[time-nuts] EIP545A 18GHz counter query

J. L. Trantham jltran at att.net
Wed Nov 28 06:16:53 UTC 2012


Chris,

Put a ohmmeter across any of the capacitors on the GPIB board and see what
the resistance is.  Since that kills the unit, I suspect the resistance is
low (?shorted tantalum) or there is a problem with one of the chips that
takes the 5 VDC buss down.  Make sure of the polarity of your DMM, + to +
and - to ground.

Alternatively, there is a short on the +5 VDC line at the connector on the
mother board that is 'actuated' by plugging the board in.  Measure the
resistance to ground of the +5 VDC buss (power off) with the GPIB board
plugged in and not plugged in.

Joe

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Chris Wilson
Sent: Tuesday, November 27, 2012 4:20 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] EIP545A 18GHz counter query




> Hi Chris,

> The first thing you should do is join the EIP_Microwave group at 
> yahoo:

> http://tech.groups.yahoo.com/group/EIP_Microwave

> There's lots of info and help there for EIP counters.

> Don't worry about the signature analyzer for now.  It would normally 
> be used if the processor was dead.  The fact that Band 1 works means 
> that the processor/memory is okay.  If the processor / memory / 
> display related diagnostics like 02, 03, 04, 05 also pass, then 
> signature analysis is unlikely to tell you anything more.

> The first thing you have to do is replace that missing chip.  Bands 2
> and 3 require the VCO and phase-lock circuitry to be working.  As far as
> I can see, U6 is not optional.  Until the 200 MHz test passes, you can't
> get any further.  Be sure to check for obvious problems.  I bought a 
> 545A parts unit that wouldn't pass the 200 MHz test.  It turned out that
> some of the board-to-board cables were plugged into the wrong connectors!

> I'm in the same position as you regarding testing at high frequencies. 
> You might be able to get a signal at the second or third harmonic of 
> your generator by cranking the level to the maximum and then using the 
> counter's Band 3 frequency limits feature to only look at that 
> frequency.  My HP 8647A only goes to 1 GHz, but I can see harmonics up 
> to 3 GHz.  I've also picked up a few cheap YIG oscillators that have 
> allowed me to test in the 1-10 GHz range. Watch out for the signal 
> levels.  YIG oscillators have lots of output!

> By the way, I'd be reluctant to purchase anything else from that
> vendor.  Chips don't evaporate overnight.  Mind you, I guess chips have
> fallen out of sockets.  Any strange rattling noises when you shake it?
:-)

> Ed




27/11/2012 22:08


Thanks Ed, someone else kindly e-mailed me and told me of the existence of
the Yahoo reflector for EIP equipment. Sadly U6 is definitely not rattling
about in the case :( Happily I didn't pay a lot for this thing :)

I have had all the boards out and double checked all the cables are
correctly connected. The only issue apart from the missing chip is that
installing the GPIB board kills the thing completely. I am not sure why, but
I can live without that.

It seems it may the power meter and DAC options, at least the buttons are
present, but pressing them gives Error 13. Are the buttons present on all
the front panels?

The processor, memory and display tests pass AOK.

If I get it running further I may try and boorow a friends microwave sig
gen, rather than try getting clever and break it agin with too high an input
signal. Thanks very much for the tips Ed, much appreciated.




-- 
       Best Regards,
                   Chris Wilson.


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