4900 Issue...best guess?

MonsterBash

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4900 Issue...best guess? ~Video added

I haven't capped it yet.. B+ was right at 130ish. I'm going through my caps tonight to make a 'kit'

Threw a known working Big Blue in...just cuz I had it

Any guesses as to what the problem is?

ETA video

ETA Progress update
So now I'm stumped...
Tried a know working monitor and works fine...thus the board and cabling is ok.

I pulled a bunch of transistors including 301..all were fine. I spent a good part of an hour with a magnifying glass looking for cold solder joints....didn't find any but touched up some questionable stuff.

As per the flow chart I change IC301..no change.

I found q302 bad..replaced it..no change
I couldn't get a reading out of the 85K Horz pot...changed that. Nothing.
Tried a know working chassis with the existing tube and yoke...worked fine
Did comparison readings on darn near every component to a working 4900

I also noticed that '30' looks like it might have had the wired jumper there at one time? I'm pretty sure I read that it's not necessary but I'm not 100% sure

I'm out of ideas...

I don't think it's a sync issue. Both the horizontal and vertical look solid...they are scrolling like i've seen with sync issue

 

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I haven't capped it yet.. B+ was right at 130ish. I'm going through my caps tonight to make a 'kit'

Any guesses as to what the problem is?

I know on a 4600 the little horizontal osc. pot will cause/fix that... I haven't even looked at a 4900 close enough to notice if there's an adjustment on it for that... but something on those lines is where I'd put my money.


 
Yeah..gave them all a twist...no change.

Kinda looks like a sync issue..unfortunately I don't have a another complete monitor out of a game to test with...this one is all original thus it's gonna get capped regardless. I'm not even 100% sure it's a monitor issue.

I really hate shot gunning stuff even though this guy probably needs it anyway. If it fixes it I really didn't learn anything =(
 
Damn...that video pretty much exactly what I got.

I'll order POTs just in case... i noticed absolutely no change when I adjusted the Horizontal.
 
doubt you have a pot issue. You can adjust the horizontal hold pot (that's the one facing up on the left side of the two directly behind the others on the edge) and replacing the caps isn't a bad idea either.

You also may have cold solder on the sync pins of the video connector pins.

And of course, this assumes you have the sync wiring correct if you perchance but a different monitor into this game than was there before...
 
I did give the sync cable the wiggle test and got absolutely no change in the picture...not even a flicker.

Ahh well...I'll cap it and see what it looks like

It was the original monitor I got with the game..that did work. Thus I'm assuming the sync is hooked up correctly.

doubt you have a pot issue. You can adjust the horizontal hold pot (that's the one facing up on the left side of the two directly behind the others on the edge) and replacing the caps isn't a bad idea either.

You also may have cold solder on the sync pins of the video connector pins.

And of course, this assumes you have the sync wiring correct if you perchance but a different monitor into this game than was there before...
 
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Post a pic

Andrew

I did give the sync cable the wiggle test and got absolutely no change in the picture...not even a flicker.

Ahh well...I'll cap it and see what it looks like

It was the original monitor I got with the game..that did work. Thus I'm assuming the sync is hooked up correctly.
 
On a monitor of that vintage - if the caps are original - CHANGE THEM ALL. They don't get better with age, they get worse. Replacing one or two is just a Band-Aid solution.

I had a Chung-Hwa that had a sync issue, after a year after a semi-capping. It was a single cap in the sync circuit. One of the very few I had NOT changed the first time, because the original cap was "still working".

If a monitor is recent, I'll troubleshoot caps, but if it's that old, I'll shotgun them all.
 
I'm guessing they are original...the neck board has the original 'glue' holding it on. Either that or someone did a real nice job of replacing it.

Unfortunately I'm missing a bunch of caps..I ordered a kit today from BR. Of course you can't just order 1 kit...so as per usual my cap kit cost about 85 bucks =)

On a monitor of that vintage - if the caps are original - CHANGE THEM ALL. They don't get better with age, they get worse. Replacing one or two is just a Band-Aid solution.

I had a Chung-Hwa that had a sync issue, after a year after a semi-capping. It was a single cap in the sync circuit. One of the very few I had NOT changed the first time, because the original cap was "still working".

If a monitor is recent, I'll troubleshoot caps, but if it's that old, I'll shotgun them all.
 
So now I'm stumped...
Tried a know working monitor and works fine...thus the board and cabling is ok.

I pulled a bunch of transistors including 301..all were fine. I spent a good part of an hour with a magnifying glass looking for cold solder joints....didn't find any but touched up some questionable stuff.

As per the flow chart I change IC301..no change.

I found q302 bad..replaced it..no change
I couldn't get a reading out of the 85K Horz pot...changed that. Nothing.
Tried a know working chassis with the existing tube and yoke...worked fine
Did comparison readings on darn near every component to a working 4900

I also noticed that '30' looks like it might have had the wired jumper there at one time? I'm pretty sure I read that it's not necessary but I'm not 100% sure

I'm out of ideas...

ETA I don't think it's a sync issue. Both the horizontal and vertical look solid...they are scrolling like i've seen with sync issues
 
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