SE Analog Board flyback and other issues.

[Juror22]

I couldn't help picking up another SE, largely because of some of the accompanying items that came with it.
I did not initially power it up because even though it was sold with pictures of the screen working (albeit with a fault code) it was going to require a lot of work to get it ready and I didn't want to break things because I was impatient. So far, I have started with the easy items and worked up to the AB, which is a later board variant and seems to have a few issues:
1) there is a hole burned through where someone poorly bridged a circuit.
2) there is some corrosion where the power connector joins up. (I have another identical revision board that also has this in the exact spot - not from any battery damage or obvious moisture anywhere else, just corrosion on a few of the power connector pins - weird - I've already cleaned up the power supply connector.
3) the CRT was grafted on - the four main connection wires were just twisted together (individually) and then electrical taped <sigh!>
4) and this is the big one -the flyback is a different number than I've ever seen on these (MF 1434) - is this even a flyback for this, or did someone just grab one from a bin and solder it up to make it work for long enough to sell it?
I've got a couple of donor boards and spare parts enough to go around that I think I will have a working board when I'm through, but WOW, really?

See 'before' pictures below and I will pass along updates of what I replace or fix as I work through it.


...can't tell so much, but C15 was so hot the covering became brittle, cracked and fell off (all before I owned it - I did not power it up like this!)
On P3 you can just make out the corrosion (green color) on the pins.

 

[chiptripper]

Wow! Some, uh, interesting choices made by previous owner / repair person. I’ve never seen that flyback before either.

Poor C15. That’s a non-polar cap too, tricky to source a replacement. I think I ended up using those big film capacitors.

 

[marcelv]

is the flyback from a classic ? according to the bomarc schematic MC-FBM-008

 

[marcelv]

the schematic is for the 820-0395-A (early classic) so the flyback is compatible with the SE

 

[Arbee]

With flybacks there's not really such a thing as "tack it in there long enough to sell". If it's not compatible and you get a picture at all, it's going to be very obviously distorted.

 

[Juror22]

the schematic is for the 820-0395-A (early classic) so the flyback is compatible with the SE

Thanks for taking a look and passing that on - I tried looking for the part and only came back with a few hits that were remotely close and those were buried French and Russian docs that still did not seem to indicate what they were. I did not think to look in the schematics for the classics, excellent call!

With flybacks there's not really such a thing as "tack it in there long enough to sell". If it's not compatible and you get a picture at all, it's going to be very obviously distorted.

Thank you for letting me know. I have largely avoided AB board issues in the past, but since they are starting to show up more (it seems), I suspect that I won't be the only one working with these more often and it was great of you to let me know what was possible, or not.
(Yes, I do have the correct amount of respect and safety procedures for these, and follow them, even though I don't fully understand what is possible or not)

For example, I initially suspected that the flyback contributed to the hole in the board, but knowing what I do now, I suspect it just points back to the poorly bridged area, likely developing too much heat.

Poor C15. That’s a non-polar cap too, tricky to source a replacement. I think I ended up using those big film capacitors.

If I'm right (I really hope that I am) I bought a few of these back when I had to replace one several years ago. Crossing my fingers now that a) its the right one and b) I can find them and c) they haven't gone bad in the interim.

 

[chiptripper]

If I'm right (I really hope that I am) I bought a few of these back when I had to replace one several years ago. Crossing my fingers now that a) its the right one and b) I can find them and c) they haven't gone bad in the interim.

I bought in bulk too, so let me know if you need one and I can pop one in the mail for you. The film caps I chose are an awkward fit for the limited space so you’ll have to get creative when installing, but they do work fine.

 

[Juror22]

The film caps I chose are an awkward fit for the limited space so you’ll have to get creative when installing

Turns out the ones that I have (found them) required a bit of interesting positioning as well - I've installed them in a 45 degree sort of thing on one of the replacement boards that I had. I have been collecting a few non-working boards for the day when I would have a really bad one and need donor parts, so I took my best donor board, and recapped it, which sidesteps the earlier flyback issue and I also reflowed several of the main components/connectors on the board.

During the past couple of months, I've finally made it through the rest of the list as well, fixing the cut CRT wire connector issue properly with solder and shrink-wrap, re-capping a couple of compact Mac power supplies ( the original Apple 820-0385-A whose caps had leaked horribly and had even started to seep outside of the case a bit and also a spare Sony CR44, in case the other one did not work out). I also cleaned and lubricated the floppy, oiled the miniscribe (in the hopes that it would work) cleaned the SE's motherboard and cleaned and retrobrited the APS external hard drive.

So last night I started reassembling the AB and Sony power supply back to the frame, installed the mother board, hooked up the cabling and fired it up. There was a chup, chup, chup noise, no startup chime - a severely compressed and dim checkerboard pattern that blinked in time to the noise and got worse as the brightness was increased. Since I had just re-capped the power supplies I was ready to test the output voltage and the 5V tested Ok, but the 12V line was less than 3V. With this much re-work there were a lot of places to start looking for issues, so the first place I started was to swap out the PSU, but that showed a very minor improvement - again a solid 5V, but with 3.2 V instead of the 12, so probably not a PSU problem. After a quick internet search for the checkerboard and low voltage issues, I found an answer that indicated my reflow work needed to be more extensive, so I put it up for the night.

Picking it up the next day, I reflowed the AB board with a special focus on the connectors, especially the one for the motherboard and that fixed the low voltage issue, so it started up with a chime, and made it to the floppy icon, but recall that earlier there was a chup, chup, chup noise and that the screen blinked in time to the noise and got worse as the brightness was increased - that was still there, although there was very little noise associated with it now. I looked for issues similar to this online, and as a result, checked the connector to the back of the CRT and also tried changing out the CRT board. None of that worked, so I turned down the brightness and made some screen adjustments.

Then I did something stupid.
I pushed (gently) on the CRT anode cap and it got better, I pushed a bit harder and it went away entirely.

After shutting down the Mac and discharging the CRT, I checked the anode cap and found that the little connector inside was not soldered onto the wire (big glob of unattached solder on the wire though), so I removed the old solder, cleaned the connector and wire, applied flux to the connector and re-soldered it. Stuck the anode back in, put in the floppy and HD, plugged in the mouse and fired it up. Perfect.

Well, almost perfect. The miniscribe tried to start and for about 30 sec there was even a happy Mac, but then it reverted back to a curious icon and the HD was in a loop where it would do three engages and then go quiet, then try again. Even non-working it was pretty cool with the sounds and the amber LED. I know they are a bit problematic, so unless there is a quick fix for that, I will probably put it (the HD) on the shelf at this stage and move on to other rescues.

I'm also still trying to work out why the APS SCSI, external HD appears to have a Quantum LPS Drive that has Master/Slave/Cable select indicators on it that would seem to mean that it is using an IDE drive. It looks absolutely original and has the internal APS company stickers on it and its hooked up to the SCSI cabling internally just fine. I'll probably post this as a separate item in peripherals when I know more.

 

[Juror22]

Okay, the miniscribe works too.
I gave it another chance, and it fired right up (relatively speaking). Poked around on it for a bit, System 6.0.8, some early networking, MS Word and a couple other things. Mainly, just seeing if it would freeze up or anything like that, but it seemed solid while it was running - it also had a pair of googley eyes in the menu bar that watched the cursor, kinda freaky...

 

[Juror22]

I'm also still trying to work out why the APS SCSI, external HD appears to have a Quantum LPS Drive that has Master/Slave/Cable select indicators on it that would seem to mean that it is using an IDE drive. It looks absolutely original and has the internal APS company stickers on it and its hooked up to the SCSI cabling internally just fine. I'll probably post this as a separate item in peripherals when I know more.

When I attempted to hook this up to another SE a few weeks back, perhaps I didn't terminate it properly, because it did not show up on the SCSI chain at all. However, when I tested it last night on my Q650, it started right up. As for the Master/Slave/Cable select, I'm guessing they just slapped a quantity of that sticker on the drives, since after I checked the underside, I confirmed that the drive clearly had the SCSI pinouts. So after re-assembly of the retro-brited exterior, I have another APS external SCSI drive with a whopping 270MB.

 

[Kouzui]

Poor C15. That’s a non-polar cap too

Doesn't look non-polar to me, if that little plus sign on the PCB and the white part of the casing are to be believed.

Edit: Nvm I'm wrong, and that "white part of the casing" is actually just the bare metal of the capacitor, lol. Still odd that there's a plus sign on the board IMO.

 

[chiptripper]

That is funny, how odd. That coil filter shouldn’t be polar either, so it’s not for L3. I wonder if this is a silkscreen error. Or does it suggest that a polar cap might work there? That would be convenient.

 

[marcelv]

Guess there are 2 options:
(From tinkerdifferent)

"The purple board is now Revision 1.3, and the C15 has holes for film capacitor.
*Also has holes for electrolytic capacitor"

 

[Juror22]

Doesn't look non-polar to me, if that little plus sign on the PCB

That little plus sign is there across two board revisions that I have laying about and I've never noticed that, until you pointed it out!

I wonder if this is a silkscreen error. Or does it suggest that a polar cap might work there?

Across two revisions its not likely an error - and the polar cap does appear to be a choice...

Guess there are 2 options:
(From tinkerdifferent)

I'm planning to use parts from the burned board along with two other non-working boards to make at least one more working board, but I had no idea that there was a project for AB board replacements, so if I need to to, I can start from scratch.