New LCII Project - No Boot

[MDMacGuy]

I picked up a very clean LCII and 12" RGB monitor from eBay last week - original box for the monitor, all disks, all manuals. No scratches, dents, dings, writing or yellowing. Got it for a good price, always wanted one, and figured I would give it a good retirement.

Was untested, and I figured it would not boot. Confirmed that when I unboxed it yesterday.

So flipping the power switch results in nothing - no noise, no fan, nothing. It is not a TDK supply. There are definitely some leaking caps on the logic board but no battery leakage. I pulled the board and washed it/sprayed it with alcohol/put it out to dry. Still no boot, no fan, nothing. I opened the PS up and there are no leaking caps or anything and it looks pristine.

I have never recapped a board before (Uniserver has my beloved Color Classic's logic board at the moment), but I want to learn. I think I am going to use this machine as my learning bed.

Does the no power/no fan seem indicative of the logic board caps on an LCII, or should I suspect the PS first?

 

[Elfen]

Tried it with a working PSU?

Yes, the logic board will need a recapping first. The PSU will too though it looks "Pristine." The caps in the PSU leak under the caps so you won't see it until you remove the caps and it gets ugly. You need to do both, but at least you need to get a working PSU to see if the Logic Board lights up or not.

 

[bibilit]

Does the no power/no fan seem indicative of the logic board caps on an LCII, or should I suspect the PS first?

Impossible to guess, what is the PSU outputting ? 

 

[MDMacGuy]

Not sure... going to look for a schematic of the connector tonight.

Bought a hot air rework station and soldering iron today - going to teach myself how to do this. I cannot find SMT caps locally though.

Where do you guys like to buy them online?

Stupid question - but if I replace these with MLCC - are the dimensions of the MLCC capacitors the same? How do I know what frequency I need?

 

[Elfen]

I get them from Mouser.com

Tantalums (most of them are SMT/SMD):

http://www.mouser.com/Passive-Components/Capacitors/Tantalum-Capacitors/_/N-75hqv/

Ceramics (these are SMT/SMD):

http://www.mouser.com/Passive-Components/Capacitors/Ceramic-Capacitors/_/N-5g8m?P=1z0z7ym

Also PM forum member Trag. He sells SMT/SMD caps at a very respectable price. I've bought from him before - great guy, great service.

Check Uniserver's site for LC Caps info:

http://maccaps.com/MacCaps/Capacitor_Reference/Entries/1992/3/23_Macintosh_LC_II.html

http://maccaps.com/MacCaps/Capacitor_Reference/Entries/1992/3/23_Macintosh_LC_II_files/LCII.jpg

The uF of the cap is its "frequency". That you do not change that in the caps. You do, if you can, get higher rated voltage caps. The 16V caps should be 20V if you can get them, if not 16V is fine. The 20V cap is bigger but they will fit in the space where the old cap was. The other caps should be fine.

Beware - On the Tantalum Caps, the polarity mark is reversed. Usually a cap is marked a the negative side. On the Tantalum caps they mark the positive side. (On Ceramics, they are not polarized so it does not matter with them.)

Do this right and neat, this should LC II should last you a good 20+ years.

 

[bibilit]

going to look for a schematic of the connector tonight.

Ground Black

5 +   V Orange 

12 + V Yellow 

12  - V Blue