age of hp 6200b power supply

[charles]

Hello everyone,

I am relatively new to electronics and have been trying to repair this hp6200b power supply that I immediately ruined upon purchase.

Anyway, I was just curious as to how old the power supply actually is.

The service manual is from January 1966, so presumably it is older than that. The serial code on the side is 6j1938, and on the actual circuit board it says hp 5020-5531. The big sprague brand caps say d38618 6730, so presumably the 6730 means 30th week 1967?

I have attached a few pictures of the supply. In the end I guess knowing the power supply's age isn't that important but I am just curious.

[nctnico]

The first digit(s) of an HP serial number is the year. They started from 1960 so your PSU is likely from 1960+6=1966.

Those rectifier diodes look quite baked. I'd also replace the electrolytics.

[amc184]

It's probably from 1967.

nctnico is right about the first one or two digits of the serial number being the date, but it's not the date of manufacture, it's the date that the particular revision of the product was first put into production.  So this revision of the 6200B was first made in 1966, but your one probably dates from late '67.

[charles]

Thank you nctnico and amc184!

As to the diodes, what is the best way to test the diodes?

I can desolder them and make sure that they are in the <1 volt range (or specifically the number in the diode datasheet if available) in one direction and OL in the other. If the diodes pass this test, does this indicate that they are fine or do I need to check other things?

As for the electrolytics, I am hoping to either get a real esr meter or use the oscilloscope/function generator technique.

In general, my big problem was originally posted here:
https://www.eevblog.com/forum/testgear/hp-6200b-power-supply-blowing-fuses/msg438749/#msg438749

Maybe I should start a new thread as I explore?

Thanks again.