Looked around and found the suicide cord, so I decided to quickly apply power to the 120B.
-Pat
Oh no you beat me to it !
I too got an HP 120B recently, meant to start restoring it pretty soon, was very excited to post about it, but too late you came first ! 
That doesn't mean we don't want to see yours, too! Post pics when you start working on it!
Mine is Gemra made, G245-00364. So S/N much older than yours, or is the S/N specific to each and every manufacturing plant ?! That's something I have never been able to determine for my old Tek scopes.
That's a serial number format I've never seen (used to
XXXXYZZZZZ, with XXX or XXXX being year (first one or two digits add to 1960 for year) and week (last two) of the engineering rev, Y being the country of origin (A for US, G for Germany, J for Japan, U for UK, etc.) and ZZZZZ a sequential serial number associated with the letter revision of the instrument, beginning with 00100.
Based on what I see in your serial number, I'd guess that Germany was using a slightly different format way back then, and conclude that yours is the engineering rev from the 45th week of 1962, and the 264th one built.
Anyway yours look beautiful with this blue CRT !
That was the main thing that prompted me to buy it - not a whole lot of use for a 450 kHz bandwidth single trace scope, and I'd bet the P11 phosphor is really rare in this model.
I immediately notice that the caps look of a newer/ better type, so your unit might quite recent.
I mean I am looking at the two side byt side axial caps at the back of the trigger switch assembly, the type that always fails I gather... on mine they are completely rotten, but yours look brand new.
Other clue : the shield on your CRT looks new, the pain I mean... mine is badly flaking off ! 
Yes, the ones on my scope look MUCH better than those on yours. That said, I've seen caps similar to those on your scope on older HP gear, and they are usually dried out and dead. I looked at a few date codes in mine just now, and the few I can find indicate that it's probably an early 1966 unit, so at least a few years younger than yours. Got a few more pics; will post them later after I get them uploaded.
I don't even know if mine will power up... it's missing half its tubes ! 
.. so no idea about phosphor colour, hey maybe I will get lucky and have a blue one like you ! No, not likely !
Anyway, looking forward to your restoration, and can't wait to start mine. Before I do anything with it, would like to buy a Variac as I can't afford to blow it.. have many Tek spares but only this one and only HP scope, zero parts handy to fix it if I screw up !
Most likely yours will be the 'default' P31 green phosphor, but there's always a chance. A variac is definitely a good thing to have for bringing things like this up; even better if you can put an ammeter in line with it to monitor current draw. I got the Sencore PR570 a few years ago after seeing it on Shahriar's channel and it's great for bringing things up and monitoring. For things that draw more than it can supply, I rig one of my DMMs in series for initial power up to watch the draw. Look forward to seeing your progress on yours as well.
-Pat
Home
Help
Search
Login
Register
