SE/30 - Horizontal line on Startup

[macsonny]

Hi All,

I have a Mac SE/30 that I picked up. Started up fine a few times but after about a week it started up with a blank screen and a bright horizontal line. Also not boot noise on power up.

So, based on lots of advice I have recapped BOTH the analog board and the motherboard. 

Now when i turn power on, i get the boot sound but still the horizontal line.

I did some further research and here I found some info: https://wiki.preterhuman.net/Macintosh_SE/30#Replacement_Tantalum_Capacitors_.28logic_board.29

I checked the P1 connector on the analog board and also reflowed each point. Same problem.

So, it loos like it's the U2 chip that's faulty. I purchased a chip (TDA1170N chip from France) and awaiting delivery. In the mean time I'm trying to work out where the U2 chip actually is as I can't see on motherboard or analog board. 

So, can anyone actually show me a pic of where the U2 chip is?

Any other advice for issues I should consider too?

Thanks

Sonny

 

[GregorHouse]

Did you clean thoroughly the boards after recapping? Sometimes electrolyte residues short the circuits, causing this kind of errors.

 

[bibilit]

Have you got only the SE/30 ? not another SE to swap boards and troubleshoot it ?

Is the cable from the CRT firmly connected ? or one of the pins dull or corroded ?

 

[marcelv]

 

[dochilli]

Did you check the voltages at the floppy port?

 

[Aziz123]

Were you able to fix this? I have to same issue and haven’t been able to find a solution yet.

 

[MrFahrenheit]

I had this same issue and I sent my boards to a fellow 68kmla member who had more SE/30 experience than I did. The QA signal line from UF8 was broken before the via that takes it to UG6. So he put in a bodge wire and it booted. 

 

[Chopsticks]

for what its worth using tantalum caps in place of aluminium electrolytic caps kinda isn't the best of ideas, they have much different 'characteristics' then each other. while it will work any sane engineer would say not to do it, if you dont want to use wet electrolytic caps to replace the old ones that leaked (and who would) then i'd suggest using aluminium polymer caps. these are rated are very close to the same specs are what was originally in there yet use a solid polymer so will never leak of dry out.
i may cop some flack for recommending against using tantalums but i looked into this extensively quite awhile ago

 

[MrFahrenheit]

for what its worth using tantalum caps in place of aluminium electrolytic caps kinda isn't the best of ideas, they have much different 'characteristics' then each other. while it will work any sane engineer would say not to do it, if you dont want to use wet electrolytic caps to replace the old ones that leaked (and who would) then i'd suggest using aluminium polymer caps. these are rated are very close to the same specs are what was originally in there yet use a solid polymer so will never leak of dry out.
i may cop some flack for recommending against using tantalums but i looked into this extensively quite awhile ago

The biggest differences between tantalum caps and others is they have different resistance ratings, and they have a 'wobble' or frequency.  I've found ones in the 100khz range are fine.  Also, the lower the resistance the better.  That's about it.

If tantalum were that big of a problem, Apple themselves wouldn't have used them.  But they did.  There are a lot of machines that use both electrolytic and tantalum caps (different ratings for each), and the IIfx has spots for both electrolytic and tantalum caps (one of the only boards I know that is like this).  On both of my IIfx machines, there were electrolytic beside an empty tantalum pad on about 3-4 of the locations.  I successfully recapped with all tantalum caps.

I have recapped over 70 Macs using tantalum caps and I have not experienced anything bad or wrong, after I figured out which resistance rating and khz frequency to use.  YMMV

 

[Chopsticks]

im not going to get into a debate over it.

 

[360alaska]

Bright Vertical Line Possible solutions:

Check/Reflow P1

Check/Reflow L2

Check/Reflow L3

Test/ Replace C15

Test/ Replace R19

Bright Horizontal Line Possible solutions:

Check/Reflow P1

Check/Replace U2



View attachment map.bmp

 

[Chopsticks]

Bright Vertical Line Possible solutions:

Check/Reflow P1

Check/Reflow L2

Check/Reflow L3

Test/ Replace C15

Test/ Replace R19

Bright Horizontal Line Possible solutions:

Check/Reflow P1

Check/Replace U2

View attachment 38118

View attachment 38117

great diagram there, check everything 360alaska has mentioned, if its not what he has suggested id be very suprised 

 

[cheesestraws]

View attachment 38118

This is a really nifty map.