Newly dead K4500

Vraz

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I picked up a Galaxian cabinet cheap and everything was going really well. Fixed the PCB, fixed a couple wiring issues, put it all together and the K4500 monitor came up. Not the greatest picture, but working. The picture was a bit narrow so I decided to try adjusting the width coil to see how much improvement I could get.

Like an idiot, instead of verifying with the manual first, I just started adjusting what looked like the horiz width coil. As I realized in retrospect, there were two problems with this:

1- Since it is a vertical game, its probably the vert width I needed to change
2- It was actually the horiz sync coil (not the width coil) I was messing with

Suffice it to say that all I initially accomplished was to lose sync on the monitor. Not having learned my lesson, I blindly blundered on trying to readjust the width/sync until at one point I heard a high-pitched whine and then nothing. No magic smoke, but am assuming I fried something. At this point, I don't see a neck glow though there is power going to the monitor.

While I am pretty accomplished on the digital side (have fixed multiple PCBs), analog is not my thing. Any hints on where to look or is it likely game over? I do have a schematic but have no experience messing with monitors.

If anybody has guidance that could help save my K4500 from my bout with stupidity, I would appreciate it. Thanks!
 
At this point, I don't see a neck glow though there is power going to the monitor.
Realizing that last night was a total disaster, I decided to recheck everything from scratch this morning. When verifying power to the monitor, my meter read ~20VAC. Looking at the schematic, it was clear the monitor was expecting 120V. Turns out of the two fuses coming off the isolation transfer had blown. Once I replaced that, I get 120V to the monitor. What I don't understand is how I was reading 20VAC with it blown. Was that "artifact" caused by the monitor power wires running in the same harness as other AC power wires and getting low-level induction to complete the circuit?

The upside is that with the power problem fixed, the monitor now fires back up. Its messed up with long vertical lines, but of course, that is because I messed up the horiz sync and the monitor is rotated. Is there a proper way to adjust the horiz sync coil (that does not require a scope)? Initially I was just going to try making half turns with frequent testing. Not sure what else to do.
 
Initially I was just going to try making half turns with frequent testing. Not sure what else to do.
So I got the monitor back into sync and it seems alright again. I also adjusted the vert size slightly (which is what I intended to do in the first place). The image definitely has some issues, but its playable for now.

k4500.jpg


The remaining issues:

The horiz position is off (its shifted too far "up" in the picture)
Too much red in the image
There is some "streaking" (like the pixels are bleeding horizontally)
The colors generally seem overdriven

Am thinking I should probably get a cap kit for it before messing with it any further.
 
get the galaxian manual
in it it has all the info on the 4500 monitor
becareful there are alot of adjment pots in there, actually too many
this guy is a beast to adj and fix, but can be done.
one thing to consider is : is it worth it to fix and adjust. meaning is the tube have screen burn and colors not bright.
most of the 4500 have alot of burn and the colors are weak (gun in the tube are almost gone).
i spent way too much time on mine gust to get it working and then i hated the look of the colors and mine had no screen burn, i later got a new monitor best thing i did.
 
one thing to consider is : is it worth it to fix and adjust. meaning is the tube have screen burn and colors not bright.
most of the 4500 have alot of burn and the colors are weak (gun in the tube are almost gone).
i spent way too much time on mine gust to get it working and then i hated the look of the colors and mine had no screen burn, i later got a new monitor best thing i did.
As I do more research on this thing, it becomes apparent that information is limited and it can be a pain to work on. Your feedback just further confirms that. At this point I am changing plans. Am going to do whatever final adjustments I can to get it looking tolerable, put the smoked plexi back in (which hides the burn pretty well) and call it a day. I have plenty of other work to do on the cabinet and will concentrate on that.

I managed to find the horiz position which let me move the image back into position. One upside is that the colors are very vibrant on it so no problem there. If anyone has ideas on how to adjust the following, that would be great:

Vertical centering: not critical, but would be great to center it a bit better. However, cannot find an adjustment for it in the schematic.

Color smearing: difficult to describe, but the scrolling stars look more like teardops. I get the feeling the colors are being over-driven (as they are quite vibrant).
 
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