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Eliot Ness · 02-27-2017, 12:43 PM

(02-26-2017, 11:39 PM)morzh Wrote: ......BTW does anyone know that the PDP-11 computer had an assembly command called SOB which stood for "Subtract One and Branch".
DEC folks had some good sense of humor.

LOL..... it's been a few years but the early CT scanners I worked on used DEC PDP 11/05's and later 11/34's. That was back in the days of massive card racks, array processors, and large vacuum tape drives for storage.

**morzh** · 02-27-2017, 01:30 PM

We in Russia started using PDP-11 when you guys were almost dome with them and even VAXes were on their way out.
So I had my fun with them, repairing (yes, troubleshooting down to a component - no luxury of swapping and tossing boards; sometimes even tracing the microcode and replacing ROM) for which I had to write short assembly programs or even in codes directly right from the key switch panel.

012737
100
177560

Means "set the interrupt bit 6 in the Console Display's Keyboard Command Register".

013737
177562
177566

means "display on the console's screen what you've just typed on the keyboard".

Fun

Eliot Ness · 02-27-2017, 03:02 PM

(02-27-2017, 01:30 PM)morzh Wrote: We in Russia started using PDP-11 when you guys were almost dome with them and even VAXes were on their way out.
So I had my fun with them, repairing (yes, troubleshooting down to a component - no luxury of swapping and tossing boards; sometimes even tracing the microcode and replacing ROM) for which I had to write short assembly programs or even in codes directly right from the key switch panel.

012737
100
177560

Means "set the interrupt bit 6 in the Console Display's Keyboard Command Register".

013737
177562
177566

means "display on the console's screen what you've just typed on the keyboard".

Fun

Most of our problems were board seating, but I did spend a few hours on my back tracing signals on the backplane to fix flaky wire-wrap connections. I used to enter code on the 11/05's but that has long since been erased from my memory banks Icon_crazy

Although I do vividly recall replacing CDC hard drives that weighed 80+ pounds and were only 80 - 160MB! I could still probably format and bad block one of those from memory....

Just so this doesn't drift too far off topic; good job on the Zenith.... the FM sure added a lot of caps and wiring to what is usually a very roomy chassis. Are you going to get the shielded wire from eBay?

**morzh** · 02-27-2017, 03:39 PM

Not sure. I have some empty shield, just need the wire Icon_smile

**morzh** · 02-27-2017, 05:19 PM

You're right...I went on eBay and there is one guy on East coast who was selling a 7-lbs reel of single-shielded wire for $34 with shipping.
I figured that is very cheap (7 lbs has to be more than 100 ft, essentially unused reel) so it is better than what I see sold around.
Bought it......

**morzh** · 03-06-2017, 12:28 AM

Done with the rewiring and recap.
The shielded wire came Friday; I now have a lifetime supply of it. So this allowed me to finish.

**morzh** · 03-11-2017, 05:04 PM

Wow what a voice, and this is without the cabinet.I tuned into 1310/1160 AM, they play 60-70s, and.....wow. Cant wait for it to go into the box.

The tone ctl is very efficient.
No antenna at this point, the station is local.
The repertoire is great to prove the music on the radio - In the summertime by Mungo Gerry, Girl you will be a woman soon...

Now to the story. (I will post this and then append it).

**morzh** · 03-11-2017, 05:30 PM

This day didn't start well, I went to transfer my vinyls to tapes only to discover that the cassettes I bought from a vendor (great tape - BASF super chrome dioxide put in their cassettes) have cracks and sone debris are in the packing box that came 2 weeks ago. I have yet to talk to them.

Anyway, my mood was low and I decided to proceed with the radio.
Cleaned the bench that was filthy, vacuumed about a jarful of debris of rubber insulation from the radio.

Checked the transformer. Good. Realized the pilot lights were not wired: I threaded the wire but did not fix the sockets. Took me 10 minutes to fix the sockets. Put the lamps in, one works, one doesn't. Swapped them places, then the one that worked kept working and the other smoked the filament. What do you know, a bad lamp. The next one worked fine.

Then I realized I need to have the speaker on the bench. Well, I need it out anyway - will have to change the cloth.
Took me about 30 minutes to understand how to take the speaker board out.
Connected the speaker, checked the B+, saw it rise and droop, touched the grid of the 42, heard it buzz.
Switched to the BC, and quickly got the local Jersey Shore station. This speaker rules! I didn't expect the sound this big from any speaker outside the cabinet.

Well, need to clean the band switch, possibly the volume ctl, and tone ctl contacts.

I am not sure what to do with FM circuit, it is the old FM and will not work. To build converter....maybe in the future.

Alignment is pending. Plus more thorough check, many radios will work with the 1st RF stage not working. Though alignment will tell if it is OK.

Well, something good today.