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Starting a Mac Plus restoration. Need a new flyback wire with anode cap

reallyrandy

Well-known member
This poor thing has been in storage since the early 90s. I was gonna use it as a donor Mac but it turns out I don't need any parts from it. So, I decided to try and resurrect it.
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I plugged it in with my Floppy EMU to try a boot and just got clicking from the PSU (not surprised). I started taking it apart and after discharging the PSU noticed that the flyback cable and the cup at one end and the rubber shield at the other end have pretty much turned back in to oil.
Are there any sources for a cable like this? Other than a donor Mac?

Also, that glue on the flyback looks pretty cracked, can I buy a tube of that stuff? It looks like it's some type of putty.


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Byrd

Well-known member
Black grime is not unusual in an old computer case, but if really sooty I'd say it's been in a fire - as evidenced by the cracked rubber anode cap
 

bdurbrow

Well-known member
Or had the fire internally; as a fire outside of the case would have melted the ABS plastic case first, before scorching the electronics inside.
 

Iesca

Well-known member
The "glue" around the flyback is an epoxy, and it can be reapplied. As for the grease under the anode cap, it seems you may be able to use silicone grease, or even Vaseline.

I would be very concerned about that flyback though.
 

reallyrandy

Well-known member
It looks as though all the soot is originating around the flyback. The soot is mainly on the flyback, the flyback cable and the back of the CRT where the anode cap is. The clear anode cap and the the cap at the other end of the wire leading into the flyback is kind of "wet" with an oily feel, like the transparent rubber is turning back into oil. Does anyone know where I can source a new flyback with the cable?

Is there a good way to clean the back of the CRT? I'm pretty sure I can't just wash it!
 

Byrd

Well-known member
Nicely cleaned up - it looks a lot better. I reckon that flyback has been arcing attracting the dust, can you see any deep cracks or scorch marks around it? I'd be wary trying it once recapped, don't get close, and prepare for your house circuit breaker to be tripped :)

This is an example of an overpriced flyback for the Plus:


JB
 

davidg5678

Well-known member
I think that you did a good job cleaning up this anode cap. All of my Macs have had degraded rubber anode caps and sooty CRTs like this. I always just cleaned up the mess with an isopropyl alcohol-soaked paper towel. After I remove the degraded rubber, the remaining (non-oily) material had always seemed more than solid enough, so I haven't been too worried by it.

There is supposed to be a dielectric grease applied in the factory between the CRT and anode cap. This grease should be left behind if you can manage it, though several of my computers are missing the grease and still work fine. I think it's supposed to prevent arcing in the event the anode cap doesn't make a good seal.

I always assumed the soot was just some kind of dust attracted by the high voltage components in the computer. From what I've seen in these pictures, I really don't think this computer was ever internally on fire, so again, no worries.

Personally, I would try powering up this computer. It looks like it has a good chance of functioning now that you've cleaned it, and the degradation I can see looks pretty standard.

The flyback may be a bit worn, but I have seen worse. The glue looks a very dark, but I can't make out any cracks, so I think it's probably fine for now. The main concern would be if there is a lot of glue missing around the flyback and that it starts arcing (and making ozone?).

The PSU in this computer may be bad, so made sure to verify its function before connecting it to the rest of the machine. Especially if this is an Apple Singapore model PSU, it may just be completely destroyed by capacitor leakage.

Remember to take safety precautions if you're unsure of anything's reliability!
 

reallyrandy

Well-known member
I'm seeing an analog board on eBay that looks clean, I may just go for that. If nothing else, I'll have a spare.
 

reallyrandy

Well-known member
I fired up the Plus after reflowing the solder joints on the analog board. I get a beep and my Floppy EMU lights up steady now. Unfortunately, the screen stays black. I'm guessing this points to the flyback. Are there some tests I can run to see if that is in fact, the issue?

I see only one analog board on eBay that looks promising. Still, that one has not been tested.
 
I fired up the Plus after reflowing the solder joints on the analog board. I get a beep and my Floppy EMU lights up steady now. Unfortunately, the screen stays black. I'm guessing this points to the flyback. Are there some tests I can run to see if that is in fact, the issue?

I see only one analog board on eBay that looks promising. Still, that one has not been tested.
I had seen in a video that if the "glue" on the flyback is brown (not yellow like it should be), there could be an issue. Also if you look at the flyback in complete darkness (while the unit is on) and you see "blue sparks" flowing inside of the flyback, that could also point to a defective flyback. At 15:41 in this video:
 

cheesestraws

Well-known member
Unfortunately, the screen stays black. I'm guessing this points to the flyback. Are there some tests I can run to see if that is in fact, the issue?

There are a number of parts on the AB that can fail in the video path that aren't the flyback. Do you have an oscilloscope or any other means to trace signals? This for me was caused by a bad inverter chip (which forms the first part of the video amplifier).
 

reallyrandy

Well-known member
I was offered an analog board by CC_333 so I'm gonna go that route and save this one to fix later. In the meantime I got my 128k and my 512k running beautifully. I had to take apart, scrub and re-grease the 400k floppies in both.
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reallyrandy

Well-known member
You shoulda seen it when I took it out. Everything was seized up, no eject, couldn't even slide a disk in. I soaked it in alcohol and then scrubbed it in Windex. I used white lithium grease on the metal parts and silicon lube on everything that touches plastic. Now it's super quiet and moves easily. The caps all look good so no re-cap… yet!
 
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