Amiga and Commodore news and topics not covered in the other forums
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intric8
Seattle, WA, USA

by intric8 posted Sun Aug 04, 2019 9:09 am

Several weeks ago a friend of mine and member of this site - Christian - told me he was going to drive to Ray Carlsen's house and drop off three of his monitors for repair. The drive is not inconsequential as it's over 3 hours one-way. So to do this drive meant sacrificing a day from his weekend.

With it being summer many of our weekends are pretty full with kid stuff, so it's not easy for any of us to do this kind of trek, I know.

In any case, Christian asked if I wanted him to take some of my monitors down, too. Well.. I had 3 monitors that needed repair. I never had the heart to e-recycle them. And now there was a chance to get them right! I accepted so fast I worried I might have been rude.

So, Christian drove down 6 monitors. Ray must have been thrilled. Hah!

Anyway, two more of my friends (Dan and Matt) drove down to Portland this weekend to buy some new goodies from Kevin Savetz (and man did they score). They offered to pick up the monitor stash on the way back up. Holy smoke I'm so lucky to have such great friends.

As it turns out, I had acquired a NOS 1080 from a connection down there as well. So they got all of it: 7 monitors.

I'll take pics of my boxed new addition very soon and share them. But for now, let me leave you with this.

It's not a sickness, my friends. It's the cure.
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intric8
Seattle, WA, USA

by intric8 posted Tue Aug 06, 2019 9:41 am

The monitor at the far-end is a 1902A, which I'd gotten specifically to pair with my C128D that has had several mods which I hope to share soon. One of the mods, however, affected the video signal. We believe that signal has been fully repaired.

Meanwhile, one day back in May the 1902A completely freaked out. It was around the same time as the 128D video mod was being done, but I was able to confirm the monitor itself had a major issue. So, it was sent to Ray Carlsen for repairs. Within a couple of weeks it was done.
IMG_1195.JPG


It's a little hard to read, but here were Ray's repair notes for the monitor.
rc-repair-1902a.jpg


Upon receiving the monitor, at first blush everything looked perfect. I was ecstatic. I tested the BASIC screens for both 80-col and 40-col modes. Then I dropped to C64 mode and it looked good there, too. To celebrate I popped in my cartridge for l'Abbaye des Morts to collect a few crosses.
1902a.png
At first, I was over the moon. Now I'm sort of landing on the moon, and skipping to the lou, my darling.


Pretty quickly, I could see something was up. Some of the colors were just wrong. Like, a solid white character had rainbow color flickering inside him. Another light blue rat was now two or 3 colors, flickering across the screen. And yet the backgrounds looked perfect. WTF?

To make sure it wasn't the game, I plugged the 128D into my beloved 1702. The game looked PERFECT on that monitor, which seemed to suggest the 128D was totally fine.

So, it seems to be one of two things. Either the cable is borked, or the monitor still has some issues. I popped in another cartridge - this time Pitfall - and again most everything seemed OK. But there was still a lot of wrong.
IMG_2961.JPG
See the rainbow colors at the edges of the white text for "Pitfall!"? Those are really there - it's not an artifact of taking a pic of a CRT. Well, and those trees!

NEXT STEPS
I'm going to bring the machine and the monitor to the next SEA-CCC meet tomorrow night. Matt is also going to bring in his own 128D and 1902A. We'll set up both side by side to absolutely pinpoint the hardware that's suffering. It's not the end of the world, but it's kinda sucky.
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intric8
Seattle, WA, USA

by intric8 posted Tue Aug 06, 2019 1:15 pm

I shared this post with Ray so he could see the photos. He wrote back and his comments are very interesting. Sharing here as it might help or inform someone else's situation in the future.

The first screen that shows discoloration over the entire screen
indicates the tube is partially magnetized. There is a metal plate
inside the tube face that is upset by the Earths magnetic field and to
correct for the error, the factory puts a degaussing coil around the
tube with a control circuit to demagnetize the tube when the monitor
is turned on. The posistor I installed replaced the bad one but if it's
not doing the job, something else is going on. Moving the monitor after
power up can re-magnetize it and the posistor has to be cold at power
up to completely demagnetize it again.
The rainbow effect (seen on white characters in another photo)
is a different problem. I've seen that artifact with after-market
S-video cables when the color part of the signal is driven too hard.
That said, if the same cable works on another monitor, the problem must
be with the monitor itself. I'll have to duplicate the exact conditions
you have to make a diagnosis.
Bottom line: I'll need to go over it again more carefully...

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