Another one! WG27k7501

SiLeNtNiNjA1

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I know i know, youre all saying "Fix what you started last week before jumping into another monitor!!" And I know I should, but I got this chassis from a retail place going out and this will get a game thats down back up again instead of just a better monitor for a game with a different one.

Anyway, to the problem. White screen, leaving a little room at the top. Scrolling horizontal bars. I can sortve see an image behind it. Pots on the remote board work fine.

Any suggestions where to go next?

FYI the game puts out a signal fine to a pentranic ch-288s that I dragged over

Edit - somehow I doubt R122 is supposed to be 0v... The TP for B+ is 137.3, and the 15v tp is @ 14.8v
 

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This is a med-res signal, right?

Has this monitor been fully capped recently?
 
This is a med-res signal, right?

Yup, a Silent Scope PCB

Has this monitor been fully capped recently?
No clue, but I armed with your cap list from an old thread, and am taking it to RS Electronics after work today.

DanV said:
Check if R811 is open.
If not, then check neckboard signals. If proper voltage is there, swap U500.

Ill dig em up tonight. Thanks
 
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The HOT isn't bad. You don't need one. (There's no value in replacing a working one either). If you can make out a picture in the background, then you have both horizontal deflection (obviously) and your sync processing is working.

I'd start by making sure the neckboard is working properly, and checking R811.
If the neckboard is good, and R811 is in value the next step is to go over the solder-side and make sure to touch up any suspecious solder joints.

Service manual:
http://www.wellsgardner.com/pdf/Service/K7500.pdf
 
Yup, already saw the service manual. The HOT I figured would be good to have 1 of on the shelf, since I have 2 of these chassis (the other one gives a single solid green line, and smell of burning death - didnt spend anytime diagnosing that!)

Found this guy NTE2354 on mouser as a replacement.

Ill be checking R811 when I get out of work tonight.
 
Wow, R811 is in a tight spot. Cant get to it w/ the monitor still bolted in the cab. Ill pull it out tomorrow. BTW - the B+ TP @ T203 is what I measured @ 137v. TP202 is 117v.
 
TP202 if I recall is the correct spot to meter at.

I had to do this on a K7400 (functionally identical) and I had one value substantially higher than the other lol. the lower one was the correct one to adjust to 117-118V. I've heard mixed reports about what it should be.

this isn't a B+ thing. it's probably that one resistor that if it goes bad, it makes the whole picture desaturated. what you're seeing is probably the contrast or screen pots jacked all the way up. back them all down. go over all the solder work on it. re-cap it, because those solve everything.
 
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I was being sarcastic, but its good preventative maintenance nonetheless lol.
Yup, I know that - Its like the monitor equiv of a stick of dynamite for a single mole in the lawn!

I checked R811, its 58,9kohm - below the tolerance (its +/- 5%) so ill replace it.

Also, R510 tests good at 29.3ohm and Z500 tests good at 0.43 one way.
 
Yup, I know that - Its like the monitor equiv of a stick of dynamite for a single mole in the lawn!

I checked R811, its 58,9kohm - below the tolerance (its +/- 5%) so ill replace it.

Also, R510 tests good at 29.3ohm and Z500 tests good at 0.43 one way.

you try mucking with the brightnesses and contrast at all? perhaps the color biases as well, since if R811 is bad it's going to produce a black and white image, and if those (or the contrast) are all cranked it'll just be a blurry smudge of a picture.
 
Havnt messed with the bias at all, I did adjust everything on the remote board to both extremes to see what changed. If I can snag a few minutes tonight, ill see what all the pots on the neckboard do.
 
How about the flyback adjustments? It could even be a really close to death flyback not just out of adjustment, as K7500 monitors are known for their junky flybacks.

P.S. Is this in a Silent Scope?
 
You might resolder the cable to and from the main chassis
to the neck board,the video B+ you tested at TP203 needs to get to the
Neck board to each of those 3 watt resistors.
Without that voltage the screen will be blank with a bright raster.
Normally thats D310 and r310 when missing Video B+
But you said you had it at the TP so check the neck board for it.
 
you try mucking with the brightnesses and contrast at all? perhaps the color biases as well, since if R811 is bad it's going to produce a black and white image, and if those (or the contrast) are all cranked it'll just be a blurry smudge of a picture.

Didnt change much with those. Ill see if that changes after changing R811 and going over the pin header's solder joints

How about the flyback adjustments? It could even be a really close to death flyback not just out of adjustment, as K7500 monitors are known for their junky flybacks.

P.S. Is this in a Silent Scope?

I thought the flyback would make it lose focus and/or brightness when it was going bad? Think its likely enough I should order one from chad @ arcadecup and toss it in while im doing the cap kit and that resistor?

Yup, this is in a silent scope, I have 2 of em :)

You might resolder the cable to and from the main chassis
to the neck board,the video B+ you tested at TP203 needs to get to the
Neck board to each of those 3 watt resistors.
Without that voltage the screen will be blank with a bright raster.
Normally thats D310 and r310 when missing Video B+
But you said you had it at the TP so check the neck board for it.

Ill check for voltage at the resistors in that circuit (and ill pinpoint em from the schematic tomorrow to! Thatll be good homework for me!) tomorrow evening and report back what I find. Mouser says stuff is shipped, so I oughta see it soon :)
 
Well, continuity from TP203 goes good past the resistors. But i did find a problem looking at the neckboard - C519 is snapped off!! Ill replace that and see what happens :)
 
Neck Board

You should sub the neck board it
is used on a few WG chassis..to confirm the problem is on the NB.
Or replace Ic U500.
I was looking for you to say i soldered the connections
Normally i solder all pins on connectors,then if theres a problem i would check continuity.
Was this chassi working after the cap kit and then failed??
 
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