Damn ! I've been overbid !! O no !
O wel, guess I'll just have to accept my loss.....
Anyway, back to business gentlemen (and the occasional lady):
After having installed the pots on the neck board it was time to finish the monitor !
I wasn't completely satisfied with the red gun's results last time I hooked up the rejuvenator so I hooked it up again and followed all the steps again to first set up the cut-off and then measure the guns to double check. Turns out the red gun was pretty much behind the other two now, do I decided to give that a "clean" as well. Well, here is the result before any rejuving:
and after:
Yes.....nice !
After that I first did some cleaning, also to check the condition of the dag. Turns out that only that part that came loose is damaged. I carefully cleaned the backside of the CRT with a moist sponge. The rest of the dag is well in tact and I'm pretty sure that missing such a small part is not a problem so I'll keep it like that.
Was one of the dirtiest monitors I've seen so far but turned out pretty nice looking from the back...
Close-up of the missing part:
After some dry time it was time to power it up to do the final setting up of the pots...
After some first adjusting I had a pretty good picture:
However I still see some "jittering" in the picture that definitely is not normal. So I start to look for a cause. I had resoldered everything on the neck board already but still I checked every part again (wiggle-wiggle) and the big resistor on the side was loose. Turned out the island had come loose a bit so had to use a wire to fix it properly. Much to my regret it had 0 result on the picture.
Next I started tapping around on the chassis with the back of an isolated (rubbery-grip) screwdriver. I noticed some extra lines happening while tapping the HOT on the right side and on the left side of the HVT. Suddenly I had another problem: the picture went pretty dim on the left while still OK on the right side... I remembered seeing that problem described in Randy Fromm's K4900 flow chart (the 5515 is largely the same as a 4900) and the flow chart pointed to replace C702. Turned out the ting was loose on one soldering !
The leg was very short though so I replaced the cap.
I also reflowed the connector to the yoke since it showed some moving pins when wiggling it and reflowed the HVT solderings and those of the HOT.
Another power up and the problem of the dark left side was gone and the overall picture was a lot better now. However I still see the flickering going on but I noticed that it actually depended on the activity of the game (/PCB).
I mean, when a steady picture was up (like a test screen) there was no flickering at all !
Also when in the attract mode when there is the almost steady map of the track there was no flickering. As soon as the Hard Drivin' logo starts "zooming in" on the top of the screen the flickering starts again. This repeated every time. Also when the car is doing a demo run around the track there is this flickering.
I was suspecting either that the PCB was somehow interfering or maybe that the test switching PSU was having trouble delivering the required current.... I put my DVM over the +5V output in AC mode (yes AC) and I could see that the ripple voltage increased in times when there was flicker. Of course the PCB set is doing it's most work (calculations) when things move on the screen SO my conclusion it is not unlikey the PSU is not keeping up....
So, I figured to leave the problem for now.
I did the best color matching (I referenced to a couple of youtube videos) I could and I am really pretty happy with the results. Yes, you can clearly see that this monitor is 22 years old and that it has been running a lot of hours. It only reminded me how insane lucky I am with the condition of my SW monitor....
If I am extremely critical there are some slight convergence errors in the corners, but they are definitely within spec of production tolerances plus, on full-screen games like this it is barely visible.
So, it is ready to go back into the cockpit !!! Yeah !!
Next will have to be removing the CP to see if I can fix the pot meter problem so we can actually try to do a real race !!
