screen. I've also checked all the power and I'm actually getting proper spec voltages from the PSU board and also proper voltage reading to each IC. I've already replaced the original sockets with new and even replaced the larger main IC chips without change on the one I'm working on. So I will be using a second INTV tonight to compare the the bus control signals between the two to see if I can find anything odd because everything checks out on the one I'm working on now with comparison to the troubleshoot flowchart. 

 

I did for one instance and one instance only, have the one I'm working on suddenly boot up the MTE test cart last night and go through a full cycle. But it was a one and done only instance. Pretty frustrating as that tells me there could just a cold solder joint on this board somewhere but I've yet to find it on the one I'm working on.

 

I will be sure to update here on anything I find with the one I'm working on to try and give you some more ideas on things to check.

 

[reverendshoebox]

On 2/27/2023 at 12:32 PM, -^CrossBow^- said:

Odd...there is even a 7805 mentioned in the parts listing for the Intellivision II. But it doesn't state specifically where. Then again the service manual aside from advising where to check the power, just states the power supply board as a single replaceable part and doesn't go into the breakdown of it.

Yeah...aggravating, as it's not like there's a stockpile of them somewhere.  Unless there is.  Maybe there's a whole mess of 'em next to the E.T. cartridges in New Mexico...

 

Let me know if you find anything interesting, I'll keep updating here with my status as well.  I've got new fuses and a new power amp ordered in case the power amp is indeed the problem.

 

Tim

 

[+-^CrossBow^-]

Well near as I can tell, the one I'm working on right now acts like there is no cartridge inserted. I spent the money to get one of the SAMS guides on the Intellivision II and I now know that the voltages are good to the ICs and from the PSU board. Additionally the main waveforms appear to be present etc. So it looks like the issue is the scratch ram (2114s). So I'm going to start by checking the traces between them and the main ICs they are directly attached to.

 

Since it did manage to power up once correctly while I was handling it, I'm still of the opinion that there is a cold solder joint or fracture in a trace to U12 somewhere on the BD lines. So that will be the project tonight...

 

After...

 

Mandolorian

 

[+-^CrossBow^-]

Isolated part of my issue on the one I'm working on now to U13 being bad. Once I replaced it, I can now get an actual MTE test cartridge to at least run through a cycle. But as I only have a V3 of the diag it does give failure codes on the model II. I usually ignore those since I expect that, but in this case. The MTE test cart is the ONLY thing I can get it to run.

 

My two flash carts I have that contain the newer diags just give me a grey screen still when loaded up or a grey screen followed by a quick flash of scattered colored bars. Actual game cartridges will not load either also giving me just a grey screen. If I turn the console on without a game inserted then it now gives me either a purple or blue solid color screen.

 

About the ONLY ICs I've not replaced at this point is the Sound IC and U7 and U8. The only reason I've not changed them out is because I haven't any spare 2114s on hand to put in there since I think the INTV II console is the only console I have that uses them.

 

I supposed it could also be the cartridge port itself as the flow charts lead in that directly also, but I've checked continuity from the contacts to the main board and to the chips they directly connect with and haven't found any breaks. I've also replaced the crystal with a spare I had but that didn't change anything either. The clock freq is a tad low on this unit, but it doesn't actually have the variable cap installed so there really isn't anyway for me to tweak that. It isn't far as it reads 3.578 vs the 3.579.

 

Anyone that might be following this thread have any ideas on why an actual 201 test cart is able to work and doesn't seem to give me any errors (Other than the J, B, and M it always gives on INTV II consoles). But won't play actual games?

 

 

[mr_me]

23 minutes ago, -^CrossBow^- said:

Isolated part of my issue on the one I'm working on now to U13 being bad. Once I replaced it, I can now get an actual MTE test cartridge to at least run through a cycle. But as I only have a V3 of the diag it does give failure codes on the model II. I usually ignore those since I expect that, but in this case. The MTE test cart is the ONLY thing I can get it to run.

 

My two flash carts I have that contain the newer diags just give me a grey screen still when loaded up or a grey screen followed by a quick flash of scattered colored bars. Actual game cartridges will not load either also giving me just a grey screen. If I turn the console on without a game inserted then it now gives me either a purple or blue solid color screen.

 

About the ONLY ICs I've not replaced at this point is the Sound IC and U7 and U8. The only reason I've not changed them out is because I haven't any spare 2114s on hand to put in there since I think the INTV II console is the only console I have that uses them.

 

I supposed it could also be the cartridge port itself as the flow charts lead in that directly also, but I've checked continuity from the contacts to the main board and to the chips they directly connect with and haven't found any breaks. I've also replaced the crystal with a spare I had but that didn't change anything either. The clock freq is a tad low on this unit, but it doesn't actually have the variable cap installed so there really isn't anyway for me to tweak that. It isn't far as it reads 3.578 vs the 3.579.

 

Anyone that might be following this thread have any ideas on why an actual 201 test cart is able to work and doesn't seem to give me any errors (Other than the J, B, and M it always gives on INTV II consoles). But won't play actual games?

 

 

The test cartridge starts at $7000 and bypasses the exec.  The ECS computer adapter also has rom at $7000.  Some early Imagic cartridges also bypass the exec using $4800, have you tried Demon Attack, Atlantis, or Beauty & the Beast.

[+-^CrossBow^-]

@mr_meI actually have tried beauty and the beast and Atlantis. I get the same results with those as well since I heard that some games would bypass some of those chips. Just a grey screen. The actual mattel game I tried was Bowling as I figured it was an early made game that might work but nope...grey screen. Which chip houses the exec in the INTV II? Because I'm pretty sure I've changed it out with the working one from my INTV II without any change.

 

Also I meant to add that I don't believe U7 or U8 are at fault because the MTE test graphics are all correct and if either of those chips was bad, the test cart will come up and give you garbled graphics usually. Also, the sound and controller test screens are working without issue so I don't think the Sound IC is faulty. 

 

I even changed out that LAD IC (U9 I think?) below the CPU and no change as it is indicated in the flow chart to cause this. But again using the one from my working INTV II... no change.

 

 

[ApolloBoy]

7 hours ago, -^CrossBow^- said:

Which chip houses the exec in the INTV II?

According to the service manual it looks like U3 (RO-3-9506) is the EXEC. 

[reverendshoebox]

So over here on my end, I've replaced the power amp and the fuse, and I'm back to square one (black screen.)  Following the guide from Console5, it looks like the voltage across TP1-TP2 is good (18VAC.)  TP8 is 21VDC when the unit is off, but goes down to like 2VDC when the system is powered on rather than the 5VDC I'm supposed to see - and the other test points seem similarly off.

 

Any thoughts on what I might wanna do to verify the power board is okay?  And what next steps I might want to take?

 

Thanks again,

Tim

 

 

[+-^CrossBow^-]

Likely some passive on the power supply board that has gone bad is the blame. 

 

The current status on the one I'm working on is just a head scratcher. So after replacing the 2114 at U13 as noted before, it will load up my MTE Test cart each and every time. However, I get one of two conditions with actual game cartridges. Most of the flash carts will behave the same as actual game cartridges. Basically, I just get a grey screen with no sound. All of the waveforms on the address lines between the CPU, both ROMs, RAM, and the STIC all check out in addition to the traces being good from the top of the IC legs to top of IC leg. What I did find out though in comparing with my working INTV II consoles, is that it seems all of the DB address lines are reading half the voltages they should be. Most should be about 3-4 volts on their readings and I'm only getting about 1.5 - 2v when the console is on with a game.

 

The exception besides the MTE test cart which, again comes up just fine all day long ... is my Freewheeling Diagnostic cart. It doesn't boot up but does cause something else very interesting. All of the waveforms across most of the address lines between the ICs and the M-sync line between them will come up briefly for a half second, and then shutdown...come back....shut down... repeating. Like it is resetting everything constantly. It is the only cart I've tried that does this.

 

At this point, I've now replaced every IC with the exception of the twin 2114s at U7 and U8 as again, the test cart doesn't show any graphic anomalies I would usually see when either of these chips is bad. But the Sound IC an all others have been swapped out between my working and non-working with no change. And yes, the ICs from the bad console loaded up on the working one, comes up and work just fine.

 

I've even swapped out the power supply boards as there were some very slight differences but nothing out of spec. No change...

 

Last thing I did was swap out the actual J1 cartridge port itself since that is about the last thing I could figure might be causing some connectivity issue between game and system. No change... And all the parts from the bad unit now reside in my main INTV II and it is working fine.

 

So I'm down to some stupid passive at this point on the main board that is bringing the entire thing down when anything other than the MTE test cart is used. But to accurately test that, I would need to remove some of the components or at least one leg of them to test them out of circuit to be sure. As an example the R1 resistor just below the STIC IC is supposed to read 5.6k but was only reading 1.5k. I removed one leg of it and it was measuring 5.6k out of circuit. I reinstalled it, and now it reads 5.6k in circuit from the board?! So I'm going to have to check them all in case there is some oxidation within their solder joints causing a crap connection. But honestly this is one of the cleanest looking INTV boards I've had with plenty of shiny solder points staring back at me.

 

I don't even want to talk about how much time I've spend on this console. But at this point it has to be something simple and it frustrates me.

 

 

[ChildOfCv]

One thing I know is that the bus control lines go out through the cartridge port and are usually routed right back in from the cartridge.  Without a cartridge plugged in, only the SRAM gets the control signals.  STIC, EXEC, etc. are completely out of the loop otherwise.

[+-^CrossBow^-]

36 minutes ago, ChildOfCv said:

One thing I know is that the bus control lines go out through the cartridge port and are usually routed right back in from the cartridge.  Without a cartridge plugged in, only the SRAM gets the control signals.  STIC, EXEC, etc. are completely out of the loop otherwise.

All of the waveform comparisons were done with cartridges in the console. Again, the only real thing I could see different was that the DB address lines were all reading only about half the voltage they did on my working INTV 2 console with the same cartridge in.

 

I've gone back through all of the resistors and applied new solder to them and when time allows, I will see about going through them all to check for their values. But thus far, I've not been able to find a broken or missing trace on any of the clock lines, BUSACK, or DB addresses. I will need to go through and check the others when time allows.

 

 

[ChildOfCv]

16 hours ago, -^CrossBow^- said:

All of the waveform comparisons were done with cartridges in the console. Again, the only real thing I could see different was that the DB address lines were all reading only about half the voltage they did on my working INTV 2 console with the same cartridge in.

Oh I misunderstood.  Sounded like you said the voltages were normal until you plugged in a cartridge.  2V is definitely too low for TTL logic, but then the Inty removed all of the TTL logic and integrated it into the chips.  Looks like the EXEC controls a lot of the peripherals directly now.

 

The DB bus is driven from multiple sources, so it's weird that they would all be the same weak voltage if the power supply is working.  Even weirder if you replaced with known good.  That does raise the question of whether or not the BC lines are reaching their destinations.

[ApolloBoy]

Bumping this as I happened to acquire another INTV II and it also just displays a black screen. So far I've taken the CPU, STIC and main RAM out of their sockets (which were crumbling apart) and soldered them directly to the board, but no dice.