SE/30 simasimac/lines/no video - Trying to fix it

[asapreta]

Hi guys,

I bought this SE/30 as is.

When I first started it I got this screen:

 ​

Then I opened it up and pressed the socketed ICs down and it showed me the simasimac screen and then, turning it off and on again, it worked.

I was able to use it for some time, tested my other Mac HD on it, tried to see if the floppy was working, but sometimes the screen went black and the same pattern above appeared. Waited a little more and the mac screen was fine.

I tried to move the mac (still on) to a better position on the table and was able to see this affected the screen.

I continued to use the Mac for sometime but the problem was still happening.

Noticed that if I knocked the mac on the site (the one with the analog board) the screen returned to work. I thought the problem was on the analog board. 

I removed the logic board and with it out of the case I tried to repeat the knocking to see what happened: nothing. I realized the problem was on the logic board. If I knocked it on the same side, the screen changed but now I was able to hear some noises coming from this area:

(this isn't my board picture, just got one from the web as example)​

 ​

Then the board just gave me the pattern from the first picutre. I noticed the + leg of C2 was hot. I replaced it but nothing changed. I saw the board was hit hard with capacitor leak and LS166 was very corroded. I used isopropanol but the damage was so severe it lost 3 legs. I removed all capacitors, washed the board, let it dry for 3 days, recapped it and replaced LS166. Now I only get the simasimac screen. I tested the memory and  ROM on another SE/30 and they are fine.

Guys, where should I look or test to get it working again?

Thanks in advance.

 

[techknight]

you need to clean and fully recap the logic board before any troubleshooting can commence. It is basically like changing AA batteries these days. its a requirement. 

 

[asapreta]

you need to clean and fully recap the logic board before any troubleshooting can commence. It is basically like changing AA batteries these days. its a requirement. 

Hi. I did it.

Removed the caps, washed (there I found the LS166 legs were gone), recapped then installed a DIP16 LS166 with wires but no luck.

 

[techknight]

"no luck" isn't very descriptive. What's it doing now afterwards? The result had to change unless you have a broken Trace somewhere

 

[asapreta]

I just returned from vacation and will post a picture how is the screen now, this is not mine but is the same:

View attachment 11315

 

[bibilit]

IIRC this screen is the one which is present with no Rom available (or not detected)

Have you tried with another set of RAM ?

Have you tried to hit the reset switch for a test ?

 

[Bolle]

I have seen quite a few different screens when ROMs are missing - the above being none of them. If I got you right you put a DIP LS166 in place using wires. Aer yuo sure you do not have any errors in there and that the replacement LS166 is actually ok?

I would suggest you replace it with a known good part of the correct SOIC type.

I have also seen the screen with visible scan lines in the original post before. It happened for me when I experimented with multiple PDS card upgrades and I tracked it down to a weak clock signal, which results in video timings getting thrown off in some manner. You might want to look into that as well. One trace of the clock signal is running along close to one of the legs of C2. I have seen damaged traces there due to badly done recaps.

A picture of your logicboard in its recent state might help.

 

[asapreta]

IIRC this screen is the one which is present with no Rom available (or not detected)

Have you tried with another set of RAM ?

Have you tried to hit the reset switch for a test ?

Hi, thanks for the answer.

I have tested the ROMs in another SE/30 (and its on this SE/30) and they are fine.
Yes, I have another set of working RAM (and one set in a working SE/30). Tried with no luck.

Yes, I tried the reset but nothing happened, just a screen blink.

Thanks again.

 

[asapreta]

I have seen quite a few different screens when ROMs are missing - the above being none of them. If I got you right you put a DIP LS166 in place using wires. Aer yuo sure you do not have any errors in there and that the replacement LS166 is actually ok?

I would suggest you replace it with a known good part of the correct SOIC type.

I have also seen the screen with visible scan lines in the original post before. It happened for me when I experimented with multiple PDS card upgrades and I tracked it down to a weak clock signal, which results in video timings getting thrown off in some manner. You might want to look into that as well. One trace of the clock signal is running along close to one of the legs of C2. I have seen damaged traces there due to badly done recaps.

A picture of your logicboard in its recent state might help.

I am struggling to buy theses ICs here in Brazil.

I want to replace all these near the UE8 just in case. But I can't find them.

As soon as I arrive home I will take pictures of the board.

I can check this track near C2.  Also I think something is wrong with the transistors Q1 and Q2. I heard "noises" prior to the motherboard failure near C2 area.

 

[asapreta]

Here are the pictures of the board, without the UE8 (LS166D) IC