K4900 help

tevans333

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I have a K4900 which has a very distorted picture. The vertical is squished too small and the horizontal is expanded too far. I cannot get either to adjust. I have just re-capped it with no luck. Any suggestions?
 
Can you take a picture?

I seem to remember a problem with 4900 chassis being mismatched with yokes. There were 'early' 4900s and 'late' 4900 and the yokes are not swappable.
 
I am at work now and don't have a picture of the tube and chassis handy, but I have taken pictures of the numbers on each peice, maybe these will be helpful.

1. Tag on the tube
2. Tag on back of chassis
3. numbers on Chassis
4. Picture of monitor on
5. Tag on monitor bracket (says electrohome, but this is a WG K4900 chassis. Not sure what tube this is)
 

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you can tell its a 4900 by the solder points for the flyback...why the frame say's electohome i have no idea...
 
you can tell its a 4900 by the solder points for the flyback...why the frame say's electohome i have no idea...


Someone swapped it out. My question now is: What all did they swap out? If this was pieced together I think my original theory of a mis-matched chassis/yoke is looking good...
 
I have a K4900 which has a very distorted picture. The vertical is squished too small and the horizontal is expanded too far. I cannot get either to adjust. I have just re-capped it with no luck. Any suggestions?
Vertical Height or vertical size adjustment pot.
 
You can tell its a 4900 by the solder points for the flyback...why the frame say's Electrohome I have no idea...

Midway shipped some games with the wrong monitor labels on them. Naturally, someone at some time could have swapped out monitors or chassis.
 
Someone swapped it out. My question now is: What all did they swap out? If this was pieced together I think my original theory of a mis-matched chassis/yoke is looking good...

If the yoke connectors are red/white/grey/brown, then yes. if they are red/blue/yellow/green, then no.

and the -055 on the board shows that it is a later series chassis.

a mismatched yoke would show foldover - one side fine and the other side squished. It wouldn't show both sides squished.

4900's are notorious for lots of bad solder in the vertical section (basically all "400" parts). You may also need to replace your vert transistors...
 
If the yoke connectors are red/white/grey/brown, then yes. if they are red/blue/yellow/green, then no.

and the -055 on the board shows that it is a later series chassis.

a mismatched yoke would show foldover - one side fine and the other side squished. It wouldn't show both sides squished.

4900's are notorious for lots of bad solder in the vertical section (basically all "400" parts). You may also need to replace your vert transistors...

Well the yoke connectors are blue/red/yellow/white.
I'll start with soldering the vertical section and see where that gets me.
 
Well the yoke connectors are blue/red/yellow/white.
I'll start with soldering the vertical section and see where that gets me.

That might be okay. I've seen some WG's with different color combos on the yokes - almost like their supplier ran out of one color and substituted another...
 
reflow the solder on the big white cement resistors in the back right hand corner of the chassis and the 2 vertical transistors.
 
Well bad news. When I was working on the chassis last night my dog went ape shit and knocked into me. I dropped the soldering iron and it landed on the anode cap. It Burt the end so bad that it no longer makes a seal when connected to the tube. Is it possible to replace just the suction cup?
 
Not safely. Now you're in for a new flyback transformer. While you're at it, you may as well get a cap kit for it and just be done with everything. Once you replaced the flyback and done a cap kit, you'll have replaced 90% of the failure parts on the whole thing.
 
I was afraid of that. I've already done a cap kit. While I wait for a new flyback to come I may try to get this going with another chassis I have. Does anyone know if the tube I have (pictured a few posts above) is compatible with a k4600 chassis?
 
The tube is, but the yoke isn't. You'd have to swap yokes.

But you CAN replace the suction cup if you need to. Just uncrimp/desolder the clips to remove it, then pull the wire out of the cup and slide it into the new cup, reattach the clips and you're good.

Or you can cut another entire cup (with a little wire) off of a parts chassis/old TV, cut off yours, solder the new one to the old wire (using heat shrink or lots of electrical tape) and that will work, too...
 
Isn't this dangerous as others have said? What do I need to be careful of? How harmful are the x-rays that could be emmitted?

"The sky is falling" "The sky is falling"

You can "safely" replace the suction cup without changing the flyback.


:rolleyes:

Yep. My Robotron's anode cup had been chewed on by a rat and was half gone. I pulled the clips and wire out a bit, cut it off, removed the bad cup, slid on another, reattached the clips, pulled it back into the cup - and it's been working fine...
 
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