Macintosh 512+ Oddities... Any ideas?

[iMac600]

These issues aren't so major, but i'm after some ideas as to why they may be occuring.

1. When powering up the Mac from a Cold Start (such as turning it on after being switched off overnight), the boot chime is about twice as loud as it's supposed to be. After idling the system for a while and switching it off, then back on (or just pressing reset), the chime is at its normal volume.

2. The raster seems to be a little out of whack. I'm assuming the CRT itself needs adjustment, but one thing i've noticed is that certain display elements will push the raster out of shape. For example when the "Welcome to Macintosh" box is displayed, the raster to the right of the box is "bending outward", so the right edge of the raster which was otherwise straight now has a "bump" in it. As soon as the "Welcome to Macintosh" box is gone and the desktop is displaying, this no longer occurs.

3. Does anyone have a guide for adjusting the CRT on these? Rings, whatever. Height and width, brightness and focus is fine, just the shape of the raster itself.

4. This little thing heats up quite a bit. Perfectly normal for a Macintosh, but this machine is going for longevity now, so it may be worth ventilating it. Instead of sticking a giant freakin' chimney on the top, i'd like to have something mounted inside the case. I can probably figure out where to wire it up, but the question is where to put the fan within the case. I'd put it directly below the vent if I could (since it seems to fit there), but it doesn't clear the analog board once the case is closed.

 

[Dog Cow]

2. The raster seems to be a little out of whack. I'm assuming the CRT itself needs adjustment,

It could even be the power supply.

 

[Mac128]

Everything you describe sounds like voltage problems. Your Mac is out of whack. Get yourself a multimeter and go to work, starting with Dr. Lee's excellent notes. Then get yourself a copy of Larry Pina's must have book for the vinate Mac enthusiast: Macintosh Repair & Upgrade Secrets, which will give you the alignment guides, and in some complete books, the software to make adjustments easier. There is also a step by step tutorial for adding an exhaust fan in the top rear chamfered vent opposite the analogue board –- the most popular location without impeding airflow. However, if you install a fan, you will want to construct a plastic dust shield to surround the 400K disk drive so as not to draw dust and debris through it further gunking-up the temperamental drive (as well as encouraging air-flow through proper channels).

Dr. Lee's guide will get your Mac back into top technical shape and help you determine if additional problems persist. More than likely you will need to start replacing aging components, as detailed in both sources.

 

[Scott Baret]

Bad geometry can either be caused by the power supply or by the little magnets on the neck of the CRT. Since those magnets are a pain to work with, I'd suggest a power supply repair or replacement first.

I verified this by using the same CRT with two power supplies (on an SE). The image was smashed on one side and not the other (if you had two circles in MacDraw, the one on the left would look more like an ellipse) when using the first power supply. The second power supply, pulled from a Mac known to have good geometry, fixed it without any adjustment to the CRT.

Of course, magnetic problems are always bound to occur on CRTs and often get worse with age (from my experiences). Even new CRTs are like this--I have a Sony TV that has a similar problem (the entire picture was tilted) and once had another Sony TV that I actually had to adjust on the inside because of this problem. (Newer monitors and TVs actually have controls to compensate for this and thankfully this isn't a problem with LCD displays).

 

[iMac600]

Well I made some adjustments, including as suggested to the voltage, and here are the results.

1. When powering up the Mac from a Cold Start (such as turning it on after being switched off overnight), the boot chime is about twice as loud as it's supposed to be. After idling the system for a while and switching it off, then back on (or just pressing reset), the chime is at its normal volume.

This still happens, not worried about this so much.

2. The raster seems to be a little out of whack. I'm assuming the CRT itself needs adjustment, but one thing i've noticed is that certain display elements will push the raster out of shape. For example when the "Welcome to Macintosh" box is displayed, the raster to the right of the box is "bending outward", so the right edge of the raster which was otherwise straight now has a "bump" in it. As soon as the "Welcome to Macintosh" box is gone and the desktop is displaying, this no longer occurs.

As does this, but the issue is nowhere near as bad.

3. Does anyone have a guide for adjusting the CRT on these? Rings, whatever. Height and width, brightness and focus is fine, just the shape of the raster itself.

Managed to adjust these myself, the CRT is now centered and working fine.

4. This little thing heats up quite a bit. Perfectly normal for a Macintosh, but this machine is going for longevity now, so it may be worth ventilating it. Instead of sticking a giant freakin' chimney on the top, i'd like to have something mounted inside the case. I can probably figure out where to wire it up, but the question is where to put the fan within the case. I'd put it directly below the vent if I could (since it seems to fit there), but it doesn't clear the analog board once the case is closed.

Now this has a positive and a negative... I have a feeling that voltage pot was set a little too high. Once I turned it down to a reasonable level the machine began to run better, but the heat output is also significantly reduced. Unfortunately the only reason I opened the case was to install a fan... and in the process of hooking up that fan I blew the fan and the fuses in quite a spectacular way. However, no harm done.

 

[Mac128]

Unfortunately the only reason I opened the case was to install a fan... and in the process of hooking up that fan I blew the fan and the fuses in quite a spectacular way.

Um, how did you plan to adjust the voltages if not by opening the case?

So, did you manage to install the fan? Or will you be seeking a replacement for round 2? What guide did you use to install the fan? Or did you just "wing" it yourself?

Did you test your +12-V supply to make sure it was optimal before adding the additional load? The fan specs should be approx. 0.9 W @ +12 V DC (+/-15%)/120mA. You splice it into the J4 connector. Red to yellow (pin 10), black to violet (pin 7).

 

[iMac600]

Unfortunately the only reason I opened the case was to install a fan... and in the process of hooking up that fan I blew the fan and the fuses in quite a spectacular way.

Um, how did you plan to adjust the voltages if not by opening the case?

So, did you manage to install the fan? Or will you be seeking a replacement for round 2? What guide did you use to install the fan? Or did you just "wing" it yourself?

Did you test your +12-V supply to make sure it was optimal before adding the additional load? The fan specs should be approx. 0.9 W @ +12 V DC (+/-15%)/120mA. You splice it into the J4 connector. Red to yellow (pin 10), black to violet (pin 7).

If I wasn't going to install that fan, then i'd never have opened the case, and i'd never have adjusted the voltages. Simple.

The fan was destroyed. Totally charred and melted. I used a guide in the fiftieth edition of the Mac 512 User Group newsletter to attempt the installation and connected it accordingly. It's possible the colour coded wires on the fan were incorrect (in which case, what a rip).

I somehow doubt i'll attempt the installation again. I'm fine with the machine now.

 

[MacJunky]

12v DC does not melt a fan.. you sure you did not bump the AC by accident?

 

[iMac600]

12v DC does not melt a fan.. you sure you did not bump the AC by accident?

I haven't a clue. Followed the guide to the word, it failed, and I yanked the power and ditched the fan. Didn't even bother to look at what could have potentially gone wrong. My only concern was getting the machine working again, which I succeeded at. After that I just left it as-is... :lol:

 

[Mac128]

If I wasn't going to install that fan, then i'd never have opened the case, and i'd never have adjusted the voltages. Simple....I somehow doubt i'll attempt the installation again. I'm fine with the machine now.

I hope that doesn't mean you don't plan on opening the case again. Aside from the fan, your analogue board is showing signs of age, despite adjusting your voltages the Mac is exhibiting symptoms that need to be addressed. It is only a matter of time before it begins to fail again. Think seriously about following Dr. Lee's capacitor upgrades. There is no way to be a vintage Mac enthusiast without routinely opening the case and general maintenance, assuming you actually want to use it. Of course a fan will go a long way toward extending the time between case crackings.

Also, G. Younk's Mac512 instructions are for installing an AC Boxer fan. It appears to me that you tried to install a DC fan to the AC power supply (CR23 & 24). Even reversed wires should not melt an AC fan (Could the fan have been a 115V installed on an international 220V PS?). Younk also shows a 12V AC fan, where Pina specifies a 115V or 220V model (not sure if Younk actually installed the pictured 12V fan as he often reports things he has not himself tested), if you followed it to the word, that would explain a few things as well. Fan installation is a normal routine procedure for those who know what they are doing, but it's your call.

 

[iMac600]

I hope that doesn't mean you don't plan on opening the case again. Aside from the fan, your analogue board is showing signs of age, despite adjusting your voltages the Mac is exhibiting symptoms that need to be addressed. It is only a matter of time before it begins to fail again. Think seriously about following Dr. Lee's capacitor upgrades. There is no way to be a vintage Mac enthusiast without routinely opening the case and general maintenance, assuming you actually want to use it. Of course a fan will go a long way toward extending the time between case crackings.

I don't see how the changing the capacitors at this stage is going to help considering the ones on the analog board are only 3 weeks old as I mentioned across the forums. I replaced them already to repair the board with great success. There is only one possible capacitor I can think of that could need replacement (and could have been overlooked in the initial repair), and maybe I could tackle that down next week some time, but we'll see if it makes a difference or not.

Also, G. Younk's Mac512 instructions are for installing an AC Boxer fan. It appears to me that you tried to install a DC fan to the AC power supply (CR23 & 24). Even reversed wires should not melt an AC fan (Could the fan have been a 115V installed on an international 220V PS?). Younk also shows a 12V AC fan, where Pina specifies a 115V or 220V model (not sure if Younk actually installed the pictured 12V fan as he often reports things he has not himself tested), if you followed it to the word, that would explain a few things as well. Fan installation is a normal routine procedure for those who know what they are doing, but it's your call.

AC and DC. Yes... that would be it. Unfortunately probably the one thing I overlooked during the installation was whether CR23 and 24 are AC or DC lines. The good news is that the fan was nothing special and the analog board was well protected. Always good to have precautions when working on hardware like this, right?

I've studied the pinouts for each connector and I can see where the fan would connect now. Otherwise very simple. However I may or may not add a fan, that's yet to be determined, but i'd imagine i'd have the case open again at some point (especially if I found a capacitor was overlooked and needs replacement) so i'll definitely have it on the "to do" list.

 

[JDW]

12v DC does not melt a fan...

Followed the guide to the word, it failed, and I yanked the power and ditched the fan.

So the fan "melted" or merely "failed" now? If truly melted, I for one would love to see a photo.

As to the need for a fan, it all depends on your usage. I for one baby my old Macs. I never have run my 512k for more than 2 hours at a time (obviously, as its not my only computer), and anytime I walk away from the machine for even 30 seconds I dim the screen to zero brightness manually to prevent burn in. I habitually touch the analog board side of the Mac to see how hot it is, and if it becomes extremely hot to the touch, I shut down the machine. So unless you are running the machine more than 4 hours straight a day every single day, you will do just fine without a fan. Eliminating the fan also means you will reduce noise and save anywhere between 60 to 200mA in the process too.

What if you want to occasionally want to run the Mac for many hours straight? If it's winter it probably won't matter (assuming you live where it gets cold in the winter). And in the warmer months of the year, just fire up the A/C and perhaps point an external fan toward you and the Mac (which you probably do anyway to cool yourself in the heat of summer).

In the days when these Macs were our main computer at home, there was a great need for internal cooling. But that doesn't necessarily hold true anymore. Again, it all depends on your usage of the Mac.

 

[iMac600]

Followed the guide to the word, it failed, and I yanked the power and ditched the fan.

So the fan "melted" or merely "failed" now? If truly melted, I for one would love to see a photo.

I just say "failed" as to not overdramatize it... although I think in saying "melted" i've already given everyone the wrong impression. The spark show was fantastic. The internals of the fan burned and heated, warping the outer case from heat... to say it melted, in hindsight, gives everyone this impression it turned into a puddle of black goo. No such dice, i'm afraid. Spectacular, but not that spectacular.

As to the need for a fan, it all depends on your usage. I for one baby my old Macs. I never have run my 512k for more than 2 hours at a time (obviously, as its not my only computer), and anytime I walk away from the machine for even 30 seconds I dim the screen to zero brightness manually to prevent burn in. I habitually touch the analog board side of the Mac to see how hot it is, and if it becomes extremely hot to the touch, I shut down the machine. So unless you are running the machine more than 4 hours straight a day every single day, you will do just fine without a fan. Eliminating the fan also means you will reduce noise and save anywhere between 60 to 200mA in the process too.

Yes well, I somehow doubt i'll be running it for more than an hour a day on certain days, so it's probably not so much of a concern. I think I have all the same habits as yourself, dimming the screen before leaving it and so on... I tend to look after my machines pretty well, if they even get so much as a speck of dirt on them, they get cleaned, and i'd never dare letting the cases get chipped or damaged... would be devastating. Needless to say i'm a real fan of the compact. (fan, compact... yeah, bad pun).

In the days when these Macs were our main computer at home, there was a great need for internal cooling. But that doesn't necessarily hold true anymore. Again, it all depends on your usage of the Mac.

I think my intention was to try and improve its lifespan, and make general operation of it just a little bit easier on the hardware inside. All about longevity. After trying to fit the fan though, I think it's safe to say that I realized trying to install it would probably reduce the lifespan of the hardware anyway... especially if it was blowing fuses. :lol:

Ah well, it doesn't need a fan. All brand new fuses in there, tested and it's running beautifully again. No big deal. I still can't work out what the go is with the CRT though. Keep in mind that it exhibited this issue before the fan accident. Although it does look as though i've improved the situation a lot by swapping in a spare CRT assembly I had here (just for the hell of it, I had some free time), it still appears lower on the top left as opposed to the top right, even though the raster is perfectly flat along the bottom edge and sides. It's the corner closest to the top of the analog board, for reference. It may be one of those large capacitors near the top, so i'll look into those when I have some free time.

C1 and its surrounding caps are original, that is I never swapped them out on the initial run... perhaps that one or two is worth looking at. Anyone have the ratings for that or the two capacitors surrounding the width adjustment coil? This is a 240v international board, not sure if that makes a shred of difference. Any tips for replacing C1 are also appreciated.