Spot The Bust Flyback Competition

[Snial]

Hi folks,

@croissantking, kindly sent me a replacement Mac SE flyback a while back. I've finally gotten around to desoldering the old one! Can you tell which is the bust one (sorry, poor lighting)!

So, the SE it belong to has been dead for about 24 or 25 years - grief, nearly 1/4 of a century! I'd taken it out of a damp basement in Manchester, UK in order to sell it at a car boot sale, but when I turned it on to test it - the flyback blew, probably due to the damp conditions it'd been in!

I thought that it'd be a real pain to desolder, but despite my profusion of S--- words it turned out to be fairly easy with a thick tip 15W soldering iron!

I was just wondering, on the spare, I've touched the outer casing. Is that a problem? Do I need to clean it (with??) to get finger grease off it? Also, what kind of grease do I need to use on the suction cup? We have vaseline (not a serious suggestion, but remember I from the UK so we might not have the same brands as in the US).

When I finally put it back together again, it'll only be a single FD SE, but I might be able to add my other Apple FD or a BlueSCSI thing. Really looking forward to seeing that old bird sing !

-cheers from Julz

 

[croissantking]

Excited to hear how you get on with this.

 

[Nixontheknight]

For the suction cup, dielectric grease should be used

 

[Juror22]

For the suction cup, dielectric grease should be used

Can I use the same stuff I use on my spark plugs?

 

[Nixontheknight]

Can I use the same stuff I use on my spark plugs?

yes you can

 

[68kPlus]

@Nixontheknight I didn't use any on my iMac G3 - it works fine

 

[Snial]

Excited to hear how you get on with this.

Thanks! So am I!

For the suction cup, dielectric grease should be used

Do we normally call it that in the UK? Or do we call it Silicon Grease, or something?

PS. Can someone confirm if I need to avoid touching the outer case of the flyback itself and if so that I need to clean it?

 

[Snial]

@croissantking, @joshc, @Phipli, just trying to bump this up again, I'll be able to make some progress if anyone knows the answer to these questions:

Do we normally call "dielectric grease" that in the UK? Or do we call it Silicon Grease, or something else?

PS. Can someone confirm if I need to avoid touching the outer case of the flyback itself and if so that I need to clean it?

 

[croissantking]

@croissantking, @joshc, @Phipli, just trying to bump this up again, I'll be able to make some progress if anyone knows the answer to these questions:

I’ve never heard of fingerprints on the housing on the flyback being an operational issue (I can’t think why it would be), but if you’re unsure I would just wipe it clean after installing

 

[Snial]

I’ve never heard of fingerprints on the housing on the flyback being an operational issue (I can’t think why it would be), but if you’re unsure I would just wipe it clean after installing

OK, so I have a little update. I wiped the outer surface of the flyback with some tissue paper dabbed in Methylated spirits. I've now soldered it in place. Although it looks a bit messy, that's because I've scratched off flux between the contacts - the soldering itself looks good to me. The 15W irons (powered by Solar PV on my roof!) did a good job, just one was needed and I only needed both of them together on the 12 O'Clock contact.



The next stage, I think, involves coating the suction cup with Silicone Grease (aka Dielectric Grease). I can get that from multiple sources. Do I need to coat the inside and out, or do I just plug the cup in place and then apply the grease? I suppose, and feel free to correct my near total ignorance, that the grease, which is waterproof, exists to reduce the chances of some kind of air-gap spark between the CRT and a ground contact in a relatively humid environment? I mean, there's 10KV hanging around there, so I guess that could make a bit of a jump? So it needs to go on the outside of the cup? Hmm, do I also need to clean the area of the CRT where the suction cup will go? (my guess, is that it's not a bad idea).

After that I need to check the SE's PCB. As I think I've said before, I think the analog PCB is OK and I don't plan to recap it all (yet). When I've done that I hope to put it all together and boot the little critter ! I do plan to boot it outside on a dry day though, because it's better for the magic smoke to escape there ;-) !

 

[croissantking]

OK, so I have a little update. I wiped the outer surface of the flyback with some tissue paper dabbed in Methylated spirits. I've now soldered it in place. Although it looks a bit messy, that's because I've scratched off flux between the contacts - the soldering itself looks good to me.

You could tidy up the flux with some cotton buds soaked in IPA. I mean, I would just because I like things neat and tidy - but it’s a cosmetic thing.

View attachment 74678

The next stage, I think, involves coating the suction cup with Silicone Grease (aka Dielectric Grease). I can get that from multiple sources. Do I need to coat the inside and out, or do I just plug the cup in place and then apply the grease?

I would have thought inside and out, but I’m no expert. I’ve run these without any grease and nothing bad happened. What does googling say?

I suppose, and feel free to correct my near total ignorance, that the grease, which is waterproof, exists to reduce the chances of some kind of air-gap spark between the CRT and a ground contact in a relatively humid environment? I mean, there's 10KV hanging around there, so I guess that could make a bit of a jump? So it needs to go on the outside of the cup? Hmm, do I also need to clean the area of the CRT where the suction cup will go? (my guess, is that it's not a bad idea).

Yeah, clean it.

 

[Juror22]

If there is a chance you will be taking it apart again very soon - like you are still working on it and troubleshooting issues, there is no need to put the dielectric grease on yet. When you are ready to assemble it for the (hopefully) final time...

Do I need to coat the inside and out, or do I just plug the cup in place and then apply the grease?

Coat here on the inside...

plug the cap into place, making sure that the clips are engaged, because when you put it back in they sometimes look like they are in, but one is really not. Once you are sure it is secure and you are not going to be removing it again anytime soon, then smear some extra dialectic grease around the outside edge of the cup's lip, making sure to go all the way around, sealing it up, but not gooping it on. I hope this helps.

 

[Snial]

If there is a chance you will be taking it apart again very soon - like you are still working on it and troubleshooting issues, there is no need to put the dielectric grease on yet. When you are ready to assemble it for the (hopefully) final time...

Coat here on the inside...
View attachment 74688
plug the cap into place, making sure that the clips are engaged, because when you put it back in they sometimes look like they are in, but one is really not. Once you are sure it is secure and you are not going to be removing it again anytime soon, then smear some extra dialectic grease around the outside edge of the cup's lip, making sure to go all the way around, sealing it up, but not gooping it on. I hope this helps.

Thank you very much!

You could tidy up the flux with some cotton buds soaked in IPA. I mean, I would just because I like things neat and tidy - but it’s a cosmetic thing.
Yeah, clean it [CRT]

Thanks, I'll do those things!

-cheers from Julz

 

[Snial]

I got most of the way to fixing the flyback and bought the Silicone Grease, but then discovered that I'd mislaid the digital to analog board cable! There's another post elsewhere where another 68KMLA user said I could buy one from Mouser. However, I didn't know what kind of connector I needed - I guess I could have looked it up.

Nevertheless, Phipli (if you remember him) super-kindly sent me a replacement cable! So, today I finally connected up the flyback cable to the CRT; applied the Silicone Grease and.. after setting it up outside on a lovely and surprisingly warm, sunny April day in the UK, I tried to power it up for the first time in 25 years!

And I got this:


It's clearly unhappy. But on the other hand, it's generating a display and not on fire!!

So I call that a win. Is it likely a DRAM issue? It didn't make a startup beep. I powered it up a second time and it did the same thing - so it's consistent! It looks like the Sad Mac code is $9090909E, $80903890 or something like that. The SE has 4MB of RAM in it, so if up to 2 sticks have gone, I have a fairly quick fix. Does the SE auto-detect RAM sizes, or is it like the Mac Plus where you have to make solder bridges to tell it how much RAM it has?

-cheers from Julz

 

[croissantking]

Nice! Did you end up using the flyback I sent you?

 

[Snial]

Nice! Did you end up using the flyback I sent you?

Yes, thank you again, v.v.v.v much! Also I managed to connect it and power it all up without electrocuting myself - I'm alive!!!

-cheers from Julz

 

[croissantking]

Yes, thank you again, v.v.v.v much! Also I managed to connect it and power it all up without electrocuting myself - I'm alive!!!

-cheers from Julz

I’m glad it could live on to give another machine a new life

 

[croissantking]

when I turned it on to test it - the flyback blew, probably due to the damp conditions it'd been in!

How did you know that the flyback had blown, specifically?

 

[Snial]

How did you know that the flyback had blown, specifically?

Because it had a massive gouge in it ! I'm outside right now, but I'll add a photo in a bit. Whew, our cat just dived after a mouse in the back garden, but being 12 years old, he was a bit too slow to catch it! Now he's licking himself in desolation!