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Macintosh LC II unsupported frequencies/resolution monitor

Hello,


I have a problem with my Macintosh LC II... A year ago, the Macintoh booted without any trouble into Mac OS 7. Then I let it off for a year but last week when I tried to turn it back on, the Power Supply made a not normal noise, so I replaced it since the computer wasn't decided to boot at all... So I installed the new Power supply, and tried to turn it back on again. But here is my problem. I Don't hear any chime from the Macintosh, but the fan is spinning and I can hear the hard drive working. Now, I plugged it in many monitors, but in all case, I can't see anything but sometimes error messages from the monitor : here are the results :


Apple 17" CRT display: black screen and yellow LED (nothing detected)

iiyama 20" Vision Master Pro 512 CRT display: black screen with yellow LED (nothing detected)

ACER 17" LCD screen : Error message (Unsupported frequencies) and green LED (signal detected)

SAMSUNG 27" LCD screen : Warning (Not optimal resolution, recommanded FullHD@80Hz) with fix blue LED (signal detected)


Does anyone know what can I do to fix this ?


Sorry for my bad English I am French...

Macintosh LC II-OTHER, Other OS, Mac OS 7

Posted on Jul 17, 2015 12:18 AM

Reply
13 replies

Jul 17, 2015 4:23 PM in response to Mø†hə®BΦ@rđ11 (MotherBoard11)

The internal battery and electrolytic capacitors are two things that may change during storage. Have you checked the battery voltage? Are there any signs of leaking/bulging/discoloured capacitors (when the logic board is inspected through a magnifying glass)? Also, you may want to disconnect/remove and reconnect/reinstall cables and memory cards.

Jul 17, 2015 11:49 PM in response to Mø†hə®BΦ@rđ11 (MotherBoard11)

Do you have access to any of the displays of the same era from

when the computer was manufactured? They should not require

special adapters and would be most likely to just work. 12" to 16"


I used to have half a dozen of these LC II models, among others

(in one room at the same time, not all turned on) for a total of 85.

Not all LC, but had most earlier pre-G PPC. Had fixed up a pile

of Macs and donated about 350 to charities and some to people

who didn't have one, and could not afford one; with software.


About the only display I have that may work on an LC, is an early

Trinitron 15-inch Apple Display with built-in speakers, it works with

a PowerMac 7600 132MHz that presently has MacOS 8.6 installed.


There had been an adjustable display adapter to connect a variety

of vintage displays with older or newer gear; however the pin type

and connectors to enable such era-correct peripherals will not help

a newer technology display. The later displays you have probably

cannot work with that old of a computer. No graphic support, etc.


You say these other displays including LCDs, work with vintage Mac?

I've been away from attempting to upgrade their function, a few years.


In any event...

Good luck & happy computing! 🙂

Jul 18, 2015 12:12 PM in response to Mø†hə®BΦ@rđ11 (MotherBoard11)

Electrolytic capacitors can be of the barrel type (with radial or axial leads), or rectangular surface mount devices. Typically, they all have C numbers on the board. In your picture, both silver-coloured barrel models and yellow SMD types can be seen. Take another look at these (a magnifying glass is usually necessary). Look for signs of leaking electrolyte, cracks, etc.


Since at least one monitor worked OK with this LC II before, and since there is no startup sound, it would probably be correct to assume that the problem is with the computer.

Jul 19, 2015 1:26 PM in response to Jan Hedlund

AGain, I can't see anything wrong with the logic board. No cracks, no damage, well plugged. And yes, I wanted to demonstrate you that my problem seriously comes from the computer it self. The logic board looks brand new. The only thing I can notice is that your "Yellow SMD" (sorry, I don't know anything about that, and as I am French, it makes things even more complicated...) is not always yellow. On ALL OF the yellow SMDs I saw on this computer, a little part of it is a little bit darker than the rest of the SMD, so I believe this is normal ? Thank you for helping me

Jul 19, 2015 2:17 PM in response to Mø†hə®BΦ@rđ11 (MotherBoard11)

>a little part of it is a little bit darker than the rest of the SMD, so I believe this is normal


I guess that you are referring to the polarity indicator on the SMD (surface mount device) electrolytic capacitor.


Bad electrolytic capacitors are quite common in computers of this age. You will find numerous articles on the Internet about this. It is not always easy to visually detect a faulty capacitor. On the other hand, it could be more or less anything else (faulty semiconductors, bad solder joints, etc), but since the problem appeared after storage, it is logical to suspect the electrolytic capacitors first.

Jul 20, 2015 1:27 AM in response to Mø†hə®BΦ@rđ11 (MotherBoard11)

Seems to be how those items are made, at least on the surface.

There are two, one in each image you posted that look alike...

User uploaded file

These two-tone rectangular bits share the same color scheme

even though I can't say if their functional purpose is similar. Yet

the color may be due to manufacture process - for identification.


Guess you'll be looking for a few more of these vintage Macs? 😐

Jul 20, 2015 2:33 AM in response to K Shaffer

TThey are all like that on the board ! And the PSU are slightly different... The seller was telling me that this PSU is compatible with all the LC models (LC, LC II and LC III). what do you think about ? On the top is the old PSU and under it is the new. Should I plain because the PSU isn't really compatible or do you think it is something else ?

User uploaded file


I Have a PowerMac G4 here but I don't think they are Vintage... Otherwise I need to get my Power Macintosh 4400/200 which is more vintage...

Jul 20, 2015 8:02 AM in response to Mø†hə®BΦ@rđ11 (MotherBoard11)

>A part is yellow and a little part is orange


The darker orange part indicates the positive (plus) side of this SMD electrolytic capacitor. See also the corresponding marking on the board.


Please note that other electrolytic capacitors may have completely different ways of indicating polarity. One should always study data sheets from the capacitor manufacturer before attempting to install/replace anything.

Macintosh LC II unsupported frequencies/resolution monitor

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