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GameDude

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    Way to many - BUT I don't care! Hoarder for life!

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  1. I have waaaay to many of these... dont want to see them anymore 400 units 25cents each ($100 per box) anyone??
  2. Its probably suicided when the battery in this game dies it does that, there is a fix for it though... From memory if this is the case you get a co processor error at boot up
  3. Sweet restoration top effort mate! Very good read all the way :D
  4. Sweet work Womble! Nice to see such care being taken especially keeping the authenticity which sadly lacks on many repairs! Star Wars is still on my want list! (I have one in the warehouse for a customer thats in bad shape coincidentally, seems to be how it goes!)
  5. WoW so long ago.... Been a while but of the top I would check the sockets especially the larger ones holding the "not so custom" sub boards, these are often responsible for problems because of there size they cause problems with socket fatigue. Just a flashing image like the sun in the background could be a ROM thats bad or also has a bad socket. You could try applying pressure to the board while running and note if the problem changes (indicating the socket problem being likely). Also check the board for damage, cut tracks from bad storage, pins bent on one another, again the location of the ROM holding the graphics in question would be the best start (you can find it by removing the ROMs one at a time and see what graphics is affected but be careful in removal and correct re insertion! With luck its bent pins, a bad trace can be repaired with wire and solder if your good at that, sockets can be cleaned in some cases if your no good at replacing them... Further to that you need a logic probe, solder iron and some basic knowledge to go further...
  6. 6volts is a bit high but it also depends on where you measured it, at the PCB is where you should do it but these are cased so harder. Its more likely its suicided though unless you know for sure its had a battery swap or phoenix (rom replacement) done to it.
  7. That video helps heaps! I would not look at the ROMs as the data all looks clean I would look at background scrolling circuits, it would not surprise me if some sort of counters or shifters in logic IC's are involved to make the parallax scrolling and the chain is broken somewhere. It does not look like ram either as the issue is with a layer of the scrolling.... You did say you noted when cold to hot the issue changes, with that you can get freeze spray or (inverted) compressed air in a can and spray IC's till they frost up and note sudden changes and they when found can be probed with the scope more closely for spikes of data that match the jumps you see on screen.
  8. I would not specifically say that, logic is formed quite specifically you can tell from weak signals to dirty signals all with a scope I would easily use it over a probe every time... Since its background scrolling I would maybe (without looking at any schematics at all) find the ROMS that hold the data and work from there... Check the ROMS are all good and the sockets are 100% (press on them or pry them a bit while the game is running and look at the screen) Also you may want to look at the shift registers (usually 74LS164, 175, 166 but may be others) https://en.wikipedia.org/wiki/List_of_7400_series_integrated_circuits And the last thing to check in this area is any ram dedicated to the background, of all things ram is often the only component complex and dynamic enough to cause randomness in errors where as specific logic always faults the same way. Have a look at mame and see where the ram regions are or the locations of roms etc, check for damage or corroded tracks or components bent over etc... There are many other tricks to try, you can piggy back spare ICs or use a pull up or pull down probe to force specific inputs or outputs and see the reaction on the screen... Anyway there are heaps of possible things, the chances of fixing are in the details of the fault, your description is just not specific enough for anyone to really say much about it, how a fault behaves onscreen as well as the shpe, and changes that happen when cold goes to hot etc all play a part in diagnostics.... Video is the best way for others to at the very least set you on a closer path to glory ;) Good luck....
  9. Those rings are convergence rings, used to line up the three colors. The yoke is the copper winding further along and is responsible for deflection of the beam. Broken rings or badly out of wack rings can also cause a really bad image similar to yoke failure. At this stage I would explore the components on the chassis and ensure the right values are being used and you test and/or replace as needed. Watch out for bipolar capacitors as replacing those with polarized ones can cause all sorts of issues probably has one on there. Check also all adjustments actually work, any that don't usually have a bad capacitor behind them or a pot that's open or bad solder joints. Issues relating to bad linearity or fold over like in the first image are usually just the caps. You can also contact JOMAC for repair if it gets to much as well, he will have the right parts to...
  10. To be honest it looks like your yoke might be about to die, the caps may have been bad as well and may even make it a little better when replaced. I would also add that while capacitors are often an issue there are many other consideration on old chassis and yokes that can die as well and are just as common sometimes repairing one thing will aggravate the others and the unit dies again. Higher wattage resistors wont affect anything when replaced unless they are out of spec as well but I doubt it would be what is in your pictures, the cap while 25volts should not replace a 50volt may still be OK as not all designs use the 50volts unless the schematics say so. generally however if it really was around 40~50volts where it was mounted a 25volt cap would die pretty quick and probably even pop its top. if you dont have the right capacitor you can bodge one by roughly remembering this rule. In series two of the same value capacitor will double voltage rating but halve capacitance. So for 50volt 10uf you could use 2x 25volt 20uf or close being 22uf in series (not parallel!) . it would at least help see if you have other issues with the chassis or yoke before buying the correct rating components. My bets on the yoke....
  11. No problem :D Pretty much if anyone wants their tube evaluated and can get it to me I will check it out for them, sorry I dont get on the forums much these days so I dont always see the messages but I am at work pretty much every day Monday to Saturday all open hours... I am also happy to provide advise or evaluate old arcade machines if anyone wants that.... no charge but you have to get whatever it is to my shop.... http://www.gamedude.com.au
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