Macintosh Plus Issues

[JawhnL5]

Got a Macintosh Plus roughly a week or two ago, with a keyboard, Apple 20SC hard drive with an OS on it, no mouse though.

Anyways, upon first boot, I plugged in the keyboard, hard drive, powered on the hard drive and then the computer. The classic Macintosh Plus *beep* emitted. Then I noticed something weird. It kept replaying the sound, as if it was resetting itself, constantly. It was, to my dismay, in a loop of resetting itself. Eventually after letting it sit and reset itself for a while, it came up and booted into Mac OS off the hard drive. Then I inserted an 800K floppy disk to test the drive, and bam, it reset itself yet again until I unplugged the hard drive and removed the disk. Eventually I was able to test the floppy drive, and it works flawlessly. The only issue is it resetting itself. Everything else works great, even the CRT is bright and crisp. Another issue is the Eveready 523 battery leaked all over the contacts but I cleaned off all the acid and corrosion, and that hasn't been an issue.

So anyways, what would be the issue? I noticed slapping the side like others suggested didn't make it anymore happy, it just seemed to work whenever it wanted. It hasn't reset itself like this for a week, I've been powering it up daily, and no matter what I do, I cannot get it to constantly reset in a loop like it did the day I got it, it's like it fixed itself, but something still has to be wrong on the inside, right?

 

[unity]

When you go to a doctor, they usually take blood pressure readings. Its just a matter of standard practice. With any newly acquired Mac in the compact line I always re-solder the areas where connectors are. On the logic board there is one. This one is almost always bad with cracked solder joints. Then on the analog board you have three. The same one going to the logic and two for the CRT. These often have slight cracks. Slapping it on the side does not always work, in fact if it does it simply shows there is an issue that MUST be addressed. If you don't fix the solder joint they can cause issue, such as burning of connectors.

So before you go further, these must be checked to rule it out. Then one can move onto any other problem solving.

Just my 2 cents though. Years past I worked on many compact Mac. And recently I acquired and serviced several more. I would have to say all had cracked solder joints from one degree to another.

 

[JawhnL5]

Step 1 is getting the thing open, in which first I gotta find a screwdriver that will extend into the handle to get the two screws out. Second obstacle is that I have no soldering experience, like at all, never touched a soldering iron in my life. I know I'd mess something up. On top of that, I know removing the analog board requires CRT discharging, which again, I have no experience with or the equipment so I could damage something or myself, and that's never fun. I think I am the last person who should own one of the compact Macs, but they're so neat I couldn't pass it up for $5. I may leave it to sit until I can get the thing repaired by someone who knows how to, because that is definitely not me.

This video was the very last time I could get it to loop resetting, after this it never did it again.

 

[unity]

Step 1 is getting the thing open, in which first I gotta find a screwdriver that will extend into the handle to get the two screws out. Second obstacle is that I have no soldering experience, like at all, never touched a soldering iron in my life. I know I'd mess something up. On top of that, I know removing the analog board requires CRT discharging, which again, I have no experience with or the equipment so I could damage something or myself, and that's never fun. I think I am the last person who should own one of the compact Macs, but they're so neat I couldn't pass it up for $5. I may leave it to sit until I can get the thing repaired by someone who knows how to, because that is definitely not me.
This video was the very last time I could get it to loop resetting, after this it never did it again.

If you have a screw driver that can take different tips, you can get an extended T-15 (torx) from a hardware store like Menards for about $4. I misplaced mine and had to buy one recently. Of course I found my other one the next day but I really need more than one anyway.

Working on compact Mac was my first venture into soldering!! And this is very easy work, the solder points are easy to get to and large. For this work a cheap/simple solder iron will be fine. If you think you will do more soldering then spend money on a digitally controlled one. But for this work, not critical.

If you get the machine to power up (no need to boot, just get the screen up), turn the brightness ALL the way up then just pull the plug. Do not use the switch. It will discharge after a couple seconds. Either way, the shock is scary but unless you have a pacemaker it won't kill you. Thats a huge myth regarding CRTs. But discharging is not too hard to do and there are plenty of instructions for doing it.

But if you feel that you would not be comfortable, certainly don't do so. But I promise if you do, you will get it done and think its one of the easiest thing you have done! Then you will be looking for more compact Macs to fix.

 

[JawhnL5]

Step 1 is getting the thing open, in which first I gotta find a screwdriver that will extend into the handle to get the two screws out. Second obstacle is that I have no soldering experience, like at all, never touched a soldering iron in my life. I know I'd mess something up. On top of that, I know removing the analog board requires CRT discharging, which again, I have no experience with or the equipment so I could damage something or myself, and that's never fun. I think I am the last person who should own one of the compact Macs, but they're so neat I couldn't pass it up for $5. I may leave it to sit until I can get the thing repaired by someone who knows how to, because that is definitely not me.
This video was the very last time I could get it to loop resetting, after this it never did it again.

Nah, I'd definitely like to get this thing up and running. If I can get past the CRT and get the analog board out, then I can probably dive into fixing it. The thing powers up no problem now, it never resets anymore, so getting the screen to come up to pull the plug would be simple. My dad can solder better than I can, I could leave the job to him, but until I can get it apart I have no way knowing if it's cracked solder joints, bad capacitors or both. Could be both, the capacitors aren't surface mount on the analog board right?

 

[techknight]

Measure your 5V Rail. if it falls too far below 5V, it will be caught in the bootloop of doom. All capacitor related I bet.

Another thing is the opto-isolator. They get weak with age, especially if it was used a ton. Most likely it was as it came from a school..

As the LED gets weak in the opto-coupler, the regulation circuit has to increase its loop gain to keep the output voltage at its correct setting, eventually the feedback/regulation circuit will get too weak, and the gain will be maxed out/saturated and the voltage will remain low all the time no matter what you do.

Also, dont forget your line-input safety caps. If you feel as though you cant accomplish the task entirely on your own, There is also uniserver which is a member here that will do the service for you

 

[unity]

Nah, I'd definitely like to get this thing up and running. If I can get past the CRT and get the analog board out, then I can probably dive into fixing it. My dad can solder better than I can, I could leave the job to him, but until I can get it apart I have no way knowing if it's cracked solder joints, bad capacitors or both. Could be both, the capacitors aren't surface mount on the analog board right?

For soldering the only thing you have to do is get it open. All the soldering points are easy to get to without removing anything besides cover sheets. You won't even have to disconnect anything!

As for caps, I don't think they are the issue, but yes one should not rule then out yet. Only because the booting is too random. Usually a component failure causes a more consistent issue. Also it seemed like once it warmed up a bit, it ran. Caps get funky once they warm up, not when cold so much. However cracked solder joints do work better when warmed up from thermal expansion.

I really would not have that thing plugged in until you get a closer look.

 

[JawhnL5]

Measure your 5V Rail. if it falls too far below 5V, it will be caught in the bootloop of doom. All capacitor related I bet.
Another thing is the opto-isolator. They get weak with age, especially if it was used a ton. Most likely it was as it came from a school..

When I get it open I'm gonna investigate it further, I'm almost certain it's capacitor related, and probably also solder joints. I'm pretty newbish with this stuff, so I am not sure what an opto-isolator is? It that something that's repairable?

 

[techknight]

Nah, I'd definitely like to get this thing up and running. If I can get past the CRT and get the analog board out, then I can probably dive into fixing it. My dad can solder better than I can, I could leave the job to him, but until I can get it apart I have no way knowing if it's cracked solder joints, bad capacitors or both. Could be both, the capacitors aren't surface mount on the analog board right?

For soldering the only thing you have to do is get it open. All the soldering points are easy to get to without removing anything besides cover sheets. You won't even have to disconnect anything!

As for caps, I don't think they are the issue, but yes one should not rule then out yet. Only because the booting is too random. Usually a component failure causes a more consistent issue. Also it seemed like once it warmed up a bit, it ran. Caps get funky once they warm up, not when cold so much. However cracked solder joints do work better when warmed up from thermal expansion.

I really would not have that thing plugged in until you get a closer look.

Not quite. Caps get better as they warm up. Not the other way around. As the dried electrolyte in the capacitor gets warm, the ESR drops and capacitance rises, improving circuit operation.

To perform an experiment, grab a capacitor meter and get a weak/bad capacitor. measure it cold. Then heat the crap out of it, and watch the measurements. they go up. It eventually plateaus and goes down, but thats beside the point and usually happens when it it reaches outside its operating temperature

 

[JawhnL5]

Nah, I'd definitely like to get this thing up and running. If I can get past the CRT and get the analog board out, then I can probably dive into fixing it. My dad can solder better than I can, I could leave the job to him, but until I can get it apart I have no way knowing if it's cracked solder joints, bad capacitors or both. Could be both, the capacitors aren't surface mount on the analog board right?

For soldering the only thing you have to do is get it open. All the soldering points are easy to get to without removing anything besides cover sheets. You won't even have to disconnect anything!

As for caps, I don't think they are the issue, but yes one should not rule then out yet. Only because the booting is too random. Usually a component failure causes a more consistent issue. Also it seemed like once it warmed up a bit, it ran. Caps get funky once they warm up, not when cold so much. However cracked solder joints do work better when warmed up from thermal expansion.

I really would not have that thing plugged in until you get a closer look.

I'm not going to plug it in anymore, I'm not sure where to start. Should I start off with tuning up the cracked soldering points if they're any? I'm going to assume there will be. If not, then I should check the capacitors? No matter how much I try I cannot get the thing to go into any reboot loops anymore, it's been like that for days. It's weird, it may even start happening again soon. Who knows.

 

[JawhnL5]

Clearly this is not something I am familiar with at all guys, sorry for all these questions. Other than this the oldest Macintosh I own is a Powerbook 5300cs that I refurbished, but it didn't require anything like this to get it up and running.

 

[techknight]

cracked solder sometimes is visible, sometimes is not.

Trouble spots are the yoke connector, power supply to logic board connector, and flyback. But if it were me, i would apply fresh solder to everything on the board. If that doesn't fix it, then you need recap.

 

[unity]

Nah, I'd definitely like to get this thing up and running. If I can get past the CRT and get the analog board out, then I can probably dive into fixing it. My dad can solder better than I can, I could leave the job to him, but until I can get it apart I have no way knowing if it's cracked solder joints, bad capacitors or both. Could be both, the capacitors aren't surface mount on the analog board right?

For soldering the only thing you have to do is get it open. All the soldering points are easy to get to without removing anything besides cover sheets. You won't even have to disconnect anything!

As for caps, I don't think they are the issue, but yes one should not rule then out yet. Only because the booting is too random. Usually a component failure causes a more consistent issue. Also it seemed like once it warmed up a bit, it ran. Caps get funky once they warm up, not when cold so much. However cracked solder joints do work better when warmed up from thermal expansion.

I really would not have that thing plugged in until you get a closer look.

I'm not going to plug it in anymore, I'm not sure where to start. Should I start off with tuning up the cracked soldering points if they're any? I'm going to assume there will be. If not, then I should check the capacitors? No matter how much I try I cannot get the thing to go into any reboot loops anymore, it's been like that for days. It's weird, it may even start happening again soon. Who knows.

Yup. Check solder point very, very closely then move onto what technight said. I would reflow the solder even if they look fine. I always do, does not take long. These are all very easy things to do. To check caps you pretty much need an ESR meter unless they have visible bulging, leaking. If they look fine, they may not be. Hence the need of the meter.

 

[techknight]

Clearly this is not something I am familiar with at all guys, sorry for all these questions. Other than this the oldest Macintosh I own is a Powerbook 5300cs that I refurbished, but it didn't require anything like this to get it up and running.

It will eventually. There are electrolytics in the logic board, and screen assembly/inverter that will go bad eventually. As with all vintage electronics, capacitors have to be replaced with age. 10, 20 years ago people were restoring antique radios and TVs made with vacuum tubes by a full recap.

Same rules apply. And its not just computers. Take for example, vintage stereo equipment which is getting quite popular lately. They all have to be recapped by now too. Most of the pioneer SA series, flouroscan stuff, Marantz stuff, etc... list goes on.

 

[JawhnL5]

cracked solder sometimes is visible, sometimes is not.
Trouble spots are the yoke connector, power supply to logic board connector, and flyback. But if it were me, i would apply fresh solder to everything on the board. If that doesn't fix it, then you need recap.

Is it safe to rule out the main logic board? There doesn't seem to be a thing wrong with it, it's just the analog board that it seems needs attention. I'd probably just tune up the entire board with fresh solder. A recap probably won't be too difficult on these analog boards? If they're not surface-mounted I can get those done, if they're surface mount then there's gonna be a problem.

 

[JawhnL5]

Clearly this is not something I am familiar with at all guys, sorry for all these questions. Other than this the oldest Macintosh I own is a Powerbook 5300cs that I refurbished, but it didn't require anything like this to get it up and running.

It will eventually. There are electrolytics in the logic board, and screen assembly/inverter that will go bad eventually. As with all vintage electronics, capacitors have to be replaced with age. 10, 20 years ago people were restoring antique radios and TVs made with vacuum tubes by a full recap.

Same rules apply. And its not just computers. Take for example, vintage stereo equipment which is getting quite popular lately. They all have to be recapped by now too. Most of the pioneer SA series, flouroscan stuff, Marantz stuff, etc... list goes on.

Well yeah, but at this current point in time it's going strong.

 

[JawhnL5]

Nah, I'd definitely like to get this thing up and running. If I can get past the CRT and get the analog board out, then I can probably dive into fixing it. My dad can solder better than I can, I could leave the job to him, but until I can get it apart I have no way knowing if it's cracked solder joints, bad capacitors or both. Could be both, the capacitors aren't surface mount on the analog board right?

For soldering the only thing you have to do is get it open. All the soldering points are easy to get to without removing anything besides cover sheets. You won't even have to disconnect anything!

As for caps, I don't think they are the issue, but yes one should not rule then out yet. Only because the booting is too random. Usually a component failure causes a more consistent issue. Also it seemed like once it warmed up a bit, it ran. Caps get funky once they warm up, not when cold so much. However cracked solder joints do work better when warmed up from thermal expansion.

I really would not have that thing plugged in until you get a closer look.

I'm not going to plug it in anymore, I'm not sure where to start. Should I start off with tuning up the cracked soldering points if they're any? I'm going to assume there will be. If not, then I should check the capacitors? No matter how much I try I cannot get the thing to go into any reboot loops anymore, it's been like that for days. It's weird, it may even start happening again soon. Who knows.

Yup. Check solder point very, very closely then move onto what technight said. I would reflow the solder even if they look fine. I always do, does not take long. These are all very easy things to do. To check caps you pretty much need an ESR meter unless they have visible bulging, leaking. If they look fine, they may not be. Hence the need of the meter.

Sounds like a plan, I'm gonna get the tools this weekend, may be a fun weekend project to make this thing a little bit more happy.

 

[techknight]

cracked solder sometimes is visible, sometimes is not.
Trouble spots are the yoke connector, power supply to logic board connector, and flyback. But if it were me, i would apply fresh solder to everything on the board. If that doesn't fix it, then you need recap.

Is it safe to rule out the main logic board? There doesn't seem to be a thing wrong with it, it's just the analog board that it seems needs attention. I'd probably just tune up the entire board with fresh solder. A recap probably won't be too difficult on these analog boards? If they're not surface-mounted I can get those done, if they're surface mount then there's gonna be a problem.

I doubt your issue is in the logic board. Yes there are a couple of axial electrolytics that need replacing by now, but thats it. logic board issues dont start becoming dominant until the SE/30. Other than the occasional bad RAM.

 

[JawhnL5]

cracked solder sometimes is visible, sometimes is not.
Trouble spots are the yoke connector, power supply to logic board connector, and flyback. But if it were me, i would apply fresh solder to everything on the board. If that doesn't fix it, then you need recap.

Is it safe to rule out the main logic board? There doesn't seem to be a thing wrong with it, it's just the analog board that it seems needs attention. I'd probably just tune up the entire board with fresh solder. A recap probably won't be too difficult on these analog boards? If they're not surface-mounted I can get those done, if they're surface mount then there's gonna be a problem.

I doubt your issue is in the logic board. Yes there are a couple of axial electrolytics that need replacing by now, but thats it. logic board issues dont start becoming dominant until the SE/30. Other than the occasional bad RAM.

It doesn't seem like the logic board in anyway, since the more I read up on this, the more I see people having this issue and noting it is the analog board. They mention a C1 capacitor on the analog board, should I replace that?