A3000 Screen Issues (Amber?)

[madgrizzle]

Since I kentucky-fried my VA2000, I want to see if I can just use the 3000's native graphics modes.  I understand the 3000 has a built in scandoubler and flicker fixer and I'm having a bit of an issue with it.  With the switch in the back turned off, I get a clean screen but lots of flicker on my Dell 2240L monitor.  With the switch turned on, I get issues.  Screenshot below.  

Any suggestions on where to start looking to get this fixed?  I know I have some issues with Denise.. it doesn't sit really well in the socket (there was lots of battery corrosion I had to clean up and maybe I cleaned up too well).  I have to press on her sometimes to get her to seat correctly.  But no amount of pressing/adjustment has improved the screen beyond this point.

[mindprober]

Sorry if this is obvious, but did you try the A3000's flicker fixer adjustment screw?

[madgrizzle]

I actually know very little about the 3000 and wasn't sure what that thing "adjusted"  I was hesitant about changing something and wasn't sure if that adjustment would help my particular issue (why I posted an image).  If it doesn't harm anything, I'll give it a shot.

[mindprober]

Yeah, adjusting it could very well correct the problem. Here is a link I found with more info:

https://www.scribd.com/document/34957992/Amiga-3000-Manual
 

I actually know very little about the 3000 and wasn't sure what that thing "adjusted"  I was hesitant about changing something and wasn't sure if that adjustment would help my particular issue (why I posted an image).  If it doesn't harm anything, I'll give it a shot.

[madgrizzle]

Thanks, it has a procedure for tweaking.. Will try tonight.

[madgrizzle]

Neither the fine adjustment or the course adjustment fixes the problem.  When I switch to DBLNTSC, I get a nice steady image, but I'm limited to 4 colors in that mode.  I was hoping to get NTSC 640x400x16 (interlaced) working with the built in deinterlacer, but it's having issues.  I pushed on all the components around Amber (and reseated Amber) and nothing seemed to make any sort of difference.

I posted a short video of it to youtube.
https://youtu.be/RdYu9Gyn2Y8

I'm wondering if there is a problem with the framebuffer.   But there's also a distinct ghosting.. All icons and mouse have a ghost shifted about 50? pixels to the right..

[giZmo350]

I was hoping to get NTSC 640x400x16 (interlaced) working with the built in deinterlacer, but it's having issues.

I know I have some issues with Denise.. it doesn't sit really well in the socket (there was lots of battery corrosion I had to clean up and maybe I cleaned up too well). I have to press on her sometimes to get her to seat correctly. But no amount of pressing/adjustment has improved the screen beyond this point.

You could admit defeat and send it to Acill :lol:

You might pull the motherboard out completely and go over all the traces, component connections, solder joints... etc. with a fine tooth comb. After that, an O'scope might come in handy.

BTW dude... Never, ever, ever sell or lose your PCD-50B!!!

[madgrizzle]

You could admit defeat and send it to Acill :lol:

Yes, not quite there yet.  I was hoping someone that saw this could perhaps give me a lead to where to focus.  My theory is that its not a Denise problem because its only there when I try to deinterlace.. and that's an Agnus responsibility.  The screen is rock solid in "DBLNTSC:High Res No Flicker" which outputs 640x400 but obviously bypasses the deinterlacer.

BTW dude... Never, ever, ever sell or lose your PCD-50B!!!

Never!  It's the greatest thing since sliced bread.

[madgrizzle]

You might pull the motherboard out completely and go over all the traces, component connections, solder joints... etc. with a fine tooth comb. After that, an O'scope might come in handy.

I think I will do that.. I noticed looking at the schematics that U480 and U477 are real close to the battery.. so there may have been some corrosion issues there.

[giZmo350]

I think I will do that.. I noticed looking at the schematics that U480 and U477 are real close to the battery.. so there may have been some corrosion issues there.

After first receiving my A2000HD I had many boot problems immediately and had to remove the battery ASAP that the PO left in to corrode. The corrosion traveled up and around the CPU socket. I cleaned everything real good and it cured the problems but, about once a year I still have to pull the MB as the green fuzzies continue to attack the CPU socket. I'll bet even right now that if I disable the 060 lib and pull my Blizz board the computer won't boot. I was j/k about sending to Acill but I know that what I really need to do is replace the CPU socket and again clean and "seal" the surrounding area.  

After you pull the board, you may be able to show some progress as inspection and cleaning proceed and you should be able to fire up and test the MB out of the case.

Also, FYI, I use these interdental brushes to clean any mild corrosion from behind & between IC pins. Run the brush lengthwise behind IC socket and IC pins and also between to break any corrosion bridge. Use some IPA or %100 percent alcohol with the bruch if desired. Also have some high pressure canned air (or other air source) to blow out any particles.

Little brushes look like this.....



There are different techniques between using logic probes, O'scopes & DVMs... mostly the differentiation being power applied to the board and no power to the board. A good DVM in "beep" mode can really help test (w/o power) continuity not to mention you can reverse the polarity of the leads to test low voltage caps & will be able to hear them charge and discharge without having to lift to test. Of course, aging PSU filter caps can cause a heap of trouble on the MB but are tested by isolating them first.

Take pics along the way and keep us informed.

[madgrizzle]

I've been able to greatly improve the screen output with the deinterlacer turned on, but I still am having a problem in the lower portion.  The yellowish lines in the picture are not steady (they flick in and out at different places) and on the left side of the screen, they seem to be "double" the amount within the first 10 percent or so.  Basically, there's twice as many yellow lines in the first column of icons as the rest of the screen.

I am wondering if this might be a chip problem since it seems to affect only a portion of the screen.  Any ideas?

[kolla]

Any ideas?

The image link doesn't work, says "forbidden".

[madgrizzle]

Does this work?
https://drive.google.com/open?id=1lD6OeRae_kOF3PeQnJdVM6-CluBg3Xds

[madgrizzle]

If I set the background to yellow, the lines yellow lines fade into it, but I can make out a flickering of blue.  The difference between the yellow and blue lines are that the yellow lines seem random in position, but the blue lines seem to have a pattern... attached is a representative drawing of the lower portion of the screen.  The blue lines weren't there at first, they sort of developed over time as the computer ran.. becoming more and more pronounced.

https://drive.google.com/open?id=1JaSzs8oFgYqLhqwg4TcsiekvYQ_Msqgd

Edit:  When I set the background to black, I get blue streaks all over the screen.  Technically, I would think I shouldn't get any blue if the color is black so that suggests maybe something wrong with the blue delay line?

[Oldsmobile_Mike]

What happens if you set it to a 2-color Workbench screen?

Also, Google Drive is not very good for attaching photos. Use the normal forum picture attachment tools.  Just IMHO.