[General] Can you identify this clock oscillator?

[shsn]

I came across some unusually shaped what appears to be an oscillator. Does anyone know what kind or type of oscillator this is?
According to Wikipedia picture here it kind of looks like P8/P2.

Thank you.

 

[FvM]

It's a SMD crystal, not an oscillator. The asymmetrical package shape is bit unusual but there are similar plastic crystal packages from major manufacturers.

 

[D.A.(Tony)Stewart]

Looks like a SAW Filter or just a lump of epoxy with a few terminals and the part numbers rubbed out in the image.

For such a huge microslice SMD crystal it must be top secret.

 

[shsn]

Looks like a SAW Filter or just a lump of epoxy with a few terminals and the part numbers rubbed out in the image.

For such a huge microslice SMD crystal it must be top secret.

The only marking it had on the crystal was "4.0000" so I'd assume the MCU (MC908 series microcontroller) was running at 4MHz. The entire PCB was coated with epoxy resin making it hard to take note of the part number unfortunately. I suppose it was designed to operate underwater so even if water gets inside the enclosure it'd still operate.

Well the 4.000 is a good clue. The epoxy coating on the crystal helps the poor moisture ingress on the epoxy.

I once was a test engineer for Unisys in San Diego where they had fiber bundles to the test floor in production for all the Intel servers being built in production. Then we had millions of dollars of shipments starting to have catastrophic failures. The clock was failing. It was a new factory and all the boards built in Roseville MN were farmed out to board shops. The Unisys assembly instructions said to install a Time of Day Xtal clock "Post Wave", and the new board shop did so but they forgot to mention that they also changed from no-clean flux to aqua clean flux and did the wave solder, added the Xtal then did a aqua flux clean.

It took me a few hours from the time the line was stopped to when it was restarted after I grinded the Xtal of a faulty Xtal in half, discovered rust and got with the QA guy and called the supplier to fix the process.

Epoxy and foil lid metal cans can have moisture ingress problems. Generally SMT Epoxy xtals can be poor reliability for aging and nothing is as good as cold-weld metal can crystals with THT but SMD versions are now avail.

Lower freq- AT-cut Xtals tend to be bigger, but this one is huge. The tiniest ones are a bigger risk for metalization growth in the quartz.( contamination) which causes drift and worst case low Q and stops the clock.
EPoxy coating adds capacitance, but I see they still included the load caps for some unknown reason. Perhaps an oversight or they dont care if it is 100~200 ppm low.

 

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View attachment 112216

I came across some unusually shaped what appears to be an oscillator. Does anyone know what kind or type of oscillator this is?
According to Wikipedia picture here it kind of looks like P8/P2.

Thank you.

It really looks like one of these. The pad layout matches.

 

[D.A.(Tony)Stewart]

good find @ads-ee
I'm glad Fox was smart to encapsulate a sealed cylindrical can crystal

"The FPXLF layout is one of the earliest conversions from Thru-Hole,
to surface mount. As such, the 2 terminations on the right are not
used for anything in the circuit. The pads are there only to provide
additional mechanical adherence to the circuit board."

 

[FvM]

It really looks like one of these. The pad layout matches.

Or any other manufacturer that uses the same form factor. The pad layout looks like a poor reproduction of the fox datasheet suggestion, the distance is too small. The pins have equal distance from the case end, but the ground pins are here sitting on the edge of the larger ground pads. Other manufacturers are using four equal sized pads for the same package, by the way, the footprint is a kind of arbitrary.

I wonder what the thread is exactly asking about. You already know that it's a 4 MHz crystal, it uses a (somewhat outdated) industry standard form factor. There's apparently no readable manufacturer mark on the crystal. Which information are you missing?