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Electrohome G07 - weird line

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minwah View Drop Down
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    Posted: 11 Jan 2019 at 11:38am
I've noticed my Electrohome G07 has a line / band across the screen. It is not noticeable at all with my Galaxian board running, but with no game running, and certain other boards it is visible:



It's the horizontal band near the top of the screen, it is static although sometimes bends slightly depending on what is going on in the game running. There are also some thin vertical lines on the left which dance around - again not always visible, depending on the game.

You can see the top band in the first screenshot in this thread running Time Pilot 84, where I had another video issue (not resolved): http://www.ukvac.com/forum/time-pilot-84-video-interference_topic367700.html

How noticeable it is seems to be dependant on the resolution, but as you can see it is present with no signal at all so doesn't seem right to me.

Any idea what it might be? I've replaced the caps, flyback, voltage regulator, HOT and adjustment pots (bar B+) on this monitor. While running Galaxian it looks great (as good as could be expected for a 1981 monitor), but I've just noticed issues while running other boards.


Edited by minwah - 11 Jan 2019 at 11:41am
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gunblade View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gunblade Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jan 2019 at 11:57am
if you remove the rgb connector from the chassis does the line remain?
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minwah View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote minwah Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jan 2019 at 12:03pm
Originally posted by gunblade gunblade wrote:

if you remove the rgb connector from the chassis does the line remain?


Good point. I haven't tried that, will do so tonight. Thanks!
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minwah View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote minwah Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jan 2019 at 7:54pm
So with the RGB and negative sync connectors disconnected, the horizontal line, and thin vertical lines (actually diagonal) are still visible, very clearly. The thin lines are dancing around. Also noticed some other issues, the picture seems to flicker a bit (goes darker momentarily) and there are some other patterns that briefly appear.

With just the sync connector plugged in (no rgb) the horizontal line is slightly less pronounced, but still there. The other issues above are still present.

I thought I'd check the B+ voltage which I did set after replacing the parts. That seems fine, steady 120.2VDC.

I put the Galaxian board in again just to check, and it looks absolutely fine. Maybe this is just as the majority of the screen is black...but on other boards the horizontal line is visible even on black screen.

The only other thing I could add is that the monitor is quite noisy. Whine / hiss sounds, from the flyback I think. It was like this when I got it, and thought replacing the flyback would help, but didn't make much or any difference.
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gunblade View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gunblade Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jan 2019 at 9:14pm
do you have an external iso you can test it with
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minwah View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote minwah Quote  Post ReplyReply Direct Link To This Post Posted: 12 Jan 2019 at 12:06pm
Originally posted by gunblade gunblade wrote:

do you have an external iso you can test it with


Isolation transformer? I only have the one in the cabinet so no. Is it worth trying to get another to try?

Thanks
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gunblade View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gunblade Quote  Post ReplyReply Direct Link To This Post Posted: 12 Jan 2019 at 12:21pm
better off getting someone to test your chassis on their cab, i am sure forum members will be willing to help
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Ropi Jo View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ropi Jo Quote  Post ReplyReply Direct Link To This Post Posted: 12 Jan 2019 at 8:20pm
Check where the RGB cables are routed. A common problem on TVs back in the 80s and 90s if the RGB cables between the chassis and tube base (neck board) were not clipped up away from the LOPT. Worth checking.
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minwah View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote minwah Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 2019 at 12:58pm
Originally posted by Ropi Jo Ropi Jo wrote:

Check where the RGB cables are routed. A common problem on TVs back in the 80s and 90s if the RGB cables between the chassis and tube base (neck board) were not clipped up away from the LOPT. Worth checking.


Thanks, didn't think of that. I don't think the neck board cables are near the LOPT, but will double check!
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minwah View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote minwah Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 2019 at 1:02pm
I found this troubleshooting guide:


Part of it does describe the thin lines I am seeing. They do not cover the whole screen, just a few inches but look exactly like this:


So that's something I can look at...


Edited by minwah - 14 Jan 2019 at 1:03pm
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gunblade View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gunblade Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 2019 at 1:35pm
thats just screen volts too high on yours
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minwah View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote minwah Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 2019 at 2:00pm
Originally posted by gunblade gunblade wrote:

thats just screen volts too high on yours


Ah so the lines are meant to be there if screen is turned up? I didn't have to turn the screen up to see them, so it's set too high? It doesn't look too bright with a game running.
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gunblade View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gunblade Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 2019 at 2:22pm
if you decrease the screen volts and the lines go then its behaving correctly, if they are there even after adjusting then there is a fault
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minwah View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote minwah Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 2019 at 2:31pm
Originally posted by gunblade gunblade wrote:

if you decrease the screen volts and the lines go then its behaving correctly, if they are there even after adjusting then there is a fault


Ok, many thanks. When I installed the new flyback I adjusted it, but only with a game running.
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minwah View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote minwah Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 2019 at 10:02pm
Turned it on tonight and I think whatever was causing the flickering before has escalated. With no game plugged in the main white screen is missing at times and flickers on/off partially/randomly:


With game in (this was fairly stable at the moment I took the photo with some flickering in the top black section):



The bright bar that was across the screen has gone now but pretty sure that is related to what I see now.

The flickering is almost like a bad connection. I've tried re-seating the header cables, neck board and fiddled with some of the pots (I replaced most of them so they shouldn't be dirty) and the screen & focus. At first I thought the screen control seemed dirty but after a while of twiddling I'm not so sure.

Wonder if something is gradually failing?


Edited by minwah - 14 Jan 2019 at 10:04pm
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gunblade View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gunblade Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 2019 at 10:12pm
its an odd fault, possibly something breaking down in 200v video b+
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minwah View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote minwah Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 2019 at 11:02pm
Originally posted by gunblade gunblade wrote:

its an odd fault, possibly something breaking down in 200v video b+


I really don't know.

I managed to get a video of it when something was happening:

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Ropi Jo View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ropi Jo Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 2019 at 11:05pm
Ah... ignore my suggestion. I thought you were talking about this line...




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minwah View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote minwah Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 2019 at 11:29pm
Originally posted by Ropi Jo Ropi Jo wrote:

Ah... ignore my suggestion. I thought you were talking about this line...


I was talking about that line initially...it has been there consistently until I started having these other problems tonight. I think adjusting the screen control may have got rid of it, but hard to tell since the display is so inconsistent now.

I did check the cables you mentioned and they seem ok, tied as they were presumably from the factory. Thanks for your help, I haven't got a clue what to do so will try anything!
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