68kMLA Classic Interface
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| Click here to select a new forum. | | Macintosh SE no video | Posted by: beachycove on 2018-03-10 12:32:16
One of the two SEs I have here boots fine (well, it seems to), but has no video. The CRT does not even glow in the dark. Yes, the brightness knob has been twiddled.
I’d like to get it going rather than condemn it, however, so help would be appreciated.
I have swapped a working logic board into the unit, with no change, so we can rule out the logic board. I’ve also resoldered the yoke pins on the rear of the analog board. No joy.
I’ve made a close visual inspection and I see nothing burned, cracked, or otherwise amiss on the analog board, though I suppose there could be unseen damage in some of the hard-to-reach areas that would only be visible on desoldering, and clearly the capacitors have to be past their best. However, the absence of physical damage, as in burns or visible leaks, means there is nothing obvious to replace as of first importance.
Any advice on what to troubleshoot would be welcome. What are the likeliest causes, in some kind of order of precedence?
| Posted by: IlikeTech on 2018-03-11 10:07:01
Is the neck of the CRT glowing when you power it up?
| Posted by: Johnnya101 on 2018-03-11 10:21:23
How are the pins on the crt? Is the video board on all the way? Corrosion on pins? Fan on AB working?
| Posted by: beachycove on 2018-03-11 12:24:22
The neck has a faint glow, enough to see it clearly in a dark room. I’m not sure how much glow is a good glow.
The fan runs, the hard drive spins up and the machine appears to boot. But no video....
The vertical board is indeed all the way on. The pins, however, are actually a bit dark (and shiny) but not corroded per se. Is this darkening a sign of something?
| Posted by: Johnnya101 on 2018-03-11 12:28:44
Hmmm... I'll have to check out one of my CRTs. If the tube is glowing however, I think the pins are fine?
| Posted by: IlikeTech on 2018-03-11 13:00:55
Can you test the CRT and neck board with the other SE?
| Posted by: beachycove on 2018-03-11 13:32:05
Can you test the CRT and neck board with the other SE? Well, that would require more or less complete disassembly of both machines, though I suppose it would make sense to swap parts one by one to nail down the problem. Having said that, I was kind of hoping for something simpler from one of the electronics geniuses that even a duffer like me could do, like (safely) checking DC voltages on some doohickey with a voltmeter.
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