Jump to content
Sign in to follow this  
AwkwardPotato

LC No Longer Chimes

Recommended Posts

I recently picked up a Macintosh LC with 12" monitor, and when I plugged it in, I got nothing. I then replaced the power supply with one I had recapped earlier, and the fan spun up, and it chimed. However, there was no video output, and when I looked inside to pull out the Maxell battery, I noticed that the area around some of the capacitors was covered in electrolyte. Upon pulling out the board, I noticed that a liquid had been spilled on the board at some point, as there was a brown goop around the back edge near the ports and on a few chips near the audio circuitry. The entire bottom of the board was also coated in a different type of residue. After cleaning the board with 91% IPA, it no longer chimes.

 

What should I do to get the board working again?

Edited by AwkwardPotato

Share this post


Link to post
Share on other sites

There's only minimal damage to a few traces, at least minimal enough to be bridged and repaired, so I'll go ahead and order new caps. Not only will it not chime, but it no longer attempts to read from the disk drive.

 

By the way, in order to test the monitor, will it display an image if connected to a PowerMac 6100? I've connected it via the HDI-to-DA15 adapter, and it won't display anything. When it's turned on, I can hear a faint buzzing noise.

Edited by AwkwardPotato

Share this post


Link to post
Share on other sites

One of my first freeycle finds were two LC IIIs over a decade ago (ex school machines). One worked fine and the other whistled when I fired it up and never booted again (until I recapped it). So bad capacitors have been a problem for a while now.

Share this post


Link to post
Share on other sites

I just recapped the motherboard, in addition to patching about half a dozen bad traces, and the machine still does not boot. I've also washed the motherboard and let it sit to dry for over 48 hours. When the computer is started, the fan starts, the speaker clicks, and the flatscreen VGA monitor I have connected detects a signal (goes from the "No Signal" screen to a solid black one, but the power LED is green), just there is no image on the screen. I have the ROMs in the correct order (I think), I've installed a stick of VRAM, the power supply voltages are all correct, and the machine has a fresh PRAM battery installed.

Edited by AwkwardPotato

Share this post


Link to post
Share on other sites

I don't know why or how, but after doing nothing to it for a few weeks, it now chimes!

 

Rarely, it will play the normal startup chime, and even eject disks that you put into it.

Less rarely, it will play the normal startup chime, and then play the death chime a few seconds later.

Even less rarely, it plays only the death chime.

Most of the time, it does nothing.

 

Even after using the double-tap method and putting in a fresh PRAM battery, it never displays a picture on either the 12" RGB or VGA LCD.

Share this post


Link to post
Share on other sites

The exact symptoms, after reset from keyboard, seem to change depending on which combination of SIMMs are installed:

 

With 0 SIMMs of any type: Almost always does nothing, if it does anything, its a full Chime of Death

With just the VRAM SIMM: Almost always plays the normal startup chime, but then plays about half of the Chime of Death, then the audio cuts out

With the VRAM SIMM and one RAM SIMM: Maybe 2/3 of the time, it plays a normal startup chime and then plays a full Chime of Death

With the VRAM SIMM and both RAM SIMMs: Seems completely random as to whether or not it does anything

Share this post


Link to post
Share on other sites

This sounds like a case of a damaged logic board from none other than capacitor goop.

 

Sometimes, cap goop can get on other things and cause problems. Before my main LC was recapped, it had a video issue where it would start displaying gibberish on any mode other than Thousands of Colors. A recap fixed the problem, and apparently it needed a lot of cleaning.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×