[time-nuts] HP5370B & HP5345B Front-End IC Redesign Effort

Bruce Griffiths bruce.griffiths at xtra.co.nz
Wed Jan 27 08:51:19 UTC 2016

Just make sure that the airflow around the OXCO isnt too great or the oven temperature regulation will suffer.

    On Wednesday, 27 January 2016 8:02 PM, Perry Sandeen via time-nuts <time-nuts at febo.com> wrote:

Wrote: Since the front end chips are mixed signal ASIC’s, it will take more than a bit of time to replace them directly. Re-doing the entire front panel board is the most likely way to “fix”the problem.. The question is - why do that at all? Just do a PC instrument that does the same thing as the counter with way less effort…..
Well, I have two reasons not to.
First I have about $1800 invested in my 3 5370’s including  the new CPU boards and blowing that off is not in my budget. I’ll kludge the living daylights out of my units before blowing off my investment.
Second, I haven’t the slightest clue on how to do a PC instrument and I have to many other projects to finish to learn something new.
Also there was much discussion about A and B cooling in the past and it seems the only things some did to their units was the addition of fan(s) on the cooling fins.  I had an external fan on a B I was running and the thing still was too hot.
IMNSHO, I believe the front end chip failure is aggravated by the high interior heat level.  I’m committed to a number of other projects so it will be a while before I can work on mine.
I’ll either rip the whole PS out and put it on another chassis, try better 3 terminal regulators instead of the installed pass transistors, install switching regulator PS’s in place of the original PS, cut holes in the top lid and install 10 or 12 computer fans. Or a combination of the afore mentioned.
I don’t give a rat’s behind how it will look. I’m only interested in it working properly.  I’ve spent 50 years in the electronics industry and I will find a way to skin this cat. I’ve done this to other equipment before. And when done I’ll tell the list how I did it.
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