Ovenaire OSC 49-38C repair possible?

[e.sotillet]

Hi folks

I recently buy a EIP 545A frequency counter with a defective Ovenaire OSC-49-38C. The +28V power supply is present but there is no output. I tried to open it but is rather difficult.

Is repair possible with this kind of oven crystal oscillators? ¿What is the most common fail of these devices?


Best regards

[edpalmer42]

Are you sure about your pinout?  That looks very wrong to me.

The connector on the oscillator is a standard 7-pin tube socket.  The numbering starts at the gap and goes clockwise.  In the photo, the pin you've labelled as 10 MHz is pin 1, +28V is pin 2, etc.  The connector that attaches to the oscillator should have the same gap as the connector on the oscillator so that you can't connect it wrong.

You're showing pin numbers that are out of order.  That never happens for obvious reasons.  Regardless of which way you count from, there's no way those pins can be 3, 4, and 5.

Unfortunately, it looks like there's an error in the pinout shown on the schematic.  There must be a ground pin and none is shown.  Does the wiring on the connector agree with the drawing in the schematic?

[e.sotillet]

Hi

Thanks for the reply. Regarding to J6, is the pinout of the connector located in the main board of the EIP 545A frequency counter, is not the conetion of the crystal oscillator itself.

I manage to open it and found that the output signal was disconected  , so I soldered it and the device comes to live againg. The most dificult part was to open the oscillator, a little of solvent help me out.

The output signal is senoidal with around 1Vpp. I took a couple of pictures of the internal modules, trying to not disassembly the hole device because the thermistor and one diode is glued to the metal thermal cage of the crystal.

Best regards

[edpalmer42]

Glad to hear you got it working.  That connector confusion had me worried.

These oscillators spend their lives running at a rather high temperature.  It's not surprising to find that components have developed bad solder joints - particularly if the component is one that has some self-generated heat.  Since you've got it open, I'd recommend that you spend some time going over the board with a high-powered magnifiying glass to check for other components with cracked or oxidized solder joints.

When you get around to reassembling the unit, I wouldn't solder the can back together since it looks like your oscillator also has screws.  Just clean up the cover and screw it back on.

[testpoint1]

as usual, if the ocxo broekn is not caused by over heating, you can repair it, if overheating long time, the inside crystal already burnt.