Post Reply 
Early HP35 again: Let's play "spot the difference"
11-19-2016, 11:46 AM (This post was last modified: 11-19-2016 11:49 AM by Harald.)
Post: #6
RE: Early HP35 again: Let's play "spot the difference"
There is a slight modification in the PCB. The point where inductor and capacitor can be connected has moved a little and the trace going around it has moved as well. That allows a slightly longer inductor to be installed, but electrically it is the same.
On the first board the 380pF goes from pin 9 to ground. The ground plane on the bottom side is a bit larger than on the top. But the capacitor is connected to it.
The Anode driver has a fault, but the clock was still working. So I am sure this anode driver (1820-0853) does not require an inductor for the oscillator.
I have now inatalled 330uH and 150pF in order to install a new anode driver. I don't have a 0853 available as a replacement
Find all posts by this user
Quote this message in a reply
Post Reply 


Messages In This Thread
RE: Early HP35 again: Let's play "spot the difference" - Harald - 11-19-2016 11:46 AM



User(s) browsing this thread: 1 Guest(s)