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Mac SE/30 analog recap challenge: Working, then Black screen, vertical white line

caver01

Well-known member
I am restoring an SE/30 and had a booting logic board and functional display. Work to date includes logic board recap and cleanup, replaced UE8 chip, removed and cleaned and resoldered ASC chip, troubleshooting SCSI—everything with overall successful outcomes. However, I came to the conclusion that I needed to finally recap the analog board and PSU, so that is what I did.

The process was straightforward, but as the title indicates, the first boot is showing me a black screen with white line:
06167145-73A6-4BFE-AD97-03BC0AEEA36B.jpeg

When I turn on the computer, I get the chime, and although no drive is attached at the moment, with blueSCSI connected internally, it starts up fine using term power, and 5 flashes (no SD card inserted at the moment). I am confident that PSU recap is fine (unless someone reads this and says otherwise) and I have tested it with a multi-meter. Showing 5.29v (tuned to that) and just over 12v, so feeling good about the PSU.

The Scrolls suggest this problem is a failing horizontal scan circuit which makes sense. I definitely don’t hear the high frequency from the CRT the way it used to work pre-anaolog-recap. Possible solutions point to an issue with R19 resistor, desoldering L3 linearity coli and using fresh solder there, or a problem with C15.

I removed and tested R19 and it checks out. Not burned. I think it is a 220 ohm resistor. Anyway, it meters fine with correct resistance. I desoldered L3 and resoldered. Finally, checked C15–this is the non-polar film cap that replaced an axial original that was installed on its end. Since everything was working before the recap, I tried putting the old C15 back into position. No change. It still does this same thing. I double-checked all of my other capacitor replacements to make sure they are not soldered backwards etc., and everything looks OK to me.

Now I am open to suggestions. I have just taken a working mac and turned it into this in an attempt to do preventive recapping maintenance. I am not beyond thinking there is a bad solder joint, or a short somewhere, but I have gone over everything and do not see it. I am hoping there is a something I can test with my cheap meter, or a part I can swap back to original to do tests. Thoughts? We can do this! Right?
 

Johnnya101

Well-known member
While we wait for someone more knowledgeable about this sort of fault to appear... How is P1 looking for solder joints? Have you redone them? I think that leads to a horizontal line, not a vertical, but you never know.
 

chillin

Well-known member
Looks like you checked this, but posting for posterity

2. A Bright Vertical Line in the Black Monitor​

Symptoms
When starting up Mac SE/30, only a bright vertical line is shown in the black monitor. The width of the vertical line is approximately 5 mm. During start-up, you can see moving raster patterns in the vertical line. You can hear spinning sound of the hard disk drive also. The hard drive seems to be OK, and the vertical line seems to show the startup picture though very compressed to 5mm in width.

Diagnosis
The horizontal sweep circuit on the analog board is broken.
Ageing and/or cracks in the soldering of either (1) P1 connector, (2) C15 electrolytic capacitor (3.9uF, 35V, 85degree C, HighFrequency, NonPolar) or (3) L2 variable inductor on the analog board is the major cause of the problem.
The most frequent cause is soldering failure of the P1 connector due to ageing and/or cracks. In this case, you will see the burnt and/or charred P1 connector.

Solutions
The first thing to do is to check the connector, capacitor or the inductor, and then desolder, clean and resolder them. If the problem still persists, replace the parts with new ones.




3. A Fine Vertical Line in the Black Monitor​

The First Thing To Do Is To Turn Off The Power!!!!!!!!!!!

Symptoms

Mac SE/30 shows a fine vertical line in the black monitor. In addition, you may be able to see and/or smell smoke coming up from the SE/30. It's burning. Shut off the SE/30 immediately, and pull out the power plug.

Diagnosis
The horizontal sweep circuit on the analog board is broken.
The R19 resistor (220 ohm, 1/4W, 5%) on the analog board is burnt out.

Solutions
Check the R19. If it is burnt, cracked and/or charred, replace it with a new one.
 

caver01

Well-known member
While we wait for someone more knowledgeable about this sort of fault to appear... How is P1 looking for solder joints? Have you redone them? I think that leads to a horizontal line, not a vertical, but you never know.
Thanks for jumping in. . . Yes, I hated to make my bloated post even bigger, but it is a good call about P1. Have completely soaked out the existing solder and replaced with fresh, strong joints. I can trace continuity from the back of the analog board all the way to the yoke when connected. Also, I cleared up these cracks a year ago too, but after this issue, I re-did them again for good measure to no effect.

@chillin thanks for the reference to the Scrolls. Yeah, I have looked into both the “bright” and the “dim” vertical line suggestions. This is not exactly a double-bright line—I would say more dim than bright. It gets dimmest in the middle of the line, brighter on the ends, but not what I would call bright.

Anyway, I troubleshooting so far:

  • Verified solder joints and continuity for P1 Pins
  • Tested R19 and meters OK
  • swapped new C15 film cap back to the one it replaced. No change
  • replaces solder on L1
  • Verified polarity of all new caps on analog board
Last night was was watching YouTube’s Adrien‘s Basement (I think he might even be local Portland, OR?) and he was troubleshooting an old 9-inch IBM CRT. Said the tube itself was probably swappable with a compact mac. Anyway, his was just dead—no high voltage—and he traced it to a shorted/bad cap. Got me wondering if I have a short somewhere in that circuit. I would be pretty happy to find my issue by following traces etc, but my inexperience is leaving me uncertain about stuff I find. For example, what I see as a shorted connection is simply because a component is a coil which exhibits continuity. I am no electrical engineer, but stuff that seems odd to me is probably perfectly normal—so I am likely missing something. . .
 

caver01

Well-known member
Hmm. Reading the notes added by @chillin I guess I missed L2, which is certainly part of the circuit—it is where you can adjust the horizontal size. Is it possible new caps have put this so far out of adjustment that it is compressed into a single vertical line? I wondered that and attempted to adjust, but it does nothing, How can I test L2?
 

caver01

Well-known member
I did a little reading of past forum posts related to the L2 inductor. It seems that most accounts describe a stuck ferrite core, and in at least one example, a crumbled core, once removed, results in a picture that is too wide—the opposite of what I have here. Besides my L2 core is intact and adjustable, so unless the winding is messed up, I suspect I am not dealing with an L2 problem, but welcome others’ thoughts. I visually inspected the solder joints on L2 and they look clean and solid.
 

caver01

Well-known member
Reading some of the symptoms and diagnosis again, I decided to inspect and resolder L2. I noticed my L2 core was almost completely adjusted out of the center. Perhaps this is normal for only the very end of it inside the core. Maybe someone can tell me what their L2 core looks like. Thankfully, mine is fully intact and moves freely through the inside threads.

I desoldered L2 and noticed some orange corrosion at one of the wired solder joints. Going to clean that up and resolder. I also removed R19 again, as it has some specks of green on it, even though it meters at 220 ohms. I might replace it.

As I nose around the board a bit checking for shorts here and there I noticed I am getting continuity across R12 and R13. Is that normal? I know there are inductors on the board so maybe continuity is expected, but if I am finding shorted resistors that might explain some things. I have not removed R12/13 to check them, but figured someone might have an SE analog board at hand and can probe these to see if theirs also meters shorts here.

I am about ready to try putting the old caps back into place—something I would rather avoid, but not sure what else to do.
 

caver01

Well-known member
After replacing R19 and deslodering L2, I carefully turned the core all the way back to the middle. I cleaned up the joints with solder wick to soak up old solder and resoldered. After putting it back together somewhat, it’s working! Wow. Another example of sticking to it pays off.

However, I noticed that my power supply that I recently recapped has the 12v rail shorted to ground somehow. Consequently, as soon as I screw it down to the analog board everything is dead. No fan, nothing. But if I loosely place the analog board in position without grounding it to the chassis or PSU, everything works great. Probing just the PSU now, I am getting 12v between the ground pin on the output cable and its housing! So, I definitely have a short to 12v on the PSU somewhere.

Two steps forward, one step back. . . but I think this is a better problem to have than something going on with the high voltage. I will take PSU troubleshooting over that any day.
 

caver01

Well-known member
Fixed! It would appear that the edge component inside the PSU that requires the hold down clip and thermal pad was slightly off the pad and conducting 12v to the case. After more careful adjustment, the 12v is isolated from the metal case and everything is now reassembled. With that corrected, the mac SE/30 is now working normally again.
 

Byrd

Well-known member
Nice work @caver01 !

Always good to know even with a fault found, you'll come out with a fully reliable Mac once everything has been checked over.
 

caver01

Well-known member
Thanks. Feeling good about the analog/PSU recap finally. Hoping for a quiet, stable system now for a while so I can do some other stuff with it.
 
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