Asteroids Plays Blind. High Voltage Issue?

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Hello everyone,

I have a Asteroids cabinet that is playing blind. As far as I can tell all game feature work including sounds/buttons. Self-Test mode does not display anything on the screen. The red LED on the game board is lit while the system is on. The red LED on the pale board next to the monitor (parallel to the side of the cab) is NOT lit. I checked video X and Y voltages off the game board and they were hovering around 3.6v. I have a oscilloscope, but only one lead so I can't test both outputs using the oscilloscope as a temporary screen. The neck on the back of the display glows a "healthy" orange. When viewing the front of the display you can occasionally see little tiny flits of static, which may not even exist. I checked the "5.5V" clip on the Regulator/Audio PCB and it seemed to be stable at 5.56VDC. I've checked all the fuses I could find.

This Asteroids has been in storage for several years but I was playing it when it actually 'went out'. I'm not sure if this description makes sense but I was in the middle of a game and the monitor faded away and my impression was that as everything was fading all the asteroids were moving away from the center of the screen. This was 5 years ago but that what I remember.

Everything I've found online points to an issue with the high voltage. My father (who has since passed and used to repair coin-op in the 80s), did say at the time that he thought it was the high voltage. I did see on the "ASTEROIDS Troubleshooting Encyclopedia" the following:
Problem: Game played but nothing on the screen except for a general glow that varied as the game was played blind, X and Y outputs were erratic
Fix: 7915CT voltage regulator at VR2 was bad – replaced

There doesn't seem to be a glow on the front, but there is on the neck, maybe this is the glow described in the "problem" section? I think not because the tube end of the monitor does not vary at all. I've heard other solutions including replacing the "Big Blue" cap in the bottom of the cab. Everything I've heard about this solution says that only usually fixes issues if you aren't getting DC on the system boards, which I am on the audio PCB.

I don't know which monitor or board rev or anything I have at this point. I can take a look at those tonight. I can tell you that this is production #6606 and has the sticker on the bottom center of the monitor. I have all kinds of tools and have a mild background in digital electronics. I am a little wary of looking at the high voltage circuits without knowing exactly what I'm doing.

Any help you could provide would be greatly appreciated. Thank you for your time.
 
A friend of mine's father in law apparently fixes coin-op stuff. I sent him this post also, here was his response:

Monitor is out. STOP playing with the game pc board, find a good monitor guy, remove the monitor from the cabinet and take it to him.

Thoughts?
 
Most likely cold solder points on the monitor boards. Remove the board(s) and resolder all the pins for all the plugs. Very common problem.
 
Most likely cold solder points on the monitor boards. Remove the board(s) and resolder all the pins for all the plugs. Very common problem.

Will remove and do that tonight. Any suggestions for safety when dealing with these boards? Whats a safe way to discharge the big caps on these?

Edit: After some research I'll check the voltage on the caps and discharge them with a resistor or a bulb.
 
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Will remove and do that tonight. Any suggestions for safety when dealing with these boards? Whats a safe way to discharge the big caps on these?

Edit: After some research I'll check the voltage on the caps and discharge them with a resistor or a bulb.

Don't worry about the caps. Discharge the tube. Stick a 1mΩ resistor inline with whatever you use to discharge CRTs.

Check your fuses, reflow all the headers on the HV & deflection PCBs, and check for shorted transistors on the frame. These things cause the majority of problems on these monitors, and they are very reliable once fixed.
 
Don't worry about the caps. Discharge the tube. Stick a 1mΩ resistor inline with whatever you use to discharge CRTs.

Check your fuses, reflow all the headers on the HV & deflection PCBs, and check for shorted transistors on the frame. These things cause the majority of problems on these monitors, and they are very reliable once fixed.

So, I reflowed the HV cage and the deflection board (the one with the two large tall blue caps). The screen still does not work but I think something may have changed. The Spot Killer light is now on but very dim. I thought I remember specifically looking at it and noticing it was off but I think it is possible that it was on the whole time. This could also be two problems. One was fixed by reflowing the Electrohome PCBs, exposing the Spot Killer, which couldn't have been on without the high voltage being on, right?

I discharged the CRT using 10 100k ohm resistors (series) and a screw driver. I heard no pop or spark, but once I removed the Electrohome housing from the cab I regrounded the CRT and the HV anode and then checked the voltage with a spare DMM. It had a voltage of 300mv so I figure I'm good. This last fully worked over 5 years ago. My thinking is that the high voltage went out and the CRT disipated over those 5 years leaving it with no charge. Any way to check if the HV is working correctly without discharging the CRT manually? This would at least assure us that the HV circuit is working correctly and we can cross that off the list.

I'm going to take a look at the voltages on the X, Y, Z outputs on the system board again.

In the mean time, any other ideas or input?

Edit: Looking at this more I'm not getting 5v on the game board or sound board. The connectors on the deflector board seem to be getting the right voltages. The ground on the PC board has continuity with the ground on the audio board and with the Electrohome enclosure. Everything appears to be assembled correctly. Maybe not?
 
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So, I reflowed the HV cage and the deflection board (the one with the two large tall blue caps).
Does your monitor look like this, with three boards? (the HV cage counts as a board)
g05-801.jpg


Or this, with only two?
4t0h_sl371915.jpg


Regardless, you need to reflow the connectors on ALL the boards. Do that, if you didn't already.

The screen still does not work but I think something may have changed. The Spot Killer light is now on but very dim. I thought I remember specifically looking at it and noticing it was off but I think it is possible that it was on the whole time. This could also be two problems. One was fixed by reflowing the Electrohome PCBs, exposing the Spot Killer, which couldn't have been on without the high voltage being on, right?

Not quite. Likely the monitor was getting no voltage of any sort before, and the spotkiller wasn't on because there was no power to run it. After reflowing, you have enough voltage to operate some circuits, and the SK can illuminate to tell you that there's still another problem.

The SK couldn't be on without voltage, but the state of the SK does not tell you anything about what's going on inside the HV cage.

I discharged the CRT using 10 100k ohm resistors (series) and a screw driver. I heard no pop or spark, but once I removed the Electrohome housing from the cab I regrounded the CRT and the HV anode and then checked the voltage with a spare DMM. It had a voltage of 300mv so I figure I'm good. This last fully worked over 5 years ago. My thinking is that the high voltage went out and the CRT disipated over those 5 years leaving it with no charge. Any way to check if the HV is working correctly without discharging the CRT manually? This would at least assure us that the HV circuit is working correctly and we can cross that off the list.

No pop or spark is common with the resistors in line like that. The charge in the tube dissipates quickly (probably not longer than a day), but you should ALWAYS discharge it before working on it.

If you have HV, there will be static electricity on the screen, strong enough to keep a piece of paper stuck to the face of the tube. If you can't do that, you've got no (or low) HV. However, even if HV is absent, the fact that the spotkiller is on means that you also have deflection issues.

I'm going to take a look at the voltages on the X, Y, Z outputs on the system board again.

In the mean time, any other ideas or input?

Listen for deflection chatter. Anything?

Try the paper test. Also, crank the brightness up. Do you get a spot in the center of the screen? Is there a partial image? Either of those are indications that HV is good and you only have deflection problems. If there's a dot in the center, turn the brightness back down, as you will burn a hole through the phosphor if you leave it like that.

The spotkiller activates when deflection through the yoke drops below a certain threshold. If it's dimly lit or flickering, that's an indication that you have partial deflection, right at the threshold where it shuts the image off. Turning the brightness up will override the spotkiller, and let you see what is going on.
 
So there was an edit to my previous post that nothing on the game board was working. I have the Electrohome G05 which has the two exposed boards plus the high voltage cage (as in your first picture).

I reinstalled the monitor, plugged it in and the monitor did not work but I was able to hear the game sounds and play. I turned the machine off to take a look in the back. When I turned it back on NOTHING happened except the attraction florescent came on. No voltage anywhere on the game boards. There was voltage on the Electrohome. After some investigation fuse F2 was blown in the power supply assembly in the bottom of the cab.

The manual shows that it should be replaced with "7-Amp, 250V 3AG Slow-Blow Glass Cartridge-Type Fuse". I pulled the fuse and it says "32 VOLT" on one end and "BUSSMDL 5" which according to a quick Google is "FUSE, 5A, 250V, T, 6X32mm, GLASS TIME DELAY" (Link: http://www.galco.com/buy/Bussmann/MDL-5 ). Perhaps this was replaced with the wrong fuse? Why does it say 32 VOLT if multiple sites say its 250V? Either way should this be replaced with a 5A or 7A fuse? Why did this fuse blow?

I think the fact that the fuse is blown means no XYZ outputs which would explain why the SK is on, correct? I'll run to the store and see if I can find these fuses (are they rare?) tomorrow. Should I just replace the fuse and give it a shot, or investigate why the fuse was blown before moving forward?

Edit: To answer your other questions: No, no chatter at the moment, but thats to be (not) expected with the game board not working. There is no static on the screen nor any of the "crackling" you hear when turning on CRTs. I put my arm close to the screen and my hair did not stand up. The SK _IS_ very dimly lit compared to what the red LED on the game board's brightness was. Hopefully when the game board is working again, we'll have more information. Fingers crossed.
 
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I went ahead and replaced the fuse with the factory recommended fuse (250V 7A) and the machine turned on and played. Still blind. The game board LED is on as expected but the Spot Killer is off (also to be expected). I can listen and hear some mild clicking from the Electrohome. I think this is the chatter everyone is talking about. This means that the deflection board is working correctly, right?

No paper sticks to the tube though the neck is glowing. Brightness control doesn't do anything. I didn't reflow the 3rd board on the side with the contrast/brightness controls. Is that still something I should do? Can anything on this board affect the high voltage circuit?

I removed the Electrohome and inspected all of the solder traces. I see no sign of cracking at all. All of the solder connections look healthy. My gut feeling is that the green block in the first picture (EHT Full Board Top) is a diode that is known to commonly fail. Any idea how to test this diode and possibly replace it? Here are the pictures. Click each picture for the full version:

EHT Supply







Deflection Amplifier







Continued next post due to image limit.
 
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Continued from previous post. Click images for full version:

Deflection Regulator







Enclosure



 
I went ahead and replaced the fuse with the factory recommended fuse (250V 7A) and the machine turned on and played. Still blind. The game board LED is on as expected but the Spot Killer is off (also to be expected). I can listen and hear some mild clicking from the Electrohome. I think this is the chatter everyone is talking about. This means that the deflection board is working correctly, right?

No paper sticks to the tube though the neck is glowing. Brightness control doesn't do anything. I didn't reflow the 3rd board on the side with the contrast/brightness controls. Is that still something I should do? Can anything on this board affect the high voltage circuit?

Both of those photos are G05 monitors. The first is the G08-801, and the second is the G05-802.

I don't know if I'd call it clicking, but yes, that is probably chatter you're hearing. I'd describe it as a staccato buzz. I really should make a video with good sound so it's clear.

So, yes, at this point you have HV issues. Yes, you need to reflow all connectors on all boards. I haven't worked on the -801, but on an -802, the power for the HV cage runs through traces on the deflection board, and cold joints there can cause HV loss.

Unfortunately the -801 is less repairable than the -802 or a V2000, and if you have chatter and neck glow but no HV, that points to a problem with the voltage doubler in the HV cage, which is an obsolete and hard to find part. And you can't swap in a V2000 or -802 cage into this monitor.
 
I did some research and found the following HERE:

This problem, called the blooming effect, is when the monitor screen keeps growing after power up. It fills the screen making it seem like you have the monitor set to magnify. After complete warm up you will only be able to see the center of the image in very large size. The adjusting pots will not help in this case. It is most likely caused by a bad high voltage (HV) diode. On the Electrohome G05-802 or Wells Gardner 19V2000 monitor the problem lies with the HV diode (D904). This diode is located in the HV cage. It is in-line with the HV transformer T900 and the suction cup attached to the monitor. Make sure to install the new diodes cathode side (usually marked with a line) towards the suction cup. This diode cannot be checked with a normal diode checker.

In the Electrohome G05-801 monitor there is no D904 diode in-line with the suction cup. The 801 uses a part called VD900,. This is a voltage doubler. This part is no longer available; but thanks to some creative thinking, it has been duplicated in the form of 2 HV diodes and HV cap. See diagram below for simple set up and parts list.

If you take a look at my original description this coincides with the "asteroids flying away from the center" I stated in the original post. This may have been the voltage doubler failing and exhibiting the "zooming" affect. I'll update as I find more.

Update: It looks like you can't find the part any more. I'm going to look up the model numbers and see if I can find one on ebay or something. If not I'll go with the "goop" strategy here: http://www.arcadesolution.com/blooming.html

Update 2: Looks like ieure beat me to it!

Update 3: Doesn't look like the part exists on the internet and everywhere I've found says "you're screwed" or something similar. I'm off to go find the parts from the link above and get to work! I'll post pictures along the way.

Update 4: I purchased a kit from ArcadeSolution that has all the parts necessary. Will reply to this post when I have received the parts and am building the new diode replacement circuit.
 
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I did some research and found the following HERE:



If you take a look at my original description this coincides with the "asteroids flying away from the center" I stated in the original post. This may have been the voltage doubler failing and exhibiting the "zooming" affect. I'll update as I find more.

Update: It looks like you can't find the part any more. I'm going to look up the model numbers and see if I can find one on ebay or something. If not I'll go with the "goop" strategy here: http://www.arcadesolution.com/blooming.html

Update 2: Looks like ieure beat me to it!

Update 3: Doesn't look like the part exists on the internet and everywhere I've found says "you're screwed" or something similar. I'm off to go find the parts from the link above and get to work! I'll post pictures along the way.

Update 4: I purchased a kit from ArcadeSolution that has all the parts necessary. Will reply to this post when I have received the parts and am building the new diode replacement circuit.

Good luck! There are other things in the HV cage which can fail as well, but this does seem like the most likely culprit.

Worst case, I think you should be able to replace the whole chassis with a G05 or V2000 setup.
 
Hello everyone! My asteroids is up and running again successfully! I purchased the Kit #2 (the HV diode replacement parts and the cap kit for the EHT). I Got some Goop just like the instructions said and got to work. The hardest part was getting the Cap + 2 HV Diodes to lay flat, but I finally got it to sit flat without holding it there. I ended up just POURING Goop all over it. The entire corner of the board was covered. I left it alone for 24hrs then did it again, repeating the process to set up four layers.

I re-assembled the HV Cage and turn it on and I saw the fuse in the HV Cage blow. I disassembled again and realized I had forgotten to insulator for the Q902/Q903 (?) components that are screwed to the side of the cage. I replaced the fuse, re-assembled and turned it on and it worked!

Thanks again to all of your help everyone. I feel a lot more confident fixing just about anything that could possibly go wrong with this thing.

Thanks!
 
this is going to sound pretty dumb...I had same issue playing blind...took a shot to crank the brightness. Bam fixed!
 
Hello everyone! My asteroids is up and running again successfully! I purchased the Kit #2 (the HV diode replacement parts and the cap kit for the EHT). I Got some Goop just like the instructions said and got to work. The hardest part was getting the Cap + 2 HV Diodes to lay flat, but I finally got it to sit flat without holding it there. I ended up just POURING Goop all over it. The entire corner of the board was covered. I left it alone for 24hrs then did it again, repeating the process to set up four layers.

I re-assembled the HV Cage and turn it on and I saw the fuse in the HV Cage blow. I disassembled again and realized I had forgotten to insulator for the Q902/Q903 (?) components that are screwed to the side of the cage. I replaced the fuse, re-assembled and turned it on and it worked!

Thanks again to all of your help everyone. I feel a lot more confident fixing just about anything that could possibly go wrong with this thing.

Thanks!

Awesome, man, I love to see vectors come back to life.
 
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