Sharp XM-1801 Problems on both monitors

TokensArcade

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Hello KLOV:

I recently acquired a Red Tent w/ Vs. Tennis on it that I bought as a project. It has a number of issues with both monitors and while I've made good progress so far, there's still plenty more to figure out and I'd like a bit of help. Note that for this diagnosis process I have been using a CGA Test Pattern Generator for video signal and a Donkey Kong Cocktail for a 100 V Power source (with all of the Donkey Kong related things unplugged).

MONITOR 1:
This monitor was vertically collapsed when I got it and after doing some tests of I601 I checked the resistor R625 and Diode D603 as instructed in the Nintendo troubleshooting guide for the monitor. They seemed to test out fine, but i replaced them anyways just to be safe, as well as reflowed some (but not all) of the points on the board. While I couldn't find a broken connection, some joints did look questionable. I was able to get rid of the collapse and now I have what you see in the attached picture.

As you can see, it's far better, but not there yet. The image is curved to the right and there's lines across the image. The lines move when I adjust the vertical hold and the curves change a bit when I adjust the horizontal hold. The best I can get is a stable, but warped pic. It also seems to be more stable on some patterns than others. I should note that it appears that the previous owner capped the monitor, though I can't say for certain if they did it right.

What would be the next step to diagnosing this monitor?


MONITOR 2:
This monitor was working fine, with the exception of no sound. However, I removed it too when I took out Monitor 1 just to give it a better look. After getting Monitor 1 to no longer collapse, I decided to test the Test Pattern Generator on this monitor, just to see if the lines or curves were caused by the generator. However, upon powering Monitor 2 up in the same way as Monitor 1, the warm-up crackling started then stopped abruptly on power-up and I had no video signal. Upon powering it up again I got the same thing, but this time I saw an arc in the tube. I have not gotten this thing to turn on properly since.

Despite the arc I DID NOT see any smoke or smell anything burning. This monitor, as far as I can tell, has NOT been capped or worked on much during it's life. This monitor was also INCREDIBLY filthy, much more so than Monitor 1, further backing up my suspicion that this monitor has not been worked on while the other one has. I know that arcing in the tube is often associated with a bad flyback, so I visually inspected the filthy flyback, but couldn't find any major meltdowns or holes (That being said, it's hard to look at them since I can't fully remove the cover without cutting wires).

One other thing worth noting is that before I got replacement keys for the red tent, this monitor did have an episode where it didn't power on until the third or so try, while the collapsed Monitor 1 did turn on. I have a feeling that's no coincidence.

Should I try getting a new flyback? Could it possibly be a B+ issue? If this is a Flyback issue, could the HOT also be jeopardized?

I welcome any advice you may have on fixing these two monitors.

Thank you very much and have a good day!
 

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the lines are because the screen pot on the flyback is turned up too high, not because it's bad. the smearing at the top might be able to be fixed by adjusting the h-hold. you should re-cap them if they havent been recently and see where you are at afterwards.
 
the lines are because the screen pot on the flyback is turned up too high, not because it's bad. the smearing at the top might be able to be fixed by adjusting the h-hold. you should re-cap them if they havent been recently and see where you are at afterwards.
I will try adjusting the screen on the flyback and get back to you.

As for the H-Hold, I did try and adjust it and I managed to get what you see in the pic. I already have a cap kit for each monitor, so I'll give those a shot.

My only concern is that this monitor seems to have already been capped by someone relatively recently (there was no dust on the caps). Is there anything in particular I should look out for beyond caps installed backwards or incorrect values? Anything that could indicate an error by the previous owner?
 
I will try adjusting the screen on the flyback and get back to you.

As for the H-Hold, I did try and adjust it and I managed to get what you see in the pic. I already have a cap kit for each monitor, so I'll give those a shot.

My only concern is that this monitor seems to have already been capped by someone relatively recently (there was no dust on the caps). Is there anything in particular I should look out for beyond caps installed backwards or incorrect values? Anything that could indicate an error by the previous owner?

replace ALL electrolytic caps and reflow all the header pins and any other suspect areas such as high wattage resistors, etc. and then see if you can adjust out those things. make sure to reflow as i show in the video DON'T just add solder to old like so many do because it will come back to bite you.

https://www.youtube.com/watch?v=6ijwL3kkw1A
 
**UPDATE** You were correct on the flyback! Screen knob turned down, then brightness turned up fixed it. In hindsight, I feel a little silly for not even thinking to try and adjust that since I have seen these lines before on other monitors when you turn up that dial really high. haha.

As for the horizontal issue, It also occurred to me that the screen is way to far over to the right too. I adjusted the H-Center as far as I could and tried adjusting the H-Width coil, but couldn't get it far enough over.

I also took a video of what it looks like currently for the hell of it.

https://www.youtube.com/watch?v=ZMIRT_JYM5E
 

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replace ALL electrolytic caps and reflow all the header pins and any other suspect areas such as high wattage resistors, etc. and then see if you can adjust out those things. make sure to reflow as i show in the video DON'T just add solder to old like so many do because it will come back to bite you.

https://www.youtube.com/watch?v=6ijwL3kkw1A
Oh wow! Thank you for pointing that out with reflowing the pins. I knew that it was generally better to completely remove the old solder, but I didn't realize how important it actually was! I'll definitely go back and redo the pins I did "reflow" as well as those header pins!

As for the caps. When you say "ALL" do you mean just the ones that come in the kit or literally all of them?
 
On Sharp/Sanyo monitors, the TPG image tends to be a bit to the right. Your case looks about 2x further to the right than usual, but do you have a working Vs/DK board to test out as well? It might be much closer to the left with an actual Vs board.
 
On Sharp/Sanyo monitors, the TPG image tends to be a bit to the right. Your case looks about 2x further to the right than usual, but do you have a working Vs/DK board to test out as well? It might be much closer to the left with an actual Vs board.
Yes! I have both, in fact! I'd need to figure out how to extend the video cable a bit from Donkey Kong as I'd rather not walk this monitor up and down the staircase more than I need to. lol

Now that you mention it, when I had the collapsed monitor in the red tent, the little I could see did appear to be centered horizontally. So maybe it is fine! Thanks for pointing that info out about the TPG!
 
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