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Starts if pressed on side

Jens Larsen

Jens Larsen

6502
Greetings
I've been enjoying my new to me Plus. Recently took off the case to see what's what. Installed a SCSI device. Testing, I found that the switch wouldn't always boot the machine. By pressing on the side, forward from the power switch, the machine would boot. If I released pressure immediately it usually quit. Holding for 10-12 seconds it would stay running.
Having read about what happens to old circuits (and feeling my own old circuits complaining a lot) would you all guess some resoldering is called for? I haven't taken it apart except to remove the motherboard. While I had it out I removed a small layer of dust and gave it a good looking over. Saw nothing alarming.
But the other, vertical, board remains unexamined.
Suggestions, any and everyone? Where to start, look for first?
Many thanks.
 
That'd be dry solder joints on the vertical, upright analog board. Have a close look at the bigger joints and you will most likely see something obvious/loose. Better to suck up some of the old solder and reflow with new. While there, new capacitors would be recommended.

My first Mac, a Plus, had dry solder joints in the early 90's - it was just as common back then as now :D We had no idea on fixing it usually a sharp slap to the side got it good again.
 
My Plus first did this around 25 years ago, and Byrd is correct…. Hitting the side was the magic cure. Does the original Mac suffer from this too? My 512k has never had this problem.
 
The AB is the same and the solder is (AFAIK; though I wouldn't rule out a change in manufacturing process, the problem seems to be common regardless of where the AB was made, which suggests otherwise) the same, so yeah. I think the reason it looks so much more common on pluses than anything else is just that there are so many pluses out there which, aside from their AB solder joints, just refuse to die. Those machines are far more robust than they have any right to be
 
nathall said:
My Plus first did this around 25 years ago, and Byrd is correct…. Hitting the side was the magic cure. Does the original Mac suffer from this too? My 512k has never had this problem.
Click to expand...
Yes. One of the 512K machines I owned in 2012 did have issues.
 
cheesestraws said:
Those machines are far more robust than they have any right to be
Click to expand...

Gotta be said that the Plus will live on with the cockroaches, and with a bit of assistance, so does an SE, yet it's fancier cousin the SE/30 has always required a substantial amount of rehabilitation to keep upright.
 
Muchos gracias. As I suspected. Gld for confirmation. This is a whole new world to me.
My previouss olde Mac is a 900 mHz iBook.
 
Unlike the 128 and 512k (and 512ke), Apple actually put out a recall on the Plus in 1990 due to the dry solder joints on the vertical card; it was a well documented issue, and anyone up until July 1991 could take their Plus to a service center and have the solder re-flowed to fix the issue at no charge.

So any Plus that had that done should be free of this issue; any that didn't... well, those solder joints will crack eventually due to heat flux on the board.

That's the only internal issue I've ever experienced on a Plus though, other than leaky batteries. For some reason, never had an issue with the caps on a Plus.
 
adespoton said:
Unlike the 128 and 512k (and 512ke), Apple actually put out a recall on the Plus in 1990 due to the dry solder joints on the vertical card; it was a well documented issue, and anyone up until July 1991 could take their Plus to a service center and have the solder re-flowed to fix the issue at no charge.
Click to expand...
How is this the first I'm hearing of this? This would have saved me years of exasperation.
My Mac Plus was my only computer for nine years, and saw intermittent use for the subsequent four. It was treated kindly for six years, then slapped silly every few minutes for the subsequent seven. I fixed it myself after reading the solution on this forum years ago.
 
cheesestraws said:
I did not know this!
Click to expand...
I found out in August 1991, and so had to pay for the repair. Hence it stuck in my memory. I can't remember for sure, but I think they ran an ad in MacWorld magazine sometime in 1990; I *think* this is where I first found out about it -- while reading a back issue. I haven't looked it up recently. Then again, I'm not sure this is for all Pluses that were made; it could have been for a limited run. I remember sending in my serial number and being informed that yes, my Plus was one of the affected ones, but that unfortunately, the repair program was concluded and I'd have to get mine repaired myself.
 
I feel fairly certain that my Plus is out of warranty...
I scoped out the analog PCB and resoldered a number of connections. Shiny solder looks so much better!
The capacitors all look to be in good condition. No leaking, cracking, swelling or ____.
Now: what's the simplest way to get 12v+ to run an exhaust fan on the top of the Plus? I know, I've read most of the pros and cons. I'm a belt AND suspenders kind of guy, and I like to tinker, ergo the Noctua fan that's been sitting since I reworked the cooling on my G4 MDD, may finally get a home in my Plus.
 
If you have a Molex crimper and don't mind the expense of the connectors, they can result in a really nice solution where you can easily plug/unplug the supply to the exhaust fan.
 
Ah ha! It is a pleasure and a delight to be on a forum with folks who are knowledgeable and helpful.

I used to ride motorcycles. Doctor told me to stop. I found one forum, specific to my bike at the time, that would do what you two just did. Folks would answer the question. No one asked "Why in God's Name would you want to do that?"

They just answered the question. How refreshing! Just as you two did! Thank you!

No Molex crimper, but I do have a few clean Molex connectors of the male and female variety. I'll sneak into the Plus sometime in the near-ish future and see what's what. Right now I'm going to simply enjoy my new Macintosh.

I just finished installing the bluescsi and an extension cable allowing me to have the SD card outside the case for easier swapping. Snaked it out through the slit on the back for, I think, a lock or cable? Works a treat. No damage to the case; easily reversed/removed.

Thanks, again, guys.

(Oh: I'll have a small 'surround' case for the fan, which will go in the handle area like some commercial products. I'll have a small toggle switch in-line and mounted to that rudimentary case so it won't run constantly. eBay has a "Blowhard MacFan" at $90 and $60. Two sellers. I'm too cheap. But I can easily be a blowhard.)
 
It's an interesting and proven technology. I have no understanding of physics or air flow, but I do know a well-built chimney can make a fire roar. No reason a well-built chimney on a Mac wouldn't draw well, sending hot(ter) air to the ceiling. If I could find a drawing, I'd give it a try. I have no audience for my computers, so could chimney away without snide comments from the cheap seats.
On another note: thanks for the document containing wiring schematics for the Plus. Just gave it a quick once-over. Should serve me quite well.
Gracias, again!
 
You could shove a fan anywhere in the Plus to keep it cool; considering it has worked for so long now you probably don't need it unless you have some sort of upgrade inside like a HD, accelerator.
 
One thing that placing a vent fan or a chimney on top does is makes it impossible to stack books/papers/etc. on top -- which was the downfall of many a compact Mac back in the day.
 
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