Author Topic: A look at my Symmetricom GPSDO / 10MHz reference (OCXO + Furuno receiver)  (Read 419067 times)

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Offline f1rmb

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Hi,

   Sorry, I'm really busy with my new job.
 
The official 2.22 has been released 2/3 weeks ago, and it just contains the negative coordinates patch I've sent to F4CTZ (thanks to Dave, who raised this problem).
I suggest you to use the version that Dave mentioned you.

Cheers.
---
Daniel
 

Offline davebb

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GOOD morning
SHF
I am using for T1 PN2907
Check that you have the display board set to 9600
Good luck
Dave
 

Offline davebb

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Hi SHF
Can you take some close up photos of your board top and bottom side, so I can have a good look
Thanks Dave
 

Offline NivagSwerdna

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I'm trying to figure out how to route the LEDs to the front panel...

There seem to be four LEDs... DS1, DS2, dual DS3 (ACT/ALM) and dual DS4.

I'm not sure of the wiring on these but there do seem to be some test points....

Above DS1 to via
Above DS2 (might be GND?)
Between DS3 and R79 & R80 (above R79 & R80)
Between DS4 and R72 & R73

I obviously want to minimise the number of wires to the front panel.  Looks like the all go to ground via 220 ohm resistor?

Any suggestions?  Did you remove the on-board LEDs?

Thanks in advance
« Last Edit: March 10, 2016, 09:15:54 pm by NivagSwerdna »
 

Offline Nuno_pt

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Nivag, normally the test points are label as TPxx, where xx is the number of the test point.

On the first picture there is one test point TP14 (+3.3V), just above and on the right of R79.

So the DSxx could be something else.
« Last Edit: March 10, 2016, 09:29:16 am by Nuno_pt »
Nuno
CT2IRY
 

Offline SHF

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Thanks Dave, the problem was the HEX file, now have the 10mhz_gps.X.production.hex.zip the PIC, it's running great.
Thanks again for your excellent help !!!!  :-+ :-+ :-+ :-+
a very good forum here!  :-+ :-+
Greeting, Dieter
 

Offline davebb

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That's great
Dave
 

Offline davebb

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Hi Dieter
You know you now have to post a photo of it working, ITS THE LAW  :-+
Dave
 

Offline SHF

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GPS- Display working  :) :) :) :) :)
 

Offline NivagSwerdna

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Nivag, normally the test points are label as TPxx, where xx is the number of the test point.
The copper circular pads are good potential test points too... don't turn it on... probe it!
 

Offline davebb

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That's good I bet you were getting :rant: with it
whats the 8pin chip a reg?


we have Daniel to thank for modding the HEX
 :-+ :-+ :-+ :-+ :-+
 

Offline SHF

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8 pin chip is ICL7660 for -5V for the LCD, the normal voltage divider is not enough for my display !
Daniel I also thanks for the good HEX File  :-+ :-+ :-+ :-+ :-+
« Last Edit: March 10, 2016, 09:57:11 pm by SHF »
 

Offline davebb

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OK what display did you use?
Thanks Dave
 

Offline NivagSwerdna

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Is only one side of the U2 RS232 level converter chip used?  i.e. Just RS232 interfacing to the pins on the header J5?

Ideally I would remove/disable U2 and use TTL levels.

Thanks in advance
 

Offline SHF

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Offline davebb

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Hi Dieter
Those displays look good, take up less height
What was the price for the one you have
Thanks Dave
 

Offline SHF

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Hi Dieter
Those displays look good, take up less height
What was the price for the one you have
Thanks Dave
Price 22 Euro
 

Offline NivagSwerdna

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OK... I'm going to need some help!  I attached 5V from my bench supply...

The unit draws only 220mA and it appears the low voltage side works...  (with no antenna attached) I have DS3 solid green, DS4 solid red and DS2 flashing green.

On the PWR pin of the OCXO I have 5V and nothing is getting warm

I have 5v on the middle and bottom pin of U1, I have 3v3 on the bottom pin of U7

On the U4? the daughterboard regulator I have +5V at both ends

What do you think? PTN04050CAS knackered?

I actually de-soldered the PTN04050CAS module and I can see that there is a 1.349k R between pin 1 and pin 3.... and doing the calculation this is meant to take 5V to exactly 12V.
This part is expensive approx US$20 but it is a good one... capable of delivering 12W... need to consider options and talk to seller :(
« Last Edit: March 11, 2016, 10:29:16 pm by NivagSwerdna »
 

Offline grumpydoc

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I bought a couple of the symmetricom units to play with.

The ones I received look like the same batch that's going around right down to the mineral oil or whatever.

One looks OK, as seems common the other is missing the antenna connector but I haven't spotted any other damage (yet).

Has anyone any tips as to replacing the connector  - it looks to be quite a crowded area of the board. I'd rather replace the connector than solder a coax.

Also has anyone traced out the ribbon cable connector?
 

Offline davebb

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Hi NivagSwerdna , were are you in the uk?

read this post from Macbeth on the 1st page,
Dave



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

« Reply #15 on: December 13, 2015, 10:40:48 AM »


Quote

 

The Symmetricom and the Trimble versions of these should run at >5V-5.5V with a 2A supply no problem, PSU lead losses accounted for. Don't go too much over 5V as the supply is directly sent (minus a diode drop) to the external antenna, which are usually 3-5V.

The Symmetricom has a 12V OCXO and uses a TI PTN4050C boost converter while I understand the Trimble uses a 5V OCXO so doesn't need this.

My Symmetricom boost converter was DOA, as was the missing MCX antenna socket and the broken MACT switch.

The seller gave me the runaround and eventually pretended to send me a replacement board out and try and get me to "wait for it" one week after the ebay dispute timeout period. Of course with my simple notification that I would involve ebay he refunded me at the 11th hour.

I'm now using a cheap XL6009 instead. There are some other issues with starting this Symmetricom board with less than 1.7A too...


« Last Edit: December 13, 2015, 10:43:09 AM by Macbeth »

 

Offline Macbeth

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Has anyone any tips as to replacing the connector  - it looks to be quite a crowded area of the board. I'd rather replace the connector than solder a coax.

Also has anyone traced out the ribbon cable connector?
I replaced the connector with one I salvaged from an old scrap board. I just kept the curly lead away and isolated all around with kapton tape then cleaned up the area, laid down some leaded solder with my iron, flux, and used the hot air to solder the salvage connector in place.

Now I did trace out most of the ribbon cable, which includes an extra com port (binary, ToD I think), but for the life of me I can't find my notes!  :palm:
 

Offline SHF

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Hi, have a soldered IPEX socket, is very small !!
Dieter
 

Offline NivagSwerdna

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Hi NivagSwerdna , were are you in the uk?
I'll tell you once I've fixed it and the GPS Survey completes.  ;)

I'm now using a cheap XL6009 instead. There are some other issues with starting this Symmetricom board with less than 1.7A too...
I'll fire it up on the bench supply if I have time over the weekend. I might try an XL6009 module but it's nothing like the original which seems to be way more complex and presumably has better ripple etc.  For .99p I guess it's worth a shot and as long as it is above the regulation of the internal OCXO ref maybe it will be OK.  Not very happy with that.
 

Offline NivagSwerdna

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My Symmetricom boost converter was DOA
This seems like a huge co-incidence... too much of a co-incidence, there really isn't much to age on that module.  I wonder if the DC-DC converter fail is actually a symptom of a problem with the OCXO from too long without use or similar?  Maybe there is a lesson to be learned as to how to power these on for the first time?
 

Offline Bryan

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Quote
This seems like a huge co-incidence... too much of a co-incidence, there really isn't much to age on that module.  I wonder if the DC-DC converter fail is actually a symptom of a problem with the OCXO from too long without use or similar?  Maybe there is a lesson to be learned as to how to power these on for the first time?

Or the seller or person before them toasted them by not knowing the required voltage and using a high voltage power supply when testing.
-=Bryan=-
 


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