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What's unpredictable are the components and traces that are rotted from electrolytic fluid and the corrosive vapors that accompany them, from the leaking caps found on an SE/30. Clock signals, Reset signals and voltages should all be repeatable from unit to unit, if there's nothing actually...

Thanks! I have a brand new Reloaded V5 board here, I'm trying to figure out what components may have been affected by the cap leaking; this is why I am asking about Y3, it was very close to UE10 which has had all of the traces toned out and is confirmed to be working, yet still no chime. I have...

I'm working from this guide step by step: https://tinkerdifferent.com/threads/macintosh-se-30-vertical-horizontal-bars-on-display-simasima-repair-guide.4705/ That's what I'm following and still have questions. I've done everything you've asked, UE10 Pin 14 is solid, yet I get no chime and...

Yes, that's correct, Pin 14 is unaffected. UE10 Pin 24 and 25 are Xtal in and Xtal out, which are the legs of Y3 if you look at the schematic above. What does make a difference in the wave form, is the physical switch on the probe, with a setting of either 1x or 10x; thanks to JDW at...

I am seeing the correct 15.667 MHz at UE10 Pin14. But at Y3, Pin 24 and 25, I'm only able to see Pin 24 has a wave form now, Pin 25 has no solid wave form and the speed is varying. Not sure why Y3 is behaving this way, this is backwards from yesterday, where I was seeing Pin 25 correctly and...

Thank you so much for looking in to that, that gives me the confirmation I was hoping for. There seems to be other errors in the Guide, which I'm also very thankful for but I'd like to help them revise the errors to improve the accuracy for everyone using it, myself included :) Just a small...

Thanks for the reply. I was able to get square waves on all of the ROM Address lines at this point, with the XC chip, it is walking the bus now but intermittently. It will need to be reset on occasion to get the square waves working. The speed values aren't lining up to the Simasima Repair...

I do have a scope, it is showing me that the Address lines of the XC chip are missing between A2-A31, many of them. The most concerning thing at the moment is Xtal Y3, it was near UE10 that was damaged by a leaking cap and Y3 also looks to be damaged. Leg farthest from UE10 - normal: Leg...

Found an issue with my Y3 Xtal, and was wondering if this is normal. On the Y1 Xtal I get a matching wave form on both legs with a clock of 32kHz: But on Y3, that is close to the UE10 chip that was corroded badly from the cap leak, I get a strange looking waveform on one of the legs: The...

I got it: XC is not a guaranteed fail - that was mere speculation. Still don't know the difference between XC and MC, or why they changed over, but I'm no longer concerned with that at this point. I'm concerned about fixing the issue of the bus walk and the strange results. I found something...

Am I still overthinking this, or is there another answer as to why my particular CPU is not 'walking the bus'?

CayMac Vintage on Youtube has experienced a bad XC CPU, in a video of his about 7 months ago. Every board in this unit has been recapped. I included a link to a thread showing everything that's been done to it, above. The CPU is not walking the bus, I have a scope and am looking at every...

I should have the new MC68030RC33B CPU shortly, I'll follow up when it arrives. If in fact my XC is bad, what would have killed it? Why would Apple switch to the MC68030RC16B, if the XC was good enough? What's the actual difference? Summary of troubleshooting and current issues with my SE/30...

Thanks for the reply. On ebay there are a few loose SE/30 boards for sale, from 1987-1988, early SE/30's like mine, where the boards look new still but they all have the simasima pattern and they all have the XC68030RC16B CPU's. I am wondering if the XC, like you said, was an early chip that...

Thank you so much!

Can I use a Motorola MC68030RC33B in an SE/30? https://www.ebay.com/itm/371776928912. The CPU my SE/30 came with was a XC68030RC16B, which seems to be very rare and I can't find an exact replacement.

Going to have to try ordering another CPU, want to replace it with the same I already have.

Tried the CPU walk the bus test and I can't get a square wave from any of the ROM slots, the wave form is a mess, with varying speeds, nothing is consistent. Is there any way to tell if a CPU is bad without another one to test with?

I was measuring RP7 pin7, not Pin2, Pin2 goes to 0V with Reset, RP7 is working correctly, my mistake. Added sockets for UB10 and 11, the Sony Sound chips, cleaned the board underneath thoroughly. I can get Pin5 on both UB10 and 11 to go to 0V with the Reset button, but Pin6 only drops to...

I did setup my scope better, I guess I won't worry about the slightly slower speeds 3.67MHz vs. 3.9 Mhz, all the clocks are where they're supposed to be. I moved on to the Reset portion of the guide and I definitely have a problem here: UB11 pin6 only drops to about 4V with the Reset. RP7...