Diagonal lines on two WG monitors

[FairlanePhantom]

I have two Wells Gardner monitors that have the same symptom:

One of them has all colors but is somewhat dim. The other doesn't particularly show a color until it's either excessively bleeding or turns the entire screen that color.

One source said to replace the transistors on the neck for whatever color the lines were, I replaced all three and the problem is still there.

 

[channelmaniac]

What model of monitor?

If this is a 4600 with the daughter cards then you'll find a shorted zener diode and blanking transistor.

 

[FairlanePhantom]

They're both K7000 series.

 

[ttooddddyy]

Does the 10 uf (afaik) electro that smooths the 180 volts supply to the video outputs look OK ?

 

[Dion]

The lines are just retrace lines which every crt will have if the brightness is too high. If they appear after adjusting the "screen" pot on the flyback down then you may have a blanking problem.

 

[Hewitson]

Mitsurugi-w is correct. VERY slowly turn your screen pot down until the lines disappear.

 

[FairlanePhantom]

They're still there until the screen pretty much goes black. Neither monitor is very bright either with even the brightness turned all the way up.

 

[channelmaniac]

Put a cap kit in. If that's not it then have the CRTs rejuvenated.

 

[Dion]

A cap kit should help but a brightness issue could be caused by a flyback that is dying also. Do a cap kit first and go from there.

 

[FairlanePhantom]

A cap kit should help but a brightness issue could be caused by a flyback that is dying also. Do a cap kit first and go from there.

I did a cap kit last year, and it actually did absolutely nothing to the picture. Today I did three resistors on the neck card that were out of range, a wrong cap, and one more original cap on the board, and nothing changed. Also did three more transistors on the main board that one source credited to loss of color, and nothing changed.

Also seems to be that when blue is introduced, the entire display turns everything blue along with the retrace lines.

 

[Hewitson]

I'm unsure about the colour problem but I would be testing the flyback if the cap kit didnt brighten the picture. Also measure your B+, this is available on the flyback input terminal and should be around 110-130VDC. Do NOT even attempt to measure the output.

 

[Dion]

Could be bad or weak tubes. If you know someone with a rejuvenator you could test the tubes to find out.

 

[FairlanePhantom]

I have a third monitor of the same series, I'll have to swap out the two in there to see if they the lines are still present to rule out the tube.

 

[Hewitson]

I really doubt both tubes are fucked but its worth trying.

 

[FairlanePhantom]

To make it easier, I just swapped the known good chassis into one of the other tubes, and it ended up with the same trouble of a dim picture and retrace lines when adjusted. So when I get a chance tomorrow, I'll have to switch them into the apparently better tube to see what symptoms still exist.

I'm sure the chassis with the green color issue with still have something wrong, but I'll have to see what exactly.

 

[FairlanePhantom]

I tried both chassis setups on from the tube with a perfect picture from another location. Apparently I did actually have two bad tubes, but they still symptoms on the new tube.

The one with the mostly green screen is still mostly green, but red is finally present, but the blue screen and retrace lines are pretty severe when adjusted. It does actually get bright now though.

The other that I said before was just dim is much brighter, has correct colors, and no longer has retrace lines, but there is fold over on the right side, and I can't seem to get a good balance between black and brightness. To get the white level about right, the black becomes washed out. This is really most noticeable on all black screens like the Neo Geo start up screen where the black is really more a dark tan.

 

[FairlanePhantom]

Got around to taking pictures of the one chassis that still has the most issues. The only thing it seems I've taken care of so far is red bleeding when it's introduced, but I still have green being way too dominant and blue automatically creating retrace lines and turning the entire display blue when introduced. The one thing I can rule out is the tube as I don't have these problems with two of the same chassis setups on there.

How it usually looks:

With red turned up, notice how dominant green still is:

With blue turned up only slightly:

The retrace lines are only there when blue is turned up.

 

[channelmaniac]

Probably a bad transistor on the neck board causing the blue problems... Either that or a horribly cracked solder joint.

Could also be a bad tube, or the green being far out of adjustment.

You need to pick up a CRT tester/rejuvenator.

 

[FairlanePhantom]

Probably a bad transistor on the neck board causing the blue problems... Either that or a horribly cracked solder joint.

Could also be a bad tube, or the green being far out of adjustment.

You need to pick up a CRT tester/rejuvenator.

I plan on picking up a rejuvenator eventually. At the moment I can rule out the tube as I can swap in either of those other two chassis setups and not have a problem with color or brightness.

I did the three transistors on the neck, along with most of the resistors as I did find a few out of range. There's one resistor on the neck to the right of R209 that my schematic doesn't mention, not sure what it handles.

Did a basic cap kit when I first got the chassis, also recently did three transistors at Q1, Q2, and Q3.

 

[FairlanePhantom]

Reflowed all the solder on the chassis and swapped in a flyback from another monitor out of curiosity, Any other ideas?

 

[Hewitson]

You may want to talk to Jomac on the Aussie Arcade forums. He is quite possibly the biggest expert in the world on arcade monitors.

 

[SetaSouji??]

how high is your focus dial turned? I had problems with diagonal brown lines with mine for the LONGEST time, and I took some of the info from here and youtube, turned down focus and up'd brightness and now it just looks sexy.

 

[FairlanePhantom]

how high is your focus dial turned? I had problems with diagonal brown lines with mine for the LONGEST time, and I took some of the info from here and youtube, turned down focus and up'd brightness and now it just looks sexy.

Adjusted those plenty, didn't improve. Does that Aussie guy have a direct contact? I just don't want to join another forum.

 

[Hewitson]

Adjusted those plenty, didn't improve. Does that Aussie guy have a direct contact? I just don't want to join another forum.

http://www.jomac.net.au

 

[grantspain]

according to the schem the k7000 has a decoder at IC1,seen that cause problems on other monitors