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.