Color Classic Booting Strangeness

2 posts / 0 new
Last post
Offline
Last seen: 1 month 1 week ago
Joined: Aug 2 2020 - 21:13
Posts: 1
Color Classic Booting Strangeness

Hello all. Having a bit of strangeness with my Color Classic restoration project. I've had the machine since 2001, and it failed a few years ago so I went on a long term restoration of it. With COVID and being at home so much I have decided to get it going again.

 

I had the Logic Board and Analog Board recapped by a well known site because of their absurd replacement cost, and my wanting this to be as perfect as possible, but it still never worked once I got it returned. That said, with a new battery and good power, it won't respond to a keyboard press. I have let it sit for days with the power switch on, power switch off, etc and no dice. I can get it doing about half the time though, but it requires one of the following: Leaving it plugged in, unseating and reseating the logic board (about 50% of the time it powers on and gives a raster but goes no further), or more reliably if I unseat and reseat the logic board it will bong, power on, rasterize and get to the flashing question mark. It will also respond to the long mouse button press to eject a disk, and it will seek a disk when inserted looking for an OS.

 

I've put a new PRAM battery in it - Lithium 3.0V as a test and no dice, I put a battery box with 3 AAs wired up to give 4.5V (measured) and no dice. Shorting the ADB pins to trigger a power on gives no dice as well.

 

I have cleaned the edge connectors and sockets, and I have given everything a strong once-over. The surface of the logic board has some sticky feeling areas, but all of the caps were replaced with surface caps and the board washed, so I don't think it is anything there - I think it is just flux or some sort of coating.

 

The last email exchange I have with the person who recapped it was from 2018 - but says "try to slide the main board in and out with the main power switch on, that can cause a force power on. The actual power on/off is controlled by the mainbaord and there is an EGRET IC there , and cap goo spills into that causing machine to not power on. sometimes i can do a re-cap on these and clean them up, sometimes the traces get degraded and can fail. " Does anyone have an idea where this EGRET would be?

 

I am going to do some googling, but does anyone have any ideas where to start? The machine is cosmetically as new - it's been retro brighted, and the display is gorgeous. I have a huge amount of sentimental value with this particular machine, and it would make me very happy to get it going again.

Dr. Webster's picture
Offline
Last seen: 4 hours 26 min ago
Joined: Dec 19 2003 - 17:34
Posts: 1704
Just because the board was

Just because the board was "washed" doesn't mean all residual electrolyte from the original capacitors was sufficiently removed. Also, that electrolyte has the unfortunate tendency to cause corrosion of solder joints and PCB traces, so I'd be confident saying that you have a component-level problem on your motherboard. (The way to rule out the rest of the system would be to try another motherboard in it -- from, say, an LC 550 or 575.)

If you could post some clear, high-resolution photos of the motherboard we might be able to spot some trouble areas for you to investigate further. Dealing with the aftereffects of failed surface-mount caps in vintage Macs is, sadly, going to become ever more common as time goes on.

Log in or register to post comments