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Color Classic Internal SCSI

raoulduke

Well-known member
Yeah I'm changing them all, essentially, at this point (until I run out of time today).  I don't see the trace rot at C9; though - is it possible you're talking about my garbage repair job?  (I'm trying to be self-deprecating, not defensive).

 

raoulduke

Well-known member
No dice after recapping and thorough washing and drying.  [sCSI Probe still shows a dot that indicates no data.]

 
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raoulduke

Well-known member
I just reseated the caps again and still no change.  However, either after that or during my recap, I didn't properly connect one side of C9 to the pad, though it was probably conductive.  Uniserver, did you mean trace rot in the silver joints on the interface?  I just doused them with Scrubbing Bubbles and now I'm going to put the board in the dishwasher for a few minutes > distilled water > hair dryer > air dry.  I'm not optimistic.

 
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raoulduke

Well-known member
Thanks.  That's what I figured.  The more interesting question is can I retrofit the 560's (550) chassis for the CC's motherboard?  That would go a long way toward showing it's a problem with the mobo.

[i figure it's bound to be something like this problem anyway:

But the CC uses a different chip (85c80) that also controls serial function; so I should also test the serial ports (though idk how much that narrows down which trace is at issue).  I found a pin labeling diagram (like listing what the pins do) but this isn't my background and I can't figure it out exactly; thus I can't figure out how to compare it with the 53c80's design/operation in the SE/30. - Well that and there's no standard 50-pin internal SCSI connector, so I have to figure out how that equates with the mobo interface.]

 
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rsolberg

Well-known member
Yes. The Performa 560 logic board and other hardware is identical to the 550. It came bundled with business software vs a home software bundle on the Performa 550. That ought to be an excellent way to rule out any CC chassis wiring issues for your SCSI problem. Personally, I'd want to keep the 560, perhaps just for the odd badging.

Oops, I typed this hours ago and it just sent.

 
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raoulduke

Well-known member
No worries.  I appreciate the response.

Unsurprisingly, the 560 board boots from the startup disk in the CC chassis; the CC board does not detect the startup disk in the 560 chassis.

Are the ROM chips swappable?  And has anyone ever tried to trace the SCSI circuit to/through the interface pins?  It's clearly (I think) giving power through the rightmost four pins and the data is somewhere in the pins immediately beside those [those being the ones right behind/in front of the SCSI data cable].

 
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CC_333

Well-known member
You know, unless you *really* want a stock CC, you should just leave the 560 board in there and call it good, as you now have the equivalent of a Colour Classic II, which is a much more useful machine than a plain CC will ever be (the CC II has no 10MB RAM limit, a faster CPU, and full 32-bitness, which makes it considerably faster).

Anyway, swapping ROMs is irrelevant here, as I believe they both use the same ROM anyway, and whether it identifies itself as a CC or 550/560 depends on what the gestalt ID is. You *could try swapping them, but I doubt it'll do anything.

There's probably some rotted traces by the SCSI chip. The trick will be finding which ones and getting them repaired.

c

 

raoulduke

Well-known member
I did actually want to make it a stock CC.  But this CC came with a MacMicro (or something) 68030 FPU/32mhz accelerator so I basically already had the CCII speed.  The RAM thing is an issue, but I have so many macs at this point that I don't really need any one of them to be specific.  It's not like I'm going to throw out the 560 chassis so it doesn't really save space.  But I might wind up using the 560 board anyway.  Still, I want to repair the CC board.

So by means of reiterating: Has anyone actually diagrammed/traced/know of the official diagram of the SCSI circuit?  I found pinouts for 85c80, but I don't exactly understand what any of it means.  There's no obviously visible trace rot on the traces out of the 85c80.  Additionally, the external SCSI works, so I was trying to explicitly trace it to the internal circuit.  I'm not sure how the serial ports play into that.  [Although I will note if you look at the blurry picture of the back of the motherboard, the underside of the PDS has a random chip soldered between two of the pins on the underside of the board; I didn't notice that at first and I have no idea how that got there - unless a service technician screwed up back in the day - I got it from the original owner].

Can the CC board (if it didn't have a SCSI problem) use the CD drive in the 560's chassis?  If so that'd be a much easier way to test the serial ports etc.

 
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CC_333

Well-known member
Can the CC board (if it didn't have a SCSI problem) use the CD drive in the 560's chassis?  If so that'd be a much easier way to test the serial ports etc.
It should, as the HDD and CD-ROM are both on the same SCSI chain internally.

c

 

raoulduke

Well-known member
So... keeping in mind I ask this because I'm not really an electrician/electrical engineer/electric personality, is there a way to bench test the board - as in to take measurements to try and trace the problem - that can occur outside the chassis [since I can't do much in there]?

I mean I know there must be some way... what's the best way?

 

olePigeon

Well-known member
A cheap multimeter can do it.  You can, at least, test the traces and capacitors.

I do have an extra Color Classic motherboard somewhere in my garage.  I think I PMed you about it a while back, but I still haven't found it.  I'll keep looking, it's just that its's a mess.  I've started buying shelving and organizing stuff, so I'm hopeful I'll come by it eventually.

 
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raoulduke

Well-known member
Really? I don't think that was me, re: the PM. I meant - I know how to actually take readings - how do you get inside the chassis above the board at an angle that would allow you to take measurements? Does the chassis open like that? I've clipped out the chassis box - like from the case front* (hugely fun...), but that doesn't change the space above the board. Is this making any sense?

*I may be using the wrong terms (?), I'm new to the CC.

 
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CC_333

Well-known member
I happen to have a CC board...

...that boots to a solid gray screen after being recapped :-/

I think the fix is fairly trivial, though (I have vague memories about an RTC chip needing to be cleaned or replaced).

Pre-recap, the SCSI DEFINITELY worked, so despite it's problem, it might be a good reference to figure out how things should be connected to the SCSI ship?

c

 
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raoulduke

Well-known member
What I mean here is not necessarily getting in "above" the board under the chassis-top, but do people adapt power cables or something... how do you actually get power to the board outside the case?

 
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