The O’Scope Restoration

These days, a pretty nice oscilloscope can fit in your toolbox and even a “big” instrument is probably something you can tuck under your arm. But that hasn’t always been the case. Consider this old HP 150A, restored by [USagi Electric]. (Video, embedded below.)

The 10 MHz dual channel scope might not seem very high-tech today, but when HP rolled it out in the 1950s to challenge Tektronix, it was quite respectable. The $1,000 price tag just for the mainframe was pretty respectable, too. Unfortunately, the scope wasn’t very reliable with more than 50 tubes in it, and HP quickly had to develop new entries in the scope market.

On the other hand, the machine was great to work on since all the boards were mounted so they would swing out for access. The case is a beast and the whole thing weighs in at about 80 pounds.

[Usagi] thought the scope would only need cleaning but — spoiler alert — it needed more than that. The cleaning and painting job was impressive, and there’s also a custom PCB milled out for the electrolytic capacitors.

There’s more to the story. A tube substitution turned out not to be such a good idea. And the power supply problems were probably due to the fact the scope was set for 230V input.

By the end of the video — which in all fairness is part one — the scope isn’t quite working. But you do get to look at the beautiful insides and it does have some trace in some modes. We’re looking forward to part two.

Really interesting to compare the teardown of an old scope like this compared to a modern one. Then again, $1,000 was a lot in the 1950s so maybe comparing it to a more modern instrument would be fairer.