Need help pointing to strange video problem on SE/30

[68kbits]

My SE/30 is showing a very strange garbled image on the screen.

The caps have been replaced, and the computer works as expected otherwise.

The screen and other componants work fine with a different SE/30 board.

I looked through this web page on common problems, and didn't see a match.

http://www.biwa.ne.jp/~shamada/fullmac/repairEng.html

Any ideas?

 

[Macdrone]

Looks like your analog board caps may be dying. Anytime board is good and video is bad the analog board is suspect. My classic and classic two look like that. I have to recap mine just have to start ordering the caps.

 

[Brett B.]

I'd start by thoroughly checking traces around the caps your replaced for continuity. If I read that right, you tested with the screen in your picture and a known good SE/30 board, so that leads me to question if something on the suspect logic board is corroded or shorted.

I like to take 91% rubbing alcohol and scrub the logic board with a toothbrush. This usually works great. RadioShack also made a spray electronics cleaner with a brush attachment that works well but I'm not sure they still sell it.

 

[68kbits]

Thanks for the replies guys.

Does this image look like an error mode you have seen before from an SE/30 or other mac I suppose?

The screen etc works normally with another logic board.

 

[TylerEss]

From the appearance, I would guess that the VRAM ICs were damaged by the capacitor goo leakage. I've got a board in this condition, but only on half the screen.

The VRAMs are UC6 and UC7 on the SE/30 board. They are hard to find replacements for, but they do come up from time-to-time.

 

[nvdeynde]

I had exactly the same problem with an SE/30 that persisted even after replacing the Vrams. So I doubt replacing them will solve the issue.

It did show up out of the blue on mine several months after fully recapping the logic, analog board including the PSU.

Only with a scope you can find the cause of this and then of course you need spare parts to fix it. It's definately somewhere in the video circuit on the logic board.

 

[uniserver]

Anyone ever had this odd video issue before? other wise the thing works 100%, This se/30 was from insanboy, who was kind enough send me.

just recapped it, and then washed it as well. sill has this pin stripe effect.

 

[uniserver]

viewtopic.php?f=7&t=19587

ok looks like the electrolyte hit some legs of this chip (UE8)

and cooked part of the IC giving a permanent line.

that is my diagnosis

 

[insaneboy]

that is my diagnosis

mine too, now that the caps have been done...

 

[uniserver]

i'm not complaining, this computer is great i like it.

Couldn't i just install one of those XCEED 256 Grey scale deals in this??

 

[insaneboy]

Yeah, but wouldn't it be easier/cheaper to get another SE/30 motherboard?

 

[uniserver]

I was going to first pester mcdermd

I know he has 2 junk SE/30 boards, maybe the chip i need is good on that one from CC_333 with bad rom?

MY god!!!! XCEED Card is 900 BUCKs and 400+ for the B/W Monitor Video board hook up.

 

[insaneboy]

MY god!!!! XCEED Card is 900 BUCKs and 400+ for the B/W Monitor Video board hook up.

wow, prices have gone up even more 8-o

 

[mcdermd]

I don't have CC's board - he does. My junk SE/30 board has that chip but it's a surface mount part and looks a little crusty. I wouldn't think that chip would be more than $5 for a brand new one from places like DigiKey, Mouser or Jameco.

 

[uniserver]

OH, so that chip might not be custom? Ah. Well I think i'm going to start an advanced SE/30 problems thread, I would like it to contain information, Issues specifically caused by leaking electrolyte. With Video issues, Pictures of the strange Video Output, then picture of the fixed solution.

(over and above what is offered Here: http://www.biwa.ne.jp/~shamada/fullmac/repairEng.html)

Do you think a heatgun + tinfoil ( like used in re-flows ) would work to remove and install new IC?

Also issues including BORNS FILTER / SOUND / SCSI / FPU?

 

[mcdermd]

For UE8, I think a Texas Instruments SN74LS166AD will do. About $1.25 from DigiKey or Mouser.

You'll need to float the old chip off with either a hot air reflow station or mask the area and carefully use a heat gun.

 

[uniserver]

I want to do the same thing with the Macintosh Portable,

consolidate all the "messages" / Links from you (mcdermd),,, and what techknight has said, into a new Advanced Mac Portable thread.

Common Problems, The issue / What parts fix it, etc.

So far I would have to say the 12v Boost regulator seems to be a problem child with the back-lit.

And same with that non-back lit, Additionally, the Hybrid riser Board?

 

[mcdermd]

I think you and I looked up those regulator chips and they all seem to still be available.

 

[techknight]

You did the good ol pin to pin, chip to chip continuity? the electrolyte can eat out vias, and trace to pad junctions. and that will cause this.