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| SE/30 No Chime / Herringbone-y Pattern |
Posted by: Michael on 2018-03-20 18:50:11
Unless I know how your metering the Bourns filters, I dont know if they are bad or not. Each pin through the Ohm meter on my Fluke 87 multimeter. Positive on the pin, to ground on the chassis.
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Posted by: Michael on 2018-03-21 02:56:59
Another thought-- I wonder if I have a break in the connection to one of the SCSI pins. The drive does sit there and flash like it's trying to be read. There's no apparent break visually, but I'd swear a light tap on the case seemed to get the thing past the flashing disk drive once in a while. I plan on running the pins to the SCSI connector for connectivity if I can find that schematic somewhere. I only have 5 schematics and SCSI isn't one of them. Thinking logically, metal expands as it heats up, if there's a bad solder or something a long wait could be just the solder expanding as the computer warms until it makes a connection. Just a thought.
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Posted by: Michael on 2018-03-21 11:40:34
Found the schematic for the SCSI chain. It's definitely not SCSI pins. Damn. I got contact between the pins, the external port, and UI12 pins. Working upstream from here.
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Posted by: techknight on 2018-03-21 16:36:54
You need to measure between the SCSI IC and the rest of the bus, like the GLU, CPU, etc... /IOW and /IOR love to break on the SCSI IC between it and the GLU.
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Posted by: Michael on 2018-03-21 17:28:23
Here's where my ignorance takes over... What am I measuring? Voltage across the trace? Or just basic connectivity looking for a broken trace? I assume the board is not powered for this.
In other news, the computer booted up fine today after my SCSI inspection. I did hit the pins with DeOxit before reassembly. Don't know if it made a difference.
I'm sure tomorrow I'll get the question mark of doom from the floppy icon brigade.
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Posted by: Michael on 2018-03-22 11:41:11
Yep, as predicted. Question mark of doom this morning.
I think I'm going to name this computer "Sybil" because it's got multiple personalities.
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Posted by: Bolle on 2018-03-22 11:52:21
I suppose your battery is new and good?
As I had to find out the SE/30 will not boot if the PRAM/RTC is not present and instead just hang at the :?: and flash the HDD activity light.
Not sure if a dying battery can cause the PRAM not to be ready when the VIA wants to talk to it but if that is the case it would explain why it's not booting.
Also did you check the term power fuse and diodes? If those go bad you will end up with weird SCSI voodoo as well.
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Posted by: Michael on 2018-03-22 12:11:44
Battery is brand new. 3.6 volts. All the voltages across the power supply check out (12v and 5v). I could check the voltages on the scope for stability and make sure I'm not getting crappy, irregular power, but everything appears to be working fine-- the CRT, the drive lights, the fan. I'd think if power were an issue I'd be looking at a wonky picture.
The diode D3 is good. F2 and F3 have continuity. I have to start running the SCSI traces between UI12 and... I think it goes to UI8-- I can't remember. I have to dive into the schematics again. At this point basic connection between points is all I know how to do, though I'm learning more and more every day.
I'd love to test chips and voltages, I don't know what they're supposed to be. I would need to do more research to know what I'm looking for and when a measurement is wrong. I have decent test equipment here now. A 4 channel oscilloscope. Still have to figure out how that all works, but I'm 50, young at heart, and curious.
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Posted by: techknight on 2018-03-22 14:37:43
Umm i have NEVER seen an SE/30 need a battery to boot, I never put batteries in any of the ones I own or work on, everythings good.
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Posted by: Michael on 2018-03-25 01:57:24
Sybil update: After a few days of sometimes it boots, sometimes not, I found a glitch. The computer won't boot with the SCSI Zip drive attached from a cold startup (switch on). With the Zip drive unattached, it boots every time. If I attach the Zip drive after it boots and do a warm restart, a reset, or if I mount the Zip in SCSI probe the computer boots and the Zip mounts.
So the termination chain is where I'm putting my money that I'll find the gremlin. I'll re-check the fuses next time I have it torn down. The termination switch on the Zip is turned on, I checked.
Gotta put the SE/30 aside for a bit. I've got an editing gig coming up and my Mac Pro has been misbehaving. Damn OWC SSD drives. But that's another forum and about as far away from an SE as you can get.
I've got a Mac Plus in the garage I'll be digging up soon. That's going to need caps, for sure. The adventure continues...
Thanks for all the help and attention. I'm enjoying the deep dive into electronics and circuitry. I learn something every day. I love all the YouTube videos, really instructive.
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Posted by: techknight on 2018-03-25 05:07:40
I wonder what your SCSI IDs are set at?
if you have your HDD and your ZIP drive on the same ID you will have these problems. Also if your Zip drive is ahead of the HDD in the chain you can have problems too.
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Posted by: Michael on 2018-03-25 09:59:51
I wonder what your SCSI IDs are set at? I have the SCSI2SD internal SSD emulator as a hard drive. I have 2 partitions on it. ID 0 for the boot partition, ID 7 for the 2nd partition (I could change it to ID 1 as an experiment). The Zip is set to ID 5 (hardware switch). All verified in SCSI Probe. Both devices are terminated.
The Zip is coming off the external SCSI port (25 pin DIN) on the back of the computer. The SCSI2SD drive is on the ribbon cable into the logic board.
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Posted by: joethezombie on 2018-03-25 16:19:17
ID 7 is reserved for the system controller, and shan't be used.
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