My Stargate needs help... 1-2-1 ram error

[quanlee]

I have a Stargate machine that has been giving me fits since I bought it a year ago. Although it was fine when I bought it, most of this past year it has not worked 100% for various reasons.

Right now, it's giving me a 1-2-1 error code when I turn it on. It shows the multi-color pixel screen which is normal, then it kind of hangs, sometimes staying on the same screen, sometimes going to a screen that looks like the game is running, but the video is all garbled. None of the buttons work, so it's pretty much dead at that point.

I understand the code 1-2-1 means, ram error, bank 2, chip 1.  I have pulled that chip out, replaced it with another from a different location, and same error. They only way I can get it to give me a different error is if I pull the chip from bank 3, chip 1, which I understand is the first chip tested, then I get 1-3-1.

I'm pretty much fed up with this, I didn't buy this thing to take up space in my rec room, I'm not playing it. I really don't want to sink more money into it, having it repaired by a onsite technician $$$$, so I'm thinking about just gutting it, selling off the boards and turning it into a multi-mame machine that plays Stargate and others.

I hate to destroy an original stargate arcade machine though.

I have a Ms Pacman that I restored using mame, but I bought that as a non-working empty cabinet, so I didn't feel so bad.

Any suggestions?

[RetroACTIVE]

Check your +5, -5, +12 supply voltages on the decoder pcb... many times power supply problems can cause ram errors...

Also... if your board is not conveted to 4164 RAMs... you should do that... its inexpensive and makes the system much more reliable.

 

Last Edit: Changed -12 to +12...oops

[quanlee]

I know nothing about electronics, can you explain in detail, what you mean by checking voltages? I understand the concept, but don't know which is the decoder pcb, or where to connect the voltage meter.

Where can I get 4164 rams?

[RetroACTIVE]

I know nothing about electronics, can you explain in detail, what you mean by checking voltages? I understand the concept, but don't know which is the decoder pcb, or where to connect the voltage meter.

Where can I get 4164 rams?

You will need a multimeter to check voltage...
The decoder PCB is the largest PCB of the 4... the power connector is towards the bottom left right below the reset button...

I may have a spare set of 4164's I could sell ya cheap... I'll have to check...

Here is an excellent site for Williams boards:

http://www.robotron-2084.co.uk/techwilliamshardwareid.html#stargate

[quanlee]

You will need a multimeter to check voltage...
The decoder PCB is the largest PCB of the 4... the power connector is towards the bottom left right below the reset button...

I may have a spare set of 4164's I could sell ya cheap... I'll have to check...

Here is an excellent site for Williams boards:

http://www.robotron-2084.co.uk/techwilliamshardwareid.html#stargate

I've been to that site, that's where I learned where the ram chips are located. I've identified my cpu board as revision B version. When you say decoder board, you mean the cpu board where the ram resides, correct?

My cpu board is actually turned 90 degrees clockwise in my cabinet, so the reset button is on the top, but I understand where you are talking about.

Call me stupid, but with multi-meter in hand, where do I place the two sensors? I believe there are multiple wires in the power connector. Do I disconnect it and test one and or all of them?

Sorry, I'm electonically challanged.

[RetroACTIVE]

Yes the CPU is the decoder...

Download the stargate upright drawing set... it has all the schematics and interconnections... here is an excerpt from the drawing set...

put your multimeter on VDC and connect the black (common lead) to the GROUND as indicated in the pic... then connect your red lead to each of the other +5, +12 and -5 and record their readings...

oh.. and don't disconnect anything... put the probe right into the connector assembly where the wire goes in... you should be able to make contact with the metal contact in the housing... be careful not to short anything....

[quanlee]

Yes the CPU is the decoder...

Download the stargate upright drawing set... it has all the schematics and interconnections... here is an excerpt from the drawing set...

put your multimeter on VDC and connect the black (common lead) to the GROUND as indicated in the pic... then connect your red lead to each of the other +5, +12 and -5 and record their readings...

oh.. and don't disconnect anything... put the probe right into the connector assembly where the wire goes in... you should be able to make contact with the metal contact in the housing... be careful not to short anything....

Awesome... thanks!

[RetroACTIVE]

Yes the CPU is the decoder...

Download the stargate upright drawing set... it has all the schematics and interconnections... here is an excerpt from the drawing set...

put your multimeter on VDC and connect the black (common lead) to the GROUND as indicated in the pic... then connect your red lead to each of the other +5, +12 and -5 and record their readings...

oh.. and don't disconnect anything... put the probe right into the connector assembly where the wire goes in... you should be able to make contact with the metal contact in the housing... be careful not to short anything....

Awesome... thanks!

We're going to try to fix this... so it does not get to the "gutting" point.... If you reach that point... then sell it as is... use the money and go for a more generic approach for a mame/multi-game solution. 

[quanlee]

Yes the CPU is the decoder...

Download the stargate upright drawing set... it has all the schematics and interconnections... here is an excerpt from the drawing set...

put your multimeter on VDC and connect the black (common lead) to the GROUND as indicated in the pic... then connect your red lead to each of the other +5, +12 and -5 and record their readings...

oh.. and don't disconnect anything... put the probe right into the connector assembly where the wire goes in... you should be able to make contact with the metal contact in the housing... be careful not to short anything....

Awesome... thanks!

We're going to try to fix this... so it does not get to the "gutting" point.... If you reach that point... then sell it as is... use the money and go for a more generic approach for a mame/multi-game solution. 

Yeah, good idea. It's just frustrating for me. I've been working on computers and software for 25 years, and feel so much more comfortible with the idea of a PC, computer monitor, keyboard encoder, and so on. I guess I need to learn something about these machines if I'm going to own one.

[RetroACTIVE]

Yeah, good idea. It's just frustrating for me. I've been working on computers and software for 25 years, and feel so much more comfortible with the idea of a PC, computer monitor, keyboard encoder, and so on. I guess I need to learn something about these machines if I'm going to own one.

You will be surprised... its not that bad... Williams boards are well documented and don't have a pile of custom ICs... all really standard stuff and pretty basic... I would say 90% of Williams failures are due to connectors and power supply voltage weakness...

Do you know if your machine is still using the original power supply or has a switcher installed?  You can tell if switcher is installed if there is a rectangular metal box with screw terminals connected to the wiring system of the cabinet... people tend to leave the original supply in and just hook up the new switcher in tandem.

[ahofle]

Just wanted to say to RetroACTIVE.

[Kaytrim]

Just wanted to say to RetroACTIVE.

I agree.  This baby is worth saving.

p.s. Maybe this thread should be moved to the Arcade Miscellaneous forum.

[quanlee]

Yeah, good idea. It's just frustrating for me. I've been working on computers and software for 25 years, and feel so much more comfortible with the idea of a PC, computer monitor, keyboard encoder, and so on. I guess I need to learn something about these machines if I'm going to own one.

You will be surprised... its not that bad... Williams boards are well documented and don't have a pile of custom ICs... all really standard stuff and pretty basic... I would say 90% of Williams failures are due to connectors and power supply voltage weakness...

Do you know if your machine is still using the original power supply or has a switcher installed?  You can tell if switcher is installed if there is a rectangular metal box with screw terminals connected to the wiring system of the cabinet... people tend to leave the original supply in and just hook up the new switcher in tandem.

My machine has this power supply, or something similar looking.



As well as a large transformer in the bottom of the cabinet.

Where can I get the 4164 ram chips? Do I need to mod my cpu board to use them?

[RetroACTIVE]

That is the original power supply... if it has never been reconditioned... then the caps are pretty old and maybe not doing their job so well...

For 4164 mod... you need a simple jumper to go between your CPU board and the CPU board power connector, basically it bypasses the +12v and -5V requirement.  Then you replace your RAM chips...

Bob Roberts sells the jumper and also 4164 ram in sets of 24... he also sells Williams power supply rebuild kits too!

[RetroACTIVE]

p.s. Maybe this thread should be moved to the Arcade Miscellaneous forum.

Yup... I've already notified moderators... 

[quanlee]

That is the original power supply... if it has never been reconditioned... then the caps are pretty old and maybe not doing their job so well...

For 4164 mod... you need a simple jumper to go between your CPU board and the CPU board power connector, basically it bypasses the +12v and -5V requirement.  Then you replace your RAM chips...

Bob Roberts sells the jumper and also 4164 ram in sets of 24... he also sells Williams power supply rebuild kits too!

Since you've been so helpful, I have another questions for you. While poking around under my control panel, there appears to be a ground ribbon that looks like it used to be connected to both the interior cabinet, and the bottom side of the control panel, possibly to the joystick housing. It's a braided ribbon.

Now, it's not attached to anything other than the bottom side of the control panel. It's attached with a staple about midpoint in the ribbon. Both ends are not attached to anything. Should they be?? I didn't disconnect them, but it's possible someone else did. At some point prior to this current issue, I was having problems with the control panel not working.

[RetroACTIVE]

Since you've been so helpful, I have another questions for you. While poking around under my control panel, there appears to be a ground ribbon that looks like it used to be connected to both the interior cabinet, and the bottom side of the control panel, possibly to the joystick housing. It's a braided ribbon.

Now, it's not attached to anything other than the bottom side of the control panel. It's attached with a staple about midpoint in the ribbon. Both ends are not attached to anything. Should they be?? I didn't disconnect them, but it's possible someone else did. At some point prior to this current issue, I was having problems with the control panel not working.

Thats the ground braid, Williams grounded every metal piece of the cabinet by strapping the braid from here to there to everywhere back to the 3rd prong of the AC plug (earth ground).  There are good reasons for grounding everything... as long as you have a good earth ground, using a 3-2 prong adapter or busting your plug... basically breaks the whole thing.  Good ground = good... bad ground = bad!  Some people choose to not ground the metal pieces just in case the unit is not properly earth grounded.  Personally, I think it should be configured the way it was from the factory... In your case... I would not worry about that so much for now... its way far away in the scheme of things.  We can re-connect it later.

Edit:

I almost forgot... the problem you were having earlier most likely the ground braid was not the case... since the controls get their ground from the wire harness... Your problem was likely weak connection back at the I/O board or dirty contacts.  You can clean the contacts rubbing a business card in between them while they are compressed.

[quanlee]

Since you've been so helpful, I have another questions for you. While poking around under my control panel, there appears to be a ground ribbon that looks like it used to be connected to both the interior cabinet, and the bottom side of the control panel, possibly to the joystick housing. It's a braided ribbon.

Now, it's not attached to anything other than the bottom side of the control panel. It's attached with a staple about midpoint in the ribbon. Both ends are not attached to anything. Should they be?? I didn't disconnect them, but it's possible someone else did. At some point prior to this current issue, I was having problems with the control panel not working.

Thats the ground braid, Williams grounded every metal piece of the cabinet by strapping the braid from here to there to everywhere back to the 3rd prong of the AC plug (earth ground).  There are good reasons for grounding everything... as long as you have a good earth ground, using a 3-2 prong adapter or busting your plug... basically breaks the whole thing.  Good ground = good bad... ground = bad!  Some people choose to not ground the metal pieces just in case the unit is not properly earth grounded.  Personally, I think it should be configured the way it was from the factory... In your case... I would not worry about that so much for now... its way far away in the scheme of things.  We can re-connect it later.

Edit:

I almost forgot... the problem you were having earlier most likely the ground braid was not the case... since the controls get their ground from the wire harness... Your problem was likely weak connection back at the I/O board or dirty contacts.  You can clean the contacts rubbing a business card in between them while they are compressed.

Got it, Thanks!

[quanlee]

Yes the CPU is the decoder...

Download the stargate upright drawing set... it has all the schematics and interconnections... here is an excerpt from the drawing set...

put your multimeter on VDC and connect the black (common lead) to the GROUND as indicated in the pic... then connect your red lead to each of the other +5, +12 and -5 and record their readings...

oh.. and don't disconnect anything... put the probe right into the connector assembly where the wire goes in... you should be able to make contact with the metal contact in the housing... be careful not to short anything....

I checked those connections and here are the voltages:

Number 9: 5.13
Number 8: 12.48
Number 7: 4.75
Number 5: 12.27

Should number 7 be 5 volts? Is that my problem?

[RetroACTIVE]

I checked those connections and here are the voltages:

Number 9: 5.13
Number 8: 12.48
Number 7: 4.75
Number 5: 12.27

Should number 7 be 5 volts? Is that my problem?

Good Job!

Ok... pin 7 should be between 4.9 and 5.1 volts... yes it looks a little low 

The rest look ok... except you listed pin 9 as 5.13.... do you mean -5.13...

[quanlee]

Good Job!

Ok... pin 7 should be between 4.9 and 5.1 volts... yes it looks a little low 

The rest look ok... except you listed pin 9 as 5.13.... do you mean -5.13...

Yeah, I must have missed the negative sign.

So... how do I fix that, new switching power supply? I'm pretty sure I can track that down if that's the case, but what's the process of installing it?

[RetroACTIVE]

Good Job!

Ok... pin 7 should be between 4.9 and 5.1 volts... yes it looks a little low 

The rest look ok... except you listed pin 9 as 5.13.... do you mean -5.13...

Yeah, I must have missed the negative sign.

So... how do I fix that, new switching power supply? I'm pretty sure I can track that down if that's the case, but what's the process of installing it?

There are two possible paths here...

Install a switcher... as you have said... or re-build your linear supply...  depending upon your comfort level either one is acceptable...

Before we go there... lets try one more thing...

You see... as connectors get old and begin to loose their resilience... they begin to loosen up and create intermittent and sometimes resistive faults... I would recommend you unplug and plug the power connector from the PCB a couple of times to refresh it... then re-measure your voltage to see if there is a change...

[quanlee]

There are two possible paths here...

Install a switcher... as you have said... or re-build your linear supply...  depending upon your comfort level either one is acceptable...

Before we go there... lets try one more thing...

You see... as connectors get old and begin to loose their resilience... they begin to loosen up and create intermittent and sometimes resistive faults... I would recommend you unplug and plug the power connector from the PCB a couple of times to refresh it... then re-measure your voltage to see if there is a change...

I had read that could help, so that's what I tried first. I did that with most of the power connections on the cpu and other boards already.

If it will help, for the cost, I'd rather just replace the power supply. I was checking on arcadeshop.com and they have both a generic "15amp switching power supply (+5vdc @ 15A, +12vdc @3A and -5vdc @1A)"



and also a "Stargate power supply conversion kit".



Which one, or something else??

[RetroACTIVE]

You could go arcadeshop or Bob Roberts... If you use Bob... you can upgrade your RAM while your at it 

[RetroACTIVE]

http://homearcade.org/BBBB/parts.html

Check the bottom of the page... he offers the Williams switcher kit for $45... with instructions 

Also

Wms 4116 to 4164 Ram Power Adaptor                        $8.50
4164 Ram (Alt Mfrs 3764 - 4264 - 4864 - 8264 - 9064)    $1.00 ea.

I think the power adapter is pricey... but if you don't have the stuff its all done for ya!

[quanlee]

You could go arcadeshop or Bob Roberts... If you use Bob... you can upgrade your RAM while your at it 

Got it... thanks.

[RetroACTIVE]

Ok... now I don't want you to get discouraged if this doesn't work... sometimes stuff seems obvious but does not always pan out... I can definitely say... your power supply is old and it is not quite keeping up the 5V rail well enough...

When you get through with this mod...(which is worth doing!) you will not have to worry about the 5V supply any more. 

[quanlee]

Ok... now I don't want you to get discouraged if this doesn't work... sometimes stuff seems obvious but does not always pan out... I can definitely say... your power supply is old and it is not quite keeping up the 5V rail well enough...

When you get through with this mod...(which is worth doing!) you will not have to worry about the 5V supply any more. 

Yeah, I know, it's a crap shoot, this thing is 25+ years old.

If I change out the power supply, I assume I'm only replacing the power supply mounted up on the side of the cab, not the ancient looking transformer on the bottom of the cab, right?

[quanlee]

http://homearcade.org/BBBB/parts.html

Check the bottom of the page... he offers the Williams switcher kit for $45... with instructions 

Also

Wms 4116 to 4164 Ram Power Adaptor                        $8.50
4164 Ram (Alt Mfrs 3764 - 4264 - 4864 - 8264 - 9064)    $1.00 ea.

I think the power adapter is pricey... but if you don't have the stuff its all done for ya!

If I use the 4116 to 4164 Ram Power Adaptor, does that mean I don't have to jumper my cpu board?

[RetroACTIVE]

You are going to leave everything as is in the cabinet... you will not need to remove anything...Just find an appropriate place to mount the switcher and the harness that Bob provides will connect to the main power harness that normally would connect to the power pcb.

Yes... the power adapter does the jumpering for you... so you will not have to modify your pcb!   

[quanlee]

You are going to leave everything as is in the cabinet... you will not need to remove anything...Just find an appropriate place to mount the switcher and the harness that Bob provides will connect to the main power harness that normally would connect to the power pcb.

Yes... the power adapter does the jumpering for you... so you will not have to modify your pcb!   

If I have an AT or ATX computer power supply (prolly do in one of my many dead computers I have in my basement) can I use that rather than buying a new switching power supply?

[quanlee]

You are going to leave everything as is in the cabinet... you will not need to remove anything...Just find an appropriate place to mount the switcher and the harness that Bob provides will connect to the main power harness that normally would connect to the power pcb.

Yes... the power adapter does the jumpering for you... so you will not have to modify your pcb!   

Could you explain the relationship of the power supply and the transformer? Does the power come into the transformer, and get distributed to the power supply? Or vice versa? What is the purpose of the transformer?

Thaks for your help.

[RetroACTIVE]

You are going to leave everything as is in the cabinet... you will not need to remove anything...Just find an appropriate place to mount the switcher and the harness that Bob provides will connect to the main power harness that normally would connect to the power pcb.

Yes... the power adapter does the jumpering for you... so you will not have to modify your pcb!   

Could you explain the relationship of the power supply and the transformer? Does the power come into the transformer, and get distributed to the power supply? Or vice versa? What is the purpose of the transformer?

Thaks for your help.

Sure...

The AC transformer has a few windings in it... for monitor isolation and stepping down the voltage for the power supply pcb... this is where the AC power comes in and is distributed out... like you stated.

The ac voltages off of the secondary winding of the transformer go to the power pcb where they are rectified and regulated.  The power pcb then puts out +5 regulated -5 regulated, +12 regulated, +12 unregulated, -12 unregulated to the different pcbs.  There is another connector on the power pcb that puts out unregulated and ac voltages to the coin door... ~6-7VAC to the lamps and ~24VDC to the lock-out coil.

So the switcher kit will replace all of the regulated voltages to each of the pcbs... that is 5VDC, -5VDC and +12VDC.... The switcher does not supply -12VDC (unregulated)... but the only pcb that needs that voltage is the sound board... which also takes +12VDC (unregulated)... and uses these two voltages and regulates them to create its own +5V DC power supply... so the switcher will supply the +12VDC and -5VDC to the sound board which will work just fine for this purpose... (basically it does not technically matter if you give a voltage regulator regulated voltages... it will still work... )

does this make sense?

[quanlee]

You are going to leave everything as is in the cabinet... you will not need to remove anything...Just find an appropriate place to mount the switcher and the harness that Bob provides will connect to the main power harness that normally would connect to the power pcb.

Yes... the power adapter does the jumpering for you... so you will not have to modify your pcb!   

Could you explain the relationship of the power supply and the transformer? Does the power come into the transformer, and get distributed to the power supply? Or vice versa? What is the purpose of the transformer?

Thaks for your help.

Sure...

The AC transformer has a few windings in it... for monitor isolation and stepping down the voltage for the power supply pcb... this is where the AC power comes in and is distributed out... like you stated.

The ac voltages off of the secondary winding of the transformer go to the power pcb where they are rectified and regulated.  The power pcb then puts out +5 regulated -5 regulated, +12 regulated, +12 unregulated, -12 unregulated to the different pcbs.  There is another connector on the power pcb that puts out unregulated and ac voltages to the coin door... ~6-7VAC to the lamps and ~24VDC to the lock-out coil.

So the switcher kit will replace all of the regulated voltages to each of the pcbs... that is 5VDC, -5VDC and +12VDC.... The switcher does not supply -12VDC (unregulated)... but the only pcb that needs that voltage is the sound board... which also takes +12VDC (unregulated)... and uses these two voltages and regulates them to create its own +5V DC power supply... so the switcher will supply the +12VDC and -5VDC to the sound board which will work just fine for this purpose... (basically it does not technically matter if you give a voltage regulator regulated voltages... it will still work... )

does this make sense?

Yes, starting to I think.

So once this conversion is done the power comes into the transformer, then is disributed to the monitor, and new switching power supply. The switching power supply provides power to all pcb's. Is the power going to the coin door still coming from the original power supply? Can that original linear power supply be removed?

I know you said it doesn't have to be remoevd, but can it?? Just trying to understand how this works.

Also... did you see my question about using a standard AT or ATX PC power supply?

[RetroACTIVE]

Yes, starting to I think.

So once this conversion is done the power comes into the transformer, then is disributed to the monitor, and new switching power supply. The switching power supply provides power to all pcb's. Is the power going to the coin door still coming from the original power supply? Can that original linear power supply be removed?

I know you said it doesn't have to be remoevd, but can it?? Just trying to understand how this works.

Also... did you see my question about using a standard AT or ATX PC power supply?

You really can't remove the transformer... its necessary for the monitor ... you could live without the coin door lamps and strap the lockout coil...so technically the power pcb could be removed... but I wouldn't waste your time... its not going to hurt leaving it in there... plus if you ever decide to sell it... it will still be "original"... which makes it more valuable...

You could use an ATX... but really the problem with that is that it is not adjustable... switchers are pretty finicky about proper loads for the regulation to be correct.... plus you will have to jumper that big honkin 20PIN header so it will turn on correctly... I would stick with the kit from Bob... its cleaner and it will save you a bunch of time and will work with little or no bother.

[quanlee]

What about this one?? Includes everything for PS and memory upgrade.

Click Here

[RetroACTIVE]

What about this one?? Includes everything for PS and memory upgrade.

Looks fine... but I'm not too familiar with that switcher... the switcher that Bob sells is the defacto standard switcher nowadays... I have used a few ... the adjustment makes it easy to calibrate the supply to your system... and is fairly cheap...

$45 (psu kit) + $24 (ram) + $9 (adapter) = $78.00... still cheaper than that ebay auction, Bob won't gouge you on shipping either. probably around 6-10bucks (depending upon where you live).

[quanlee]

I installed the new switching power supply and upgraded the ram and it still gives me the 1-2-1 error code on the ROM board. What now??

[cw]

check the for the proper voltages on the ram then start looking for broken traces to that slot.

[RetroACTIVE]

I installed the new switching power supply and upgraded the ram and it still gives me the 1-2-1 error code on the ROM board. What now??

It could very well be the socket itself... over time they loose thier strength and can be intermittent.... you can check this by disconnecting the board and using your multimeter to measure the resistance from the pin of the chip (top side) to the solder connection below...

Also like cw stated... double check your +5V

Don't give up yet...