Macintosh Classic (one) with no power.

[Magicanz]

Hello! I have a Macintosh Classic with an analog board that (I think) doesn't output any power. When trying to turn it on, no sound, no picture, only nothing. I've tried measuring current through the molex connector with no success. There is also no visible leakage or damage at all. Therefore I think the Analog board is just not outputting any power.

The thing is, I have 4 other compact macs (not Classics) with working analog boards. I was just thinking if it would be possible to use an Analog board from a Macintosh Plus/SE in the Classic just to see if it runs. I would never do this without being absolutely sure, and because I'm no expert and haven't been working with Macs or electrics for much time I ask here.

If using another analog board doesn't work, does anyone have any idea of any checks I can make to see what the issue might be?

Thank you!

 

[Johnnya101]

They are COMPLETELY different things.

Classics and CLassic IIs need new caps. All around. Every. Single. Time. All the time. Dont even bother trying to do anything without attempting to replace caps first.

It might not be the cause of your issue, but it will rule it out.

 

[Magicanz]

They are COMPLETELY different things.

Classics and CLassic IIs need new caps. All around. Every. Single. Time. All the time. Dont even bother trying to do anything without attempting to replace caps first.

It might not be the cause of your issue, but it will rule it out.

Alright, I will check it out. Since I don't know too much about these things (or high-voltage electrics in the first place) do you think it would even be a good idea to try? There are no recapping services in my country as far as I know.

 

[Johnnya101]

Id send it out and have them done. Here in the US, usually something like this would cost around $50-$80 USD. I dont know what country you are in, but there might be another member that could do it for you?

 

[Magicanz]

I live in Sweden, and I've seen several people asking for people to help them do it but never getting an answer.

 

[Johnnya101]

There should be someone there or in one of the surrounding countries. Maybe most a WTB - Recap service in or near Sweden in the trading post.

 

[Magicanz]

So using the analog from an other Macintosh is a big no-no then?

 

[Johnnya101]

Yup. Completely different things. 128k-Plus AB work with only those, SE-SE/30 work only with those, Classic to Classic II AB only work with those. Physically different and electrically different. Someone tried plugging an SE board into a classic (Or maybe other way around) and it didnt damage anything, but didnt work either.

 

[Magicanz]

Thank you! I will look into other solutions then.

 

[LaPorta]

I'd do it for you, but I am sure that shipping would likely be prohibitive.

 

[Magicanz]

Macintosh Classic Analog Board

This is how the analog board looks when taken out of the computer. I see no big problems, no bulging capacitors or things of the sort. The only thing I notice is the brown sticky-looking gunk that is around almost all solder holes, can that have anything to do with it?

I won't go much longer than this "alone" (I always have someone else at least nearby) but I do know some people who are better with electrics that might be able to help. 

Anyone see anything that looks really wrong?

 

[Bolle]

Those caps don't bulge on top when they fail but instead they leak underneath so no way of seeing it without removing them.

The Classic analog board is known for notoriously bad caps and I have yet to see one that still has good caps these days.

 

[bibilit]

Probably not only related to capacitors. 

Two diodes are bad on those most of the times. 

 

[Magicanz]

Probably not only related to capacitors. 

Two diodes are bad on those most of the times. 

Yup, I've read one of your old posts and I have the exact same symptoms! Will change those diodes, and change the capacitors as well.

 

[dochilli]

Check the fuse!

Check the solder points of the power cord connector. I had an analog board where all three were broken.

Replace TDA4605, CNY17G, IRFBC40.

Read "Mac Classic & SE. Repair and Upgrade Secrets" from Larry Pina.

Read the shown thread and the links in the thread!



  

 

[Magicanz]

I got the Macintosh running! I replaced 2 diodes and 1 zener diode (from one of bibilit's posts) and recapped the board, but the thing that really got the computer working was replacing the TDA4605! It could have been a bit more beautifully done, and it could definitely have been done faster, but as this was one of my first dabbles in electronics, I thought it went very well!

Going to try to run some programs tomorrow, didn't have the keyboard and mouse accessible.

 

[Elv1s]

I live in Sweden, and I've seen several people asking for people to help them do it but never getting an answer.

I do recaps, I live in Stockholm. E-mail me: elv1s@me.com (write ”recap” in subject)

 

[Dogmander]

Check the fuse!

Check the solder points of the power cord connector. I had an analog board where all three were broken.

Replace TDA4605, CNY17G, IRFBC40.

Read "Mac Classic & SE. Repair and Upgrade Secrets" from Larry Pina.

Read the shown thread and the links in the thread!

Sorry for necroposting, but are there any good guides to test those chips before replacing them? I’m working on my Classic analog board and don’t want to have to buy more replacement parts (already recapped AB) if I don’t have to.