Author Topic: How to open an OCXO?  (Read 14797 times)

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Offline jadew

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How to open an OCXO?
« on: July 14, 2014, 01:21:40 pm »
Hey guys,

I'm trying to open an OCXO and I have very little success. I even tried heating it up with hot air and then using a desoldering station to suck up the solder, but it just wouldn't melt properly.

Tried adding more solder, heating it up + desoldering gun - no success either.

Any suggestions? I'd like to stay away from the oven so I preserve the sticker on the front.

Thanks.
 

Offline eurofox

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Re: How to open an OCXO?
« Reply #1 on: July 14, 2014, 04:55:34 pm »
Hey guys,

I'm trying to open an OCXO and I have very little success. I even tried heating it up with hot air and then using a desoldering station to suck up the solder, but it just wouldn't melt properly.

Tried adding more solder, heating it up + desoldering gun - no success either.

Any suggestions? I'd like to stay away from the oven so I preserve the sticker on the front.

Thanks.

 :-DD :-DD :-DD
eurofox
 

Offline jadew

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Re: How to open an OCXO?
« Reply #2 on: July 14, 2014, 05:00:28 pm »
haha, good one!
 

Offline edpalmer42

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Re: How to open an OCXO?
« Reply #3 on: July 14, 2014, 05:02:23 pm »
We need to see a picture before we can give you any reasonable suggestions.  Of course, if you want unreasonable ideas .......  :)

Ed
 

Offline KJDS

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Re: How to open an OCXO?
« Reply #4 on: July 14, 2014, 05:42:51 pm »
Use an axe.

It's possible that it's been laser welded, or soldered with a high temperature solder, or is just too big a heatsink for your hot air gun, therefore the only sensible solution is an axe.

Offline jadew

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Re: How to open an OCXO?
« Reply #5 on: July 14, 2014, 05:45:42 pm »
We need to see a picture before we can give you any reasonable suggestions.  Of course, if you want unreasonable ideas .......  :)

Ed


They're all pretty much the same, metal cans, soldered shut.
 

Offline jadew

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Re: How to open an OCXO?
« Reply #6 on: July 14, 2014, 05:47:20 pm »
Use an axe.

It's possible that it's been laser welded, or soldered with a high temperature solder, or is just too big a heatsink for your hot air gun, therefore the only sensible solution is an axe.

I suspect high temperature solder + pretty big.
 

Offline eurofox

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Re: How to open an OCXO?
« Reply #7 on: July 14, 2014, 06:03:33 pm »
Use an axe.

It's possible that it's been laser welded, or soldered with a high temperature solder, or is just too big a heatsink for your hot air gun, therefore the only sensible solution is an axe.

I suspect high temperature solder + pretty big.

 :-+

eurofox
 

Offline grumpydoc

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Re: How to open an OCXO?
« Reply #8 on: July 14, 2014, 06:05:10 pm »
 

Offline jadew

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Re: How to open an OCXO?
« Reply #9 on: July 14, 2014, 06:06:35 pm »
Thanks, I'll give it a try.
 

Offline andy_silicon

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Re: How to open an OCXO?
« Reply #10 on: July 14, 2014, 06:47:47 pm »
I have actually done this :-)

I used a domestic hot air paint stripper.
Place the ocxo on some ceramic tiles ( to protect your work surface ).
With some oven gloves hold the leads of the ocxo with pliers.
( best to hold the ground - it is probably better secured - but you don't want the pliers to act as too much of a heatsink )

Heat with the hot air gun - round and round the joint with occasional tapping to loosen the top cover.

You may need to pry the joint a little with a flat screwdriver and maybe try adding normal solder to lower the melting point of whatever is already there.

Why did I do this ? I had busted the unit up by accidently supplying 15v to the 5v supply ( it was a dual supply unit - with a separate oven supply ) . So I had nothing to lose.

In regards preserving the sticker - I peeled mine off before doing this.

I did manage to fix the unit - I had killed an R and a zener.

In fact you might have seen the very OCXO taped together with kapton in one of Gerry Sweeneys videos about the OCXO upgrade for the HP 53131A.

http://gerrysweeney.com/wp-content/uploads/2013/10/IMG_6161.jpg
« Last Edit: July 14, 2014, 06:52:56 pm by andy_silicon »
 

Offline edpalmer42

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Re: How to open an OCXO?
« Reply #11 on: July 14, 2014, 06:51:32 pm »
Start with a utility knife (Xacto knife, razor knife, whatever it's called in your area).  I use one that has a blade that you snap off when it's dull.  Use that to dig as much solder out of the joint as possible.  But don't use the sharp edge.  It's just going to try to push the solder aside and there's nowhere for it to go.  Use the back edge of the sharp tip so that it cuts the solder like a lathe cutter.  If you're able to dig a deep enough channel, you may be able to use a screwdriver to twist the sides apart and crack the remaining solder.  Depending on how much room there is in the solder gap, you might be able to dig all the way through it without adding any heat.

Another trick I've heard of is to grind off or cut a slot vertically through the soldered part of the corners.  This makes it much easier to flex the sides out and crack the solder joint.

You haven't mentioned why you want to open the oscillator.  Is it dead and you want to fix it or do you just want to see inside?  Obviously, the goal determines how aggressive your entry method is.

Ed
 

Offline jadew

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Re: How to open an OCXO?
« Reply #12 on: July 14, 2014, 07:07:12 pm »
Very good suggestions! Thank you.

I want to fix it, doesn't seem to draw any current.

Thank again!
 

Offline G0HZU

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Re: How to open an OCXO?
« Reply #13 on: July 14, 2014, 08:33:41 pm »
I've had devices like this opened in the past as well...

eg OCXOs, metal DCDC converters and big crystal filters.

Sometimes you can do it with a BIG soldering iron with a suitably big bit (also use a vice and a clamp) but other times it can be physically cut open with a scalpel or a rotary dremel.



« Last Edit: July 14, 2014, 08:36:43 pm by G0HZU »
 

Online T3sl4co1l

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Re: How to open an OCXO?
« Reply #14 on: July 14, 2014, 11:38:35 pm »
Gold standard method is an induction heater, but not all of you people have one...  ^-^
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Offline sunnyhighway

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Re: How to open an OCXO?
« Reply #15 on: July 15, 2014, 07:00:29 am »
Get yourself a bigger iron.



Seriously, these sheet-metal irons used by plumbers work like a charm.
 

Offline rf-loop

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Re: How to open an OCXO?
« Reply #16 on: July 15, 2014, 09:11:59 am »


They're all pretty much the same, metal cans, soldered shut.

If I have this what is your attached picture. It takes one minute (+ pre work) and it is safely open without any damage so that it can later resolder so it is like it was.

When not have induction equipments...

Simply, small size gas torch (gas soldering pen)
There is screw holes. Fix it to some metal plate with screws so it is some mm distance from plate (pins are then under this plate free free gap)
Fix this plate to place where it is well fixed and so you have enough room for heat every side equally. OCXO can top is now to down. If it is tight it may need some pliers attached with some soft material what do not smelt or burn and do not shrink this can. Typically needed force is light after all solder have smelted between bottom plate and cover.

and sidenote. If there is screw for adjustment, take it off and also plastic/rubber seal out)

Now start heating. Heat these sides near solder joint. Do not so much heat bottom plate for avoid damage in pins joints) Carefully enough fast (not too fast) turn torch around this can over and over until you see solder have smelt (typically after this bottom can drops to floor (note that it is hot so keep something under it.  If need pull outer can down with some low force using pliers  (pull directly down - if it come some side or corner first it may make it tight. )

Depending torch heating power it need be patient and give enough time for that all solder smelts inside can joint and still keep its electronics without damage. So it need do enough fast for avoid too much time to internal overheat)  With some cans it may need even combined cooling and heating but this you have is not this kind of extremely sensitive thing. Just "Brute force" torch and it is open.

It is difficult with what ever kind of irons.

Do not heat bottom plate, heat outer sides, result is better and more safe.

When you close it agen. just do opposite (and if there is adjustment hole take screw and possible rubber seal out)  but now it do not need be fixed with screws to any plate. Just free on some suface what is ok for soldering. If you have Metcal or equal it can even solder it but also it can do with torch. Just heat over smelt point and use solder wire. pB solder is better.

When you open it, look carefully if there is inside some tin (or other metal) wiskers. They are not rare inside some these cans.

I have repaired many Rockwell-Collins filters and also of course OCXO's.
Some times not failed but if have need improve some specs.
(example readjust OCXO XTAL temperature regulator so that it setpoint is exactly in XTAL temp/freq turn point for get better temp stability. )

Torch method is fast, bulletproof, easy without expensive tools and also safe (after some knowledge and experience how to avoid pins damage and how to avoid overheat or other damages) .

For get experience there is easy availabe lot of cheap or frree surplus / failed OCXO's for exercise before take some expensive rare OCXO under work.




« Last Edit: July 15, 2014, 09:26:56 am by rf-loop »
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Offline jadew

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Re: How to open an OCXO?
« Reply #17 on: July 15, 2014, 09:59:04 am »
Thanks for that rf-loop and to everyone else - all good suggestions, but I just opened it. I used a more powerful heat gun and I had it attached with some screws to a piece of wire so I could wiggle it.

The bad news is that the wiggling resulted in 2 pins falling off + some internal components. By the look of it, some pads are broken as well - pretty weird.

Edit: the pads didn't came off, it's just bare copper. At least now I know where those components came from :)
« Last Edit: July 15, 2014, 10:38:52 am by jadew »
 

Offline SeanB

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Re: How to open an OCXO?
« Reply #18 on: July 15, 2014, 05:49:58 pm »
Oven works almost as well.
 

Offline G0HZU

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Re: How to open an OCXO?
« Reply #19 on: July 15, 2014, 07:05:16 pm »
Get yourself a bigger iron.



Seriously, these sheet-metal irons used by plumbers work like a charm.
Yes, at work we have something with very similar dimensions. It is fantastic for removing seam soldered screens or seam soldered RF connectors. eg it can cleanly remove a seam soldered RF connector in just a few seconds.
 

Offline Fraser

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Re: How to open an OCXO?
« Reply #20 on: July 15, 2014, 07:37:39 pm »
I see that most (all) suggestions have been to use some form of heating. Call me chicken but I avoid applying large amounts of heat to a module unless I know exactly what resides on the other side of the can. I have seen many units ruined by people applying too much heat and many smt devices desoldering themselves and PCB's warped/burnt. I did like RF-Loops method though, it appears to offer the lowest risk of the heating methods. Prolonged heat is bad news for the components and even the crystal itself.

In my experience I have had great success with nothing more than a junior hacksaw cutting just above the solder line. No chance of overheating, a small chance of metal particle contamination and a relatively simple, low risk task. Rebuilding the can may be done with a quality copper foil adhesive tape. Some people use a Dremel mini disk cutting tool but it is easy to make mistakes with such a high speed cut and dive through the case into the contents  :o  There is also a lot of fine metal contamination of the module contents.

My worst experience with modules was a miniature transmitter that was housed in a pair of overlapped brass 'clamshell' halves. The overlap was the full depth of the case ! The solder refused to melt at lower temperatures so a very large soldering iron (designed for soldering large copper HF antenna earth straps and copper sheets) was tried. It worked in that it melted the solder and the two clamshell halves could be separated......but..... in one clamshell half I found a lovely clean unpopulated PCB. In the other clamshell half I found every SMT component secured in place with an epoxy  :scared:  I had desoldered the case and the whole PCB at the same time. That was a specialist module and likely would not have been repairable easily using any form of disassembly method. That module went in the bin and new one was procured. You learn by your mistakes !

Aurora
« Last Edit: July 15, 2014, 11:48:53 pm by Aurora »
 

Offline rob77

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Re: How to open an OCXO?
« Reply #21 on: July 15, 2014, 08:47:07 pm »
I see that most (all) suggestions have been to use some form of heating. Call me chicken but I avoid applying large amounts of heat to a module unless I know exactly what resides on the other side of the can. I have seen many units ruined but people applying too much heat and many smt devices desoldering themselves and PCB's warped/burnt. I did like RF-Loops method though, it appears to offer the lowest risk of the heating methods. Prolonged heat is bad news for the components and even the crystal itself.

In my experience I have had great success with nothing more than a junior hacksaw cutting just above the solder line. No chance of overheating, a small chance of metal particle contamination and a relatively simple, low risk task. Rebuilding the can may be done with a quality copper foil adhesive tape. Some people use a Dremel mini disk cutting tool but it is easy to make mistakes with such a high speed cut and dive through the case into the contents  :o  There is also a lot of fine metal contamination of the module contents.

My worst experience with modules was a miniature transmitter that was housed in a pair of overlapped brass 'clamshell' halves. The overlap was the full depth of the case ! The solder refused to melt at lower temperatures so a very large soldering iron (designed for soldering large copper HF antenna earth straps and copper sheets) was tried. It worked in that it melted the solder and the two clamshell halves could be separated......but..... in one clamshell half I found a lovely clean unpopulated PCB. In the other clamshell half I found every SMT component secured in place with an epoxy  :scared:  I had desoldered the case and the whole PCB at the same time. That was a specialist module and likely would not have been repairable easily using any form of disassembly method. That module went in the bin and new one was procured. You learn by your mistakes !

Aurora

if the smt parts were secured in epoxy - then you should have just apply some solder paste to the PCB , place that PCB over the components in the epoxy and apply some heat !  :-DD
 

Offline Fraser

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Re: How to open an OCXO?
« Reply #22 on: July 15, 2014, 11:52:42 pm »
Nah pcb was warped by the heat  ;)

When I kill something, I do it properly !
 

Offline edpalmer42

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Re: How to open an OCXO?
« Reply #23 on: July 16, 2014, 02:43:18 am »
Thanks for that rf-loop and to everyone else - all good suggestions, but I just opened it. I used a more powerful heat gun and I had it attached with some screws to a piece of wire so I could wiggle it.

The bad news is that the wiggling resulted in 2 pins falling off + some internal components. By the look of it, some pads are broken as well - pretty weird.

Edit: the pads didn't came off, it's just bare copper. At least now I know where those components came from :)

It looks like too little heat is just as destructive as too much.  If you use heat, you have to use lots of heat, but it has to be concentrated at the solder point.  I have an oscillator that I'll probably have to use heat to open.  I've got a precision propane torch that will hopefully do the job.

Sorry that your repair turned out like this.  I hope that oscillator wasn't one you really wanted to get working.

Ed
 

Offline mazurov

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Re: How to open an OCXO?
« Reply #24 on: July 16, 2014, 04:06:01 am »
I have had good luck opening those with a preheater( AKA hot plate ). You set it slightly below melting, heat the can on it,  then heat locally as usual - iron, hot air, whatever.
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