SE/30 analog board adjustment

[billynomates]

I've recently had to transfer my re-capped SE/30 logic board into another (SE/30) Mac, as I'd managed to damage my analog board with some resoldering I tried to do (flyback clicking, no startup, no bong, fan spins, no HD - a problem for another day!).

When I power up, it appears that the screen has some 'ghosting' - e.g., the 'OK' button of most of the dialogs ghosts (to the right hand side only) into the white space around it. The menus, when pulled down, ghost around their border. It's almost like a feint trail of black into the white - sort of a blurring on one edge, but only in the X axis. The Y axis is clear.

E.g., - this is an 'OK' button...

-----------0o...
|   OK    |0o...
-----------0o...

Where the '0o...' represents the 'ghost'. Apologies for the extremely poor ASCII art attempt

I've tried adjusting the analog board's usual control-ables - but with no effect to this issue. The 'brightness' (visibility) of the trails is adjustable with the brightness control on the Mac, so at the brightness maximum setting, the trails / ghosting is at it's worst. At lower levels, it appears better (but never perfect).

Does anyone knowledgeable about this sort of thing have any recommendations of things to look at? Do you think it would it be more likely that the screen is faulty rather than the analog board?

Is there anything I could look at adjusting? Re-flowing solder? (even after the last try! )

Thanks!

 

[Bunsen]

As this is a common problem with CRT TVs and displays, I would suggest searching for the TV Repair FAQ on the internet and seeing if there is a procedure there.

 

[CC_333]

Hi,

I really don't know a whole lot, but I'll try:

It's possible that it's being caused by some bad capacitors somewhere on the analog board, maybe? These computers are, for the most part, are in need of new ones pretty much throughout (including the analog board).

Do you think it would it be more likely that the screen is faulty rather than the analog board?

It seems like it's probably an analog board problem. Although I don't know much about these things, I kind of doubt the screen (or CRT) itself could be at fault.
You could try re-soldering things and see what happens.

Also, this is a wild guess, but if it is the screen, maybe it needs degaussing?

These machines don't have degaussing circuitry built-in (to my knowledge), so it would have to be done manually somehow.

I hope this helps!

c

 

[billynomates]

Thanks Bunsen and CC_333.

I've swapped the video board over, and it's the same on screen, so it's not that bit.

I've replaced the solder around the flyback, and reflowed the joints around the variable pots. I didn't want to overheat anything else, as I think it's heat that killed the semiconductors on the last board.

It's better, but I am still seeing some ghosting. This leads me to agree with you CC_333; I believe it's the board.

Apart from that, the screen's great - excellent geometry, and good focus.

That search recommendation is excellent by the way - lots of information about all sorts of interesting things.

Thanks again!

 

[billynomates]

I've just replaced the CRT, and that's much better. The ghosting is gone, even with the same analog board.

Cheers once again.