Fixed: Undulating picture

[whammoed]

I have a pac cocktail where the graphics sort of undulate/wave across the screen, sort of like a waving flag in slow motion.  Everything else about the picture is great.  Is this indicative of needing a cap kit for the monitor or perhaps something to do with the game board?

[qrz]

possibly poor regulation. more likely excess ripple caused by weak caps (pwr sup).
or a beat pattern caused by a faulty ( loose)  ground....

would be helpful to see what ya gots.... pics-make/model ?

qrz

[whammoed]

possibly poor regulation. more likely excess ripple caused by weak caps (pwr sup).
or a beat pattern caused by a faulty ( loose)  ground....

would be helpful to see what ya gots.... pics-make/model ?

qrz

Yeah, that's possible too, I will try to get a video up tomorrow.  Thanks.

[Mrjamma]

This is a fairly common problem with pac games after all these years. Its called Hum Bar.

It is AC that is getting around the regulation of the board due to a bad or resistive connection on the 2 AC inputs to the board.

One is 14 volts ac, the other is 7volts ac.

Try to wiggle the board edge connector and see if the problem goes away, the power pins on the edge connector and the connector itself is frequently burned and crispy. If so, then repair your edge connector on the board and or replace the edge connector pins on the wiring harness.
If you are good at soldering, replace the entire edge connector with a new one.

I have done this on a Ms Pac that was giving a lot of grief with resetting or  locking up,etc.

The other neat fix is replace the fuses with new ones that aren't corroded and replace the 4 fuse holders in the bottom of the cabinet with new ones. The originals are brass and will be well tarnished by now and provide resistance that causes this very problem.

New fuse holders will work wonders.

[whammoed]

Thanks.  I see no corrosion whatsoever on the board or edge connector, so I will start with the fuses and fuse block and go from there.

[whammoed]

Replaced the 4 position block and the 3 position just for good measure.  No change.  I will pick up some new fuses tuesday.

Before:



After:

[whammoed]

Here's a video of the issue:  (just the waviness, not the bar...bar is a result of making the video)

[youtube]http://www.youtube.com/watch?v=H0E9h2x6sac[/youtube]

[Lutus]

Those fuses look almost yellow on the end.  Should be replace even if it doesn't fix your problem.  The new fuse holders make the old fuses look gross.   

[whammoed]

Installed fresh fuses.  No change.

I will probably replace the filter caps next, since I planned on doing that as well as the rest of the eloctrolytics on the pcb.  If I still have an issue I will replace the pins in the edge connector.

[grantspain]

if you disconnect the video signal from the monitor do you still get the interference?

[whammoed]

I was pointed here about this problem in another thread:

http://www.therealbobroberts.net/hum.html

This corresponds with what Mrjamma advised so I think my next step is the edge connector.  If that doesn't solve the issue I will look into the caps.

[whammoed]

if you disconnect the video signal from the monitor do you still get the interference?

It does seem like it's still there even when the signal is unplugged.  I'm also getting good DMM readings when testing the edge connector from the pcd to the transformer like bob does here:
http://www.therealbobroberts.net/pacpower.html
so I am dubious that it's the edge connector at this point.

[grantspain]

sounds a caps/earth issue with the monitor but also check the power wiring to the monitor

[whammoed]

sounds a caps/earth issue with the monitor but also check the power wiring to the monitor

I'll probably pull a monitor from another game and see what it looks like before deciding what to do next.

[whammoed]

I've confirmed it's the monitor.  It exhibits the same symptoms in my Pole Position.  I will order a cap kit and the B+ filter from Bob.  I won't do the flyback since it's been home use for over 20 years, otherwise I would consider going ahead and raplacing that too.

[whammoed]

I did a cap kit and replaced the B+ filter and no more waviness.  I thought the picture looked pretty good before but now it is perfect.

[youtube]http://www.youtube.com/watch?v=DshGewWLuTc[/youtube]

[WunderCade]

Cool...what is the B+ filter, and which monitor was this? I have a WG 19" K4625 in mine.

[whammoed]

Cool...what is the B+ filter, and which monitor was this? I have a WG 19" K4625 in mine.

The B+ filter is the large capacitor that filters the current after the bridge rectifier.  Here's Bob's page on it:
http://therealbobroberts.net/bplus.html
I have an Electrochrome G07.