k4600: recapped but experiencing some brightness/color issues

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k4600: recapped but experiencing some brightness/color issues

Before I recapped this k4600 it had some pretty distinct bleeding colors and a brightness/ flashing brightness issue.

Anyway, now that I have recapped it, I feel like the bleeding colors were somewhat due to the adjustment of the black pot on the left daughter card. irrelevant now I suppose since I changed the pot.

My trouble is:

I cannot get the brightness high enough to be consistent.
When I turn the black pot (left daughter card) up, it makes the colors bleed, so I keep it right at the point where it doesn't.
I then go to adjust the screen pot on the neckboard, and when I get the desired brightness, I get this random flashing brightness to the screen, where it warps very very slightly and gets a level or 2 brighter. It goes in and out of the super brightness.

Should I change the pot on the neck board, this appears to be the issue, but I wouldn't know. Just my sense of what's happening.
While adjusting this pot (neck board) there is no gradual gain in brightness, it tends to lurch to super brightness, or not appear to do anything at all.
 
after reading up on some other threads, it turns out the black pot on the neckboard has a high failure rate.

Can I get one of these at fry's or radio shack?
 
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I have NEVER had the "Screen" pot on the neckboard of a 4600 series monitor go bad. The resistor located directly behind it does go bad alot though.
 
I have NEVER had the "Screen" pot on the neckboard of a 4600 series monitor go bad. The resistor located directly behind it does go bad alot though.

lol I was reading a thread from awhile back where I thought you said the pot went bad, but it was probably the g07 you were talking about.

Well at least I can probably get the resistor from radio shack or fry's huh?
Any chance youknow the value (is value theproper term?)j


oh and could this be the cause of my brightness adjustment not working?
 
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No, wrong resistance value. Supposed to be 330 k not 330 ohm.

When this resistor goes bad, it causes the black level pot to act like the screen control.
 
No, wrong resistance value. Supposed to be 330 k not 330 ohm.

When this resistor goes bad, it causes the black level pot to act like the screen control.

hey thanks a lot.

I am heading to fry's in a bit.
I appreciate your help!
 
R419 which is 330 k @ half watt. Not stocked at Radio Shack.

ok well I went to fry's and they did not have this exact resistor.

Since I spent $5 in gas getting there, I went ahead and purcahsed

240k 1/2w and 470k 1/2w

will either one of these work?
 
ok, this cocksucking piece of shit is pissing me off.

I changed the resistors (both of them behind the screen pot on the neck board)

1st one was 330k I put in 340k 2nd one was 470k I put in 470k.

The screen simply varies in brightness throughout gameplay.
starts low, flashes high, stays kind of high, next thing you know it's too dark again. Not too dark to play, but too dark.

Any idea what the next move is?
 
Has the black level pot on the video interface board been replaced? If you bought your capkit from Zanen Electronics, then it would have included a new pot in the kit.
 
I got it from bob and he said "they are extinct" (referring to the pot)

guess I had better search for one.

he talked about dust particles(or something to that effect) circulating in the neck.

and when they circulate it changes the brightness of the screen. I thought I may rejuve it, to see what that does. though it doesn't need a rejuve. the screen is awesome aside from the obvious.

Yeah in my opinion the pot could be bad, because it does nothing noticeable unless it's cranked all the way up!
 
If that's the original black level pot, they fail all the time. It's got a harline crack inside it in the resistance carbon element and that causes wide flucuations in brightness and/or erratic brightness. Zanen Electronics has no problem getting those pots since they include the pot in every 4600 capkit they sell.
 
If that's the original black level pot, they fail all the time. It's got a harline crack inside it in the resistance carbon element and that causes wide flucuations in brightness and/or erratic brightness. Zanen Electronics has no problem getting those pots since they include the pot in every 4600 capkit they sell.

I think we are talking about 2 different things.

The left of the 2 "daughter boards/cards" interface board I guess, it has been changed, and it works beautifully.

The black pot on the neck board ( the one bob says he can't get) hasn't been changed, and that is the pot that appears to not work. I mean it kind of works if you crank that bitch all the way up. but otherwise, it simply does NOT give a gradual change to screen brightness as you adjust it.
 
The pot on the neckboard is the "SCREEN" control. It's special because it operates on 800 volts!

You may have a tube problem. Suggest connecting tube to a rejuvenator for testing. The 4600 tubes do fail alot.
 
The pot on the neckboard is the "SCREEN" control. It's special because it operates on 800 volts!

You may have a tube problem. Suggest connecting tube to a rejuvenator for testing. The 4600 tubes do fail alot.

thanks bud, next move
 
ok I rejeved it. no change.

being a guy that knows nothing, obviously: I think the adjustment pot is either bad or not making good connection. Iwill test that tonite.
 
pot tests out as good, and I rejuved it twice. the picture is awesome!!!

the constant changing of brightness levels is not.

Is it reasonable to assume it's a tube problem now? I can sell the rebuilt chassis to someone if that's the case.
 
Resolder the connectors on the video interface card and mates on the main board.

It's possible that you could have a transistor problem on the video interface card. I have seen instances where one of the two brightness transistors located above the electrolytic capacitor have gone flaky.
 
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