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

paul swed paulswedb at gmail.com
Wed Jan 27 15:34:33 UTC 2016

Some great comments and like all of you I like my 5370s and 5345s. Real
buttons no mouse. Must be a throw back to the dark ages.
Always knew about the fan issue on the 5370 and have added fans to my main
operating unit.
But it had not occurred to me that the way the front panel is laid out
there may be little actual airflow across those chips. Thats quite a
So for those with working units that may be a completely seperate thread.
How hot do they get? Then some solution for that.
Essentially fix it before it dies.
Then there is the question I posed.
Skipping all of the details like adjustable slicing polarity and such. What
is the minimum to get a signal into the counter as a way to return it to
some usable service and certainly verify the bad frontend. Lets call this a
poor but useful answer.
>From that point it returns to this discussion.
But a full new front panel. As Perry says most likely not.
I do have 2 X5345s that I am pretty sure I need to dive into the front end
on. My excuse other projects...

On Wed, Jan 27, 2016 at 7:46 AM, Bob Camp <kb8tq at n1k.org> wrote:

> Hi
> Ok, well let’s put some dimensions on it.
> Say that the new board for the counter costs $400 each. (and that’s
> probably low). How many are people likely to buy?
> If so how much would you pay for a working 5370?
> Bob
> > On Jan 26, 2016, at 11:08 PM, Perry Sandeen via time-nuts <
> time-nuts at febo.com> wrote:
> >
> > Hi,
> > 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.
> > Regards,
> > Perrier
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