SE/30 Strange Display Problems - Any Ideas

[lampcov]

Hi everyone,

Thanks for looking at my post, just so you know, I DID use the search button before posting. I just picked up a bunch of old Macs SE, SE FDHD, SE/30, etc.

The SE/30 (the one I want the most) has an odd display problem. And I have already replaced the analog board and it had no effect. The machine boots up no problem, and I can see the screen, but it's got sort of a "every other line" shift of the display and a sort of flicker.

Here is a link

of the screen problem.
Any help would be appreciated.

Thanks,

Marc

 

[tomlee59]

That looks very much like a RAM-related problem. It's most definitely not an analog board problem (as evidenced by stable and correct raster geometry, good brightness and good focus). Try reseating/replacing or otherwise checking the SIMMs, and that will quite likely solve your problem.

 

[lampcov]

Thanks for the suggestion.

I removed all the ram, cleaned the contacts and reinstalled, and still have the same issue. I even swapped some ram from another machine. Any other ideas? Am i looking at an "on logic board" ram issue of some kind perhaps.

Thanks,

Marc

 

[kastegir]

Am i looking at an "on logic board" ram issue of some kind perhaps.

Nope. The SE/30 has no on-board RAM. Just what you put in the SIMM sockets.

 

[trag]

Is the video RAM for the SE/30 separate from the DRAM? I have a vague memory that says it is. The video circuitry has it's own ROM chip on the logic board. It's really the equivalent of a very simple video card tacked onto the logic board to provide the built-in video capability. If the video RAM is separate from the DRAM, then replacing the SIMMs wouldn't have any affect. Darn, I wish I had my copy of GTTMFH handy.

 

[wally]

UC6 and UC7 are video DRAM, mine are soldered into the PCB. They have been known to go bad. But also on the suspects list is the row of video address and data multiplexers/shift register UA8 thru UG8 that are vulnerable to electrolytic leakage particularly from SMT cap C2. Inspect carefully for signs of moisture leakage and trace shorts/corrosion. If the video ROM UK6 and video timing generation PAL parts UE6, UG6, UI6, UE7, and UG7 are in sockets, they should be carefully (keeping ESD in mind) removed, leads cleaned/straightened, and reseated, just in case a bad socket contact is causing the problem.

 

[lampcov]

Again,

Thanks for all the ideas. I removed, cleaned, and reseated all of the removable chips that I could and still no joy. The UC6 & 7 look good and clean, but who knows if they are bad, I could remove them but don't have replacements. As for the SMT UA8 - UG8, there doesn't appear to be leakage from C2 at all but they aren't as "clean" is I might like.

It's starting to look like she's going out to pasture....

Marc

 

[tomlee59]

Before giving up, here's another simple thing to check. I'm sure you knew this already, but just in case not...The SE/30 requires RAM to be installed in groups of four, not groups of two. What is your current configuration? How many simms of what capacity in which banks?

For details on acceptable configurations, see http://lowendmac.com/ram/se30.shtml

I hope it's something simple. The SE/30 is a wonderful machine.

 

[lampcov]

The machine had all 8 slots full, I removed, reinstalled had only 4, swapped them around, etc. All no difference. The screen still looks the same. The SIMMS aren't clearly market so I'm not sure what they are.

The 4 SIMMS in the last 4 banks have 2 chips each marked MCM14256AJ10, and have a sticker with 670-0256-A and are made by Apple.

The 4 SIMMS in the first 4 banks have 8 Chips each aXM41C1000AJ-8 and are made by Legend with the model LG 41000

I've tried numerous combinations and all to no avail....

 

[lampcov]

The latest status is...no change.

Well, I took the plunge and washed and dried the motherboard to get any cap leakage off, just in case that had something to do with it.

Good news...It booted back up! I didn't trash the board washing it.

Bad News...Same problem.

I had another working SE/30 so I swapped out the ROM and RAM SIMMS and all the chips in sockets. Nope. still no dice, exact same behaviour. Even swapped cases. No dice.

Does this provide any more insight to any of you? I'd really like to get this thing back to life. If anyone has an SE30 board they'd part with i'd be interested to talk about that too, maybe swap plus $ if you think you can fix this one?

Thanks,

Marc

 

[equill]

Assuming that in your RAM in-and-outing, especially if you are not aware what capacities the SIMMs have, you did not mix unlike cards (check the chip markings) in the two banks, you are, most likely, now looking at a complete capacitor replacement exercise. That is, having removed the capacitor goo from the board, you have exposed the capacitors as incapacitated. (Groan.)

Trawl these forums for detail. At least one member can supply you with replacement capacitors of the correct values and specs. Comment on technique there is aplenty. Encouragement will be plentiful if you need it.

de

 

[JDW]

Since we're talking about SE/30 logic boards again in this thread, I thought it best to mention that I've uploaded 7 shots of one of my boards this evening. This is a board I recapped with electrolytics. The "top" photo has the longest description. All are 1024 pixels wide, which lets you see a fair amount of detail. But alas, I couldn't upload anything bigger because Flickr limits me to 1024 (for a free account). I shot the originals at 5MP though. Enjoy.