WG 27K7391 - Power? - Worth fixing?

[BrianAg95]

Ok, so... I bought a nonworking cabinet, and I was planning on stripping it all out and using it for mame....  I decided to do some testing first, plus If I could use the 25" monitor in it.. bonus....

Game powers up. game sounds fine but no monitor...  Guess what it's got no power  I start dealing with the rats nest of wiring..  come to realize the monitor has no power connected to it.  Whaaaaaa

I tested the wiring up to the monitor itself and it is getting the correct power.  But will not turn on.    Even though the main monitor board has all the V and H synch adjust knobs...  another board was soldered onto the main board and has another set of these controls....  Obviously this monitor board has had issues before....

From my research this is a pure cga monitor.   

Is it worth getting it fixed? 

For those who might say keep the cabinet original.... thats almost not possible with this thing....  it has been through the ringer.  the wiring is all jacked up, there are 2 power supplies,, and if you power EITHER one the game will turn on....  Yeah thats a weird one.... and it kinda makes me nervous...   There are several plugs not plugged into anything (missing maintenence panel perhaps)  The wiring to the monitor is too small in my opinion (compared to every other cabinet I have looked at)   There are 3 holes in the top panel that shouldn't be there...  The control panel is basically destroyed (plastic bad, graphics destroyed (under the plexi), mismatched joysticks, 3 holes drilled into the side for no apparent reason...  t molding destroyed in one place, back panel screwed on in pieces..   In other words bad...  Hence my plan to mame it.

And since the monitor doesn't work,, I'm thinking my options are:
A: fix arcade monitor $$ - run soft15/powerstrip(difficult setup? (I havent done this before)
B: use TV tube (free) - use video card that outputs to tv(basically free, I may even have one laying around so free)
C: Use modern LCD TV $$ - higher res in windows, and easy to hook up and work on.. and much lighter

I don't need an arguement on the pros and cons of each solution... just general thoughts on if I should fix the monitor (I haev read all the threads I care to about the arguements pros and cons of each solution)

[epicfatigue]

I would repair it but thats just me.


First off did you connect it to an isolation transformer, check that this require one by finding the manual.

When you turn the monitor on is it completed dead?
Turn the screen pot on the flyback transformer all the way up does that change anything? do you get lines on the screen.

If no get a multimeter out and measure your B+ line see what you are getting you can do this on the largeest white resistor measure both sides and report your findings.

Photos are always helpful

[BrianAg95]

Yes I pulled the manual, and yes it requires an isolation transformer.  Voltage is correct all the way to the monitor board (ie before and after the isolation transformer). 

Yes monitor is completely dead.  it makes no noise,( like you would expect) and nothing shows up

 I'll see if I can check the B+  When I was looking at the monitor manual and the diagrams, it didn't look easy to do, and the troubleshooting said to
"check B+ at IC4 Pin4 Neck Board, P202 Pin 3"    Those are the exact words....  slightly greek to me... 

[BrianAg95]

Ohhhkay...

Trouble shooting - I checked B+ at p202 pin 3, results 185 dc volts.... 

Next step says "Check for shorted B+ regulator ic4 pins 1-4"    I have no clue how to do that.

Here is the piece of the manual I am following...

[BrianAg95]

Heres pics of what I'm working with.

Photo 2 -label
Photo 1 - Overall view
Photo 3 - Weird added on board
Following 2 pics have 5 wires that connect that board to main board.. they are green, white, red, brown, and yellow.
photo 4 - wires from addon board.. where they were soldered on
photo 5 - maybe better view of connections...
There is marker that says cap 4-18-05 I assume a cap kit was done to it on that date.

I vacuumed as much dust as i could get off the board without touching it.

[ed12]

ya thats a "hot" chassic,needs "isolation".
the add on board just replace's 4 of the pot's that were on the main board >easier to adjust
in theroy<,if the unit is out ? lay it on it glass face >use a towel to portect the glass<,
on the bottom u will find 4 1/4" screw's remove them,put unit back upright,chassic will
slide out toward's the right hand side >looking at the back of it<,DO NOT UNHOOK ANYTHING,AND DISCHARGE THE HIGHVOLTAGE FIRST. also make sure it is not plugged in
to anything at this point..now u can service it. p.s the chassic pan and chassic will come out as a pair,then u remove the chassic form the chassic pan,
from there if u want to service it u can do it easly.

ed

[BrianAg95]

Ohhkay.. Did some web searching found out to check resistance across the pins for the IC4.   

Do I need to take the IC4 off the board for this test, or can it be on the board...

If it can be on the board, then it shorted as I got 0 resistance from all 4 pins.