What's this weird interference on my k7400?

action53

Well-known member
Joined
May 17, 2016
Messages
1,764
Reaction score
91
Location
West Columbia, South Carolina
It was crystal clear then the power supply died and I replaced it with a switcher. I zip tied the monitor power wire to the frame so it didn't pull on the chassis, could that be causing it? It's slightly wavy.




attachment.php
 

Attachments

  • tmp_5754-20170106_190830102730522.jpg
    tmp_5754-20170106_190830102730522.jpg
    200.5 KB · Views: 109
did you ground the switcher and is the AC coming from cabinet AC or off the same source as the monitor.
 
did you ground the switcher and is the AC coming from cabinet AC or off the same source as the monitor.

The switcher is grounded and the monitor comes from the same source. The ac for the monitor goes though that silver thing, I think. Should I run a ground from the switcher to the frame of the monitor?
 

Attachments

  • tmp_5754-20170106_214510327379974.jpg
    tmp_5754-20170106_214510327379974.jpg
    199.3 KB · Views: 22
your ground on the switcher should be attached to the green ground wire that goes out the plug to your wall outlet. be sure you haven't created a ground loop which can cause interference.
 
Last edited:
your ground on the switcher should be attached to the green ground wire that goes out the plug to your wall outlet. be sure you haven't created a ground loop which can cause interference.

So jump green ground to black ground? I have green ground connected to the bottom and black ground connected to the top.
 

Attachments

  • tmp_5754-20170106_235317-13154562.jpg
    tmp_5754-20170106_235317-13154562.jpg
    196.3 KB · Views: 23
FG ground is the earth ground for the AC line voltage and the GND1 and GND2 are the DC voltage ground. they do not get hooked together.
post a picture where the Green ground wire is hooked to in your cabinet.

have you checked your line filter?
 
Last edited:
if you have an isolation transformer, that will cause this. for whatever reason monitors that don't need them have this happen.

a factory mod that Williams/Midway used was a wire to bridge between earth ground and logic ground. this is if you wish to maintain earth ground to your monitor -- you could alternatively de-pin the monitor power plug or snip the wire in a convenient spot. I was previously anti-earth ground to the monitor but I saw a post here a few months back that was pretty enlightening as to why that's not always the brightest idea. :p
 
I'll try bypassing the isolation transformer and then un earth grounding the monitor and see if that changes anything. It just blows my mind because the picture was clear with the computer power supply in it and I wired the switcher exactly the same.
 
I've run into this before with cheap switchers. Replacing with a quality part solved the problem for me.
 
All fixed, finally. After extensive research and reading Mecha's wise words in this topic and Ken Lawton's in another topic I decided jump earth ground to logic ground and all the interference went away
 

Attachments

  • tmp_21831-20170314_1946011184001265.jpg
    tmp_21831-20170314_1946011184001265.jpg
    535.7 KB · Views: 13
  • tmp_21831-20170314_1946242062722799.jpg
    tmp_21831-20170314_1946242062722799.jpg
    579.5 KB · Views: 21
Last edited:
if you have an isolation transformer, that will cause this. for whatever reason monitors that don't need them have this happen.

a factory mod that Williams/Midway used was a wire to bridge between earth ground and logic ground. this is if you wish to maintain earth ground to your monitor -- you could alternatively de-pin the monitor power plug or snip the wire in a convenient spot. I was previously anti-earth ground to the monitor but I saw a post here a few months back that was pretty enlightening as to why that's not always the brightest idea. :p

actually, I said that. but more power to you.
 
Back
Top Bottom