Prototype HP/Agilent GPS based refererence clocks generator - Page 1
Forum section: electronics / testgear

author: TheSteve
author_rank: Unknown
timestamp: March 25, 2016, 11:44:36 pm
content: More late night ebay trolling lead to this purchase. This is a "Ericsson GE Precision Reference Clocks" - HP part # 58XXXA. The unit produces 10 MHz, 19.2 MHz, 9600 kHz and 100/300/600 Hz. It was most likely made for cellular base station testing based on its outputs. It looks to have been made 95/96 just as the Ericsson/GE partnership came to an end. The part number on the front makes it pretty clear it was a prototype. HP has several GPS based time/frequency references with part numbers with the format of 58xxxA. The serial number is "EGE001P", but the most convincing part are the two hand built boards inside. The front and rear labels are also simple printed labels. I believe the true part number is 58501A.Inside is has a main board with part # 58501-60001, a 10 MHz OCXO part # 05071-60219, a Motorola GPS part # 84D43215M02, a hand built board which generates (likely phase locked) 19.2 MHz from the 10 MHz, a hand built board to hold the three front mounted LED's and a third party power supply.At power up the front panel power LED comes on and a second later the GPS and ALARM LED's toggle on/off in sequence. The main board LED's also all toggle and then one of them flashes once per second. I can communicate with the unit via SCPI using 9600/8/N/1 RS232 data. I was able to verify the GPS does receive a signal as the time is correct and the date updates but is 1024 weeks behind(GPS rollover bug). However the "GPS LOCK" and "ALARM" LED's never do anything. The 10 MHz out the back does travel between 9,999,997 and 10,000,003 Hz which follows the EFC test point voltage that goes between -5 and +5 volts. I have found very few SCPI commands that work. At this point they are:*IDN? which gives: HEWLETT-PACKARD,58501A,0,Fiji_EGE*CLS*TST? which gives 1 (possibly indicating a rom error)PTIME:DATE?PTIME:TIME?SYSTEM:ERROR?I have pulled the four firmware roms and reseated them as well as the Xilinx chip, it made no difference. So the question is, did it ever work or has something failed?I find it to be a fascinating piece of equipment and think the hand built boards are super cool to see, but lets face it, it would be more fun if it worked.So I welcome all comments/thoughts on things to test or try.

author: TheSteve
author_rank: Unknown
timestamp: March 25, 2016, 11:45:39 pm
content: More pics

author: TheSteve
author_rank: Unknown
timestamp: March 25, 2016, 11:51:48 pm
content: Here is the firmware if anyone feels like taking a look.

author: uncle_bob
author_rank: Unknown
timestamp: March 27, 2016, 01:27:32 am
content: HiGiven the construction techniques, who knows if you'll ever get it working.Bob

author: Vgkid
author_rank: Super Contributor
timestamp: March 27, 2016, 01:45:43 am
content: That certainly looks like a prototype. Lets see how it performs.

author: TheSteve
author_rank: Unknown
timestamp: March 27, 2016, 01:56:41 am
content: If nothing else it was cheap. Will need to take a good look at the firmware to see if I can find more commands.

author: uncle_bob
author_rank: Unknown
timestamp: March 27, 2016, 02:03:01 am
content: Quote from: TheSteve on March 27, 2016, 01:56:41 amHiI'd try the normal SCPI HP commands. There are a number of lists running around to provide the "usual suspects".Bob

author: Vgkid
author_rank: Super Contributor
timestamp: March 27, 2016, 02:43:41 am
content: Atleast the ocxo is of the 10811B variety, so it is worth something.

author: FFFF00
author_rank: Contributor
timestamp: March 27, 2016, 03:44:13 am
content: The main board looks very similar to the 58503a just with many of the components shuffled around, try checking the programming manual for commands.Try SYSTEM:STATUS?, it might print out a formatted status page.

author: TheSteve
author_rank: Unknown
timestamp: March 27, 2016, 05:26:11 am
content: I have tried all of the commands I can find in the various manuals for the HP GPSDO products with pretty much no success. I have a 58540A here so I am pretty familiar with the normal SCPI commands. I may even try the firmware from one of the other units if I can find it posted. I should also look for a program that will combine the MSB and LSB firmware files so it is easier to look through for ASCII readable commands.

author: FFFF00
author_rank: Contributor
timestamp: March 27, 2016, 06:09:59 am
content: Ah, that is unfortunate.I can help you with the last bit, I wrote a program to accomplish the same thing for the 58503a. I've attached the combined firmware files you uploaded previously.

author: DimitriP
author_rank: Super Contributor
timestamp: March 27, 2016, 06:38:26 am
content: QuoteGo oodJb

author: FFFF00
author_rank: Contributor
timestamp: March 27, 2016, 06:54:11 am
content: Quote from: DimitriP on March 27, 2016, 06:38:26 amI may be missing something (it is late), but the contents looked reasonable... Inspecting the bin files with a hex editor shows properly aligned data where I could see anything human readable.

author: DimitriP
author_rank: Super Contributor
timestamp: March 27, 2016, 07:09:38 am
content: I saw "ntued Saestig" in one file and "Isrmn tt etns" in onotherand when I searched for "Instrument State Settings" in your combined file, it was there in all it's glory !

author: TheSteve
author_rank: Unknown
timestamp: March 27, 2016, 08:18:08 am
content: Quote from: FFFF00 on March 27, 2016, 06:09:59 amVery nice, thank you.I'll have a tour through, maybe myself or someone else will get lucky and find something useful.edit - I see lots of good stuff, perhaps even a status screen, but how to get any of it displayed remains a mystery.

author: DimitriP
author_rank: Super Contributor
timestamp: March 27, 2016, 08:47:53 am
content: All there were bunched up together:QuoteSTATE looks like a good one to try

author: TheSteve
author_rank: Unknown
timestamp: March 27, 2016, 09:05:00 am
content: Quote from: DimitriP on March 27, 2016, 08:47:53 amI agree, but trying it only gives me the standard error 113.But it does look like it recognizes WAI TST STB SRE RST OPC IDN ESR ESE CLS as you can see here:scpi > *WAIscpi > *TST?1scpi > *STB?+0scpi > *SRE?+128scpi > *RSTscpi > *OPC?1scpi > *IDN?HEWLETT-PACKARD,58501A,0,Fiji_EGEscpi > *ESR?+0scpi > *ESE?+0scpi > *CLSWhile the unit boots I think the root of the unit not functioning is related to the *TST giving a result of 1. On pretty much all HP gear it should return a 0 if everything has passed.

author: uncle_bob
author_rank: Unknown
timestamp: March 27, 2016, 03:27:01 pm
content: HiThe Forth in the ROM's looks pretty standard for HP. I suspect that when operating properly it *will* respond to all the usual SCPI commands. The question now becomes: What's broke and how do you fix it?Bob

author: scopeman
author_rank: Frequent Contributor
timestamp: March 27, 2016, 04:05:25 pm
content: Steve,Any chance another FPGA (or something else) should be in that socket that is unpopulated or can you see if perhaps someone pulled it for proprietary reasons.Just a thought.SamWorst case you have a great case OCXO and a power supply and a basket of chips!

author: uncle_bob
author_rank: Unknown
timestamp: March 27, 2016, 04:15:27 pm
content: HiI suppose there is another possibility here:What we are looking at is an attempt to turn the unit into something else. It's a bit odd that they have a nicely done stencil printed back panel and point to point boards inside. A normal design process usually does it the other way around. The connector locations are "firm" once the board is debugged. You can get the print for the panel in near zero time, you do it at the last minute.Indeed the giant empty FPGA sized socket does look a bit alarming.Bob

author: FFFF00
author_rank: Contributor
timestamp: March 27, 2016, 05:21:02 pm
content: I would guess the empty socket is fine. Going back to my previous post that the main board isverysimilar to the 58503a, the extra socket is used for the 59551a "Measurements Synchronization Module" configuration. You can also see unpopulated (or just direct solder) attachment points to the left. Picture attached for reference from a working unit.Can you verify there is a PPS output from the GPS module?

author: TheSteve
author_rank: Unknown
timestamp: March 27, 2016, 06:25:38 pm
content: I agree, I don't think the empty socket is an issue. The board also does generate all of the requires signals out the back.I can see the serial packets and the 1 PPS out from the GPS receiver.

author: TheSteve
author_rank: Unknown
timestamp: March 28, 2016, 12:05:41 am
content: Just a little update. I am communicating with the GPS directly now and it looks to be in position hold mode and the last location stored in it is from Maryland, USA. I will attempt to have it perform a self survey.

author: uncle_bob
author_rank: Unknown
timestamp: March 28, 2016, 12:47:38 am
content: Quote from: TheSteve on March 28, 2016, 12:05:41 amHiRecord the location before you erase it. You never know when you might want to call up the previous owner to have a chat.Until you blow that location away, you will have very little luck with the gizmo. It *is* odd that it would prevent the status screen from coming up... :SYST:STAT? has always worked for me on the HP boxes.Bob

author: TheSteve
author_rank: Unknown
timestamp: March 28, 2016, 02:59:02 am
content: OK, we have lock!I manually set a reference location and the date to get around the 1024 week bug this receiver has. I can see the EFS voltage is nice and stable at -56 millivolts and it is putting out 10,000,000,00X,X MHz. Obviously how much phase noise there is remains to be seen. The power supply packed it in earlier this afternoon so it is running on three external supplies.I expect the unit will not work properly if power cycled as it not store the week correctly and who knows if the GPS has the proper location stored or if the main unit has a stored location in its eeprom. It is nice to see it really does work though so it worth further investigation and likely the purchase of an updated Motorola GPS. This one is so old it communicates via RS232 to the unit, not even TTL, the sensitivity is also beyond terrible.I have still not been able to find any other SCPI commands. I figure there must be more, and there should be a command to change the 600 Hz output to 300 or 100 Hz(base on the back panel labeling).EDIT:Removed power for a few minutes and it seems to still have the proper date some how, yet the location is back to 37.3586547 -79.1746364 degrees. I do see packets from the 58501A to the GPS receiver so I assume it is sending configuration data. Now to determine if it sending an initial location or is it saved inside the GPS.EDIT 2:The GPS receiver is storing the correct location but the 58501A is programming a fixed location 10 seconds after powering on into the GPS and messing it up, it also programs the GPS to position hold mode so it will never get a proper fix.

author: mmagin
author_rank: Frequent Contributor
timestamp: March 28, 2016, 03:35:41 am
content: Hmm. Some aspects of this are reminiscent of the oldest of the GPSDOs I own.The front panel says Z3804A Oscillator and Distribution Amplifier, and *IDN? saysHEWLETT-PACKARD,59551A,Prod. Eng.,3618-AIt also suffers from the 1024 week bug, and on the inside it looks like they grafted a GPS board onto a product that was previously just a nice OCXO and 10 port 10mhz distribution amplifier. Also I can't seem to get the holdover uncertainty below about 19-20 us. (My newer Samsung-rebranded Z3805A settles down to 800-900 ns) Nothing about it is as prototype as yours, but it feels like a smaller volume thing for a particular customer.On the other hand, lots of 10mhz outputs and a line voltage supply, so I use it. Also IRIG-B output, which I bought a cute little Datum Timeview display for.

author: TheSteve
author_rank: Unknown
timestamp: March 28, 2016, 04:17:56 am
content: Sounds about right, this has got to be one of the first. In your case I assume the SCPI commands work properly to set the location and such. This one wouldn't be too bad if it just took forever to find its location at power up but being they set to hold position only it will never lock on its own. I figure I can remove the 28C64 that has the data and try to edit it manually or add a microcontroller that modifies the position packet sent by the 58501A to the GPS receiver. Or perhaps at some point I'll find more SCPI commands that work, but that seems unlikely.

author: mmagin
author_rank: Frequent Contributor
timestamp: March 28, 2016, 03:58:59 pm
content: Yeah. Resetting it to defaults and then setting the time I got things to do a position survey and get into a correct state. It works mostly like the newer HP GPSDOs you can find documentation for on the net. Although the serial port occasionally becomes unresponsive (like now) and there is another serial port which is a mystery to me.I would take some pictures of the insides if I didn't have it in operation :/

author: TheSteve
author_rank: Unknown
timestamp: March 28, 2016, 04:35:06 pm
content: I had looked for a second serial port with no success. I'll have to check again, being such an odd/old unit for all I know there is another one that will give me some management options.

author: TheSteve
author_rank: Unknown
timestamp: April 01, 2016, 06:02:15 am
content: Well some progress was made - the stock power supply is fixed. It was a royal pain in the butt and a replacement off ebay would have been cheap but there is that whole principle thing.It was mostly dead but worked once briefly - so I was thinking bad caps as it is from the 90's. I checked the caps in circuit with an LCR meter and they all met spec. I figured I'd resolder the board and when I did the odd connection sizzled a little and smelled bad - leaky capacitor bad. Sure enough a few of the caps had started leaking and the nastiness they leaked was conductive. Again though they meet capacitance and ESR specs just fine, even after being removed. I replaced a few caps and gave it a try, at this point it worked great again. So I fully reassembled it and it promptly blew the fuse and the main switching power FET. It was long discontinued but I found a local seller on ebay that had a few and met up with him to get them. I then replaced every single cap, leaky or not and replaced the FET. It was totally dead still. I removed several parts to check and finally found a bad MPS2222A. With the MPS2222A replaced the supply is again working fine.btw the leaky caps are made by Nichicon and were spec'd at double or triple the working voltage so I am a little surprised they are failing like this. The power supply is still sold brand new many places and is far from cheap. It is a Powerone MAP55-4003.As for the unit itself the location is clearly hard coded in the 58501A's 28C64 EEPROM. Next Digikey or Mouser order I'll get a PLCC32 socket so I can try reprogramming the eeprom myself(we'll see if it has checksums). I have also ordered a Motorola Oncore UT Plus GPS off ebay to replace the horrid one that is in the unit. The original uses RS232 and the new one uses TTL but the 58501A mainboard happens to have jumpers for the GPS TX/RX lines to switch between RS232 and TTL.If I power the unit on, let it initialize the GPS, then manually reprogram the location in the GPS to my coordinates and then reconnect the jumpers back to the 58501A it will lock as long as it is receiving satellites. At times it locks 5 but quite often it is only 1 or 2. Its sensitivity is clearly in the crapper.I also looked for a second serial port without success and found no other commands that work.

author: mmagin
author_rank: Frequent Contributor
timestamp: April 01, 2016, 04:21:51 pm
content: Mine has the same supply. It was working until I accidentally dropped things a couple inches on the bench and the physical shock killed it. Seemed like it should not have died so easily, but maybe it was merely precipitating other problems. In my case, I waited until one reasonably priced showed up on ebay.I've been getting better at diagnosing switching supplies though. Didn't give up on the supply in an HP 8648B until I discovered a transformer winding had opened up! Sadly those seem to be unobtainable for reasonable prices. I'm tempted to modify it a bit and just put suitable DC power supplies in a separate box. It's not such a high end signal generator that I'd feel bad about the modifications.

author: robert_
author_rank: Regular Contributor
timestamp: April 01, 2016, 05:21:11 pm
content: Nichicon PL?Same as Chemicon LXF and Panasonic HF* , these love to leak after 20years+ because the sealing rubber degrades. Doesnt matter if used or not, they also will leak in their original bag, given enough time.Chemi-Con LXY is a good replacement for those, KY might be a bit low ESR for some badly-designed PSU of that time.

author: TheSteve
author_rank: Unknown
timestamp: April 01, 2016, 06:44:05 pm
content: Quote from: mmagin on April 01, 2016, 04:21:51 pmIf you do decide to try to fix the original I'm happy to help. Most of the parts it uses are pretty common. The PCB is delicate though and easy to damage. At this point it likely needs all new caps. You can buy a power supply out of china that will work for so cheap though, it is almost hard to justify.I paid 41 USD plus shipping for the 58501A so for me it is worth the time and is a cheap/fun project. I also didn't want the power supply to "beat" me...

author: mmagin
author_rank: Frequent Contributor
timestamp: April 01, 2016, 07:42:26 pm
content: Quote from: TheSteve on April 01, 2016, 06:44:05 pmOne winding of the transformer was definitely open. Do you have any suggestions for such problems, aside from a painful rewinding job? It was my impression that the transformers in most off-line switching supplies were custom parts.

author: TheSteve
author_rank: Unknown
timestamp: April 08, 2016, 07:35:33 am
content: I removed the 28C64 EEPROM today and installed a PLCC32 socket(what a pain!). The EEPROM does have a bunch of data in it, it also appears to be checksum protected. I changed two bytes to edit what I believe is the fixed elevation value ($698F) as a test and it then ignored the EEPROM. On the plus side with the EEPROM removed or blank the unit powers up and seems to work. It will use the last position stored in the GPS receiver and acquire/lock within 10 minutes. So while it would be nice to figure out everything in the EEPROM and alter the fixed location perhaps it is best to just leave it blank. I also checked that if the EEPROM is blank it will never write any data to it even after it locks and switches to position hold mode. Lastly with the EEPROM removed/blank/corrupted etc there are still no further SCPI commands that work.Not sure what else is all in the EEPROM, there is quite a bit of data considering it runs without it - I may be missing some useful setting data for the OCXO, that would be a shame to lose.I have attached the file in case anyone is interested in taking a look. The fixed coordinate data I know is stored in it is:37.35865472 -79.17463639 270.23

author: mojoe
author_rank: Frequent Contributor
timestamp: April 28, 2016, 03:07:51 am
content: I just looked up the GPS coordinates that your unit was hard coded to. Very interesting location.Harris has two facilities in Lynchburg, VA. One of them is for training and tech support. I have been there a few times myself. As I understand it, the history goes something like this: The GE division that sold radio systems was a joint venture with Ericsson. GE later sold it's share to Ericsson, which was later sold to MA-COMM, which was later sold to Tyco, who very quickly sold it to Harris. Our EDACS system at work has all five names on various pieces of equipment.The coordinates you listed places the location on the campus of Liberty University. Perhaps GE/Ericsson was doing some R&D in cooperation with the university.

author: TheSteve
author_rank: Unknown
timestamp: April 28, 2016, 05:14:04 am
content: I was thinking maybe the entire facility was HP engineering back in the 90's and it was sold to the university at some point. I think it is neat you can see the equipment shed where the antenna would have been mounted.

author: uncle_bob
author_rank: Unknown
timestamp: April 28, 2016, 11:39:20 am
content: Quote from: mojoe on April 28, 2016, 03:07:51 amHiThe GE land mobile radio group in Lynchburg goes back to the WWII era. For many decades it was number 2 in that business to Motorola. With the advent of trunked systems and then cell phones, they became less important to the GE empire. They slowly spun off from them.Bob