need help with wei-ya 820H chassis

[redfivexw]

I just installed a wei-ya monitor chassis on my old monitor tube.  The tube reads about 35 on my meter for impedence.  I installed the 820H, which is a high impendence chassis.  When i powered on the unit, my picture is scrambled, the colors look correct, but everything is scrambled up.  I connected the RBG and sync wires, everything is connected as it should be, and the board is fine.  What do i need to do next to correct this problem? 

[grantspain]

got a photo?
if you had the yoke spec wrong then i would expect a meltdown on the deflection circuit rather than any video issue

of course you have adjusted the horizontal hold

[redfivexw]

I can post a photo if it will help, but basically it is just all scrambled.  I have tried to adjust the hold but it does not help.  I have installed quite a few of the weiya chassis, sometimes they work perfect and sometimes i have problems.  I was wondering if it is because the Impedence is 30 instead of 50.  Usually when i take a reading of impedence it is either 12 point something or 50 point something.  I have a couple of tubes here that read in the 30's and one that is 6.  I will take a photo and post shortly.

[redfivexw]

here is what i am getting.  At first i thought it might be  a sync issue, but there is only one sync wire and i have it connected. 

[grantspain]

that is a sync issue-looks like horizontal hold
is the pot ok

[redfivexw]

it is a brand new chassis.  is it possible that the tube is not compatible with the chassis, or are they all compatible as long as you have the right number of pins and the right impedence?  I know you say it is a sync issue, but if i have the sync wire connected, the ground wire connected and the RGB wires connected, what is left?    Like i said before, sometimes (especially with wells gardner low impedence monitors) i just plug these in and they work perfect, other times they dont.  I dont know what to adjust from this point

[Deadly]

You make me think you're ordering chassis and plugging them in without really knowing why you need certain chassis. Impedance and pin count determines the chassis needed.
Sync depends on what PCB you have it hooked up to. Use the pots on the back of the chassis to see if it helps otherwise tie BOTH sync wires together and see if the results are different. And new out of the box doesn't mean the pots are set to the optimal settings. Every tube is different. I've had to adjust every We-Ya chassis I received in some way shape or fashion.

[redfivexw]

I measure the impedence and  # of pins, order the chassis to match.  Usually it works with only minor tweaking.  there is only one sync wire on the wiring harness, and one sync wire coming from the chassis.  I know some of the older chassis had two sync wires, but this one only has one.  I know how to adjust the pots, but i cannot get a picture.  Like i said, this really looks like bad sync.  I have seen this same thing with older monitors and i would tie the two sync wires together and it would cure it.  But there is only one sync wire from the wei-ya chassis to the one sync wire of the jamma harness.  I am sure i am just missing something here, but i dont know what it is.  I have tried 2 different pcbs and they both give the same result. 

[Ken Layton]

What game boards are you using them with? The Wei-ya chassis only accepts composite NEGATIVE sync. Boards that generate positive sync won't work with these.

30 to 50 ohms is considered the high impedance yoke.

Now it's possible something in your cabinet is not wired correctly. Follow your sync wires in the cabinet to make sure everything is ok and there are no connector problems.

Of course there's also the possibility that you have a bad chassis right out of the box.

Remember, the 820 series needs to be operated from an isolation transformer.

[redfivexw]

Hi Ken,
Thanks for your input.  I am using a 48 in 1 jamma pcb, brand new.  I also tried a vigilante board that i use for testing.  Both gave the same result.  The machine was originally a street fighter, and i am using the original wiring that only had one sync wire.  The monitor, however came out of an older machine that had an unknown chassis on it.  I removed that chassis, measure the impedence as 30 and it has 10 pins.  I ordered the 820H because that is the appropriate chassis.  Now, the chassis has RGB ground and sync.  The jamma connection has RGB ground and sync.  I connected all of those and got what you see.  If i adjust the horizontal hold it does make the lines move faster and slower, but never gets clearer.  I realize the chassis might be bad right out of the box, but i am more inclined to believe it is my hookup, but if there are no other adjustments, that might be what i am left with.  UPDATE- i spent a bit more time adjusting the vertical and horizontal hold.  I was able to get the lines to stop moving and i can tell what game is showing, but it is still bad, everything is repeated.  This photo shows the attract screen for Donkey Kong jr off the 48 in 1 board:

[Ken Layton]

I wonder if this model has a "sub horiz hold" on the main chassis board kinda like on Nintendo Sanyo monitors?

Of course with the trip overseas these monitor boards make, I'm sure you might find a few with cracks in the foil.

By chance is your 820 equipped with a remote adjust board or all the pots on the main monitor board?

[redfivexw]

all the pots are on the main monitor board.  I have 2 other 820H chassis here, today i will install another one and see what happens.  I just did not want to give up so quickly on this one.  I see no other adjustment pots on the board that would affect this.

[qrz]

you were closer on the first screen (Hfreq too low ) . last pic , Hfreq is sevral times higher than it needs to be .   i.e. multiple pics
vert appears sync locked.

the question is why it didn't sync in the first place.  missing drive / polarity  what ?
not found a schematic and unfamiliar with model . so, can't get specific. sorry

[redfivexw]

Ok,
so i tried a different chassis, the exact same problem so no way it is the chassis being broken. What else can be wrong, is it possible they are incompatible? 

[HaRuMaN]

Is your xx-in-1 board video output switch set correctly? 

[redfivexw]

I had 2 boards and both of them had the #2 dipswitch in the up position.  I pushed it down and now a nice picture is there.  I am an idiot