[time-nuts] Z3801A Freq jumping

Mark C. Stephens marks at non-stop.com.au
Tue Jul 23 06:33:41 EDT 2013


Hi George,





Oddly enough, I have seen the Self-test error and EFC error on three Z3816A I have in for repair now.



All have had one of two problems.

1. The weight of the OCXO breaks the solder joint on the PCB and intermittently causes huge TI jumps.

2. The insulating washers are missing from the pins of the OCXO causing a short between the case and the EFC line.



Problem 2 has been seen twice from eBay seller YIXUN. Unfortunately, they seem to more interested in grabbing your money than supplying decent products.

I'd steer away from Yixun HK personally.



I have one particularly bad Z3816A on hand at the moment where the OCXO plated through hole has been ripped out of contact with the board.

These Z3816A must have been thrown about pretty hard for the oscillator to rip itself out of the board!

Interestingly enough the TI jumps up into the ms, never mind 60us! See attached.



Actually, I'll take some photos of the repair job and post them on the blog.

The repair is basically grinding down around the plated through hole until I find the layer that connected to the plated through hole.

This is done with the finest diamond point dremel.



I'll get back to you with the results ;)



As for your Z3801A, I am doubtful it is a problem with the 10811, I would be inclined to suspect GPS related.

You could always pull the 10811 and run it standalone and monitor the output for intermittency.

The only problem I have heard of is the thin blue cables that go to the 10811 having intermittent grounds.



I am working with WarrenS to produce an article on improving the grounds in the 10811 amongst other performance and functional improvements.





-marki







-----Original Message-----
From: George Sintchak [mailto:wa2vnv at optonline.net]
Sent: Tuesday, 23 July 2013 8:04 PM
To: Mark C. Stephens
Subject: Re: [time-nuts] Z3801A Freq jumping



Marki, If I undersdtand what you're saying is that the two receivers are not compatible and can't be swapped.



Yes, the Z3816A has an EFC error and as I remember it, is reading 0. I haven't looked at it for some time now. Not having a schematic, I didn't look any further into the problem. It could be the driver Op Amp circuit or the MTI oscillator.



Tnx for your info,

George



----- Original Message -----

From: "Mark C. Stephens" <marks at non-stop.com.au<mailto:marks at non-stop.com.au>>

To: "George Sintchak" <wa2vnv at optonline.net<mailto:wa2vnv at optonline.net>>; <time-nuts at febo.com<mailto:time-nuts at febo.com>>

Sent: Monday, July 22, 2013 11:19 PM

Subject: RE: [time-nuts] Z3801A Freq jumping





> George,

>

>

> The Z3816A is 8 channel, the Z3801A is 6 channel.

>

> What is the problem with the Z3816A?

> EFC error?

>

>

> -marki

>

> -----Original Message-----

> From: George Sintchak [mailto:wa2vnv at optonline.net]

> Sent: Tuesday, 23 July 2013 12:34 PM

> To: Mark C. Stephens; time-nuts at febo.com<mailto:time-nuts at febo.com>

> Subject: Re: [time-nuts] Z3801A Freq jumping

>

> OK Marki, I have a Z3816 with a possible bad  5 MHz oscillator. Maybe I

> can swap out the GPS rcvr. I have to see if they are compatible. Does

> anyone out there know?

> Tnx,

> George

>

>

> ----- Original Message -----

> From: "Mark C. Stephens" <marks at non-stop.com.au<mailto:marks at non-stop.com.au>>

> To: "Discussion of precise time and frequency measurement"

> <time-nuts at febo.com<mailto:time-nuts at febo.com>>

> Sent: Monday, July 22, 2013 12:32 PM

> Subject: RE: [time-nuts] Z3801A Freq jumping

>

>

>> George,

>>

>> Looking at your graph, as far as I can see, the EFC jumps appear to be

>> tied to the TI

>> From the graph, your hitting +/- ~750ns. Normally, one sees +/- ~50ns.

>> nax

>> (although one particular basket case I have goes up into the milliseconds

>> occasionally,

>> It is a defective GPS module, I have proved this by swapping the module

>> with another unit and the fault follows the GPS module.)

>> I am not sure of the mechanics of how the EFC follows TI, perhaps one of

>> the other members can chime in?

>>

>>

>> -marki

>>

>> -----Original Message-----

>> From: time-nuts-bounces at febo.com<mailto:time-nuts-bounces at febo.com> [mailto:time-nuts-bounces at febo.com] On

>> Behalf Of George Sintchak

>> Sent: Tuesday, 23 July 2013 1:30 AM

>> To: time-nuts at febo.com<mailto:time-nuts at febo.com>

>> Subject: [time-nuts] Z3801A Freq jumping

>>

>> Hello all - Not sure what's happening to my Z3801A. Doesn't unlock, but

>> EFC jumping all over.

>> Is my oven controller dieing? I did a reacquire satellites abt 10 days

>> ago - no difference.

>> See plot below of the last ~36 days. Any thing to try - restart from

>> cold,

>> etc ???

>> George

>>

>>

>

>

>




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