Well it’s my fault. I should have known better and checked this but I had tossed in the incorrect horizontal output transistor. I had purchased a box of 5 replacements off of eBay for a Wells Gardener 25K7401. That monitor however had a silicon insulator pad that kept the back of the HOT insulated from the heatsink. The SI-727 however, does not. When I stupidly installed that part in the unit, it was shorting out and giving me tick-tick-tick noises because the switching power supply was trying to fire up but went into protective shutdown.
Once I fired the monitor up, the picture looked terrible. Looking into the cabinet though you could tell an amateur did the harness hack. He twisted wires together and poorly electrical taped them. This was not the problem but I fixed it. Ultimately the problem was that the signal ground came detached in the process of fixing the monitor. For the life of me, I could not find the proper place to attach this wire but ultimately I found one suitable at least.
The monitor still isn’t quite right. The picture grows and shrinks slightly when going from light to dark scenes(monitor bloom) and the image does not quite fit the screen. As annoying as this is though, the game is at least playable now.Lessons learned?
Always make sure none of the legs of the HOT have continuity with the heatsink unless of course it’s designed to do so and if you picture every looks inexplicably bad, check your grounds.
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Did you ever figure out what was causing the monitor bloom? I have the same monitor in my 4-Slot Neo Geo and it’s driving me nuts. I re-capped it a while back which helped two other issues but not the bloom and then my flyback died… The lack of info and schematics on this monitor makes working on it tricky as well.
The bloom is not terrible. Right now for the moment we have decided to live with it until we get the rest of the machine ironed out a bit better. We have a whole second side that is in pretty bad shape. Once we get that going we’ll get back to the first side.
Have you replaced your flyback yet? Try that and see if it still blooms. I’d also check and see if the B+ voltage drifts at all.
Hi
I recently bought one of these chassis … I have been search in vain for a schematic as well .I eventually emailed the vendor I bought the chassis from ..He seemed to think there isn’t a schematic / repair manual that Sharpe Image had gone out of business .That if I had and issues to just email him any questions he really is a great guy … you might want to email him at jomac@jomac.net.au
mary