#tektronix 2445b

[commodorez]

Recently, someone was asking me about dedicated waveform monitors for verifying video signals. In a pinch, if you don't have a waveform monitor (like me), you can use an oscilloscope to the same end. Here's my Tektronix 2445B showing a simplified set of 75% NTSC color bars. Trigger the scope on the falling edge of the back porch within the signal, and adjust scale and timebase from there.

I'd love to find a calibrated rack mount set of 1720 and 1730 models from Tektronix, as they're a quintessential pair of dedicated waveform/vectorscopes for broadcast signal analysis from the good ol' days.

[commodorez]

Nova 1200 power supply linear section waveform measurements

[commodorez]

There’s 60Hz interference on the disconnected telephone lines in my home.

[commodorez]

Hewlett Packard 1650B Logic Analyzer

[commodorez]

My test equipment awaits a new bench.

[commodorez]

Huh. Nice waveform.

[commodorez]

Data General Nova 1200 power supply progress:

The new rectifier has been installed, and it seems to be running well enough.  The inductor squeals something fierce, and I haven’t a clue why.  Voltages look good, and the current ripple is surprisingly acceptable.  I’m almost inclined to reassemble the chassis and test the front panel, but I need to check with my trusted friends in vintage computing before I cross that bridge.

[commodorez]

Look at these beautiful timing waveforms on the Cactus, as I debug the 6551 serial card.  That last one is kinda fucky though.

[commodorez]

Back to debugging the busted 6551 card on the Cactus.  So far not so good.  Try as I might, my 4 channel analog scope is not a suitable stand-in for a large  logic analyzer.

[commodorez]

[commodorez]

I decided to see if the CPU, RAM, ROM, and serial boards would just... run.  I mean, this is the one part of the Cactus I’m directly copying.  So when that doesn’t run, I find myself particularly frustrated.

I would love to have a proper digital oscilloscope or some way to probe the bus during that short burst of time after I reset the CPU to see what the hell is going on.

[commodorez]

Oh hey, so that’s how the manual measurement function works on this beast.

[commodorez]

Umm... I’m out of my element here.

The drawings on the official Commodore schematics for the PET-2001′s video section are hand drawn, and therefore kinda vague. 

[testequip]

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[testequip]

[SALE!] $177.5 Tektronix 2445B 200MHz Oscilloscope 4 channel CLICK HERE!

[testequip]

[SALE!] $39.95 Tektronix 2445B or 2465B Oscilloscope Front Control Panel in working condition. CLICK HERE!