A reasonably happy Macintosh SE (with minor issues)

[greystash]

After years of neglect I finally pulled my SE FD/HD out of the closet, opened it up and gave it a brief clean. It looks surprisingly good after a thorough air dusting, and I can't see evidence of the capacitors leaking yet. I'm going to re-cap it and will give it a good alcohol clean when I do this. I did notice one component has a rusted leg (maybe the beginnings of leaky capacitors). I just have a few questions that can hopefully some of you will be able to answer:

- What is the component and value at Y1 with the rusting leg? I'll replace this if I can find another.
- There are some dark spots along a lot of the traces, is this an issue or part of the production process?
- Some of the capacitors have their values obscured, are all the ones on the logic board 16v 33uf?
- I installed a big Quantum HD years ago and it's very close to the CRT. I've noticed that whenever it's loading something the clicks shake/distort the screen. The image is starting to sag at the bottom also (which I think is a more recent change), could this be due to the HD? I plan on replacing it with a SCSI2SD soon.
- I installed a network card which I've had for a few years that I believe is an Ethernet card. It has a coax(?) port but I'm not sure what sort of adapter I should be using here. Any ideas?

Thank you in advance!

 

[rjkucia]

That’s a Thinnet/10BASE2 connector. You’d need a media converter to connect it to a modern network. Something like this: 10BaseT RJ45 UTP to 10Base2 Thinnet Coax BNC Media Converter | Ethernet Adapter 10Base-T/2 https://a.co/d/cHjRvYu

Although there may be a cheaper solution.

 

[cheesestraws]

It's usually cheaper to go and buy an old hub with 10Base2 and 10BaseT ports than to buy a media converter, even though they're functionally the same thing.

 

[Berenod]

I think the oxidation you see has another source.
The SE logic board doesn't have any of those leaking SMD capacitors, the axials you see normally don't leak.
Doesn't hurt to replace them though, capacitance will be nowhere rated, and ESR will start creeping up...
SE logic boards usually die due to battery leakage!

The analogue board is a bit of another story, cracked solder joints, out of spec capacitors etc can be an issue, wobbly image on the cart etc can be symptoms of those...

 

[mdeverhart]

Y1 is the crystal for the real time clock (RTC). The Bomarc schematic says it’s 30 kHz, but no other details are shown. I’d probably recommend leaving it unless you’re seeing issues with the RTC (not keeping time/date, time running fast/slow, etc). If you do replace it, I’d recommend trying to get the part markings and replace it with an identical component - crystal oscillator circuits are intended to be tuned with specific components (e.g. it’ll specify the characteristics of the quartz crystal itself, the capacitors and other discrete components tuning the circuit, etc).

 

[greystash]

Thanks for the help that's really helpful @rjkucia, @cheesestraws, @Berenod and @mdeverhart.

@Berenod I didn't realise capacitance and ESR could start changing, I'll stop using it for now and will get some replacements for the analog board also.

@mdeverhart I'll see if I can treat the oxidation and if that's not possible I might trim the legs. Worst case scenario I'll look for a replacement.

Thank you!