Getting acquainted with our new (old) Hitachi Oscilloscopes
With the goal of expanding our electronics tinkering/troubleshooting capabilities, I’ve had my eye out for a cheap oscilloscope on craigslist or eBay. The search paid off a couple months ago when I picked up two old analog Hitachi oscilloscopes, along with a square wave generator and a couple other vintage items.
The scopes in question are the Hitachi V-152F and V-134, seen below. I haven’t been able to locate any date of manufacture for these things, but they’re completely analog. The 134 even has an analog storage function, which is pretty cool.
They both worked to some extent once I got them home and remembered how to use an oscilloscope. Both scopes displayed a trace and responded to the settings on the panel, but they were pretty finicky as you changed various knobs. The V-134 Volt/Div and Time/Div settings were pretty bad, and the V-152F’s calibration knobs had some bad spots. When adjusting the settings, the trace would drop out and/or jump around. It usually took a few taps/wiggles on the knob to settle the trace back down.
Through a little googling and some help at AllAboutCircuits, I determined that the switch and pot contacts likely just needed cleaning. I figured I’d take a stab at cleaning them.
I unplugged the scope and left the power switch on overnight. I’m not sure if that really did anything to improve the safety of the operation, but it made me feel better. No sense getting zapped if I don’t have to!
I then removed the case, and got my first look at the guts of a vintage scope. Look at all that stuff!
I quickly located the switch contacts. They weren’t at all what I was expecting. For some reason I thought they’d be a discrete component that would be hard to get to. In actuality, they were wide open, custom designed for this scope I’d assume.
I shot each switch plane with a small amount of Anti-Corrosive Lubricant Spray I picked up at RadioShack, and worked the knobs through their range a few times each. After letting it sit a while for any residual cleaner to dry up, I fired it up, and was greeted with a much more consistent trace. Success!
I’m sure there’s still a fair amount of error in the scope’s readings (who knows when the last time they were calibrated), but they at least provide a good qualitative view of what’s going on in a circuit. They’ve already proven to be more than helpful in my MC2100 project, and Joe’s used them quite a bit on his guitar effects pedal work. Here’s a fun video of a phaser pedal for example. The top trace is an A note from a tuner, and the bottom trace is the output from the pedal.