Nanao MS8-26SG (Aero City) Focus issue, corroded pin? [fixed]

[MagicianLord77]

Hi guys,
The Nanao MS8-26SG monitor from one of my Aero Cities takes around 30-45 minutes to "warm up", to be focused. When turned on image is completely blurry, after waiting all that time image becomes and stays perfect I'd say.
I've recapped this monitor some time ago so this shouldn't be a cap related issue. I've seen on different places that this kind of focus issue could be related to some issue with the socket, seems like a focus pin could get corroded or broken so I disconnected the neckboard to take a look, also I've taken the focus wire cap off:

socket pins seem OK, no signs of corrosion.

Inspecting the focus pin, I see it's soldered correctly to the focus wire, and that it has a 3rd connection to somewhere unknown

Inspecting from the left side, there is a corroded pin that comes out from the socket, but I don't know if it's the pin that's connected to the focus wire from the previous photo, multimeter gives no connection between them. I've done the same connectivity test but with the monitor of the other aero city cabinet that focuses well, and also got the same so I don't really know, what's the purpose of that pin? where is it connected from the socket?

For reference, the corroded pin goes there.

Would this corroded pin be related to the focus issue? Found the monitor of the other aero city also has the same pin similarly corroded, but its focus works perfectly. What would be the purpose of that pin?
What else could I do/try to troubleshoot this long time to focus issue?

Any help appreciated

 

[Mukuro_W]

You have to replace the socket, for sure it is corroded inside, you need not the same but just a suitable one (same pinouts)

 

[MagicianLord77]

You have to replace the socket, for sure it is corroded inside, you need not the same just a suitable one (same pinouts)

I could found these sockets, I guess MP1042 would be the most appropriate replacement since there isn't an exact match..
https://www.arcadepartsandrepair.com/store/monitors/monitor-parts/cr23-crt-socket-mp1039/
https://www.arcadepartsandrepair.com/store/monitors/monitor-parts/cr23-crt-socket-mp1040/
https://www.arcadepartsandrepair.com/store/monitors/monitor-parts/cr23-crt-socket-mp1042/

 

[MagicianLord77]

Another question, this same monitor also tends to have a delay when you turn on the cabinet, to turn itself on.
It can take up to 20 seconds to turn itself on when cabinet is plugged in. The monitor from my other Aero City turns itself instantly.
Both have been recapped. When waiting for it to turn on it doesn't make any noise at all, no typical crt hi pitched noise or anything.

Does anybody has an idea what could I check related to this issue, could the CRT socket be related to this issue too?
Thanks!

 

[MagicianLord77]

Well, received the replacement parts and got down to work. First by removing the old socket, with the monitor discharged, using a soldering iron along with a regular solder sucker it wasn't difficult to desolder the socket pin by pin, didn't have to take the monitor out of the cabinet!:

After that, I wanted the socket to reveal its secrets, had to destroy it for that, since it was all "riveted", unserviceable. (luckily new sockets aren't like that). It was pretty corroded:

New sockets don't have a redundant pin old socket had. Also, the most further away pin is at a different location on the new sockets, but the neck board has already a hole for that from factory!:

Also, check out what's inside new sockets, new and shiny plates. Ended up choosing the MP1040 just because it was ready not like the other that needs a hole drilled inside. I'd say they're the same:

Soldered it. Then soldered the "focus wire?" coming from flyback, closed the plastic cap, fits like a glove on the CRT:

After that it's time to turn the power on, and it's a success, instant sharp focus! left: with old rusty crt socket, right: with new crt socket, both after 1 minute of powering on:

 

[opt2not]

Very nice fix! Congrats.

 

[Mukuro_W]

There is a last mod,, if you want use the spark gaps, those are usually connected at pin 9 on all Nanao socket but on the replacement socket this pin is the 12 so you have connect the pin 12 to neck board ground.

 

[MagicianLord77]

There is a last mod,, if you want use the spark gaps, those are usually connected at pin 9 on all Nanao socket but on the replacement socket this pin is the 12 so you have connect the pin 12 to neck board ground.

Hi Mukuro, I guess the spark gap is being used with the replacement socket too, here's a picture about the connections of the old socket

• (green) pins match with the new socket
• there is a unused pin (blue) that is not connected to anything in the socket (measured w/multimeter), new socket doesn't have it, didn't make a difference
• (magenta) focus pin changed its location a bit in the new socket but monitor PCB had a hole for it so no problem, it's connected.

Is some connection missing? Can you explain the mod a bit more? Thanks!

 

[Mukuro_W]

I'm sorry ,to be clear, in order to connect the spark gap protection to the new socket then you have to link pin 12 of the new socket to ground.

 

[Asobu]

Love a happy ending. Very informative!