davepl1968
Member
- Joined
- Dec 13, 2016
- Messages
- 36
I received the PDP-11/73 that a viewer kindly donated, got it spiffed up with Simple Green and compressed air, and proceeded to power it up. Dead, not a whimper. So having just seen Usagi Electric’s experience with a very similar looking MicroVAX, I checked the RIFA caps in the power supply and they looked pretty bad, so I went ahead and replaced them today. We have a place nearby called Vetco which is an electronics components superstore, the only one I’ve seen like it. I try to patronize them, but it was late Saturday so I wound up Amazoning an assortment of them. Installed all five this morning.
Put it all back together and, nothing… still dead.
I thought about it a while and then remembered the viewer saying they had brought it with them from Australia. So I checked, and duh… yup, 220V power supply. One site I found said there were two different supplies. I asked ChatGPT and it said I needed to reconfigure the power supply distribution board. I asked it for a citation and it pointed me at the PDP-11 Technical manual for the machine, but the section didn’t exist. But it did say that there’s a voltage selection switch.
At first, I couldn’t believe the little window was anything more than an indicator, but after some flailing I figured out that you slide it with a paperclip and it flips to 130V. I plugged in the power cable, and presto! Everything worked. Well, everything except the LED display on the back panel, but minicom came to life on the USB port as soon as I flipped the switch.
It booted to the memory test, but failed that immediately. After some basic troubleshooting I grabbed the memory board from my 11/23 and fired it into the QBUS backplane, and it passed all nine steps of the memory test. The full height factory hard drive, however, wasn’t spinning up. I reseated the power supply connector and it came up on the next try, but as the system inspected the drive, it made several “thunks”, the kind that are synonymous with a borked hard drive.
So, I grabbed the 11/23 drive that I bought which purports to have RT-11 on it. The system could see the drive, but claimed it was never ready. Next I plugged in a spare ST-251. Depending on how I jumpered it got either “No Drive Present” or “Drive Not Ready” so I went with the latter. I’ve got an MFM emulator if it comes down to it, as it did when I was fixing my D9090. But I’d rather have a drive in it.
I tried to connect to the PDP-11/73 using PDP-11GUI, software which connects (I think) to the monitor program over serial to drive it and so on. It looks like it can even write boot images, but I’m stuck trying to get it to connect. I’ll keep on tinkering with it! I’ll achieve PDP-11 glory one day!
If anyone has suggestions on what I can try with PDP-11GUI, and where to find a useful image of something like BSD 2.11 to write with it, I'm all ears!
Cheers,
Dave Plummer
Put it all back together and, nothing… still dead.
I thought about it a while and then remembered the viewer saying they had brought it with them from Australia. So I checked, and duh… yup, 220V power supply. One site I found said there were two different supplies. I asked ChatGPT and it said I needed to reconfigure the power supply distribution board. I asked it for a citation and it pointed me at the PDP-11 Technical manual for the machine, but the section didn’t exist. But it did say that there’s a voltage selection switch.
At first, I couldn’t believe the little window was anything more than an indicator, but after some flailing I figured out that you slide it with a paperclip and it flips to 130V. I plugged in the power cable, and presto! Everything worked. Well, everything except the LED display on the back panel, but minicom came to life on the USB port as soon as I flipped the switch.
It booted to the memory test, but failed that immediately. After some basic troubleshooting I grabbed the memory board from my 11/23 and fired it into the QBUS backplane, and it passed all nine steps of the memory test. The full height factory hard drive, however, wasn’t spinning up. I reseated the power supply connector and it came up on the next try, but as the system inspected the drive, it made several “thunks”, the kind that are synonymous with a borked hard drive.
So, I grabbed the 11/23 drive that I bought which purports to have RT-11 on it. The system could see the drive, but claimed it was never ready. Next I plugged in a spare ST-251. Depending on how I jumpered it got either “No Drive Present” or “Drive Not Ready” so I went with the latter. I’ve got an MFM emulator if it comes down to it, as it did when I was fixing my D9090. But I’d rather have a drive in it.
I tried to connect to the PDP-11/73 using PDP-11GUI, software which connects (I think) to the monitor program over serial to drive it and so on. It looks like it can even write boot images, but I’m stuck trying to get it to connect. I’ll keep on tinkering with it! I’ll achieve PDP-11 glory one day!
If anyone has suggestions on what I can try with PDP-11GUI, and where to find a useful image of something like BSD 2.11 to write with it, I'm all ears!
Cheers,
Dave Plummer
