K4675 Bowing

VerySadFace1701

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Good afternoon folks!
I'm currently working on my k4600 series and have gotten the monitor SO CLOSE. Went from a dead monitor to almost working, struggled to get the horizontal/vertical hold to work, but figured that out! Turns out there didn't need to be a jumper on the vsync cable.

The next thing I'd like to solve is the bowed image it seems to have, and it looks like it's got a tiny bit of folding happening at the right side (the top of the vertical). Check out the pic. I don't have a TPG yet, so I'm using a raspberry pi with a jamma adapter to test it out for now.

I'm not at a loss just yet, just loving learning how these monitors work since this is my first ever time working on a crt!
 

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I just had one of these. I believe, from memory, replacing the filter cap, and the paper cap in the top right corner fixed the issue. I just replaced both of those at once.

I originally thought it was the filter cap, but replaced the paper cap (.1uf 1500v) also and the image is perfectly square with no bowing now.

I apologize if you need a more definitive answer than this, but that is what I would do if I had it here to repair.
 
What have you done so far?
- cap kit
- reflow/cold solder joints
- test B+
Aaah! I totally forgot to include that in my post, srry!! I have recapped the whole thing with the "Arcade Parts and Repair" site. I replaced the filter cap with what they had, I've reflowed the solder on each of the boards (which I can definitely do again if that is going to help fix my issue). My B+ read 124.5.
 
I just had one of these. I believe, from memory, replacing the filter cap, and the paper cap in the top right corner fixed the issue. I just replaced both of those at once.

I originally thought it was the filter cap, but replaced the paper cap (.1uf 1500v) also and the image is perfectly square with no bowing now.

I apologize if you need a more definitive answer than this, but that is what I would do if I had it here to repair.
You know what?? I'm just headed out the door for work and took a quick peek at the monitor before leaving... I didn't replace that cap. It's one that didn't come with my kit so I didn't even think of it, let me order a replacement and try that out. I'll report back as soon as I try that. Thank you.
 
Aaah! I totally forgot to include that in my post, srry!! I have recapped the whole thing with the "Arcade Parts and Repair" site. I replaced the filter cap with what they had, I've reflowed the solder on each of the boards (which I can definitely do again if that is going to help fix my issue). My B+ read 124.5.
make sure to bring that B+ up to 127vdc.
 
You know what?? I'm just headed out the door for work and took a quick peek at the monitor before leaving... I didn't replace that cap. It's one that didn't come with my kit so I didn't even think of it, let me order a replacement and try that out. I'll report back as soon as I try that. Thank you.
yes that C621 cap should be replaced when doing these but there are alot of hold outs that don't want to but if you ever have question on stuff to replace just email me and i can tell you my recommendations and optional stuff.

 
Nice Peter didn't know you had those
 
yes that C621 cap should be replaced when doing these but there are alot of hold outs that don't want to but if you ever have question on stuff to replace just email me and i can tell you my recommendations and optional stuff.

Oh dude you rock, thank you.
 
yes that C621 cap should be replaced when doing these but there are alot of hold outs that don't want to but if you ever have question on stuff to replace just email me and i can tell you my recommendations and optional stuff.

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yes that C621 cap should be replaced when doing these but there are alot of hold outs that don't want to but if you ever have question on stuff to replace just email me and i can tell you my recommendations and optional stuff.

WAIT I didn't know you were who I was buying caps from online 🤣 how awesome is that! I just sent a thank you message on the site earlier today not connecting the dots lol! Seriously thanks for the knowledge and genuinely good parts dude.
 
K4600 from work Galaxian. had the jittery picture thing which is symptomatic of C621 failure. I wasn't anticipating it just being apparently dead though. I don't understand how that's possible.

IMG_20240718_232036514_HDR.jpg

and a new one from APAR
IMG_20240718_232010534_HDR.jpg

absolutely a required part to replace

and the filter cap for posterity

IMG_20240718_230741812_HDR.jpg
 
K4600 from work Galaxian. had the jittery picture thing which is symptomatic of C621 failure. I wasn't anticipating it just being apparently dead though. I don't understand how that's possible.

View attachment 768380

and a new one from APAR
View attachment 768381

absolutely a required part to replace

and the filter cap for posterity
That's interesting that it also caused the jittery image, fingers crossed that this is my problem, C621 was literally the only cap that wasn't replaced, so here's for hoping. Just out of curiosity, I'm going to test my C621 to see what it's value is.
 
1000015665.jpg
Voila! Got me a nice stable square image now!!
You guys ROCK for pointing me in the right direction. Every single comment helped in some aspect or another, I've never had that happen in a forum before, so thank you.

*I still have to bring B+ to 127v, but it's got glue all over the potentiometer, so I'll get that replaced the next time I sit down to work with it and adjust B+ accordingly. Fingers crossed.

**My sync cable was not plugged in right either, so fixing that and replacing C621 worked perfectly.
 
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