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

Bob Camp kb8tq at n1k.org
Sun Jan 24 21:35:47 EST 2016


Hi

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…..

Bob


> On Jan 24, 2016, at 6:02 PM, Dimitri.p <dimitri at dotp.com> wrote:
> 
> Someday , someone will get bored with everything else and give it a try, you know, in their spare time.
> The time when these counter were new was a long while ago.
> Back then an amplifier chip with 500MHZ BW was a much bigger deal than it is in 2016.
> ...but spare time is permanently on backorder .... :)
> 
> Dimitri
> 
> At 06:15 AM 1/24/2016, Bob Camp wrote:
>> Hi
>> 
>> Back when these counters (5345, 5370, 5335) all were new, the inputs were
>> the weak link on all of them. There were known “don’t do that” things on the line
>> that would blow out each of them. Regardless of the level of care and yelling, inputs
>> blew on a fairly regular basis. Probably 10% of the counters went back
>> for repair over a 5 year period. It was always a “swap out the entire board” sort
>> of repair and never was under $1K. We regularly spent the price of a new counter
>> each year on repairs. If there had been an easy way to fix them,  (or even to just
>> pay $500 for the chip) we would have done it.
>> 
>> Bob
>> 
>> > On Jan 24, 2016, at 8:34 AM, Dale Cannon <dalecan1 at cfl.rr.com> wrote:
>> >
>> > Funny,
>> >
>> > A friend asked me if I could replicate the front end for a 5370A, a many
>> > years back. I related to him that replicating the input chip was not a
>> > trivial task. His 5370A had been used (by someone else) for direct testing
>> > of controlled-motion DC motors and the front end had obviously been
>> > overstressed by voltage spiking. At the time, I had considered replicating
>> > the front-end probe circuit of a K100D logic analyzer: FET diff. pair
>> > followed by an ECL 10216 line driver. Obviously most daughterboard or dead
>> > bug modification approaches have downsides; in the end I just couldn't cut
>> > up the HP front end and told him to search for a more qualified repair
>> > facility.
>> >
>> > BAMA boat anchors has the K100D manual and probe schematic.
>> >
>> >               Dale Cannon  KS4FA
>> >
>> >
>> > -----Original Message-----
>> > From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Mathew
>> > Breton
>> > Sent: Friday, January 22, 2016 5:15 PM
>> > To: time-nuts at febo.com
>> > Subject: [time-nuts] HP5370B & HP5345B Front-End IC Redesign Effort
>> >
>> > I was gifted an HP 5370B with the usual problem: front-end problems,
>> > probably due to overstress. It is currently up and running again with a set
>> > of 5345A series A3/A4 boards as I wasn't able to get a cheap pair of
>> > 5088-706x hybrid ICs.
>> > This sounds like a common problem. As a result, I'm designing an open-source
>> > drop-in (hopefully) replacement. My hat is off to the original IC designer,
>> > as it is not a trivial effort due to the wide input signal common-mode
>> > range, and very tight trigger timing requirements. Other items (like the
>> > E-ECL) output) are also adding a bit of extra effort.
>> > I'm hoping that someone(s) might be interested in working with me on it. I
>> > would like to have my assumptions and math checked before I start the
>> > detailed design phase, and perhaps contribute some better ideas.
>> > In addition, it would be really helpful if someone could run a few rise-time
>> > dispersion tests on an instrument with a working "B"-series A3/A4 PCB set
>> > (my unit obviously doesn't qualify).
>> > Regards,
>> > Mat Breton
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