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techknight

SE/30 video issue that has ME stumped!

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Well the PALs have been changed. UE8 has not been by me yet.. the trace is good, and no shorts between it to the rails. So unless the substrate capacitance is too large, i am unsure. 

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UE8 may be worth a replacement, but it could also be the inputs to the PALs: garbage in, garbage out. In that other thread, whether or not there was a card in the PDS slot caused the problem to come and go. That would seem to suggest that at least one signal connected to the PDS is somehow involved, though I'm still not sure how.

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I think the PDS card thing was a fluke, because in my case its consistent.  

 

Only other thing I can do is monitor the data bus coming from the CPU, because I have seen 1 case, and ONLY 1 case that the CPU was bad. the CPU would run through the addressing without the ROM in. 

 

But as soon as I stuck the ROM in, the data signals fell down from 5V to more like 3V, and no boot. Swapped the CPU, and presto. 

Edited by techknight

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Hi techknight.

 

I had same symptoms like yours(v-lines all over the back but cursor and floppy icon are displayed).In my case,washing mb and recap worked.

here is video 

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I have a similar issue with one of my boards.

 

New caps all around, the board chimed but got a black screen.

 

I removed and replaced UE8 UF8 and UG8, this time the screen lit up and got the question mark, but the left screen side had rounded borders while the right side square ones, while testing the board a little further i got those vertical lines coming and going also, more or less the same pattern.

 

The pattern is not present at startup, only after a while.

 

Any solution found on your side ?

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@Techknight

 

The symptom i have but you didn't is the right side of the screen having square angles while the left side are correct, have you ever seen this before ?

 

I am thinking both troubles are probably linked together, and solving one will probably solve the other;

 

What part is responsible from turning the square screen at bootup to rounded ?

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@ apm and Technight

 

Not made any picture yet, but... looking closely at the picture that Technight posted some time ago, the screen is rounded on one side and flat on the other... not the same pattern but also unusual

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Here are some pictures

 

post-1736-0-06401200-1495731058_thumb.jpg

 

Left side

 

post-1736-0-27140200-1495731107_thumb.jpg

 

Right side

 

To be honest, i only have the lines when activity is needed, less sensible when there is no activity, and when booted from cold there is no lines at all.

 

post-1736-0-22659400-1495731283_thumb.jpg

 

No lines either when a window is present.

 

 

post-1736-0-38921200-1495731389_thumb.jpg

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If i change the background, lines are not there, i can see some flickering, but nothing else.

 

post-1736-0-92606000-1495731596_thumb.jpg

 

post-1736-0-38812600-1495731637_thumb.jpg

 

Oh, yes, booting from a Jaz, don't know if something related, but the SE/30 is not able to boot from a good HD... will a bad SCSI chip be able to boot from a SCSI external drive and not internal one ?

Edited by bibilit

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that... is weird. But its right up the same alley. 

 

I am wondering if it isnt an address or data wire that has "resistance" instead of a full break, or full short (like it should). 

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Hi,

 

some questions.

 

Made some progress, the board is booting from the hard drive once again and the lines have gone.

 

Concerning the square problem, i think this is related with the screen not been properly built a 100 %.

 

I explain it, the mouse cursor goes to the left and bumps to the  left side, but doing the same thing on the right side, the cursor goes further and get hidden in the process..

 

Looks more or less the same problem here:

 

https://68kmla.org/forums/index.php?/topic/26542-hidden-menu-bar/page-6

 

But this time on the vertical side, where the right side goes too early and have no time to finish the curved side.

 

Any idea ?

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When you take a screenshot (Cmd-Shift-3), do you see more on the right side of the picture than actually shows up on the screen? That would point to something similar to the other thread. It's normal for the cursor to go almost totally off the screen -- I think you should still see one column when it's all the way over.

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On 9/3/2017 at 8:29 AM, bibilit said:

Hi,

 

some questions.

 

Made some progress, the board is booting from the hard drive once again and the lines have gone.

I have an SE/30 that is not booting from the internal HDD, what did you do to fix the issue?

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On 26.5.2017 at 1:21 AM, techknight said:

that... is weird. But its right up the same alley. 

 

I am wondering if it isnt an address or data wire that has "resistance" instead of a full break, or full short (like it should). 

 

It may be the clock line that is the issue here.

When testing my multiple card setup I got noise on the screen that looks similar to what bibilit posted. It also comes and goes when CPU load changes.

I narrowed the issue down to the clock signal bugging down when three extension cards are installed. So the issue might as well show up in combination with PDS cards. If the clock output is weak or there is high resistance in the line somewhere the video signal will start to act out just the way as seen here.

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Actually now that you mention it, I need to watch that signal. Could be noisy. It comes from the PAL thats in the center of the board, next to the main oscillator. Those things only have a gate fan-out of a certain amount anyways on a good day. 

Edited by techknight

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Techknight, did you say that you had tried swapping out the VRAM on that mystery problem board?   I ask because the weird similar-to-AND-gate behavior you're seeing could be caused by certain RAM failure modes.   If you have a leaky structure in a RAM the behavior can be affected by neighboring cells which would look alike AND gate behavior.

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Sorry to necrothread but I just had the exact same problem. Turned out that pins 4 &5 on UE8 which go to 22 and 23 of UC7 were shorted on the underside of the logic board directly where the vias came through by a tiny solder blob that made it look like the vias were actually connected. Everything passed my trace tests because I was testing 4 to 22 and 5 to 23 of UE8 and UC27, only by chance did I trace UE8 pin 4 to UC7 23 and realised that there was a short. 

Edited by bonsaichop

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Hi,


 

 

I solved this issue on one board i had at home.


 

 

The exact same problem, lines coming and going or fixed, and no lines on the floppy.

 

 

after spending most of the day removing and replacing chips (UE8, UD8) that looked bad, checking continuities and heating the board (the board worked fine when heating UD8 at first, but not as soon as it cooled down)


 

 

In the end, using a spare board i had (destroyed by a Maxell bomb) i piggybacked the PALs, until the picture came perfect.

 

UI6 was bad, i replaced the PAL for good.

 


 

 


 

 


 

IMG_0980.jpg

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IMG_0983.jpg

IMG_0984.jpeg

IMG_0985.jpg

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