WG4900 Help

[Netropolis]

I have been lucky so far,..

Aside from throwing away a perfectly good 20EZ in my early days of collecting...  *I didn't know better - but regret it every day now.
Every arcade I have aquired has had a perfectly good monitor (some have a little burn-in) but other wise never a problem.

In py previous post about my Championship Sprint restore... I mentioned i have a monitor issue.
My WG4900 works!!  it has neck glow it crackles when it gets power but, no matter what knob I turn in the back this is what I see.



I can sometime change the colour... aside from the thick line, I can also see some very thin lines on either side of it that flicker.
Like I said no matter what knob I turn...  nothing changes.

Asking is this HOOPED or is there ONE cap I need to change or is this a fly-back thing?

As I mentioned, I have been lucky until now so aside from discharging them I haven't had to with monitor issues.
Any Monitor-Docs out there care to weigh in... I am ready to so what I need to to get this game going.

[John's Arcade]

Vertical deflection problem.

Check this out:

http://s172.photobucket.com/user/modessitt/media/K4900Flowchart.jpg.html

4900 Medium Res? I don't know much about them. But, I'm sure the flowchart can help.

[Netropolis]

Thanks John - that was the first thing I looked at was the flow chart.

I couldn't tell if that was actually the exact problem (vert deflection) Your trained eye though... I am convinced.
These C311,306,308 & 313 are all things I can order from someone like Ian yea? 

It also said Transistor Q302, 303 and Resistor R313... Ian if you read this - do you have a kit for all that for a med res WG4900 for sale?

[John's Arcade]

Thanks John - that was the first thing I looked at was the flow chart.

I couldn't tell if that was actually the exact problem (vert deflection) Your trained eye though... I am convinced.
These C311,306,308 & 313 are all things I can order from someone like Ian yea? 

It also said Transistor Q302, 303 and Resistor R313... Ian if you read this - do you have a kit for all that for a med res WG4900 for sale?

Basically, start with a cap kit which should contain those 4 caps.

[Netropolis]

WILL DO John!  Thanks for the advice!
I am on it... poppin my cap cherry on a championship sprint!
WHOOOO!!

[John's Arcade]

WILL DO John!  Thanks for the advice!
I am on it... poppin my cap cherry on a championship sprint!
WHOOOO!!

If that is a medium resolution monitor, just make sure you get the right caps. Not sure if the 4900 medium or standard res are the same values or not!

[iankellogg]

K4915 is the same cap kit as any k4900

The K5515 is only one cap different than the K4900

[Netropolis]

UPDATE: Mr Kelloggs Cap Kit arrived and I was finally able to do it tonight.
My Solder sucker sucks though... or rather DOESN'T suck very well.  But I got it done.

Anyway, after putting the chassis back in and checking and triple cheking every wire and cup and molex was in the right place in the right direction.
I flipped it on... *Drum roll*

NOTHING... Same line across the screen.  
I can report this though... the center of the board has slices in it... I dont want to say 'holes' like someone took a miniature skill saw and put a few hacks into the board.  it looks weird but none of the caps/trans/resistors are affected.  it also looks like it was worked on before...  lots of old flux and BIG ASS solder dolops etc.

So now that I am officially stumpped. what should I do?  Try and find a K4915 med res chassis?  
Any further advice?

Note: I do have a K4906 Std Rez Monitor...  but I know from other conversations that wont work... but WHAT ABOUT the Chassis???  are thos inter-changable?

to the trained eye - is this the same chassis for my med Rez?
http://www.ebay.ca/itm/WELLS-GARDNER-WORKING-K4900-MONITOR-CHASSIS-19-CLEAN-/151879253550?hash=item235cb57e2e:g:4q0AAOSwAYtWQIP4
NVM - it is NOT a 4915 - confirmed by the seller.

[iankellogg]

I guess I never did reply to this thread properly.

Thats vertical collapse and it is pretty straight forward to fix but you need to actually do a bit of work to test stuff.

What you need to do is make sure you have a resistance from the yoke coils.
measure between the V labeled pins on the picture below


If there is no connection between there, your yoke is damaged and might be repairable.

After that, make sure its plugged back in correctly and possibly reflow the header.



Next thing to check would be the vertical deflection transistors

you can test these in circuit using diode check on your multimeter (if you dont have that, ohm reading might work)
Measure basically every combination of two pins to see if there is any 0V or 0ohm readings. If so you have shorted drivers.

Other options are C313 not being installed correctly, and VR303 being broken.

If all else fails maybe IC301 is bad. I doubt it if you are getting high voltage and horizontal deflection but its still a possibility.

[Netropolis]

OK WOW!  This is way over my head!!! 
What happened to Recapping fixes everything?  Sigh!  LOL

Where would one find transistors?? 
Does anyone sell kits for this?

In your post there was no picture - but my yolk seems ok I get glow and all that jazz.
when I play with the RGB pots on the neckboard the colour changes on my line I get...

One last thing - I didn't change one of the caps - it was the one where it said something about a transistor in the same holes??
you marked it as a D and not a C in the kit?  306 I wanna say?  (at work rt now).
Anyway I wasn't 100% sure what to do... replace the component there with the cap provided?  Put them BOTH in there together?
do you think that one cap could be a miracle fix? 

I was worried about doing a cap kit, and now, I am lost.

[iankellogg]

The picture is loading on my side in the post but if you cant see it i got it from bob http://arcadecontrols.com/BBBB/yokeplug.jpg

I seriously don't recommend replacing things unless they are actually bad. the more unneeded time with the iron is just going to damage the monitor PCB. If you need the transistors you can get them from bob or a few other places. I will at some point stock them but at the moment I don't. Don't worry too much about replacing the one diode/cap combo, its really not that critical.

[Netropolis]

I ended up taking a good close look at the neckboard tonight. That round thingie that plugs into the glowing shot glass - stop laughing... One of the points was never ever soldered to the board. Did that, then another 5gi was missing-on close inspection it was pulled out under the round thing soldered to a wire that went over to a mini board attached to the metal side of the chasis with a cap on it?
Like I said this chasis has been hacked and re-hacked cut burnt!
Anyway, after reflowing anything that has anything to do with Vertical or Horizontal... I get the exact same line... No matter what pot I manipulate.

Does anyone fix these on the side? 

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[Netropolis]

Also on the photo you supplied, the RED wire was scorched as was the grey plastic connector.
That wire is close to this tall cone thing with a copper coil which also had some scorching...
I reflowed the connector that plugs into and while the monitor was on - I crossed my fingers and touched the wire and connector after it had been running a while - not hot - so the black was likely from before a previous fix?

[iankellogg]

did you ever check the resistance of the yoke coil? There is no point in fixing the board if your yoke coil is bad.

[Netropolis]

Wanted to ask about that!!
So i plug in the chassis except that one molex and put my multimeter in the hole and flip on the machine?  I just wanna confirm and dont want to fry myself.  Sorry for the remedial questions.

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