full on geek is now complete.

I am now capable of using one of these... (that's the test. If you can use an oscilloscope, you are a geek.)

I inherited this 1960s vintage Tektronix 453 Oscilloscope from my friend Scott, who died a while ago.




The company that designs and makes the kits I used for building my stereo pre-amp and amp issued an updated version of the pre-amp that had two new features, MONO, and HUSH. MONO does exactly what it says. It combines both stereo channels to create a MONO output. This is good for listening to the old MONO recording. I still have to get an actual MONO phono cartridge. The HUSH function drops the output by 20db. It's sort of a 3/4 MUTE lowering the volume to conversation level without completely muting it.

When they announced these new features, I sent an email to them asking if there was an upgrade available for us version 1 owners. $99+shipping later, I receive the upgrade in the form of a tone board kit that will replace the existing tone control board in the pre-amp.

So, I build the tone board. It is an updated design for sure in that it has an additional relay, one less op-amp (which should decease distortion ever so slightly. Not that it was a problem in the first place), some additional resistors, and diodes, and extra pins on the connector that mates the tone control board to the selector panel board.

I install it, anticipating the new features. I power on, start to turn up the volume and this horrible distorted noise starts to spew forth from the speakers. WTF??? I quickly power down and wonder, what the hell did I do wrong? I was very methodical and careful in the assembly, like I was the first time around.

I redo all the shielded wiring from the tone board to the other boards in the system but I install the original tone control board to see if it is the new board or if I really screwed something up and damaged the rest of the boards. It worked just fine. I rewire the new board in, same distorted repeated clicking and distortion coming from the pre-amp even when no signal was present on the inputs. Something was definitely wrong with this new board.

The owner and designer of my preamp spent 2.5 hours on skype with me one night this week. He taught me how to use the oscilloscope and to signal trace the problem I was experiencing after building the tone control board upgrade. Seems I had 4 resistors in the wrong location. The value listed for the pairs that I switched were 24R9 and 24k9. Lol. Once we found that and I desoldered and reinstalled them in the proper location, everything works perfectly.

I installed an app on my phone, called Frequency Generator. I connected to the Topping DAC through bluetooth, and connected the RCA out to the Tape1 input on the preamp. I could send any frequency signal I wanted. Watched it change in the oscilloscope as I changed it in the phone. Pretty cool geeky stuff!

There will be many more opportunities to use the Oscilloscope in the future, as I delve into the world of vacuum tubes.

Tubes are completely artificial.

Nature abhors a vacuum.

Have fun with your new toy, Mark. Being a "portable" scope, those things were very rugged. I used one during my undergraduate EE electronics labs.

We had a Polaroid camera that attached to some of our scopes to document the waveforms we were viewing. Unfortunately, the Polaroid sheet film was rather expensive so shortly thereafter we got self-adhesive tranparent film overlays to paste onto the screen and then trace the image by hand.

Big Al

os·cil·lo·scope
/əˈsiləˌskōp/
Learn to pronounce
noun
a device for viewing oscillations, as of electrical voltage or current, by a display on the screen of a cathode ray tube.


So much fun.

Very cool, Mark!

Vintage instruments floating around in my basement. Dad was an EE.

No idea where the German one came from; I think the other one was one he brought home from work.

I believe there’s one of those in my mom’s basement. It was my dad’s. He’s been gone since 2001.

I dread cleaning out that house someday...

Wow, a Simpson 260. That was the go-to portable instrument when I started working in industrial plants. It was superceded by the Fluke digital meters as technology marched on.

Big Al

Dad worked at Argonne National Laboratory. His thing was instrumentation (neutron detectors and such) in a couple of the nuclear power plants that the lab ran.

One was at Argonne ( CP-5 ) and the other was in Idaho ( EBR-II )

I have a piece of graphite from CP-1. People at the lab used to get one for special occasions like a milestone anniversary.

Congratulations! I had no idea you can still build these things. My dad was a stereo designer and had entire banks of oscilloscopes in his workshop. One of these days I'm going to get the tuner/amp he gave me refurnished.

I cleaned it up a bit...

quote:

Originally posted by big al:
Wow, a Simpson 260. That was the go-to portable instrument when I started working in industrial plants. It was superceded by the Fluke digital meters as technology marched on.

Big Al

I also have, and use, a Simpson 260. The Simpson will perform tasks you just cant do with a digital.

Mark, that ‘scope looks terrific.

When I was in engineering school the Tektroniks was the one we all used.