Electrohome (Pac Man) monitor alignment

[AlanS17]

I recently bought a Pac Man. All in all, it's pretty good. However, the monitor isn't quite where I'd like it to be. It's a vertically oriented game so horizontal controls vertical and vice versa.

My biggest problems are that the screen is quished a little from top to bottom (technicaly width-wise) and shifted too far to the right (technically up).

Also, I've noticed that there seems to be some distortion in the screen. Depending where on the screen I am at the moment, my Pac dude seems shorter, taller, thinner, etc. I haven't spent the time to figure out what distortion is on what part of the screen yet.

The controls I'm finding on the back of the monitor for width/height/centering adjustment aren't helping me much, and I have no idea how to fix the distortion. Maybe I'm just not making the proper adjustments, or maybe I know less than I realize. I know this seems liek a very rookie question. Can someone help me out? Thanks in advance.

[pcb]

Have you tried the width coil?  You need a set of Radio Shack plastic hex tools (TV Alighnment toolset) to adjust it.  Do NOT use a standard metal hex wrench, it will get VERY hot and may damage the coil too.

[AlanS17]

Have you tried the width coil?

[Brunnen-G]

Before you mess with *any* screen adjustments, put a cap kit in there.  That will probably get rid of all of the distortion problems.  Remember that the monitor is nearly 25 years old, and the electrolytic capacitors break down over the years.  You might want to go ahead and get a cap kit for the Pac Man PCB as well.  Bob Roberts has the Electrohome G07 cap kit and the Pac cap kit.

The fuse block on Pac Man is notorious for having bad connections, using a high quality contact cleaner (DeOxit, ProGold) on it will get rid of that problem.

www.therealbobroberts.com   for cap kits.
www.caig.com  for DeOxit, ProGold, PreservIt, and many other chemicals.

[MonitorGuru]

Vertical linearity is out of wack if he seems squished or stretched. I would work on your controls before buying a cap kit. A cap kit solves lots of problems but doesn't solve them all.

To adjust vertical linearity, attempt to connect the board to a game that outputs a white grid of squares. This will help adjust so that each square is identical in size. The VLIN control is the 2nd one in from the left (the left is where the power cord goes in).

You can get cap kits for the G07 cheapest on eBay (there is one up for $5 + $1 shipping right now vs $5 + $6 shipping from BobRoberts. .but order from Bob if you need other stuff)

For the Fuse block that will only cause a roling band across the screen going from right to left about once every 3 seconds.  Don't need to spend lots on cleaners/chemicals to fix that.  Either remove all the fuses and take a wire brush and brush all the insides of the fuse contacts and also the ends of the fuses (make sure you write down which fuse goes where), OR simply go to a farm/auto/home improvement sttore (NOT radioshack) and buy a new multi-fuse block for about $1.50 and pop it in.  If you have no rolling band, you dont need to replace the fuse block.

[Brunnen-G]

Not big on preventative maintenance, are you?   

Adjusting the controls before installing a cap kit will likely make his job harder in the long run.  I doubt that all the distortion will come out with the PCB adjustments, and even if it does, it will probably go out of whack again either when the board heats up after being on for a couple of hours or as the caps inevitably continue to fail.  Replacing the capacitors will give a nice baseline for adjustment that should last for years.  Otherwise, it might require tweaking and adjustment every couple of months.

The same for the contact cleaner.  Putting a bit on the fuses on the fuseblock and turning them a bit (with the machine UNPLUGGED) will remove the corrosion there, as well as leaving a protective film to prevent it from happening for a long, long time.

As far as the cap kits on eBay, I haven't used them.  When you buy a kit from Zanen or Bob Roberts, you're at least reasonably sure to get capacitors of not only the proper capacitance and voltage, but also temperature rating.

Cleaning connections and installing new capacitors will help assure trouble free operation for many years.  All adjusting the monitor will do is assure that the capacitors will have to be replaced eventually.     

[Ken Layton]

Pac and Ms. Pac already have the grid pattern built into the test mode. Just read the manual.

[AlanS17]

Well the image takes a little while to come on, but when it does it's bright and clear. The image is just a little wonky. I'll try the stuff mentioned here that doesn't involve the cap kit. If I can get that working then I won't worry about it. If I still have issues I'll worry about the cap kit. After all...

If it turns out I'm going to have to do it sooner or later, why not just do it later?

[MonitorGuru]

Not big on preventative maintenance, are you?

[AlanS17]

I'll try everything I can tonight.

Can anybody tell me how to adjust a width coil? Also, should it be done while powered on or off?

[Brunnen-G]

Powered on, otherwise you wouldn't be able to see the effects of what you're doing.

[MonitorGuru]

Do NOT use anything metal to turn the ferrite core of the coil. It's not hardened steel.. it's a very fragile rough iron core with a hex hole.  Also using a metal hex wrench or anything else will affect the coil directly (since that's what you're doing--adjusting a piece of metal in the coil center). Therefore if you adjusted it and pulled out the metal wrench, the image would be wrong.

Get a plastic/nylon hex TV Adjustment wrench from Bob roberts. I doubt any RadioShack has them anymore since I've heard most RS have dumped all electronic parts and supplies from their stores to become comumer-based instead of hobbiest-based (though you might be lucky). Bob has a set of 4 for $2 + shipping, so you may as well order the cap kit (if it hasn't been capped recently) and anything else you need.

Also, most G07's have a broken coil to begin with due to storage or shipping with wires against them or the heat breaking up the plastic shell. So if yours is broke, add that to your order from Bob as well.

You adjust it with the power on but with the non-metal device. Turn it one way and the image will shrink horizontally (in the case of PacMan orientation--shrink vertically) and the other to make it expand.

You will also probably need to adjust the horizontal position jumpers.. The G07 doesn't have pots to control where the image starts on the screen, just 2 sets of jumpers you must move.

Do yourself a favor and download a G07 manual online to familiarize yourself with where things are and what they do before you start.

Adjusting the width and positions and linearity should take no more than 5 minutes once you know where everything is at.  Yes, if you end up replacing the coil and/or doing a cap kit, you may have to go back and tweak some of these settings as well.

[AlanS17]

All very helpful stuff. Thanks.

[Ken Layton]

Radio Shack parts numbers for those tools:

64-2220 5 piece alignment set (prefered) $2.99

64-2230 3 piece alignment set $3.99

64-2223 2 piece alignment set .99

All the Radio Shacks here in Washington state still have parts and tools in the stores.

[OldSchool79]

If you do a search for capkit on www.ebay.com it takes the liberty of changing it to carkit for you. A search capacitor kit found them.

[AlanS17]

Well I'm 90% certain that my width coil is broken. It rotates with no result. So my screen is still a little short vertically. But everything aside from that is great now. I was able to adjust away just about everything else, though.

[Darth Nuno]

Hi,

I have exactly the same problem than you  I can have a bigger picture than this :



How do you finally fix the probem ?

Yeps, I know, It's been a while... 

[dabone]

Again, Thanks to Bob Roberts for the following link!


http://homearcade.org/BBBB/wc.html

Pay close attention to the following paragraph.

Don't beat up your coil for no good reason. If it doesn't have the travel you think you need, make sure first as it could be that it is already at it's max position & you have circuit troubles rather than an adjustment problem. A common incidence of this would be in a G07 chassis that you have recapped & installed a new width coil, but failed to adjust the B+ voltage up to 120 VDC causing a lack of width in the pic that no coil will ever regain for you.




Also, do your cap kit.
(I have a k7000 that was giving me fits with horz compression that turned out to be a cap issue.)


Later,
dabone

[fredster]

Yeah, width coils don't adjust much most of the time. 

I stuck an allen wrench in one once when it was running.  It's isn't that the allen wrench will break the core, it's that it becomes an INDUCTION HEATER to the allen wrench.

I about burnt my fingers in 1.032 seconds with it on.

Learning it the hard way is for slow learners.  Me, I'm really really slow sometimes.

[censei]

darth, it seems like you have h-shift/h-pos problem. You can try adjust the trim pot for this adjustment on the chassis and see what happens.