WG 7302 in an RFM - power problem

walkingfish

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Hi guys,

My RFM has the WG 19k7302 screen.

If it has been left off for any amount of time, eg 12 hours, then when powered up there is no sign of life from the screen at all, if I turn the power off then on again, it starts and runs fine.

If it is left running, then anytime from 1/2 hour to longer (its random) then the screen appears to power off.

Other than these issues the screen is great when it's going, no fuzzies, good color and brightness.

Should i replace all caps, just the caps around the power circuits, or is there other components i should be looking at?

Look forward to the wisdom,

Brad
 
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cap everything. then check the B+ (you'll have to find this out on your own, I don't know this monitor lol) .. if it's like the K7000 at all then there's no way to adjust it I think, so you'll have to do caps, and I think if the voltage regulator's bad it'll cause the B+ to go wonky.

to answer your question though, the problem is being caused most likely by high voltage shutdown, hence the caps and you maybe needing to check other parts.
 
Thanks Mecha,

So if I am going to take the shotgun approach to replacing the caps, what are the other likely suspect components that i can replace at the same time, I am getting confused by all my searching on the web.

Thanks,
Brad
 
well, good news I suppose. the K7300 is just the 19" version of the K7400.

had a K7500 in a Carnevil do the same exact thing you speak of. I wound up capping the chassis, and the problem where the monitor would shut off persisted. the B+ adjustment pot was plastered in epoxy, and I wound up breaking the pot trying to get the epoxy off. I was able to part another B+ pot off a junk chassis I had laying around..

there should be a B+ test point on the back right side of the chassis, it'll be a pin that sticks out, I think it even is labeled as like B+ TP or something like that. get some alligator clips out, clip one end of your meter to that, and then use the ground pin on the video signal header for the ground. according to the troubleshooting sheet on WG's site for the K7400 it calls for no more than 120V on the B+... I'm not entirely sure if it's higher or lower or if it's just the same on the K7300 however. I think I adjusted that K7500 to 118, seemed to be the number everyone on KLOV was throwing out for setting it to.

most likely it's too high. either that, or the X-ray Protect pot got damaged. ironically, the epoxy that WG used supposedly damages the pots over time.

so there's your problem points to check lol.

if you wanna go overkill, I say replace the flyback along with the caps. you might have to do some research on what kind of flyback you need though, I'm not sure if it's the same as the K7400 or not. never encountered one of these before... only a Vision Pro variant of a U2000, which incidentally was in our Star Wars Episode 1 pinball (same application as you lol)
 
The RFM I recently picked up has a dim monitor. I decided to go the LCD route. I found a 19" non widescreen monitor off CL cheap. I ordered the cga-vga adapter from Nixs and built my sync adapter today. I'm hoping to have the monitor working this weekend if the parts show up.

I've had no success with k7000's in general, so I decided not to put any time or money in it. - Barry
 
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