K4600 - need help

Matt_Johnson

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I picked up a Defender project. I rebuilt the power supply and got it running with voltages right on the money. I then moved onto the monitor, a WG K4600 and found it to have vertical collapse. It had some cracked solder joints on the XY daughterboard so I reflowed all connector pins, did a cap kit and I found no change. I then replaced the two vertical transistors (I never actually tested them) and found that I had an image that wasn't fully collapsed but still not quite there (pictures attached)

So anyway, I was hoping someone could lead me into the right direction to get this problem solved.

I'm also attaching an image of the neck board. I found some ceramic caps that have been removed or broken off. They were clearly soldered on the board at one time and the legs are still. I don't know if it was done when it was new or clipped off later for some reason. I mean it seems obvious that they have broken off but it's just odd that two of them aren't bent. they are C408, C409 and C410.

Maybe someone can tell me if these caps are present on their neck board.


Thanks guys!

Matt
 

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did you do the plugs on the cards AND the headers on the chassis they plug into? I go alternate pins, add solder, remove solder, re-solder. do the odd numbered pins first, you do this so nothing moves. then do the even numbered ones.

those almost undoubtedly probably account for the majority of vertical collapse issues. also be mindful that the yoke is not just a plug on these, it's a set of wires that connect directly to the 2 vertical and horizontal terminals. they're each labeled which color goes where. just verify those are plugged in right too.
 
I did reflow by adding solder to both sides of the connectors but I didn't remove the old. I'm going to do that right now. Thanks!

The yoke wires are correct.

There was one other oddity on this board. There is a jumper wire coming off the horizontal coil and then connecting to a male pin on top of the main. Underneath that is another jumper but the two jumpers are connected to different pins.

Looking at pictures of other K4600 boards this jumper wire (on the top of the board) is in different locations.

In the picture it looks kind of like it's connected to the same pin but it's not. The top is connected to the center of the three and the bottom is on the right.
 

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did you do the plugs on the cards AND the headers on the chassis they plug into? I go alternate pins, add solder, remove solder, re-solder. do the odd numbered pins first, you do this so nothing moves. then do the even numbered ones.QUOTE]

I went and removed the connectors on the daughter cards and checked them for continuity and soldered them back in and checked continuity again. All were good. I also did the main board connectors the same and all of them were good too. But I have no change. At least I'm certain all the connectors are good. I'm going to pick up some contact cleaner and make sure they are clean too.

I ordered new ceramic caps for the neck as per the manual 68pf 50V. I'd still like to find out if they were removed for a reason. It just seems odd.

On the upside it does look like the game board is doing something. But it doesn't seem to everytime I power it up, just sometimes.
 
Well I figured that I would pull the transistors off the X/Y card and the first one I checked was bad - TR301. It's supposed to be a PNP but it doesn't conduct in any configuration. I'll order replacements for all of them. Cold solder joints can wreak havoc!
 
Have you teplaced the case transistors on your 4600 yet? I would also consider the pots as suspect too. It's been awhile since I worked on one, but I can dig into a schematic.
 
Have you teplaced the case transistors on your 4600 yet? I would also consider the pots as suspect too. It's been awhile since I worked on one, but I can dig into a schematic.

Thanks, I'm going to at least test those today.



Update: The vertical hold was a little off, it's supposed to be 250k but tested 210k (probably acceptable), the other two were right on. I think the chassis transistor is in the B+ circuit which tests correct voltage.
 
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i have two working 4600 and two parts chassis i use to keep them going, going out for the day but later tonight i can post pics of the neck boards so you can compare with yours.
 
no time for pics but two of mine have them and two don't. the ones without look like a factory delete and one of those factory delete is on a working monitor.
 
no time for pics but two of mine have them and two don't. the ones without look like a factory delete and one of those factory delete is on a working monitor.



Great. Thank you. I guess I'll leave them off for now.
 
I replaced TR301,302,303,304 and I now have full vertical!

Now I just have to get the game working.
 

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Well, I spoke too soon. after a few power ups it went back to its original state, except this time the image isn't stable.

Not sure what to do at this point...
 
Okay, I went and cleaned all the connectors with Deoxit and I found that I overlooked the top connector pins on the interface board, they were corroded so I cleaned those up, plugged everything back together and got a working monitor again. So I'm crossing my fingers that I got it. Time will tell.

This kind of stuff is why I restore the cab first to give me a reason to hang in there and get the boards working. The game looks awesome, especially given that I had to replace all of the MDF because the machine had spent time outside. Apparently in the rain. WTF is wrong with people?

Unfortunately the game board is doing nothing.
 
my two working chassis were both dead or pretty much damm near dead when i got them. i reworked the daughter boards in them and that brought them back to life. i reflowed everything and swapped out the caps. i bought a cap tester so i could test the caps as i pulled them and also test the new caps to replace, i was surprised how many new caps that were also garbage. check the pot on the horizontal/vert hold card ( has the long black adjustment pot, H-HOLD) that pot had broken traces on every card i had ( i have 6 of them) .
one of my monitors was dead but snapping from the fly like a bitch, swapping a known working horz/vert card brought it right back. reflow everything on that card, pin headers also and the pin headers on the main pcb board it attaches to also.
 
BTW: in your original post you stated you reflowed solder by adding new solder to the old. DON'T do that. you should always remove the old solder and then reflow new solder. when you reflow and mix old and new solder you are adding all the contaminants into that solder joint that was crusted onto the old solder and i have seen those joints not have a perfect electrical connection when that is done. this is especially bad since the chassis was never cleaned of the 35 years of crud build up on it.
 
BTW: in your original post you stated you reflowed solder by adding new solder to the old. DON'T do that. you should always remove the old solder and then reflow new solder. when you reflow and mix old and new solder you are adding all the contaminants into that solder joint that was crusted onto the old solder and i have seen those joints not have a perfect electrical connection when that is done. this is especially bad since the chassis was never cleaned of the 35 years of crud build up on it.

Thanks, I went back and did that.

The monitor is working now. I think mostly it was dirty connections and cracked solder joints, and dead transistors on the X/Y daughter (where the joints were very cracked). I'm still working on getting the defender boards working.

Thanks everyone.
 
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