Yet another Analog/Logic Board problem

[Jaek_3]

Alright, so I just got a new Mac Classic I, and when I went to try it out for the first time, I discovered that the Logic board would not output sound - swapping it out with another Logic board proved that the problem was not with the Analog board. I screamed in annoyance, because at this point, it seems that I am the lord of broken things that get turned into slightly less broken things. So, I open it up, and swap hard drives with my other mac. When I tried turning it on though, I got nothing! - it was as still as a rock. I tried swapping the fuses: no luck. I tried checking for cracked solder joints: no luck. Any ideas as to what might be happening? I'm assuming that something is blown, though I unfortunately lack the technical ability to replace the parts.

 

[BadGoldEagle]

Correct me if I'm wrong but you have one Classic Analog Board, right? You didn't swap Analog Boards, did you?

I think sir that you have not one but two problems  :-/  Were your boards recapped? If not then you have bad caps on both the AB and LB.

     -> no sound because your caps failed on your Logic Board. It had to happen one day. Caps can't live forever.

     -> no power because old caps on Analog Board. Did you experience difficulties when trying to boot it up previously? Usually Classic ABs don't die right out of the blue. I knew one guy who had to switch it on and off at least 3 times before it actually booted. 

Try leaving it plugged it for a while (20 mins), switch it on for about 2 minutes and then switch it off. Wait 30 seconds before switching it back on. If it works then your caps are toasted. Don't worry though, because if you replace them it will be as good as new.

Now I too lack the technical know how. That's why I have my board recapped by other people 

Yes, it will cost you more money, but people here on this forum are really good at it. Contact Uniserver for a quote, he's on eBay as well.

 

[tanaquil]

I am confused - it sounds like you changed too many things at once.

Sound problems do usually indicate a problem with the logic board - bad caps or corrupted traces. Fixable by a skilled recapper.

(By "swapping it out with another logic board", I gather you put another logic board in the machine, and the sound worked?)

Why did you swap hard drives? Did you change anything else when you did the swap? I don't understand why swapping hard drives would suddenly result in a previously good (if sound-deprived) machine not powering up. Have you checked and re-checked all your connections? Any cables left unplugged?

 

[bibilit]

Usually Classic ABs don't die right out of the blue.

I have had two with the same problem recently, no caps related, still tryng to find the root cause.

Worked once then didn't worked anymore, so far have replaced caps and ordered optocoupler for a test.