How to start finding board and monitor problems?

[unclet]

I obtained a free Space Encounters cabinet recently which had some problems.

[RayB]

Photos. I don't think anyone here knows off the top of their head what the inside your your cab looks like.

That said, when you measure the power voltages, you'll find out if perhaps THOSE are the cause of the garbled graphics. RAM can "fail" when there isn't enough voltage to power them up. Which means fixing the voltage level fixes the RAM error too.

Now if the voltages are all correct, then you're closer to RAM being actually bad, but again it can also be bad connections somewhere, or a chip not sitting properly in a socket.

[APFelon]

Sounds like you need a manual! 

http://www.arcadedocs.com/vidmanuals/S/SpaceEncounters.pdf

Can you read schematics? Most everything is there is you know how to read it.

Good luck, and I hope this is a good start for you!

APf

[paigeoliver]

I am going from memory here, but I seem to remember Space Encounters being a Midway 8080 class, in that case the power supply is nice and labeled and easy to check the voltages on. Also means that any of the guys who fix space invaders boards can fix that one.

[ShinAce]

I just started skimming throught that schematic and within 2 seconds found something good.

If you've opened the door, and left it open, the machine will not turn on. Either close the door, or find the switch the door activates.

[paigeoliver]

A black and white Atari game often won't boot if the microswitch on a coin mech is bad or not hooked up. Not sure if Space Encounters does that, but the Sprint games do.

[unclet]

Thanks for the PDF file.   I have a lot of what is in there already, but not everything so I will defintely print a nice copy of it.

I do not know how to read schematics, so this will definitely be a learning experience.

As for the switch on the back door ....... I did notice it was there and made sure to tape the switch closed so everything "should" work even if the back door was off.

The machine does not have any coin mechs so there are no switches.  I believe the previous owner got the monitor to come up all garbled even without the coin mechs so I am not sure if the missing microswitches caused this problem.  Although, since I can not tell you if the machine actually "booted" (ie: all I know is that the monitor originally came up all garbled) then maybe this could still be a cause to the problem.

Here is a picture of the Sound PCB and also the power supply board.  Also another close up shot of the power supply board as well.

[unclet]

Here are photos of the L-shaped boards (gamePCB and the MainPCB):

[unclet]

This is what  is mounted to the bottom of the cabinet floor .

Here are some pictures of the isolation transformer:

[unclet]

Finally, some close up of the isolation transformer:

[SirPeale]

Isolation transformer.  I think it may also act as a power supply as well, of a sort.

[APFelon]

That isn't the power supply. Don't start there, it is not likely the cause of your problems. Check page 48 (actual page 45, 48 on the PDF file) of the manual I referenced, that it the power supply board.

Double check that back door switch to see if it functioning correctly. It may have gone bad (it IS nearly 25 years old) and be the cause of the primary problem.

Check to see if you are getting the 110vac everywhere it needs to be. Check from the cord on up (where it hooks in to the filter / "silver thingy" and work your way back. You could even have an internal break in the cord.

Keep us updated, I'd like to see how this progresses.

APf

[unclet]

Let me state again, that I have no experience with trying to test stuff with a multimeter and no real experience withj electrical stuff (other than hanging fans and wiring up my other Mame cabs).

APFelon: That being said ..... I really do not understand what "see if you are getting the 110vac everywhere it needs to be" .... since I have no idea where it "needs" to be         Where would I place the multimeter probes to test for 110vac going into the filter/"silver thing" on the transformer board?  Perhaps one probe goes on one wire and the other probe on some other wire?

Finding page 45 or 48 is impossible since the link you provide me with (http://www.arcadedocs.com/vidmanuals/S/SpaceEncounters.pdf) only has 42 pages.  Are you referring to the document at this link or some other link?

As for the backdoor switch, would you recommend I simply connect the wires together to simulate the switch always being closed, thus eliminating the use of the switch at all?

If I have some time tonight, I will play around with it later and see what I can find.

Peale:  Are you saying that the thing mounted on the bottom of my cabinet is called an isolation transfornmer or are you referring to something else?

[APFelon]

Let me state again, that I have no experience with trying to test stuff with a multimeter and no real experience withj electrical stuff (other than hanging fans and wiring up my other Mame cabs).

APFelon: That being said ..... I really do not understand what "see if you are getting the 110vac everywhere it needs to be" .... since I have no idea where it "needs" to be         Where would I place the multimeter probes to test for 110vac going into the filter/"silver thing" on the transformer board?  Perhaps one probe goes on one wire and the other probe on some other wire?

Well, just check where you *know* line voltage is supposed to be-- the monitor, the marquee lights, the filter, etc.. Set the multimeter to "VAC", touch the black probe to a known ground (perhaps one of the green FG wires that are probably hooked to everything) and test from there. You should get 110-120 VAC "everywhere it needs to be".

Then check the leads to the power supply board (my apologies for the earlier mistake on the page number) it is actually on page 25 of a hardcopy or 26 of the PDF.  Where I got those other page numbers I don't know.    Anyway, if you get 110 to the power supply, check the voltage coming from the supply itself. It looks as though the power supply has voltage regulation pots on it, so if you see any funny voltages, adjust those pots until you get the juice you need. (a poorly adjusted PS could be the cause of "junk on the screen" problem the seller told you about)

As for the backdoor switch, would you recommend I simply connect the wires together to simulate the switch always being closed, thus eliminating the use of the switch at all?

You sure can, and I have seen it done a lot. If you are getting ZERO power to anywhere on the cab (aside from the filter), I'd bet money this is where the problem lies.

That big block with all of the wires coming out of it is the isolation transformer. I have yet to see one die of "natural causes".

APf

[unclet]

I understand what you mean to test for 110Vac, but as to where to place the probes, I have not a clue.    I am not sure where 110Vac should be going into a monitor or going into the filter.   Actually, not sure what you mean by "leads into the power supply board" either.   There is a molex connector with many wires going into the power supply board ..... do your mean test a couple of these wires or something different?

I do see the 3 Pots on my Power Supply board.   The diagram in the PDF of the power supply board shows the Pots are -5V, +12V and +5V.   Should I check for these positive and negative values, or should they all have 110vac?  Basically, what is the difference between V an vac?  Not real sure where to put the probe on the wires leading into the pots either ..... I will try to play around with it.   

I just got back in from the garage trying to probe around loking for 110vac (before reading your latest reply), and I felt like a real idiot and having no idea where to put the probes.   I gave up.   I will retry again and see if I feel any smarter ......   

I feel bad about this, but I am also laughing a bit as well at how inept I am at even understanding what most of you consider trivial stuff.   Hopefully you will continue to hang in there with me before going completely mad.....

 

[APFelon]

I understand what you mean to test for 110Vac, but as to where to place the probes, I have not a clue.    I am not sure where 110Vac should be going into a monitor or going into the filter.   Actually, not sure what you mean by "leads into the power supply board" either.   There is a molex connector with many wires going into the power supply board ..... do your mean test a couple of these wires or something different?

I do see the 3 Pots on my Power Supply board.   The diagram in the PDF of the power supply board shows the Pots are -5V, +12V and +5V.   Should I check for these positive and negative values, or should they all have 110vac?  Basically, what is the difference between V an vac?  Not real sure where to put the probe on the wires leading into the pots either ..... I will try to play around with it.   

I just got back in from the garage trying to probe around loking for 110vac (before reading your latest reply), and I felt like a real idiot and having no idea where to put the probes.   I gave up.   I will retry again and see if I feel any smarter ......   

I feel bad about this, but I am also laughing a bit as well at how inept I am at even understanding what most of you consider trivial stuff.   Hopefully you will continue to hang in there with me before going completely mad.....

 

Heh, we all have to start somewhere. Thank God you have a "screw around" machine to toy with. Well, let's start with the basics.

When I say "VAC", that stands for "Volts Alternating Current", or the stuff that comes out of your wall. An arcade machine power supply (or a computer power supply) takes that current and turns it into something that is OK for a circuit board, or "V" (volts, understood to be DC or "direct current").

There are a few things that use VAC in your cabinet. The monitor uses it and the marquee lights use it. Everything else is converted by the power supply (the circuit board, the coin lights, any motors the machine may have, etc). SO, you put 110 VAC into a power supply, and it spits out +5v, +12v, -5v, etc. (if working correctly).

So in essence, you need to get the 110 VAC to three things in order for the game to work as intended. The coin door switch that you have will kill the 110 to everything on the other side of the switch, so if it is "open", it'll look as though the game is completely dead-- no marquee, no monitor, no game. The wall voltage will stop at that switch, and no current will go anywhere.

To see how to measure for 110, go ahead and stick the leads in to the wall socket. It'll register as 110VAC. Next, plug in the game and follow the cord to the next "step" in the circuit, in this case the filter. Check the VAC on the other side of the filter. You should get 110 VAC there, too. If not, you may have a break in the wall cord. This can sometimes happen if the cord gets pulled or crushed, so it is a possibility.

Now follow the two wires to the next step in the chain (skip the isolation transformer, as I doubt that it is bad). It should be the door kill switch. Close the switch (you can probably pull the switch out so it says "on" while you have the door open) and check there. If you get no voltage there, the switch is probably bad.

Other places to check for AC- The monitor should have a thick black cord running up to the monitor that can be detached at a Molex plug. Detatch the Molex and stick the probes into it, and look for 110.

So, where do you put the probes? Well, I would take an alligator clipped wire and attach one end to the black probe of your multimeter, and the other end to the green wire lead on the right hand side of your filter. That is known as the "field ground" and it should be okay for your ground as long as your line cord has that third prong on it. The red probe is the "live" probe and you use that on places that should have juice.

Just remember, be careful when you are probing the 110. Once we get through this part and start looking at the 5v, 12v, etc, the shock hazard will be minimal. But 110 is the wall voltage, and if you take a zap, it'll sting.

I hope this helps and you find the problem (but I have a feeling that this is just the beginning). Just keep me updated and I'll help the best I can.

APf

[unclet]

Thank you for your patience .....    Yes, part of the reason why I am giving this a try is because the cabinet was a FREE one.  I would be scared to mess up a valued cabinet just to play around with...

Ok, I think my confusion is that I am misunderstanding your naming of the parts of my machine.   I think I have now learned what you are referring to, but I want to make sure......

Is the silver box in this photo the "filter/silver thing" you referred to?  The wires which come from the plug in the wall go into this little silver box thing.  If so, then are you saying to place my black probe on the green wire there and then place the red probe on one of the remaining two wires going into this filter?   Also, if that is a correct description of what you are saying then I guess you also are telling me to test the blue and brown wires coming out of the other end of the filter as well?  If so, then assuming I keep my black probe on the green wire going in to the filter, then which of the two wires remaining (blue or brown) should register the 110Vac.

Also, in the picture below, is the round thing with all the wires coming from it represent the isolation transformer only? 

Next, when you say the next step from the filter for the 110vac route is the switch on the backdoor ... to basically just follow the wires to it .... seems to be a problem since the blue and brown wires coming from the other side of the filter lead into the isolation transformer and a bunch of wires come out of it, thus making it hard to follow to the switch.   Anyway, there are two wqires on the switch.  Most likely a wire connected to "Normally Open" and one connected to the "Common" of the switch.   Are you saying these two wires are going to have 110vac going through it.

Oh yeah, also, the switch which "kills" everything seems to be located against the "backdoor wood" panel.  when I take off the back door wood panel, the switch button pops out.  When the door is replaced, the button gets pushed in.  I have no coin door or coin mechs at all, in this cabinet, so there are no switches related to a coin door.

Ok, enough talk, I am going to play around now ......

PS: I still feel stupid at this point, but hopefully that will change.

[unclet]

and ..... is this complete board called to "Power Supply"

[APFelon]

Is the silver box in this photo the "filter/silver thing" you referred to?  The wires which come from the plug in the wall go into this little silver box thing.  If so, then are you saying to place my black probe on the green wire there and then place the red probe on one of the remaining two wires going into this filter?   Also, if that is a correct description of what you are saying then I guess you also are telling me to test the blue and brown wires coming out of the other end of the filter as well?  If so, then assuming I keep my black probe on the green wire going in to the filter, then which of the two wires remaining (blue or brown) should register the 110Vac.

I'm not too sure. I have been spoiled on the black/white/green color code of modern games, and my pre-JAMMA skills are a bit wanting, so I'm not too sure on how the wires are color coded. But that doesn't matter, you can find out for yourself. Test them both. One of them should give you 110, and then you know which color wire is "live" with 110 in your cabinet.

Also, in the picture below, is the round thing with all the wires coming from it represent the isolation transformer only? 

Yep, that's the monster.

Next, when you say the next step from the filter for the 110vac route is the switch on the backdoor ... to basically just follow the wires to it .... seems to be a problem since the blue and brown wires coming from the other side of the filter lead into the isolation transformer and a bunch of wires come out of it, thus making it hard to follow to the switch. 

That shouldn't matter, either. You know where the 110 is supposed to be, there should be no need to chase the wires coming out of your isolation transformer (unless there is a break, which is improbable).

Think of it this way. You tell a friend "Leave your home and meet me at the bar". You don't need to meet your friend at his home and follow him to the bar, you know he will meet you at the bar. Same thing with the voltage. If the 110 is coming from the filter, just go to the next place it should be (the kill switch).

Man, I hope that made sense.

Anyway, there are two wires on the switch.  Most likely a wire connected to "Normally Open" and one connected to the "Common" of the switch.   Are you saying these two wires are going to have 110vac going through it.

Yes, it should. If it doesn't, that's where your problem is.

If this switch is like the ones found on other Midway games of that era (Pac Man et. al), the switch has three positions. "in", which is when the back door is closed, "out", which is when the back door is open, and "way out", which is when you pull on the switch.  While you are doing your testing, give the switch a firm tug in order to close the circuit and check for voltage.

Oh yeah, also, the switch which "kills" everything seems to be located against the "backdoor wood" panel.  when I take off the back door wood panel, the switch button pops out.  When the door is replaced, the button gets pushed in.  I have no coin door or coin mechs at all, in this cabinet, so there are no switches related to a coin door.

The coin switches shouldn't matter. I know Paige mentioned that Sprint had issues of the coin switches were removed, but I have never heard of this on any 80s-era games. But who knows? It is possible. But since you aren't getting 110, we don't have to concern ourselves with that just yet.

PS: I still feel stupid at this point, but hopefully that will change.

Don't. When it comes to technical issues, I am not exactly Mr. Clarity so your confusion is understood. Here is a labeled photo so we can be on the same page.

APf

[unclet]

Ok ...... success has been made!

When I stuck the probes into a regular plug outlet, then my V-Ac reading was 125V-Ac.

[D_Zoot]

Double check the slam switch on the coin door by looking at it.

[unclet]

D_Zoot:
Thanks for the input....

You mention to look for the slam switch on the coin door, although I have no coin door mechs or anything, so I am not sure what you are referring to.

[D_Zoot]

The slam switch (Midway called it a "tilt" switch) would have been located on the inside of the coin door, near the door lock. It would be nothing more than two strips of metal with two wires going to it. These strips are mounted together with one of them having a small weight on it.  When the door was "slammed" inertia caused the weight to move and flex the metal strip it was attatched to, thus making/breaking contact with the other metal strip.

The wire colors I reference are right out of the manual.  Sadly, there is no "Standard" wiring or colors with these old games.   You might want to print out the schematic page that shows this wiring so you can follow along with the measurements you are taking and see how it works..

Good luck!
D

[unclet]

I looked at the game board logic PCB and the main PCB and the connection at the junction point looks ok.  I did not notice any strain pulling the solder points away.

I also looked around the coin door area for two metal strips and found nothing.  After asking the previous owner, I found out that the monitor went on and displayed a garbled image without having the coin door installed at all, so I do not think we need to worry about any metal strips which might be causing power to be interrupted .... I think....

I then performed the Ac and Dc tests on the power supply board (ie: white colored board). I tried to locate the schematic in the PDF file which related to the white power supply board and I think I found it on the page marked "Page 26", however, I could not figure out for the life of me how you determine the wire colors based on that schematic.   I saw in this schematic the values of 16.5V, 9V, 9V and 16.5, 12V, 5V and -5V and saw that each one had a number next to it (as if the line drawn on the schematic was assigned a number).   Does this number get mapped to a wire color somewhere else?  Any hints here on how to find wire colors so I can follow/learn a schematic would be nice.

Anyway, here are  the results:

V-Ac tests:

1) One lead on the White/Green wire and the other on the Yellow/Blue wire resulted in "6.9V-Ac" but should have been 12V-Ac

Note: The Yellow/Blue wire was all Blue with yellow marks on it.   I would assume this wire would be called a Blue/Yellow wire, however, since no yellow wire with blue marks existed, I used the Blue/Yellow wire for this test

... for tests 2) thru 5), I was suppose to place one lead on the yellow wire, although when I looked and the molex connector plug on the power supply board,  there were two yellow wires going to separate holes.   I simply placed one lead on the yellow wire which was closest to the wire color I was testing.

2) One lead on the Yellow wire and the other on the Black wire resulted in "19.38V-Ac" but should have been 16.5V-Ac

3) One lead on the Yellow wire and  the other on the Orange/Black wire resulted in "10.5V-Ac" but should have been 9V-Ac

Note: I was suppose to place the lead on Orange/Blue, but no wire with this color existed so I assumed Orange/Black was the next closest thing.

4) One lead on the Yellow wire and the other on the Red/White wire resulted in "10.5V-Ac" but should have been 9V-Ac

5) One lead on the Yellow wire and the other on the Grey wire resulted in "19.4V-Ac" but should have been 16.5V-Ac


V-Dc tests:

1) One lead on the Orange/Red wire and the other on the White wire resulted in varying V-Dc values steadily increasing to 265V-Dc, until I decided to pull the probes out.   The moment I placed the second probe, then the V-Dc values rose steadily .... 24, 55, 100, 150, 222, 250, 265 ....... do not know what this reading was all about.....  I tried this multiple times with always the same result.  This value should have resulted in 5V-Dc only

2) One lead on the Orange/Red wire and the other on the White/Brown wire resulted in 13V-Dc but should have been 12V-Dc

3) There is no Blue/White wire for me to perform the Orange/Red wire to Blue/White wire. 

Note1: There are two Blue wires going to the molex connector on the power supply board.   One is a Blue wire with yellow marks (which I used in the first (1) V-Ac test above) and the other Blue wire had brown marks (or maybe they were dark purple or something ..... hard to tell).    Anyway definitely no Blue/White or White/Blue wire, so I could not perform this test.


**IMPORTANT:   I will be leaving for vacation for one week, so this should conclude my testing until I return.   Please feel free to leave me some ideas on how to proceed though and I will read everything and reply when I return.   Thanks for all the help so far.....

[RayB]

(don't go pulling off or plugging in molex connectors while the power is on!)

[D_Zoot]

Wiring color I got right out of the schem link you posted. 

Wire color "lingo" generally runs along the lines of "R" = red,  "O" or "Org" = orange...    and so forth and so on....

It's possible I mistook some abbreviations on the schem, it is a pdf scan...    I'll look at it again...


D

[unclet]

I will look again when I get back from vacation but I was unable to find any letters "R" or "O" , etc...   If I saw any letters then I would have figured they meant colors.   Perhaps I looked at the wrong PDF page number......

Anyway, gotta finish packing .... leaving for vacation in 9 hours..... I will be looking forward to your reply when I return ......thanks for the effort...

[unclet]

Ok, back from vacation ........  I am ready to play around with this machine again so if you have any other recommendations on how to continue please let them be known .....thanks

[unclet]

D_Zoot:
Ok, I had time to relook at the power supply and found the page with the letters which represent colors.   I mapped all of the colors of the wires which I have and compared them to the documented page information.   I found a few differences (noted below in BOLD).   Anyway, when I retested the wires based on the colors I have, I received all V-Ac and V-Dc readings like you mentioned.

The V-Ac readings I received are as follows:

White/Green wire and Yellow/Black wire = 13.9V (which is ~12.0V)

Yellow wire and Black wire = 19.0V (which is ~16.5V)
Yellow wire and  Orange/Black = 10.3V (which is ~9.0V)
Yellow wire and Red/White wire = 10.3V (which is ~9.0V)
Yellow wire and Grey wire = 19.0V (which is ~16.5V)


The V-Dc readings I received are as folllows:

Orange/Red wire and White wire = 5.0V (exact)
Orange/Red wire and White/Brown wire = 13.0V (which is ~12V)
Orange/Red wire and Black/Green wire = -5.0V (exact)

Do these readings mean my power supply is fine?   Any ideas what to test next and how?

[unclet]

Ok, I found/replaced a missing 1.5Amp fuse for the monitor and now the monitor tube light up.  The image displayed is just solid white though. 

I friend sent me some pictures of his Space Encounters cabinet and I was able to see that the coin door present in the cabinet did have a slam switch attached to the back of it.   I do not have coin mechs or a slam switch on my cabinet .... all I have is the metal door front attached to the cabinet with no actual coin door parts behind it.  There is also a molex connector which is just hanging around from the wiring harness which is suppose to be used to connect to a fully functioning/populated coin door.

Anyway, do you think since my cabinet is wired for a slam switch and knowing I do not have the actual slam switch present on my cabinet, then I might need to connect the two wires together which were intended for use as a slam switch?  Is this a cause of my troubles?   Also, paigeoliver mentioned that maybe since the coin mech switches are not present then this might result in the game not booting ......

Basically, should I tried simply connecting all the coin mech switch wires to each other simulating that a coin mech is there?  Also, do I do the same with the slam-switch wires?


IMPORTANT FINDING?: I just verified my power supply board still was producing the 5V, 12V and -5V as stated in my previous posting ....  and it does as long as the "Main PCB Plug" (see labelled photo) IS NOT plugged into the Main PCB.   

When the "Main PCB Plug" IS plugged into the Main PCB, I get the following readings:

Orange/Red wire and White wire = 5.0V-Dc
Orange/Red wire and White/Brown wire = -56V-Dc
Orange/Red wire and Black/Green wire = -110V-Dc

Is this change in the V-Dc readings explainable when the plug is plugged into the board?