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

Bob Camp kb8tq at n1k.org
Wed Jan 27 18:01:13 EST 2016


Hi

Ok, what else is on the same board as the front end? 

Is this a “chop a big hole in the board” project or is it a more elegant, replace the whole board approach. If you are just going to chop 
a hole in the board, what else buried in there. 

There is way more to this than just an input circuit. 

Bob


> On Jan 27, 2016, at 3:38 PM, Bruce Griffiths <bruce.griffiths at xtra.co.nz> wrote:
> 
> Something like the attached schematic should suffice however an extra gain stage would probably be necessary to achieve the 100mV sensitivity.NB Vcc = 15V, Vee = -15V.
> Bruce
> 
> 
>    On Thursday, 28 January 2016 5:02 AM, paul swed <paulswedb at gmail.com> wrote:
> 
> 
> 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
> thought.
> 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...
> Regards
> Paul
> WB8TSL
> 
> 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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