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Ok Baby - Monitor Issues: H. Width and Pincushion

coming2u

coming2u

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Hi Everyone,
Definitely in a bit over my head on this one. I am restoring an Ok Baby cabinet I bought from auction and things were going well. I had it up and running and the monitor was good but with a few issues:
  • Horizontal Width Pot - barely shrinks picture, still goes over the edges
  • Pincushion Pot - doesn't seem to have any effect on picture
  • Image - some curving on the sides which i could not adjust out
  • CRT bending.jpg
I assumed at this point I needed to figure out what cap-kit to order and give that a shot. However the chassis of this thing is a mystery, can't google anything relevant from the model numbers. I believe its a generic universal. It's apparently a Yatta 988 chassis.

This morning, I reoriented the monitor from vertical back to horizontal. Plugged it back in, and turned on the cab. "BBBBZZZZTTT" some brief light came from the back of the cab and when I poked my head in to look I see a capacitor dispensing some tasty foam:
PXL_20231009_161925018~2.jpg


Should I just order a new board and give it a shot? Something like this: AliExpress CRT Chassis
I could also use help determining size to order, is this a 27? 29 inch? Sticker on the side of the cab says it does 28" or 29"

PXL_20231009_203023933.jpg


Restoration Thread - https://www.arcade-projects.com/threads/weche-ok-baby-arcade-cabinet-restoration.27302/

Any advice welcome, thank you.
 
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Take a pic of the tube sticker on the back of the CRT. Should have a manufacturer listed (i.e., toshiba, hitachi, etc.) and list a model for the tube (i.e., A68xxxx or A66xxxx). That should confirm your size.
 
I saw on your other thread that this is a A68 tube. That means you have a 27"/29" monitor. As for your horizontal size issue. There is are two jumpers next to the width coil that corresponds to one being "narrow" and the other being "wide". Try swapping the plug to the vacant header and see if that decreases your size.
 
Thank you, I'll have to try that after I get it running again.
 
Pulled the CRT out of the cab again today. One of the fuses blew again (F802 , the same one I found blown when first getting started on restoring the cab). Replaced it with a spare and the monitor came back on, in its previously performing state. I'm guessing this means there's a (intermittent) short somewhere?

blown fuse #2.jpg

I also tried swapping the widescreen jumper as mentioned, it was on the bottom jumper before I took this pic. Unfortunately the image is still too wide in test mode even dialing down horizontal width as much as possible.

Wide Screen Pin.jpg

Sidenote does that big cap look funny at L902? Tried swabbing the top with alcohol its just permanantly black.
 
I actually grabbed this pic from a different OK Baby thread, but its the exact same board.

I'll need to pop the CRT out of the CAB again this evening to dissassemble the chassis mount to look at the bottom for anything that stands out.
Example CRT Board.jpg
 
I'm like 90% certain that chassis requires an isolation transformer. I'm also leaning towards that since you started having problems after redoing the AC wiring, introducing earth ground, and trying it with an MVS.
 
Updated thread title since the chassis has been ID'd.

I'll look at ordering a isolation transformer and probably a line filter as well.

One interesting thing I found today was a thread on another forum with the same chassis and same.issues with horizontalwidth and pincushion.
https://forums.arcade-museum.com/threads/is-this-horizontal-width-coil-broken.484726/

The person claimed replacing the cap near the pots cleared this up. I've checked and confirmed I have the same layout.

I was going to order a cap kit but I haven't found anything that mentions that chassis model anywhere. Does anyone know if a Wei Ya kit or another model uses the same capacitors ? (Not looking forward to checking every single one)

In addition I did go ahead and order a generic chassis as well. I figure if this one dies (by itself or by my hand), it will be a good plan B.

Thank you for all the help so far!
 
So the capacitor came in for the horizontal pot and I wanted to share some pics of the board for some opinions:

  • Bottom of chassis:
    bottom of chassis.jpg

  • This jumped out at me, should that blue capacitor be here on the bottom side??? (100uF v50)
  • capacitor supposed to be here.jpg
  • Topside to that blue one, at C322 is this capacitor: (220uF v16)
  • topside capacitor cropped.jpg

  • Also noticed this, should I trim it off or just leave it?
  • solder problem 2 cropped.jpg
 
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So that first link I reviewed 4 times, don't see a C322, this site here doesn't list a C322 for that model: http://macros-arcade.com/monitor-capacitor-kit-listings/

The 825HR & 826HR have C322 as 100uF 16v :
1697751743194.png


1697751795413.png


Neither match the out of box capacitor, but 16v is consistent between the Wei ya and the stock capacitor. So that leaves me with a 220 or 100uf v16 as the correct choice.

---
Decided to go ahead with the one cap here (C907) for the horizontal width and pincushion:
replaced capacitor.jpg

Horizontal width, positioning and pincushion all work now! Picture is much better.

I should probably go ahead and get that other mystery cap off the bottom and replace the C322 cap. I'm going to look at some comparable chassis and see what I can find that has a similar capacitor list and order a kit.

Consider this one solved everyone! Thank you so much for the help!
(flyback was up to high on screen dial when I took pic, but you get the idea)
fixed picture.jpg
 
Good job!

What was installed before and what did you replace it with?
 
nem said:
Good job!

What was installed before and what did you replace it with?
Click to expand...
I ordered an exact replacement for the C907 cap that was present. It was a 4.7uf 100v.

P.S. I did order a isolation transformer to add to the power supply setup and I will remove the mystery capacitor from the solder side of the chassis in the future when I replace multiple caps.
 
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Plymelk said:
This is a Wei-ya universal for sure and isolation transformer is required. https://twistedquarter.com/index.php?main_page=product_info&cPath=200_204&products_id=376
Click to expand...
Hi apologies for piggy backing on this thread but I had a couple questions to ask.

I have an okbaby that I've restored (thanks to coming2u for the tips and advice). I pretty much copied this setup

http://arcadecontrols.com/BBBB/acwiring.html

Problem is, I'm not getting any power to the monitor from the Iso transformer.

Everything powered on correctly (Jamma, LEDs, and case fan).

The monitor plug should go directly to the iso transformer right?
 
bgwelistyl said:
Hi apologies for piggy backing on this thread but I had a couple questions to ask.

I have an okbaby that I've restored (thanks to coming2u for the tips and advice). I pretty much copied this setup

http://arcadecontrols.com/BBBB/acwiring.html

Problem is, I'm not getting any power to the monitor from the Iso transformer.

Everything powered on correctly (Jamma, LEDs, and case fan).

The monitor plug should go directly to the iso transformer right?
Click to expand...
It would be best if you could post pictures of your setup.

Can you measure the voltage going into and coming out of the isolation transformer? Is the AC power working everywhere else as expected?
 
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