WG K7203 - dead - won't start on first power up - Solved

[TopJimmyCooks]

Ok, I'm new to arcade monitors, never had one before.  I picked up a newer Ms Pac man cab with a 19" WG playing blind, screen completely dark.  the chassis made a hissing sound - so flyback trouble is indicated from what I've read.  Got it home, discharged, pulled the monitor and had a look.

Mfg date 2004.  No caps obviously bulged or leaking.  No cracked/bad looking solder joints on the solder side, everything looks fresh and bright.  Flyback has white goo coming out under the control pots.

Caps look good visually:


Flyback - I suspect this discharge is not normal.  (That's what SHE said)


I really appreciate any input.  Questions:  what should I try/check out?  Should I go ahead and get a flyback? and a cap kit?  Are there any good guides to troubleshooting this type of problem (i've briefly looked at bob roberts/arcade cup vids).  Thanks.

[TopJimmyCooks]

upon further review, I think the white substance on the flyback was adhesive over the "screen" control.  I popped it off and found no apparent visual damage. 

[TopJimmyCooks]

disregard - got it working. 

[MTPPC]

Please elaborate.

[TopJimmyCooks]

Unplugged, replugged all the connectors,  pulled the glob of adhesive off the flyback screen knob.  Reassembled chassis.  Reinstalled in cab.  Plugged it in, got a pic, with whine.  unplugged and replugged a few more times and the pic is decent, flyback whine went away. 

Missing yellows, however, even after playing with the color controls, and a little ghosting on the icade select game screen (none in games).  So I'm ordering a cap kit.  I let it run for two days with no change in operation, so I think it's pretty solid.  It's only 9 years old.  ZERO burn in.   

[MTPPC]

You can't be missing yellows. You must be missing Red, Green Or Blue. Yellow is not a primary color. I'd make sure all 3 colors are working before sinking any more money or time into it.

[TopJimmyCooks]

Agree. I'm paranoid that it's related to the crappy source (bootleg icade board).  Symptoms: ms pac man is red, both red and orange ghosts are basically the same red color, and the galaga bees look like they never had yellow pixels at all.  I wish I had another jamma board to try.  This weekend if I can get into the test mode hopefully I can get some color bars to better play with the settings and see what's up. 

[TopJimmyCooks]

In accordance with MTPCC's advice I took another look and feel that no GREEN is being displayed at all, hence no yellows.  Haven't ordered any parts yet.  I'm going to carefully check through all the connectors and solder joints on the neckboard, switch another color input plug etc to see what's going on. 

I had to go to my mame rig for comparison to realize the frog in frogger is supposed to be green not black. 

Thanks to randy fromm for reversing my grade school learning and letting me know that red plus green = yellow.

[MTPPC]

I'm no expert, but if you can switch the colors around and you still have no green, then it's time to put the tube on a rejuvenator and find out if the green gun is open and the tube is trash.

[TopJimmyCooks]

will do.  stuck with yardwork today but I'm on the case in the morning. 

[TopJimmyCooks]

my poor soldering skills are killing me on this.  I'm sick of pulling off components that test fine and then putting them back on.  I guess I've gotten used to soldering on big, beefy pinball boards and components - the tightly packed neckboard is kicking my butt.  Lifted a trace on a transistor lead, made a mess trying to bridge solder over to it, decided to call it a day. 

I would happily send the boards off for repair, but I'm paranoid something's wrong with the tube.  I reversed the green and blue input wires and still got no green.  So I'm going to call local tv repair place downtown and see if they will look at the crt and chassis together, test the crt. 

The transistors on the green section tested ok off the board and now I've got the lifted trace issue so I think I'm at the end of my troubleshooting ability.   

[TopJimmyCooks]

Short:
Got it fixed. Replaced 2 transistors in the green section of the neckboard. 

Long:
Talked to a TV repair guy who mentioned that Transistors can sometimes be bad even if they test ok off board.  So I ordered replacements for the first two transistors on the troubleshooting guide (drive and one other) from Mouser.  Super glued a couple of dodgy pads back down. Put the Tx's on and used the long leads bent over to get past the burned/missing traces.  Tested everything for continuity/bridging with the MM.  Put it back in, turned the red and blue drives down some and got the green. 

  Looks like Ms. pac man will be for sale for some more Green soon. 

[TopJimmyCooks]

New problem has developed.  first plug in from cold gives flyback whine and a black screen.  (stuck a toothpick in there, didn't help).  Unplug and plug right back in, works as before, no flyback noise. 

Read an earlier post with the same power problem that Ken Layton replied to recommending a cap kit.  Interested in input from those who know CRT's.  Thanks.

[lilshawn]

your biggest main filter cap (c101?) might be shot. it's extra load might be bringing the whole b+ down

OR

your b+ is too high and causing the power supply to shut down because of the dangerous x-rays "intermittent shutdown" (Q203, C011, U101, Q002)

check the items in the troubleshooting for "shuts down" (C101, Q002, D001, C012, R101, C117, C102, U101, Q501, C511, VR001, T601)

[sarge]

http://forum.arcadecontrols.com/index.php?topic=108075.msg1150691#msg1150691

I know he labeled the thread wrong but the most common fix for your problem is in this.

[TopJimmyCooks]

thanks for confirming guys.  where's the best place to get a cap kit for this display?

[TopJimmyCooks]

Cap kit solved power problem.  had no impact on colors. 

[boardjunkie]

If the chassis was in H shutdown, you'd get no f-back whine since the whole H section would be disabled.