HP3300A Function Generator Restoration

I blame ‪@CuriousMarc‬ for getting me hooked on this particular line of devices. Not that I ever can afford decent ones, mind you, but I think the restored one I have now is also quite OK for my type of projects.

The HP 3300A function generator is a model that was released in 1970, according to the only information about that I could find.

The lock/unlock feature of the plugin might be clear as day to others, but I had not seen this device before and it did come banged up so I didn't see how it was supposed to work.

I decided to do my usual recapping and contact/potentiometer cleaning on the unit; sadly though, I have to admit that one of the potentiometers suffered "catastrophic failure". The wiper element is a (sintered?) carbon element and it got stuck between parts during assembly and cracked. If anybody knows where I might get a replacement for these strange potentiometers, I'd appreciate a hint. It has an odd axle diameter, the 5k linear would be easy as pie.

Also, if anybody out there knows where I might get my paws on an affordable 3302A and 3305A plugin... just to complete my collection, it's not that I have immediate use for these, but you know the ground rule of test gear: you never know what you need until you need it RIGHT NOW.

As for the metal break, I didn't bother filming that; mostly because I didn't expect any problems at all and then it kinda spiralled out of control on its own... Other than the shipping damage, it works quite well I must say, quite happy with it.

Sorry for not showing any close ups of the circuit presentation section: the printouts turne dout to be too blurry and you can actually see more in the overview version.

Injury count for this one: 2 - cut finger on sheet metal burr and stabbed paw with screwdriver

UPDATE: The broken potentiometer seems to be a "Clarostat Model 63C3" with 5k lin.

0:00 Intro / Presentation / Disassembly
2:20 Oven / Dial Polish / Case and Plugin
4:38 Plugin Lock / Finish Plugin Disasembly
5:40 Limits of Disassembly
7:00 Power Socket Replacement
8:09 Recapping
9:15 Potentiometer and Switch Cleaning
10:15 Broken Potentiometer Slider
12:28 Bummer in the Oven / Transistor Fix
14:40 Case Assembly / Knob Cleaning
16:30 First Power Up / Tuning Issue
18:25 Rack Bracket Cover-up
19:10 Function Description and Demonstration
21:05 Quick Circuit Overview / Finishing Touches and Presentation / Outtakes


Music:
My Train's A Comin'
Unicorn Heads
(YouTube Audio Library)

You can support me on Ko-Fi: https://ko-fi.com/atkelar

Vintage HP catalog, featuring the unit and plugins on page 321 and 322 - http://hparchive.com/Catalogs/HP-Cata...

HP functin generator history page: https://www.hpmemoryproject.org/wb_pa...

Definition of "PEBCAK" (just in case you are wondering) - https://en.wiktionary.org/wiki/PEBCAK