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Electrohome G05-802/805

This page is for reference when working on G05-802 monitors (G05-805 is the 15" cabaret version, but essentially the same monitor) found in later Asteroids (originally the G05-801 was used in Asteroids), Asteroids Deluxe, Battlezone.
 
The cap kit for this monitor is available from Bob Roberts for $11.00 and includes 9 caps and 4 'bottle cap' chassis mounted transistors ($5.00 for the kit minus transistors).  4 are located in the HV cage, and 5 on the main deflection board.  The two caps NOT included in the BR kit are the 2 large filter caps on the main deflection pcb, they are 6800uf 50V radials.
 
 
THE HV DIODE: 
There is an HV diode located in the HV cage and is on the main wire that connects the flyback to the anode cup.  The original is a VARO H1802 and has been discontinued.  Some other replacements are NTE527A (discontinued), SK7333 (discontinued).
Here is a link that describes the replacement process and has an alternate part that can be made to work, the NTE505.  Don't forget to use the RTV silicone or you'll have a fireworks show on your hands!
 
I've also seen this diode for sale on Bob Roberts site, but he is currently out of stock (2-23-2010). 
Arcadeshop.com carries them (as of 2-23-2010) for $12.00.
Arcadechips.com also has a replacement (H1812 or H1809) for $10.00.
 
If your monitor is 'breathing' (picture expands and contracts), you need to check out this diode as it may be very dirty (clean it thoroughly with rubbing alcohol and allow to completely dry), or it may need replacement.
 
Here is the main deflection pcb with caps circled.
 
And this is the HV pcb with caps circled.  One cap is not visible in this photo, but is right next to the flyback.  Note the HV Diode, inspect and clean it while you're in there.  If it's toasted, replace it.
 
Here's the cap map for the main deflection pcb.
 
And the cap map for the HV pcb.
 
Here's the G05-802 PCB after recapping it.  When I fired it up, fuses F100 and F101 immediately blew.  No burning smell and no picture, also the spot killer is OFF.  Replaced both with 4A slow blow (supposed to be 5A, but it's all I had) and tried it again.  This time F101 blew, but F100 held and I had a great picture, but still some 'breathing' of the picture.  Possibly the bridge rectifier (DB100) is bad and/or the HV diode which is more than likely causing the 'breathing' issue.  Both fuses are supposed to be 5A slow blow.  I found a 3 Amp in F100, and a 4 amp in F101 so the new caps may have pushed the fuses too far since they are supposed to be 5A.  Off to Frys tomorrow to pick up the 5A fuses and DB100 bridge rectifier NTE5313.
 
2/26/2010 update.  I replaced the bridge rectifier at DB100 with part#NTE5313, also replaced the rectifier diode at D100 with part #NTE5801 (3A 100PRV).  Replaced all fuses with correct size and speed (SB/FB).  Fired up the game and it works fine now.  No more blown fuses.  I believe it was the bridge rectifier that was bad.  Found all these parts at Frys in Renton.
 
2/27/2010 update.There was still some distortion on the monitor that changed depending on where the objects were. They got longer in the center of the screen and narrower when closer to the top and bottom. Adjusted the linearity pots on the pcb and it took the distortion right out.
 
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Torin Newman,
Feb 23, 2010, 5:31 PM
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