Macintosh LC, no battery, but very bad caps leakage

[amedeo_68k]

I have I recovered a Mac LC in a garage, when I opened it I see that there were no battery installed, which is good, but after a deeper inspection I realized that capacitors did a quite big mess.
Do you think I can try to recover it ?
Thank you
Amedeo

 

[jajan547]

Absolutely should be, vinegar bath followed by distilled water wash. Remove old solder add flux and new solder and it should boot fine. take extra care in cleaning UB10.

 

[joshc]

There's a lot of cap goo there. The old capacitors need removing. The area needs cleaning with flux.

The Egret chip might need removing and resoldering.

If you're not sure how, these videos might help

https://www.youtube.com/playlist?list=PLxfPY-Ebzlk1sb7PFoh4DS7f7tuWc4PuN

 

[LaPorta]

The EGRET is a PITA, and is in that place that it always gets that goo. I'd do what the others say and really clean it up. That is nowhere near as bad as a battery explosion. The one thing with the EGRET is that it is very sensitive: I destroyed one once trying to desolder and resolder it, just by the heat. Do the caps and cleaning first; tiny interdental brushes with the vinegar or IPA can help clean up a lot of the crud on the pins of the chips. Doesn't tell you if anything is shorting things underneath, but once cleaned and recapped try it. If it works, perfect. Only if it is not, then take a look for other problems under the chips.

 

[amedeo_68k]

I'm quite confident at recapping / resoldering..., my concern is that this time I see the board in a very bad state,,,

 

[jajan547]

I'm quite confident at recapping / resoldering..., my concern is that this time I see the board in a very bad state,,,

Shouldn’t have any issues clean it and then post some pictures.

 

[amedeo_68k]

Hi, I was not expecting winegear to be good for cleaning boards.
I have done a first cleaning and I tried to powerup the 5V. I can barely hear the chime !
Tomorrow I'll start recap, better cleaning and some reflow.
I'm wondering one thing... why egret chip on an hardware poweron machine ?

 

[jajan547]

Hi, I was not expecting winegear to be good for cleaning boards.
I have done a first cleaning and I tried to powerup the 5V. I can barely hear the chime !
Tomorrow I'll start recap, better cleaning and some reflow.
I'm wondering one thing... why egret chip on an hardware poweron machine ?

View attachment 41131

EGRETcontrols power functions on these machines

 

[amedeo_68k]

Update, all caps removed and some new one has been already installed. I'm waiting for the 10uF / 16V, hope to get these by Tuesday.
I think the Egret works fine as I could barely hear the chime at startup and, triggering interrupt by Command-Power on keyboard, I can hear also listen at the death chime.
Looking at the board,... close to the battery holder there is a "jumper block" A21/A20/CPE, do you know what is the purpose ?



There is also a small connector called J2 near the display out port, ideas?



Thank you

 

[jajan547]

Update, all caps removed and some new one has been already installed. I'm waiting for the 10uF / 16V, hope to get these by Tuesday.
I think the Egret works fine as I could barely hear the chime at startup and, triggering interrupt by Command-Power on keyboard, I can hear also listen at the death chime.
Looking at the board,... close to the battery holder there is a "jumper block" A21/A20/CPE, do you know what is the purpose ?

View attachment 41214

There is also a small connector called J2 near the display out port, ideas?

View attachment 41215

Thank you

Those are left as is, no need to worry about them.

 

[amedeo_68k]

I’m not worrying about. Just wondering they are meant for

 

[jajan547]

I don’t recall off of the top of my head but I can send a schematic probably some unimplmented or used feature, Apple loves to do that.

 

[amedeo_68k]

Hi everyone, sorry for the late, I finally recapped the entire logic board, it took a while to obtain all the new tantalium caps. Now the chime sound is mych better, crystal clear, attached floppy Emu and it s reading it. I cannot connect a display right now but I should be able in the coming days.
Hopefully everything works.
Btw, the power supply is failed, I'm going to recap that one too, so for now I tested with an alternate power source.
Thank you very much!

 

[jajan547]

Hi everyone, sorry for the late, I finally recapped the entire logic board, it took a while to obtain all the new tantalium caps. Now the chime sound is mych better, crystal clear, attached floppy Emu and it s reading it. I cannot connect a display right now but I should be able in the coming days.
Hopefully everything works.
Btw, the power supply is failed, I'm going to recap that one too, so for now I tested with an alternate power source.
Thank you very much!

Sweet she lives

 

[amedeo_68k]

Hi,
I just recapped the power supply too and now machine boots untethered, I have also installed additional VRAM in order to support VGA resolution. Everything works, but now I have very low or no sound, should I try to reflow the sound chip ?

 

[jajan547]

Hi,
I just recapped the power supply too and now machine boots untethered, I have also installed additional VRAM in order to support VGA resolution. Everything works, but now I have very low or no sound, should I try to reflow the sound chip ?

I would remove it, remove old solder from the pads, clean with alcohol, and then solder it back on.

 

[amedeo_68k]

I think I found the issue, it should be the the audio amplifier 34119
I removed it and the traces are quite messy can be fixed. I have already ordered the IC, let see next week.

 

[jajan547]

I don't think it alone would cause the issues.

 

[amedeo_68k]

Hi everyone, after replacing the amplifier chip no luck, that I removed the Apple sound chip, cleaned the pads and the chip, re-soldered it... and YES, everything is ok now! crystal clear sound !
Thank you all

 

[jajan547]

Hi everyone, after replacing the amplifier chip no luck, that I removed the Apple sound chip, cleaned the pads and the chip, re-soldered it... and YES, everything is ok now! crystal clear sound !
Thank you all

Sweet happy she’s running again!