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HELP - 512K won't power up

68kPlus

68kPlus

6502
Hi,

I was just removing C37 (RIFA) from the 512K I recently bought.
It was blown, so I de-soldered it and also cleaned up some battery corrosion on the battery contacts.

After putting everything back together, I powered it up and nothing.

What do I do? Is C37 vital for the Mac to work?

Any help is much appreciated.
 
Take it apart again, and carefully put it back together again as a first step. While you're there inspect your handiwork for solder bridges and trace/pad damage.

Its best to remove a part from a working machine when you have a replacement - there wasn't really a need to remove it.

Lastly, don't worry and don't do anything in a panic. It will be fine :) it will just take some time to find whats wrong.
 
Phipli said:
Take it apart again, and carefully put it back together again as a first step. While you're there inspect your handiwork for solder bridges and trace/pad damage.

Its best to remove a part from a working machine when you have a replacement - there wasn't really a need to remove it.

Lastly, don't worry and don't do anything in a panic. It will be fine :) it will just take some time to find whats wrong.
Click to expand...
Thank you for the info.

I decided to remove the capacitor as it was blown and I thought it might be safer to remove it and then keep using it.

I have taken it apart and put it back together again and nothing.

I got shocked too which is weird. I was pulling the plug out and touched something and it shocked me (It hurt). not sure what is going on there. Does the vinyl cover for the AB need to be on for it to work?

Thank you for the help.
 
68kPlus said:
Thank you for the info.

I decided to remove the capacitor as it was blown and I thought it might be safer to remove it and then keep using it.

I have taken it apart and put it back together again and nothing.

I got shocked too which is weird. I was pulling the plug out and touched something and it shocked me (It hurt). not sure what is going on there. Does the vinyl cover for the AB need to be on for it to work?

Thank you for the help.
Click to expand...
Analogue boards are dangerous and capacitors don't discharge instantly. The cover is there to stop you getting a shock or even killing yourself. Take a step back and think about what you are going to do. What have you touched / unplugged? Have any components got bent over and shorted? Did you put the wrong screw in a hole and it is touching something. What did removing the cap do?

I'd recommend comming back to it after a break.

Don't touch the uncovered board while its plugged in and give it a chance to discharge before going near it. Analogue boards bite, neckboards bite. Enough to kill. Take your time.
 
Phipli said:
Also, its probably an idea to share some high res photos of the board.
Click to expand...
Ok, I'll do that. Maybe after some time of leaving it there, as I am going to do something else for a while.
Are there any measures I can take regarding safety when working on a compact Mac? I don't really know any as I believe a grounding wrist-strap is actually a terrible idea for these older CRT Macs.
 
68kPlus said:
Ok, I'll do that. Maybe after some time of leaving it there, as I am going to do something else for a while.
Are there any measures I can take regarding safety when working on a compact Mac? I don't really know any as I believe a grounding wrist-strap is actually a terrible idea for these older CRT Macs.
Click to expand...
I tend to leave things for a day before working on the high voltage and still treat it as charged. I would check large caps are discharged by shorting them carefully, and if possible work with someone in the room that knows you're working on high voltage electronics (safely).
 
Phipli said:
I tend to leave things for a day before working on the high voltage and still treat it as charged. I would check large caps are discharged by shorting them carefully, and if possible work with someone in the room that knows you're working on high voltage electronics (safely).
Click to expand...
That is a good idea. I will continue working on this Mac later.
Will you be online in the next several hours? I might need more help.
Again thank you very much for the information, it really helps!
 
68kPlus said:
That is a good idea. I will continue working on this Mac later.
Will you be online in the next several hours? I might need more help.
Again thank you very much for the information, it really helps!
Click to expand...
Its 3am :) I should be asleep, but will be awake at a more reasonable time later ;)
 
Phipli said:
Oh wait - it isn't on the mains - its on the rectified side. You need that cap. Its part of what smooths the lumpy full wave rectified supply into DC. You have weird bumpy power atm.
Click to expand...
OH - so if I put it back (despite it being broken) it should work? I'll buy a new one too.
 
68kPlus said:
OH - so if I put it back (despite it being broken) it should work? I'll buy a new one too.
Click to expand...
No sorry, I was just not paying attention - I assumed the mains was on the right. It isn't.

Its also the 120V circuit. But should still inform.
 
68kPlus said:
I didn't change anything else
Click to expand...
This isn't likely to be true, you mean "I don't know of anything else I changed".

Wait for people used to working on these boards to come online. I just didn't want you to rush in and hurt yourself or worry too much.
 
Phipli said:
This isn't likely to be true, you mean "I don't know of anything else I changed".

Wait for people used to working on these boards to come online. I just didn't want you to rush in and hurt yourself or worry too much.
Click to expand...
That's true. I actually called up my parents after being shocked (they weren't happy as they aren't home), and they said I have to find what other safety measures I can take before working on it again. I can understand why they want this as they wouldn't want to find me dead in my bedroom working on an old Mac. I'll wait for others to show up, and see how it goes then.
I'm going to start to sound like a broken record, but thank you so much for helping me! I wasn't expecting such a response.
 
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