Tank II

[ChadTower]

You would have paid the same $14 without the moon pies. $7 shipping on each order is the standard (and minimum) rate that he charges. Your moon pies were free. If you had ordered everything at once in the first place it would have only been $7 shipping, and you probably still would have gotten the moon pies to boot.

The point is that he shipped them at the same time so he could have shipped them in the same box.  That and the fact that both boxes said $4.50 on them.

[ChadTower]

Found the tester manual... it's a BK520 Transistor Tester.  Found it attached in a thread on an audio forum.  I tried to attach it here for the next guy that Googles it but the PDF is higher than the max attachment size here.

EDIT:  this thing is cool.  Hook up the three clip leads to the transistor in circuit any way you want - then just move the knob through the settings.  If it's good it will beep on one of them and tell you if it's PNP or NPN.  You don't have to know which leads are which.  If it never beeps, take it out of circuit, and test again with deeper tests.  It checks diodes too, of course.  I took a peek on Ebay and this unit sells for about $35 before shipping.  Anyone who works with a lot of transistors (like on a pin driver board) should absolutely have one of these.

[MaximRecoil]

You would have paid the same $14 without the moon pies. $7 shipping on each order is the standard (and minimum) rate that he charges. Your moon pies were free. If you had ordered everything at once in the first place it would have only been $7 shipping, and you probably still would have gotten the moon pies to boot.

The point is that he shipped them at the same time so he could have shipped them in the same box.  That and the fact that both boxes said $4.50 on them.

You need to read this page thoroughly - http://therealbobroberts.net/ordering.html

And I would imagine that he already had your first order boxed up and ready to ship, if not out the door already. Bob seems pretty set in his ways and he easily deflected that monkey wrench that you tried to throw into his works. Two orders = two shipping costs. It's pretty simple.

[ChadTower]

You need to read this page thoroughly - http://therealbobroberts.net/ordering.html

Gee, it's not like I actually talked to *him* about it or anything.  You'd know that, though, having been involved.

Oh wait.

[MaximRecoil]

You need to read this page thoroughly - http://therealbobroberts.net/ordering.html

Gee, it's not like I actually talked to *him* about it or anything.  You'd know that, though, having been involved.

Oh wait.

What does talking to him about it have to do with anything? Did he tell you he would combine your two separate orders into one package/shipping cost? Did he tell you that he would [inexplicably] charge you less than his standard/minimum shipping rate of $7 per order (up to 1 lb.) that he charges everyone else? If not, then your talking to him is irrelevant.

You didn't get treated any different than anyone else, and the way he does things is made clear on his Ordering FAQ page.

[CheffoJeffo]

Oi, Maxim - loathe as I am to get between you and Chad ...

If I promise to lay off of Nintendo sticks (and I hope you noticed that I have), will you stop cluttering up interesting (do what you will with the uninteresting ones) project threads with pedantic arguments ?

Please ?

EDIT: And, yes, chad shouldn't ---smurfette--- about being charged basic shipping on each order he made.

[shardian]

How many Moon Pies are we talking about here? You may have actually made out on the deal.

[MaximRecoil]

Oi, Maxim - loathe as I am to get between you and Chad ...

If I promise to lay off of Nintendo sticks (and I hope you noticed that I have), will you stop cluttering up interesting (do what you will with the uninteresting ones) project threads with pedantic arguments ?

Please ?

EDIT: And, yes, chad shouldn't ---smurf--- about being charged basic shipping on each order he made.

Carry on.

I think it is great that Chad is restoring or refurbishing this machine.

However, Bob Roberts is definitely one of the "good guys" and has been since before most of us were even in this hobby.

[ChadTower]

If it were just this one instance, I wouldn't really care.  The cap kit for this game came with a good number of the caps wrong - half the required voltage.  He flat out told me it wasn't possible and stopped one step short of calling me a liar despite the fact that I wasn't asking for replacements.  I was asking for advice on whether or not the incorrect caps he gave me may actually work in the circuit.

I'm not even the only person in this thread who has had that problem with him and there's only like five of us here.

[ChadTower]

I'm trying to work out exactly what path to use in diagnosing the missing 6.3v on pin 9 in the monitor chassis.  I see 6.3v should be coming right off the transformer.  The immediate question, and one I can't just eyeball from where I'm sitting, is which one?  The iso on the chassis or the cabinet main?




Placeholder post for the time being... will be using this photo as reference.

[ChadTower]

Hey.  Just found the Motorola XM Series Technical Repair Manual.   

[ChadTower]

Just musing around the diagrams a bit...

The missing 6.3v is on pin 9 on the chassis.




R1 is just next to pin 9 in the image above.

Here is R1 in the schematic.



I probably replaced C1.  I'll verify that the polarity is correct. 
It appears to be straight from P1-1, which is pin 1 in the main chassis connector.  P1-1, if you reference the wiring diagram above, comes from edge pin 21 on game PCB2.  Pin 21 is video - pin 22 is video ground.

When I get home I'll pop the leads onto pins 21 and 22 on PCB2 to see if there is any video signal coming off the boards.  Any idea on what range I would reasonably expect to see?

[ChadTower]

Bah... what is that combo of black circle and white circle between P1-1 and R1 in the schematic?  Is that pin 8?

If it is, I need to go back towards the drawing board a bit.

Yep, found pin 9, straight off the transformer and labeled as 6.3v.  Looks like it makes a whole lot more sense.  Question:  I don't see a BR there like I do on the other transformer outputs.  Does this mean I would expect this to be 6.3v AC?

[Level42]

Looks like it. 6,3 V is a common used voltage for the heater in the CRT. If it's really low this could explain the dim picture.

[ChadTower]

Looks like it. 6,3 V is a common used voltage for the heater in the CRT. If it's really low this could explain the dim picture.

It could also be explained by me measuring it as DC.  I'll recheck that when I get home. 

BTW, good call.  Looking at the "back of the board" diagram, pin 9 is sitting right next to "heater CRT pin 8".

[ChadTower]

Okay, with that to check, on to looking into why 5v logic is low.  Found this in the repair manual I linked a couple of hours ago.  Clipped together from a couple of sections.  5v and 12v do indeed get powered off the monitor.  Now to find R4.

[ChadTower]

EDIT:  found the 5v driver transistor... it's q19 on the little audio plugin board.  It has a resistor between B and C that is not in the schematic and the telltale flux of some tech's fingerprints.   

That resistor... I wonder... could that be a factory mod to regulate the 5v output?  The service manual for the monitor seems to imply that it should be done after the load is placed on the 5v supply.  If Kee was building a bunch of these they may have decided a static resistor is cheaper than a potentiometer someplace...  and of course, now that the stuff is 30 years old, there is enough leakage that on a later game we'd be turning the power supply up in order to get 5V into the game boards.

Or does that sound like a half assed guess?

[Level42]

Uhm...why not use a switching power supply to hook up the +5V and +12v for the moment ? It's just to power the game PCB's right ?

Anduhm, yes measuring any AC voltage in DC setting will give you around 0 (even mains voltages )

I get a feeling we're trying to fix two (or more) things at a time...

Somewhere I lost you...

[ChadTower]

Uhm...why not use a switching power supply to hook up the +5V and +12v for the moment ? It's just to power the game PCB's right ?

It's not a bad idea.  I might have to figure out how to do that.

I get a feeling we're trying to fix two (or more) things at a time...

Yep.

[ChadTower]

6.74vAC present.  I was chasing a wild goose on that one.   

[Level42]

6.74vAC present.  I was chasing a wild goose on that one.   

Glad to be of help...

[ChadTower]

On the positive side, a year ago I didn't know the difference between AC and DC.  Yesterday I was able to look at the schematic, recognize a design element grouping, interpret what it likely meant, and make adjustments in my plan based on that.  That's a pretty big leap from where I was not too long ago.

[Level42]

I know and I tell you that's some accomplishment ! Just trying to help you learn even more

[ChadTower]

I know and I tell you that's some accomplishment ! Just trying to help you learn even more

Did I say something that came across badly?  I didn't mean to if I did - and apologize if that is the case. 

I'm trying to decide what to do about the low 5v.  In a later game I would adjust the power supply upwards a little bit, right?  I don't have that direct option here.  Options I do think I have:

• Take that "hacked in" resistor off of the 5v driver and see what difference that makes, after finding its value and if it is small enough to not be a dangerous tactic.
  
• Find R4 and swap in a lower value resistor.
• Try bridging in caps for some of the big big caps on the monitor frame (I think they're power supply filters).  I do have the replacements I got from Moonpie Bob.
  

Or there is another thought.  If you look at that wiring diagram, there is no 5v input to the game PCBs.  PCB1 is taking in 6.3v on contacts 2, 3, 4, and 5.  I may be better suited to figure out where exactly that 5v is supposed to be coming from before I go shotgunning actual changes.  That will be pushing my schematic reading skills at this point.

[Level42]

Not at all, Chad, not at all ! If I made you think that, _I_ am sorry

Sometimes this text-only communication is just to limited...

OK, so 6,3VAC is OK.

What is the problem with the monitor itself right now ? I mean, apart from the supply voltages to the PCB. I personaly would really use a seperate switcher on this one. I normaly am all for restoring the original power supplies, and I still think a conventional PSU will last longer than a switcher, but in this case....
It would save you a lot of worries about getting these voltages OK.

From that clip of the manual, I would think that R4 is a potmeter, not a fixed resistor......because they say it's adjustable....

[ChadTower]

What is the problem with the monitor itself right now ?

I am assuming it is not getting valid signal from the game board.  It does display the VCR signal, albeit dimly, so I know it mostly works.  I figure the game board should be showing up just as dimly.  Instead I get a blank screen full of what are probably horizontal retrace lines from the game boards.

From that clip of the manual, I would think that R4 is a potmeter, not a fixed resistor......because they say it's adjustable....

That would make sense, but if R4 is actually on the power/audio daughterboard, then it's not a pot.  There are no pots on the daughterboard.  I'll take a look when I get home - they may mean the R4 that is on the main chassis PCB.  If that is a pot we're good - but I don't remember a +5v control pot on the main PCB.  This is a case of my not completely understanding the schematic.  In one place the +5v circuit is laid out entirely - no marking for crossing PCBs - but in reality most of the parts shown cannot be on that daughterboard.  It is too small.

I would have to figure out how to use a switcher to power the game board.  It's a decent idea just to further testing along if for nothing else.  I'm sure I have one around someplace.

[Level42]

That Service Manual PDF shows R4 to be in the contrast circuit.... Could it be they used the same part numbering on different PCB's on that monitor ? Would be very stupid, but possible.

R5 is definitly a potmeter on that part of schematics....

This has to be asked: do you have a working TV around that has a composite input ? (Those yellow RCA female plugs) ?

I suggest using that for testing the PCB. Just hook up the video output to the center of the RCA, ground to the shield.

[ChadTower]

That Service Manual PDF shows R4 to be in the contrast circuit.... Could it be they used the same part numbering on different PCB's on that monitor ? Would be very stupid, but possible.

I don't think they did.  There really isn't very much on that daughterboard.  That circuit has to be crossing PCBs.

This has to be asked: do you have a working TV around that has a composite input ? (Those yellow RCA female plugs) ?

I suggest using that for testing the PCB. Just hook up the video output to the center of the RCA, ground to the shield.

I have a few things I could use for that.  My workbench has a VCR and Commodore monitor on it - that's what I used to test input to the monitor.  I agree it's time to try and get known good voltages into the game PCB and see what comes out of it on a known good monitor.  I assume to do that I'll need 4 6.3vAC lines into edge contacts 2, 3, 4, and 5 on PCB1.  Then I mock up a video cable similar to the one I made for VCR->monitor testing but in reverse.  I think I can accomplish that using the spare eyelet connector I bought from Bob and maybe some clip leads for video.


EDIT:  wait.  That doesn't sound right.  I measured the 6.3vAC inputs on those pins - they are all good.  If I'm already getting good inputs to the boards, but +5v is still low, then there has to be a problem in the board someplace, probably in the 6.3vAC to 5vDC conversion.  I can still mock up a cable to test output with the existing power supply but as I get deeper, if there is an actual link between that 5v supply on the monitor and 5v in the game board, I'm not seeing where it gets in.  The only voltage inputs on the game PCB are on PCB1 in those four 6.3vAC lines.

[Level42]

Mmmmm, there could be one problem with this. The PCB is probably outputting TTL levels (5V). A TV would like it to be a little lower. You can use a series resistor to lower it. I thinkg around 500 Ohms should do the trick enough....

[Level42]

Let me check the Tank PCB schematics...

[ChadTower]

Mmmmm, there could be one problem with this. The PCB is probably outputting TTL levels (5V). A TV would like it to be a little lower. You can use a series resistor to lower it. I thinkg around 500 Ohms should do the trick enough....

Hrm.  I hate to add a variable here... but my Commodore monitor has a TTL input on the back.

[Level42]

That's solved then

Is it an RGB input ? If so, connect the video to one of the colors. Green comes into mind as a nice retro-looking color

[Level42]

O wait, the sync is on that composite video signal......can't use RGB input with that .....

[ChadTower]

That's solved then

Is it an RGB input ? If so, connect the video to one of the colors. Green comes into mind as a nice retro-looking color

I'm not sure - I've never used it.

Wait - if the board is putting out TTL levels - and TTL levels are higher than composite levels - and I was testing with composite output - then the monitor would be expecting higher levels than I was testing with - meaning the monitor could be better than I think?

Erg.  I'm all over the place now.  I'm heading out - it is snowing like a mofo here and the roads are getting really bad.  I should have time this weekend to try a couple of things and make more rambling posts.

[Level42]

Yes of course. Someone mentioned that in this thread already !!!

[Level42]

I'm out on a roadtrip to Belgium tomorrow to see if I can fix two Star Wars cabs.
One is an upright that is "poorly" working, the other a dead cockpit !

[Level42]

I took a first look at the Tank II Schematics and it looks to me like the PCB is creating the DC voltages itself.

There's a transformer on the bottom of the cab. Since the Motorola doesn't need an isolation transformer, why would there be that 2nd one ?

I think the power supply to the PCB's are not coming from the monitor.....

Or am I missing something obvious ?

[ChadTower]

Yes of course. Someone mentioned that in this thread already !!!

Yeah.  I didn't understand it then, though.

The motorola doesn't need an ISO because it has one of it's own, my guess.  It does "need one" because it "comes with one".

That's quite a road trip.  Good luck!  Fill us in on how it goes.

[Fozzy The Bear]

Wait - if the board is putting out TTL levels - and TTL levels are higher than composite levels - and I was testing with composite output - then the monitor would be expecting higher levels than I was testing with - meaning the monitor could be better than I think?

Isn't that what I said to you a couple of pages back???

Best Regards,
Julian (Fozzy The Bear)

[ChadTower]

Isn't that what I said to you a couple of pages back???

You spoke of impedance... which seems correct but I didn't understand enough to know what it meant yet.  What you just witnessed was me connecting the dots.

I have just about every game console that has been released in North America.  Any recommendations as to one of them from which I can snag a similar TTL signal to feed to this monitor?  Seems to me some of the earlier ones may have TTL inside before being modulated to television levels.  Maybe the Channel F or an old Pong clone?  The Odyssey 2, perhaps?