Asteroids Monitor Fix: Size Changes After Warming Up

jasonbar

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Asteroids Monitor Fix: Size Changes After Warming Up

Howdy-

First off, I apologize--I live in CA & my brother's Asteroids is in MI. I'm trying to help him troubleshoot it, but I don't have it in front of me, & electronics is not my brother's forte.

He says that, after about 30-40 minutes, the screen size will change--the image will shrink & then grow. Sounds as if something is heating up & going wonky. I suspect a bad solder joint.


I recommended the following troubleshooting procedures:

1 - Remove all connectors, clean, & re-attach.

2 - Pop all socketed chips, clean legs & sockets, & re-install.

3 - Reflow solder on all connector solder joints.

4 - Set up a mirror so he can see the monitor image from the back of the cabinet. Spray freeze spray on the monitor board in various places until the image fixes. Then address that region by reflowing solder.

5 - Set up a mirror so he can see the monitor image from the back of the cabinet. Push gently on various parts of the monitor board until the image changes. Then address that region by reflowing solder.



Any comments to add/remove?


He also bought a replacement PCB on eBay, but it arrived with a broken component that he's having trouble identifying. I can't seem to find the schematics showing the layout of the monitor PCB & listing its components.


Any/all help is much appreciated!


Thanks,
-Jason
 
I assume you have a Wells Gardner V2000 in there.

Your issue is called 'blooming'

Do some googling around this site to see what you need to do. Most likely a cap kit is in order for the monitor's chassis, if it hasn't already been done.

Sometimes the blooming can be caused by a faulty high voltage diode.

But hit up the cap kit first if that's not been done.
 
Your Brother has a bad HV Diode or connection to the HV Diode. Replace the HV Diode.

That's the first step. I've seen a few blooming issues after the HV diode was replaced, and reflowing the large connector on the deflection board made that go away...
 
Howdy-

Thanks for your quick & helpful replies. My brother's been busy, so I didn't get follow-up info till just a few hours ago.

He's got the Electrohome, not the Wells-Gardner. He says it's a 38-G05-801-00.


Can you please elaborate on which component is the HV diode & what its specs are & what's a recommended vendor for getting one? (Unless it's an easy off-the-shelf Radio Shack item.)


Electronics & soldering aren't his strong suit (but he can remodel a home & rebuild a motorcycle from scratch!), so I'd prefer to hold his hand with just the diode replacement before recommending a full cap kit.


Thanks again,
-Jason
 
WARNING: before working on your monitor, you need to safely discharge it. You CANNOT use the simple grounding technique to discharge a vector monitor - you can damage parts if you don't bleed off the high voltage safely. You should use a high voltage probe to discharge the monitor. Read up on how to do this!

E-home or Wells, it really doesn't matter. Both of those monitors are very similar.

Before you attack the high voltage diode as a concern, I'd be sure you've capped the monitor's chassis board first. Also do the resistor mods at R100 and R101. Read the FAQ (link below) for more info. If you cap the monitor's chassis and still have blooming, then proceed...

The high voltage diode is located in the high voltage cage. It's a separate shielded metal box outside of the larger monitor PCB. The high voltage diode is located inline with the anode lead, just outside the flyback transformer. In the following picture, the high voltage diode is encased in a rubber connector at 10pm:

hv-764x1024.jpg


Before attempting to replace the diode, sometimes it's a good idea to re-seat the connection. I've seen a poor connection cause blooming. If you do decide to replace it, make sure you take note of which direction the diode is installed. There will be a white band near one end.

Most of the time, there is no real 'lock' to the installation of this diode; it's more of a press-fit connection inside the rubber housing. Just make sure the new diode is securely fit inside, and that the connection is snug. Use new dielectric gel if needed. If the new diode is bigger or doesn't fit properly, you CANNOT use electical tape to insulate the connection. Electrical tape is not hardy enough to contain the thousands of volts moving through that connection - it will fry the tape and arc to the high voltage cage.

You should read the vector monitor FAQ before getting started with any of this. Educate yourself first. Vector monitors are a different animal than raster monitors. You need to be aware of what you're doing or you could cause more problems than you solve.

The FAQ:

http://www.arcade-museum.com/manuals-monitors/FAQ Black and White XY Version 1.1 dated 7 Feb 02.pdf
 
Ummm,nope guys. He has the G05-801. That is the one with the 2 large blue caps in the middle of the monitor frame. He probably has a problem with the voltage doubler. Unfortunately these aren't available and you have to make your own. Sometimes Chad at arcadecup makes up a set and then sells them for something like $75. Not sure exactly. Before trying to replace that, make sure the rest of the monitor is good. There are lots of cold solder joints on that board with the big blue caps that need reflowing. I have seen blooming as a result of those cold solder joints so that would be the first thing I check.
 
Also, on an unrelated note; you can purchase those HV diodes on eBay for the V2000 and G05-802 monitor for $11 + shipping. The guy only has a few left so get them while you can. Look up Varo 1802.
 
Thanks for the further posts.

I've already instructed my brother to reflow the solder on everything on the monitor PCBs, but I think he's finding that to be too daunting a task...

The fact that the monitor works OK for 30-40 minutes before blooming suggests to me that it's a cracked solder joint that's heating up & opening...

He pulled the PCB--indeed, it has 2 medium-sized blue caps in the middle of the board (attached).


Thanks,
-Jason
 

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That wasn't the board to which I was referring. That is the deflection board for an 801. So, we are at least talking about the correct monitor. There is another board with a large heatsink attached to the bottom of the monitor frame under the tube between the deflection board and the high voltage cages on the side. Tell him to pull that and relow all the connections on the bottom of the board and check the screws on the 2 very large capacitors on the bottom to make sure they are snug.
 
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