Investigating a video problem on a Neo Geo AES from 1991

[NeonPeon]

Hello! I was referred to this forum by an admin over at neogeoforever.com, as I understand there are some helpful folks here who can help troubleshoot Neo Geo problems. I'll just lay out the facts of my problem as clearly as possible:

1. The patient is an early Neo Geo AES, from 1991. I dug it out from storage last year and cleaned it up.

2. This is my own unit that I acquired in '91 and it was never even opened up until I cleaned it last year.

3. I got a new power supply: https://www.digikey.com/en/products/detail/WSU050-4000-R/237-1420-ND/3094946

4. The graphics are garbled; audio seems fine, and the games run OK otherwise.

5. I cleaned the cartridge slot and the contacts on three different cartridges; same result with all three. When cleaning the slot, I used the credit card/cloth/isopropyl alcohol technique. I believe I cleaned it well. Wasn't that bad to begin with. I cleaned it twice: when I retrieved it from storage last year, and again just two days ago to be sure.

6. Without a cartridge plugged in, screen is completely blue, which I understand means all diagnostic tests passed.

7. Here's a video of the issue:

8. Here's a video of when I press on a certain spot on the board, note the video output changes:

8a. I saw on a video by the Global Garage guy, that suggested this pressing-on-tne-board technique to locate suspicious locations where traces may be bad.

8b. However, in Global Garage's video, pressing on the suspicious spot alleviated the problem while the finger was held down. In my case it seems to compound the problem. Not sure if that's meaningful but worth noting.

9. I quickly eyeballed the area on the board (see #8) and didn't notice any obvious damage to traces. I'm about to look more closely now that I have more time.

Well that's where I'm at. I definitely welcome and appreciate any advice from those more experienced than I am. Thank you!!

 

[max 330 mega]

Wouldn't hurt to start by reflowing all the solder joints on the back of the board and see if the issue clears. My gold system failed 3 times in the past 2 years and each time, reflowing another large chunk on the back of the board fixed the issue. In hindsight, i should have just sat there and reflowed the whole board at once, and not been lazy and do spots at a time. Id have had 2 less fails if so!

 

[BIG BEAR]

Press down on top of that chip and see what happens..if the problem improves,you may need to reflow the LSPC.In my previous experiences,it's usually a broken track or two that connects to the LSPC
BB

 

[NeonPeon]

Thank you for the suggestions guys! I will look into reflowing - I am basically competent with a soldering iron (and I've desoldered too) and a multimeter, but I don't know that term. No need to explain it though as there's always google.

Pushing down on the chip doesn't change the video by the way, just the area right next to it does.

Thanks again!

 

[BIG BEAR]

Thank you for the suggestions guys! I will look into reflowing - I am basically competent with a soldering iron (and I've desoldered too) and a multimeter, but I don't know that term. No need to explain it though as there's always google.

Pushing down on the chip doesn't change the video by the way, just the area right next to it does.

Thanks again!

It reads like there are broken tracks relative to the LSPC .BEFORE YOU THINK ABOUT REFLOWING,see if any broken tracks exist relative to the LSPC before you start a reflow..
You can compound the problem by attempting a reflow and not doing it properly..A POOR REFLOW attempt could have you attaching solder to two or more legs of the LSPC before you can really confirm what is wrong.
Try pushing on the edge of the LSPC in the same area you are pushing down now and see what happens...
I could also take a look at it if you live in the USA.I would have you remove the top portion of the casing before shipping.
What are the specs on that power supply btw?
BB

 

[NeonPeon]

Cool, thanks for the heads up about reflowing. I'll definitely investigate further before jumping into that.

Pressing anywhere on the LSPC itself has no effect. I tired on the center, all edges, all corners, and on the pins and nothing appears to be different in response to my presses.

Thanks for the offer to check it out! I am indeed in the USA. Can I take you up if I get really stuck? I'd love to have it working, but I'd also love to learn and attempt to fix it myself. But that really is an amazing offer, so thank you.

Last night I started doing a lot of continuity tests on all pins coming from this LSPC chip. It's a work in progress still as it's not easy to find a large block of time lately. I'm documenting all of them that I test by just circling sections of traces in a photo on my phone, so I don't lose track.

There are some traces that actually look they might be slightly off? They either have some crap stuck onto them (I tried Q-tips/IPA to no avail) or perhaps they are broken. Another way to put it is discoloration. BUT, continuity tests show they are ok apparently.

Here's an image of one example. Any opinion on how much I should be concerned? Again the continuity test SEEMS to indicate that it's just fine.

Thank you!!

 

[NeonPeon]

Oh, and the power supply specs:

 

[BIG BEAR]

if you getting continuity, you're good. Check your LS273's
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