K4600 vert collapse - not the usual suspects

mtnyeti

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K4600 rebuild came up with vertical collapse after cap kit. Re-flowed everything on the XY board and interface board, as well as all the headers on the main board while doing the cap kit. So....

Switched in the XY board from a working monitor, no go.
Switched in the interface from a working monitor, no go.
Switched in both sub boards from a working monitor, no go.
Diode tested the HOT and got a similar "flash up" reading as I did on the working monitor's HOT, so I don't think it's the problem. Also made sure good connection on the yoke wires.

So I've ruled out the XY board, the interface board, and best I can tell, the HOT.....Pretty much every probable suspect I've found in threads that would cause vert col on a 4600. Never got anything but the green line running up the middle of the monitor. Am I missing something here, or is there something on the main board left to check? Any suggestions where to look next greatly appreciated!
 
have you tested all the transistors in the 300 section? i assume you replaced EVERY cap on the board?
 
Yeah, did a full cap kit from Ian Kellogg (only had left the 3 optional caps which weren't on my board, but verified their spots were all factory soldered shut).

Didn't test the 300s transistors since I switched in a known working xy board from another 4600 I just rebuilt.

And double checked the yoke wires attachment on the yoke; cleaned the terminals so I could make sure they were connected well.

Is it worth ordering and replacing the HOT? I feel like the problem has to the the main board, or is it possibly something on the neck board?
 
Yeah, did a full cap kit from Ian Kellogg (only had left the 3 optional caps which weren't on my board, but verified their spots were all factory soldered shut).

Didn't test the 300s transistors since I switched in a known working xy board from another 4600 I just rebuilt.

And double checked the yoke wires attachment on the yoke; cleaned the terminals so I could make sure they were connected well.

Is it worth ordering and replacing the HOT? I feel like the problem has to the the main board, or is it possibly something on the neck board?

when you reflowed the solder on the pins for both daughter cards did you do it with the cards installed or our of the main chassis?? second question: did you remove the old solder from those pins and reflow NEW solder or did you mix new and old solder on the pins?

BTW: replacing the HOT is only needed if your old one tests bad. Test it and don't just throw parts at it without testing them.
 
If your hot wasn't working you wouldn't be able to even see the vertical collapse. It drives the High voltage to turn the tube on and drives the horizontal coil.

Well if you have a known working X-Y board and it still doesn't work then your problem has to lie on the main board.
As with all cap kits, absolutely 100% make sure you have the right caps in their place and in the right polarity. Caps installed backwards act like shorts. Check the board closely for any solder bridges. Every spot your iron touched needs to be reinspected. Also look for any places you might have accidently dropped solder.
 
when you reflowed the solder on the pins for both daughter cards did you do it with the cards installed or our of the main chassis?? second question: did you remove the old solder from those pins and reflow NEW solder or did you mix new and old solder on the pins?

BTW: replacing the HOT is only needed if your old one tests bad. Test it and don't just throw parts at it without testing them.

Removed the cards to do the cap kit and reflow. Mixed new solder with the old, but 99% sure its not the "daughter cards" since I've switched them out with known working cards from another 4600 and get the same result.

I'm not one for throwing parts at a board, tested the HOT installed on the chassis, and best I can tell it's testing good, but this is the first time i've tested them that way, per a thread of Dokert's I found, so as I think it's good, I could be wrong. Set to diode on DMM, red lead to HOT casing, black lead to monitor chassis (ground), flashes a 3 digit reading (or two) then back to zero. as i understand, as long as it reads, it's good. I know it't not dead shorted.
 
i would check what Ian said.

one note is i see too many people not cleaning their boards and then when they only add solder to old your just mixing in all the contaminants on the old solder with new which i have personally seen it many times where that causes a so called cold solder joint (bad electrical connection). the solder should ALWAYS be removed and new solder reflowed on that connection. i have also seen that on this specific chassis. this is all assuming you don't have another issue from capping as Ian stated to check.

ALWAYS reflow solder on headers/pins with the connector installed!! remember your problem seems to be in the main board and the header pins for the daughter cards are in the main board.

Make sure to do this with a connector on the pins otherwise when you heat them to remove the old solder the pins may drop out of the PCB and also the connector will keep the pins straight.
 
i would check what Ian said.

one note is i see too many people not cleaning their boards and then when they only add solder to old your just mixing in all the contaminants on the old solder with new which i have personally seen it many times where that causes a so called cold solder joint (bad electrical connection). the solder should ALWAYS be removed and new solder reflowed on that connection. i have also seen that on this specific chassis. this is all assuming you don't have another issue from capping as Ian stated to check.

ALWAYS reflow solder on headers/pins with the connector installed!! remember your problem seems to be in the main board and the header pins for the daughter cards are in the main board.

Make sure to do this with a connector on the pins otherwise when you heat them to remove the old solder the pins may drop out of the PCB and also the connector will keep the pins straight.

Thanks for all the input guys....I do seriously appreciate it. I did actually notice a couple of the male pins on the connectors drop when I reflowed them....so I reheated and pushed them back up flush. I'll try having the card on there next time though to save the extra step....good tip.
I do think I'm going to pull the main board again and go over everything (thanks Ian for chiming in) I did. I washed this chassis a couple weeks ago prior to removing and starting the work, so I don't think contaminants would be a big deal, but if I don't find any other issues, I may remove old and fresh solder all the headers on this thing just for argument sake.
TO be continued......
 
simply reflowing the card headers I've found doesn't work. it's a lengthy process, considering it's 32 solder joints that you have to lay new solder down, then suck that solder out, then do new solder again. that's 96 points! :)

the method I use so you don't wind up moving the headers at all is to alternate the odd and even pins. the board's labeled on the bottom with the pin numbers. pretty easy. you'll have to repeat the process again on the cards themselves, so yeah, another 96 times.

I haven't needed to go balls to the wall with the X-Y cards yet. 4600s are tricky to sort out, but when you do they actually have beautiful pictures; more-so assuming they didn't come out of a screen burning game. destroys the 4900, IMO.
 
http://forums.arcade-museum.com/showthread.php?t=383570&page=2

see the last post with very common results when reflowing new and old solder together. its very common that people add to the old solder and i see this very often. may not be your problem but it is way too common that reflow is taken as add to the old solder when you should never do that.
 
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