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Aero City PM-1736 monitor showing wavy patterns and jitter – normal or issue?

matthijs

matthijs

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I’m looking for a bit of advice from people more experienced with CRT monitors.

For some background: I have a Sega Aero City cabinet with a Sanwa PM-1736 chassis. The chassis had a bunch of issues, so I sent it to Sharp Image Repair in Las Vegas to get it serviced. It took me a while to get around to reinstalling it, but I recently finally put the chassis back in the monitor and powered everything up.

Overall the result looks great and the monitor is working again, which I’m really happy about. However, I’m noticing a couple of things that I’m unsure about.

First, there are some wavy patterns visible on the screen mostly visible when the images on the screen are light. I can't remember if this used to be the case before the repair as well (I don't believe so, but it's been awhile), but when I compare the image to my Blast City the difference seems quite big. I’ve attached a short video below showing what I mean. I’m wondering if this might be related to how I installed or configured the chassis, if there’s something I should adjust on my end, or if this is simply something that can happen with a CRT of this age.

Second, the image seems slightly jittery. It moves very subtly from side to side quite quickly (see second video). It’s not extreme, but it is noticeable. Again, I’m not sure if this is normal behavior for an older monitor, something related to the chassis repair, or possibly something in my setup.

Has anyone seen something like this before with a PM-1736 or similar monitor? Any suggestions on things I should check or adjust would be greatly appreciated.

Thanks!


View: https://youtube.com/shorts/SdxQapmn6A4


View: https://youtube.com/shorts/n-v50-7Y9vU
 
Looks like your tube is burnt. Nothing you can do about it.

Hard to really tell what's going on in the second video as it's 4 seconds long, but probably nothing to worry about.

Just get stuck into the games bro...
 
My bad, shouldn't have clipped it so short. It's more the wavy pattern in the first video than the second vid that concerned me though.

I'm not overly worried about it, I'm just surprised by how much better my Blast City looks and wondered if it was maybe due to user error on my configuration of the tube. I'd be surprised if it's burn, this cab was barely used when I got it (unless burn is possible on minimal usage?).
 
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Could get a UV blacklight to confirm if it's burn in. For the jitter I have heard of certain sets having that when the aquadag around the rubber annode cup has dried up.
 
My Aero has a slight wobble in the image as well - after I got the chassis serviced and the power supply. I wrote to JOMAC and he replied…

With MS8-26 it wont be the chassis causing the wobble it will be the chassis displaying something in the cabinet that's causing it, there are endless things that can cause interference, I have posted a lot of info on Aussiearcade because its such a common issue.
The most common cause is magnetic interference from speakers or isolation transformer to close to the tube, it can even be the degaussing circuit so try disconnecting the degaussing coil, failing that check out AA and search under interference.
 
Since you're in Euroland like me, do you have a stepdown inside or very near the cabinet? Try moving it outside the cab a bit and see if that improves things.
 
Appreciate all the insights everyone. So looks like it's interference related to grounding. The odd thing is however, whenever I take the tube out of the cab and connect it up again it seems to run great without the wavy pattern (keeping the same cables/connections). Anyone have ideas what mounting it in the cab changes to mess up the grounding vs running it on the floor?

Going to try to to find all the grounding points now and if I missed anything.
 
nem said:
The monitor shouldn't be grounded at all, it should be floating. The frame normally sits on plastic spacers.
Click to expand...
Oh interesting, I think I have them for the bottom two mounting screws but none for the top two. You mean these grey ones right?

IMG_1965.jpeg


Missing on top:

IMG_1966.jpg
 
nem said:
Grey ones, yes. Try placing cardboard in between at the top.
Click to expand...
That seemed to do the trick, image looks great now! Seems like there's still a slight jitter when I start it up but it goes away after a minute or so. The interference is completely gone

JohnRambo'sKnife said:
You can always stack some nylon washers if you can't find a set of original spacers.
Click to expand...
Appreciate the suggestion, am afraid that won't work as the frame of the monitor is also pushing against the right side of the cab frame, so it needs a nudge back to the left in addition to being lifted up/forward. Luckily I have a 3D printer so I'll make a few out of solid ASA.
 
matthijs said:
The odd thing is however, whenever I take the tube out of the cab and connect it up again it seems to run great without the wavy pattern (keeping the same cables/connections). Anyone have ideas what mounting it in the cab changes to mess up the grounding vs running it on the floor?
Click to expand...
If its outside the cab I am.assuming it is far away from your 240AC transformer block.

I don't know where your aero came from but at some point in time a large number of them made the way to the Netherlands via a German(?) Arcade importer who fitted them with internal unshielded transformer step-down. Also some were painted in wierd colors. (I'm old and forget the whole exact story.)

The transformer is not supposed to be in there. Put it outside the cab or live with the monitor wave.

Arnyway take some pictures of the inside and the power situation please. Maybe relocating the transformer or shifting it sideways 90○ is an option.
 
Asure said:
If its outside the cab I am.assuming it is far away from your 240AC transformer block.

I don't know where your aero came from but at some point in time a large number of them made the way to the Netherlands via a German(?) Arcade importer who fitted them with internal unshielded transformer step-down. Also some were painted in wierd colors. (I'm old and forget the whole exact story.)

The transformer is not supposed to be in there. Put it outside the cab or live with the monitor wave.

Arnyway take some pictures of the inside and the power situation please. Maybe relocating the transformer or shifting it sideways 90○ is an option.
Click to expand...

This one is indeed from that batch, I bought it 15 (!?) years ago when they first made their way to the Netherlands, and it's fitted with a 240V transformer. Looks like breaking the contact between the monitor frame and the cab like @nem suggested already did the trick though. Or would you still recommend taking the step-down out?
 
If that already fixes all the shimmer and flicker, then there is indeed no reason to take out the stepdown, and i am wrong.

I've seen several aftermarket stepdowns causing a similar issue where it flickers in the bottom right because of the transformer, so i really thought that would be your issue. I guess not, and it saves you putting live electrical things where people can touch them/buying a separate one in a plastic case :)
 
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