A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)

[uncle_bob]

Hi

The "FPGA VCXO alarm" looks like the key. If it's not in range (EFC is pegged), nothing is going to be happy.

Bob

[ZigmundRat]

Bob - I agree that doesn't look good. But I don't know if that's a transient startup error that is normally seen, or what. Hopefully we'll see some other logs and get some idea of what's normal and what's not. I'd like to quickly identify if this is a bad unit or not so I can get replacement/refund/credit if necessary.

[uncle_bob]

Bob - I agree that doesn't look good. But I don't know if that's a transient startup error that is normally seen, or what. Hopefully we'll see some other logs and get some idea of what's normal and what's not. I'd like to quickly identify if this is a bad unit or not so I can get replacement/refund/credit if necessary.

Hi

If it runs for 5 minutes and still shows the FPGA VCXO alarm, its toast. The VCXO has a *much* wider range than the OCXO (after a few minutes warmup). There is no way it will unlock simply because the GPS has not done it's thing yet.

Bob

[davebb]

Hi I had this fault and I had some caps missing and U25 was ripped of the board , there are some very good photos that helped , good luck
Dave

see this page

 https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/75/

[davebb]

Hi yes you have a bad unit , fly seller will tell you he will send another one but he will not send,tell him you want a refund, open a case with ebay, he asked me to close the case I opened as he said  he had sent another one,
I did not close the case, and ebay refunded me from his account , and the replacement unit never did arrive ,
still I did get the broken one working, as I put on a new u25 inverter chip and caps
Dave

[ZigmundRat]

I can confirm that it is toast. U25 is missing, ripped off the board. missing pads, etc. Also L17 but the pads are still there, and C45 is attached by one pad only. In the event that I am stuck with this, what was the original U25? I can't make out any part number in the picture and of course mine is missing Did you document your fix? I can make out the traces and where they go (thankfully does not look like directly to any vias) but would be nice to have confirmation. I don't imagine L17 is critical.

Message sent to the seller. I'd rather not have to repair it. We'll see what happens...

[SHF]

Hi Dieter , you may well have to fix it, but there are plenty of good photos on here
if it does not work the seller will tell you that he will send you another one, but he does not send it, you will have to put a clame  in with ebay, don't let me put you off as when they are working they work well
Dave

Thank you for your reply !

[davebb]

 Hi U25 is, NC7SZ04P5X
 . Wired it up with 30awg single stand mod wire, I used a meter and found that what tracks I had left went to 
U25 is a 5 pin inverter chip
Only 4pins connected
Pin 3 of the chip goes to gnd,
Pin 2 of the chip goes to the round test point to the right of u25 writing that is also connected to the blue resistor to the Right of u25, top pad of the resistor,
Pin 4 of u25 goes to the bottom pad of that resistor,close to
The edge of the board,
Pin 5 of u25 is vcc, goes to right pad of L17, it looks as L17
Is there to filter the power
Then when it worked I then used hot glue over u25 as I only
Had one pad holding it.
Good Luck.
Dave

[davebb]

See page 4 for good photos of the board
Dave

[PA0PBZ]

Hopefully we'll see some other logs and get some idea of what's normal and what's not.

You already found out what the problem is but I posted a 'normal' log here:

https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg819369/#msg819369

[davebb]

this is what I also found,

Hi due to the brilliant photos that shempe posted it looks as i now have mine working,it is running a Survey,when i looked at u25 to l17 in the photo i could see there was a track going to the 2 caps to the left of u25 that i had left out as my u25 inverter had been ripped off the board,
thanks Dave

Command Complete
UCCM-P > SYSTem:STATus?
-------------------------------------------------------------------------------
090-03861-03   serial number W561028299   firmware ver 1.0.0.2-01     LINK mode
-------------------------------------------------------------------------------
Reference Status __________________________   Reference Outputs _______________
   Ref 8KHz 0: [LOS]
                                              TFOM     2             FFOM     0
                                              UCCM-P Status[ACTIVE]

>> GPS: [phase:  1.33e-08]
ACQUISITION ................................................ [ GPS 1PPS Valid ]
Tracking: 6 ____   Not Tracking: 2 ________   Time ____________________________
PRN  El  Az  C/N   PRN  El  Az                GPS      21:27:39     21 JAN 2016
  2  27  83   40    24  23 135                GPS      Synchronized to UTC
  6  17  41   35    31  31 303                ANT DLY  +0.000E+00
 12  47  71   43                              Position ________________________
 14  43 245   42                              MODE     Survey:   13.6% complete
 25  82 332   35
 29  41 193   37                              AVG LAT  N  50:51:38.301
                                              AVG LON  W   0:56:00.451
                                              AVG HGT           +16.08 m  (MSL)




ELEV MASK  5 deg
-------------------------------------------------------------------------------

Command Complete
UCCM-P >

Command Complete
UCCM-P > POSSTATus
-----------------------------------------------------------------------------
1/21/2016 21:37:30
-----------------------------------------------------------------------------
 Position : LAT(N 50:51:38.202) LON(W 0:56:0.300) H(23.20 m MSL)
-----------------------------------------------------------------------------
 Geometry : PDOP(28.0) HDOP(17.5) VDOP(17.5)
-----------------------------------------------------------------------------
 Channel Status
   num of visible sats > 8
   num of sats tracked > 6
   ------ Receiver Channel State ------
     CH 0 >  SateID(2) TrackMode(pos avail) SigValue(39)
     CH 1 >  SateID(6) TrackMode(pos avail) SigValue(34)
     CH 2 >  SateID(12) TrackMode(pos avail) SigValue(41)
     CH 3 >  SateID(14) TrackMode(pos avail) SigValue(41)
     CH 4 >  SateID(25) TrackMode(pos avail) SigValue(39)
     CH 5 >  SateID(29) TrackMode(pos avail) SigValue(44)
     CH 6 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 7 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 8 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 9 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 10 >  SateID(0) TrackMode(code search) SigValue(0)
     CH 11 >  SateID(0) TrackMode(code search) SigValue(0)
-----------------------------------------------------------------------------
  Rcvr Status(1) :
-----------------------------------------------------------------------------
  Antenna Voltage: 5088 mV,  Antenna Current: 28 mA
----------------------
UCCM-P > STATus

                 - UCCM Slot STATE -



1-1. #Now ACTIVE STATUS ---------------- [Master]
1-2. #Before ACTIVE STATUS ------------- [Master Holdover]
2-1. #Reference Clock Operation -------- [Not Used]
2-2. #Current Reference Type ----------- [LINK]
2-3. #Current Select Reference --------- [GPS 1PPS]
2-4. #Current Reference Status --------- [Good Accuracy & Stable]
     #GPS STATUS ----------------------- [Available]
     #Priority Level ------------------- [LINK > GPS]
     #ALARM STATUS
     #H/W FAIL ---------- [ LINK ]
3-1. PLL STATUS ------------------------ [Enable]
3-2. Current: PLL MODE ----------------- [NORMAL 2 MODE]
Command Complete
UCCM-P >
Modify message

[davebb]

Hi again
take photos of all the missing and damage parts/board and put them on ebay, this will help you when getting your money back from ebay, as the seller will not send a replacement, he says he will, do not believe him
get a refund, but do try and fix it, u25 is very small but you can do it,
get a flux pen to help with your soldering.
let us know how you get on.
Dave

[ZigmundRat]

The seller responded, requested pics which were sent along with the diag log via eBay message. No further reply yet but I'm GMT-5 and he's in China so not worried at this point. In the mean time I'm investigating repair. I found a board with a donor Z04 so I will make an attempt. Nothing to loose here at this point. Thanks everyone for the tips, log copies and all the info!

[uncle_bob]

Hi

We are past the holidays in China so it's reasonable to expect a reply. Earlier this month a long delay might be the expected thing. If there is nothing back fairly soon, I'd escalate the issue.

Bob

[davebb]

Hi
good luck, glad you had the chip on an old board,like I say in one of my posts there is a very fine track that goes to the 2 caps to the left of u25 that was also damaged on my unit,
good luck.
Dave

[Macbeth]

If the seller is STILL selling these as good working boards, despite all the feedback he has been getting, and his ridiculous "why u not go fix it? u can fix cheap! jus' need soddering iron!?" then I don't think anyone should worry about obtaining ebay refunds. Just don't bother with the ebay option like I and many others have done in allowing him to send a replacement because he won't, he is just biding his time and hoping for ebay guarantee to time out.

Having said that they can be made good. Just order two and end up paying for one maybe?

[ZigmundRat]

I find it curious that it was the same U25 an L17 that got ripped off (although I also had two other caps missing). Curious but serendipitous as I think it made sharing info easier. Thanks to davebb and everyone for the assist. Attached images of the before and after. Not my best work, but for crying out loud I used a .4mm tip and it was still too big ! It will have to do. My diag log now reads:
UCCM-P > DIAGnostic:LOG:READ:ALL?
Log status: 10 entries

L1:1980-01-06 00:01:20:Log cleared
L2:1980-01-06 00:00:02:Power On
L3:1980-01-06 00:00:37:Survey mode started
L4:1980-01-06 00:01:53:Time set to GPS
L5:2016-02-29 00:37:28:Time set to GPS
L6:2016-02-29 00:39:56:GPS lock started
L7:2016-02-29 02:35:42:Position hold mode started
L8:2016-02-29 02:35:42:Lat: N,+41,+37,+34.0
L9:2016-02-29 02:35:42:Long: W,+70,+39,+27.2
L10:2016-02-29 02:35:42:Height: +105.7
Command Complete
UCCM-P >

That's a little better!

AFA the seller: I didn't buy a 'for parts or as-is' piece of gear. There needs to be some accommodation.

[davebb]

that brilliant news
it is strange it was the same u25, have you tested the 10mhz out
its good to help, as people have helped me,
my next project is to find a job? as I have gadgets to buy and bills to pay
Good luck Dave

[Gork]

Hi
Thanks for an excellent thread.  Very good info.
I bought a Symmetricom GPSDO from ebay. Same seller as others bought from. Seems like i was lucky, as mine was complete, including oil. 
After cleaning i tested it, and it seems to work ok so far.  Ordered a cheap GPS mouse with SMA conn which seems to work ok.

Now i need to find out about the LED on the pcb, DS1-DS4. DS3, and DS4 are dual LED.
Do anyone know what function the LED's have ?  I can only find marking for DS3, which is ALM and ACT.

[haydenph]

Hi All,
I have been reading this thread with interest. I want to get a few of these boards, however I want to make sure they will be suitable for my application.

In one of the previous posts @davebb noted that the units go into a survey mode every time they are powered up. Someone else mentioned this is 2 hours. Does the OCXO onboard when warmed up output 10MHz? Or do I have to wait 2 hours for the GPS to do it's thing before I get a 10MHz output.

Also if GPS fix is lost, does the OCXO then take over until GPS is re-established?

Also does anyone recommend the Trimble units over the Symmerticom? The trimbles are a bit more expensive, but seeing most are the same seller, do they come busted up?

http://www.ebay.com/itm/Used-10MHz-Trimble-65256-GPS-OCXO-Precision-Clock-circuit-board-oscillator-/111770391613?hash=item1a0608d43d:g:dzcAAOSw9r1V9ORq

My application only requires a stable 10MHz output. I require a 10MHz reference for a transmitter that is stable enough to keep it on frequency within 1Hz or so @50MHz. Obviously if it takes 2 hours every time the power goes off (not that it would under normal operation), this could be a pain.

Thanks


 

[davebb]

Hi it will output 10mhz without gps fix , you can press the mach button
the gps is not doing the 10mhz it is the OCXO that gives the 10mhz, the gps  is linked to pro/pll to ajust frq of ocxo,
if you loose gps fix it goes into holdover to hold it stable,
if you get the Trimble unit,it only does survey mode once so it will not do it again after restart, so go with the trimble,
has your radio got 10mhz input or are you using a board to convert to the radios ref
Dave 2E0DMB

[haydenph]

Hi Dave,
Does the MACH button require pushing and holding? Or just a single press enables the 10MHz output?

OK on the trimble, that sounds good, but more expensive.

No this radio is a repeater for 6M with a 12MHz reference. I've done some calculations in the EPROM data for it to work with 10MHz.

[Bryan]

Hi Dave,
Does the MACH button require pushing and holding? Or just a single press enables the 10MHz output?

OK on the trimble, that sounds good, but more expensive.

No this radio is a repeater for 6M with a 12MHz reference. I've done some calculations in the EPROM data for it to work with 10MHz.

I may be wrong, because I haven't thoroughly tested it but the MACH button does not do appear to do anything to the 10Mhz output as long as a antenna is detected and a satellite is in view. If the antenna is disconnected the Mach button when connected will output a 10Mhz signal, or when it is trying to do a survey. Not sure what it will do if it is in holdover?.

Note, you can also set the Mach button operation with software as well..

[bseishen]

Thank you all for all your information!. Just got my Symmetricom module in cant wait clean up all the oily slime off of it and to fire it up. Picked up a 19" video distribution amp dirt cheap that is basically empty inside. Will post some pics when its complete.

[SHF]

Hello
I have a LCD of F4CTZ http://www.f4ctz.fr/?page_id=692# recreated what setting do I configure ??
I get no data displayed ?
where the signal for the display is tapped ?
Pin assignment GPS RX ?
 for example: SYST:COMM:SER2:BAUD 9600

Please Help, greeting Dieter