Color Classic logic board powers on from keyboard then nothing...

[ComputerCompulsive]

Good Evening,
So I've been picking up a few systems locally and wanted to start recapping them for either my personal collection or to sell/trade. I've had a number of successes including two Mac Classics, a Classic II, and a Color Classic. All were "working" before the recap in that they at least booted up but usually had issues with sound.

I also acquired two additional Color Classic boards, one was battery bombed and I've been tinkering with that one to see if I can restore the traces and get it working. The second more recent one looked extremely clean but would only turn on from the keyboard (no chime, some hard drive access noise, no screen).

I decided to try and recap the board that looked clean but wouldn't boot and alas it behaves in exactly the same way as before the recapping. It will power on from the soft power, no chime, the harddrive starts to make a noise then stops, then the system just sits there with a blank screen.

I'm curious what the order of operations is for the color classic to start? I understand that the cuda (egret?) chip in vital to the startup sequence but I assume that since it will power on from keyboard that chip must be working. What happens after that? Are the roms accessed first then the sound chip for the chime? Wondering if understanding the order of what gets accessed when would help narrow down the issue.

Any assistance/insight would be appreciated. I don't have an ultrasonic cleaner I'm afraid so any cleaning being done would be by hand with a brush and 99% alcohol.

 

[wottle]

I had a board that behaved this way. It ended up being a broken pin on the edge connector of the board, so maybe inspect those. Mine had been bent back, so it wasn't making contact, and then it snapped off when I tried to bend it back. Some incredibly bad soldering with a pin I cut off something and I was able to get it to boot. Worst case I might be able to see which edge pin was broken and maybe you can find where that should go and see if it leads you to a specific chip? I try not to remove the board because I'm not sure how it will hold up to multiple removal and insertions.

 

[ComputerCompulsive]

I had a board that behaved this way. It ended up being a broken pin on the edge connector of the board, so maybe inspect those. Mine had been bent back, so it wasn't making contact, and then it snapped off when I tried to bend it back. Some incredibly bad soldering with a pin I cut off something and I was able to get it to boot. Worst case I might be able to see which edge pin was broken and maybe you can find where that should go and see if it leads you to a specific chip? I try not to remove the board because I'm not sure how it will hold up to multiple removal and insertions.

I don't have any real magnification I'm afraid beyond a simple digital magnifier but I don't think the edge connector on this board has any issue. It looks intact.

 

[ComputerCompulsive]

I was chatting with Amiga of Rochester on Facebook today about my board issues and he mentioned that both the CC and the 550 can be test run without capacitors. This is the first I've heard of such a thing, anyone else heard of this?

 

[Cam]

I had a system that behaved like you're describing.
I recapped the analog board and reflowed any questionable solder joints (on the neck board too). The whole thing started up no problem after that.

 

[ComputerCompulsive]

I had a system that behaved like you're describing.
I recapped the analog board and reflowed any questionable solder joints (on the neck board too). The whole thing started up no problem after that.

I have two working boards (another CC and another 550) that work fine in the same chassis so I don't think that's the issue. I also have two other chassis and they all behave the same way, I'll be recapping the analog board on at least one of these chassis this weekend though so I'll certainly give it a try in that when I'm done.

 

[nyar]

I have two working boards (another CC and another 550) that work fine in the same chassis so I don't think that's the issue. I also have two other chassis and they all behave the same way, I'll be recapping the analog board on at least one of these chassis this weekend though so I'll certainly give it a try in that when I'm done.

Hey! Did you ever manage to get this working? Mine is having a similar problem

Thanks!

 

[ComputerCompulsive]

Hey! Did you ever manage to get this working? Mine is having a similar problem

Thanks!

Hi, Nope tbh I wasn't sure what else to try so I have sent the boards to Amiga of Rochester for his expert diagnosis/repair.
Last time I spoke with him he thinks the 550 is fixable but is unsure as to what is going on with the color classic.

 

[Elemenoh]

How well did you clean up the EGRET? In my experience cap goo around that IC will prevent boot. In some cases scrubbing with a brush and IPA will work, but in others I've had to remove the chip, clean underneath and then solder it back on. Good luck!

 

[Diogenes]

I know I'm late to the party here, but for reference I have just been working on a CC with exactly the same issue. Board has been recapped. Analog board / CRT work perfectly with known good CC logic board. But the faulty board behaves the same - soft powers on with keyboard, no startup chime, hard drive spins up then down, blank screen. The issue turned out to be a bad high ROM 341-0532. Putting a good high ROM into the faulty board brought it back to life. Now I just need to find a replacement high ROM - I'm having no luck at all!