RaSCSI stopped working

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rollmastr

New Tinkerer
Oct 31, 2021
19
14
3
Hello together,

unfortunately my favorite vintage mac gadget stopped working a few days ago. The Pi seems fine as I can access it with the web browser, ftp or ssh, but three different Macs no longer regognize the attached SCSI devices through RaSCSI while other devices (I tried a BlueSCSI and a Zip drive) work. The issue can be reproduced with different cables on different Macs (and I also tried to turn off termination on the RaSCSI and daisychain it to an SE and an external drive. The internal drive and the external one were seen, the RaSCSI was not.

This is what I see in SCSIProbe:
IMG_1844.jpeg

ID 5 is a disk image
ID 6 is the DaynaPort adapter.

I tried to reinstall RaSCSI from scratch which did nothing so I assumed that I have a hardware problem. What makes the thing even worse is that currently the RaSCSI kits are out of stock and Pis are also not available.

Next I got a set of jumper leads to create a loopback cable as described in the troubleshooting guide...
github.com

Troubleshooting

PiSCSI allows a Raspberry Pi to function as emulated SCSI devices (hard disk, CD-ROM, and others) for vintage SCSI-based computers and devices. This is a fork of the RaSCSI project by GIMONS. - Pi...
github.com github.com

IMG_1895.jpeg

The result of the loopback test was:

Code: 
pi@RaSCSI:~/RASCSI/python/loopback_test $ python3 test.py

Error: GPIO D0 should drive ACK low, but did not
Error: GPIO D1 should drive SEL low, but did not
Error: GPIO D2 should drive ATN low, but did not
Error: GPIO D3 should drive RST low, but did not
Error: GPIO D4 should drive CD low, but did not
Error: GPIO D5 should drive IO low, but did not
Error: GPIO D6 should drive MSG low, but did not
Error: GPIO D7 should drive REQ low, but did not
Error: GPIO DP should drive BSY low, but did not
!!!!!!!! Test FAILED !!!!!!!!

Total errors: 9

Apparently I lost the D signal/voltage. I just measured the voltages on the underside of the PCB. D0 to DP were all around 3.08V as stated in the troubleshooting guide, TPWR was 4.9V.

Do I have a bad Pi or bad bus transceiver chips?

I am using a RaSCSI 2.4a with a Pi Zero 2W btw.
 
Last edited:
landogriffin

landogriffin

Tinkerer
Sep 23, 2021
42
44
18
Iowa
piscsi.org
Hi @rollmastr. Great job troubleshooting!

Its possible that its a bad transceiver (I've had a couple go bad over time). It is odd that the misbehaving signals are spread across multiple transceivers though.

Do you have a multimeter that you could put on pin 24 (gpio8) to see if it is toggling high/low when you run the loopback test? Also, do a visual inspection of all of the pins (especially pin 24) to make sure that there aren't any cold solder joints. Feel free to post close-up pictures of your board too. Maybe there is something we can see?
 
R

rollmastr

New Tinkerer
Oct 31, 2021
19
14
3
Thanks for the help!

I just did resolder the transceivers before and now I also went over all of the GPIO pins on the pi and the RaSCSI.
The loopback test still fails with the same result as above. Pin 24 (GPIO 8) does fluctuate during the test between 1.6 and 2.9V.

The light sucks right now, but here are some pictures of the board I took a few hours ago before I went over the GPIO pins:
IMG_1900.jpegIMG_1901.jpeg

Also, I can rule out the DB-25 connector as it does misbehave exactly the same when using the 50pin with an adapter to 25pin.
 
R

rollmastr

New Tinkerer
Oct 31, 2021
19
14
3
Thanks! The purchase of an Ersa Analog 60W soldering station and a MG Chem flux pen improved my soldering quite a bit.

So far I only tried the LED test and it behaved as it should.
raspi-gpio set 4 op dh # ACT LED should be ON
raspi-gpio set 4 op dl # ACT LED should be OFF
raspi-gpio set 5 op dh # ENB LED should be ON
raspi-gpio set 5 op dl # ENB LED should be OFF
Click to expand...

I also ruled out the power adapter. The pi behaves exactly the same with a genuine raspberry pi adapter as it does with an ipad power adapter with a random micro USB cable.

Let me try the other steps...

Also, for fun here's a picture of the RaSCSI when it was still working hooked up to my "new" PowerBook 165. Dongle mania isn't a new thing for Apple users.
IMG_1668.jpeg
 
R

rollmastr

New Tinkerer
Oct 31, 2021
19
14
3
I can confirm the result of the loopback test with my multimeter.

The output of D0-DP stays at 3V after setting the signal to low via raspi-gpio set 10-18 op dl
The output of MSG does switch from 3V to 0.2V after telling it to raspi-gpio set 23 op dl

/edit: I just did another round of testing and measuring.
GPIO 10 - 17 always stay at 3V which would be D0-D7
GPIO 18 - 27 do what they should which I find interesting as GPIO18 is DP which does fail during the loopback test.

I also measured about 270 Ohms of resistance between all the lines, none are shorted together.
 
Last edited:
R

rollmastr

New Tinkerer
Oct 31, 2021
19
14
3
So... I received my new RaSCSI kit from intriguing industries today after paying almost 20€ for customs and soldered it together.

Code: 
pi@RaSCSI:~/RASCSI/python/loopback_test $ python3 test.py
-------- Test PASSED --------
Total errors: 0

This means my Pi is good and something on my old RaSCSI board has died. But what?
 
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