| Products > Test Equipment |
| Hewlett Packard 522B counter |
| << < (5/5) |
| MaxFrister:
It can count! After completing the recap I installed just 2 of vacuum tubes and brought up the machine on a variac and dim-bulb. After verifying that the -105V rail was present, I added 2 more tubes and tried the +200V rail. Also present. At that point I removed the dim bulb and reassembled the machine. Again I bought it up on the variac and confirmed that current draw was okay. Somewhat to my surprise it almost worked. The count was off but consistent. After 50+ years since the last calibration, the machine was due for adjustment. After I adjusted the power supply and the “phantastron” dividers it passed self-test. After tweaking the OCXO, it was accurate. Summary: Replaced AC cord. Replaced 8 vacuum tubes Replaced the selenium rectifier Replaced paper and electrolytic caps (I left the original precision paper/oil caps as they tested okay). Adjusted the machine. Beware: It turns out that 2 of the caps are marked in reverse polarity in the original schematic and the machine was wired that way. I’m not sure how they got away with that but maybe old caps are not as touchy about reversed polarity as new ones. Anyway, C130 and C131 should have the polarity reversed on the negative rails. |
| Cubdriver:
Looks great! Nicely done! -Pat |
| Navigation |
| Message Index |
| Previous page |