It is also used to check ROMs and RAMs for good data. The service manual will often contain 'signatures' for each pinout of a device, as it runs through a set, respective routine. Specific start, stop, and clock signals are defined in the service manual.
A very valuable tool. I have a 5005A. Also comes equipped with a voltmeter, ohmmeter and counter. Nothing a nice logic analyzer can't do, ...just simpler and quicker. -Don -------------------------------------------------- From: "Bob Quenelle" <[email protected]> Sent: Tuesday, November 27, 2012 10:05 AM To: "Discussion of precise time and frequency measurement" <[email protected]> Subject: Re: [time-nuts] EIP545A 18GHz counter query > Not that it's likely to help you, but a signature analyzer uses a shift > register with feedback to generate a 4 hex character "signature" from a > serial data stream. It would only help if the troubleshooting tree includes > a list a bad signatures for specific failures. > http://www.prc68.com/I/HP5004.shtml > Bob > > -----Original Message----- > From: Chuck Harris > Sent: Tuesday, November 27, 2012 7:45 AM > To: Chris Wilson ; Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] EIP545A 18GHz counter query > > This one is usually an easy fix. The EPROMS on the controller > card are using tin plated sockets, and they become tin-whisker > cities. The counter will usually have enough oomph to blow any > transient whiskers away if it is left running, but if it sits > the whiskers will grow quickly and prevent the CPU from passing > its power on self-test, and you get the "------" display. > > Take a high pressure air gun and blow under, around and through > the EPROM sockets from all directions and angles. When you plug > the board back in, it should start to work again... for a while. > > A more permanent fix involves removing the sockets and replacing > them with gold plated sockets with machined pins. > > Also, on many of the 545A counters there is a design mistake on > the power supply board where the wire tie that holds an electrolytic > capacitor passes through the board. The holes the wire tie passes > through are plated, and come through alongside of the +9V unregulated > traces... bringing ground and +9V together. Drill or file the plating > out of the holes to prevent spurious blowing of the mains fuse. > > -Chuck Harris > > Chris Wilson wrote: >> >> >> 27/11/2012 14:18 >> >> I bought a 18GHz EIP545A counter which the vendor said was working >> fine the day before and when on overnight soak test, and also when >> last used some months ago. But when he checked it on the morning of >> my coming over to see it he found it had developed a fault... I bought >> it off him cheaply, as seen, hoping it might be fixable. >> >> >> Here's the basic tale: >> >> It was acquired displaying just dashes. I checked the PSU voltages and >> found the PSU section outputting well away from the manual figures. I >> corrected these and checked supplies for ripple and they were all >> good. I then decided to remove any board that was not essential to >> operation. It came with a GPIB option board, so I pulled it. Luckily >> this did some good and a working display appeared. There were three >> tantalum caps on this board, as a matter of interest I pulled a leg on >> each and tested them, all were OK. Refitting it killed the display >> back to "dashes" again, so I set it aside as having an "unknown >> fault", and continued. I can get it to accurately display up to >> EXACTLY 188.9999 MHz Inputting 190.0000 MHz gives zeros. It has three >> frequency bands. Band one works perfectly right up and well beyond its >> 10 Hz to 100 MHz range. Band two often doesn't work at all, and just >> displays zeros, it's a 50 ohm input, compared to the 1meg 20pF Band 1 >> input. Sometimes by ramping the frequency up slowly from 100 MHz I can get >> a >> seemingly random reading. Band 3, the GHz range, doesn't work at >> all. Again, only zeros are displayed. >> >> The machine has quite a good range of self diagnosis tests. Tests are >> via the key pad. The first test checks the VCO and other stuff, and >> should display an accurate 200.0000 MHz It displays well over, always >> in the range 253.5**** and the display isn't stable, it hovers over >> several KHz. There's a tree menu to see where this issue could lie. >> One limb suggests using a known good counter on the output of the VCO. >> I did this and the output is miles high in frequency, about double, >> and unstable. The tree menus goes on to suggest a phase lock circuitry >> fault. >> >> Further tests seem to depend in part upon using something called a >> Signature Analyzer, which I have never even heard of They suggest an >> HP5004A, which is apparently pretty ancient. Is there a cheap way of >> acquiring something to do this sort of testing? I believe given a few >> pointers my scope, multi meter, sig gen and my other (working) Racal >> counter could take me further. >> >> It's a nice old thing, and I would quite like a means of counting into >> the higher frequencies it offers, but don't want to spend too much >> time or money on it. It works a damned sight more than when it first >> landed, which has kind of given me incentive to push a bit further, >> given I have a .pdf copy of the repair manual. Here's the page of the >> schematic I think is relevant, if it is a phase locked loop problem. >> >> This morning I realized there's a chip missing from a socket on the >> board in question. It's U6, a flip flop, part of the pre scalar I >> think? I assumed it was for some option, not fitted, but I am not so >> sure now. A Chinese EBay seller is breaking one of these machines and >> he lists all the boards separately, with decent photos. His board has >> this socket populated, and looking at the schematic, (linked at the >> bottom of this post), I think it's probably a vital component? I am >> sure the seller must have known about this, but who knows... >> >> I have ordered a new chip and will fit it when it arrives tomorrow. >> >> Now, assuming I ever get this thing up and running fully, is there a >> quick and dirty way of producing a test signal in the upper limits of >> its range to check it out, given my Marconi sig gen stops at 1040 MHz? >> Perhaps using a diode to give some harmonics? >> >> Diagram of the board I believe is faulty and missing the chip is at: >> >> http://www.gatesgarth.com/phaselockloop.jpg >> >> The text for this section, from the manual is at: >> >> http://www.gatesgarth.com/phaselocklooptext1.jpg >> >> and at >> >> http://www.gatesgarth.com/phaselocklooptext2.jpg >> >> Thanks for looking! >> >> > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
