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View Full Version : MFJ-962C FSWR Cross Needle not Working?



K4ZOT
06-11-2013, 07:48 PM
Perhaps someone can point me into the right direction to fix my MFJ-962C tuner. The FSWR cross needle (left side) collapsed during tuning to below the screw on the bottom of the case. Is this a diode issue or is the meter just bad. Any adivise is appreciated.

Thanks,

Glenn - K4ZOT

KE3WD
06-11-2013, 08:13 PM
If the needle rests there when no power is going through the unit, the problem is likely mechanical, in the needle meter movement itself.

K4ZOT
06-11-2013, 08:27 PM
The FSWR needle is below the screw in the meter case about 1/2" below "0". The Reflected needle is on "0". So you believe it is mechanical and not electrical?

KE3WD
06-11-2013, 11:11 PM
What I believe is that you haven't said what the needle is doing when no power is applied to the meter.

If the needle is stuck there when no RF is being sent to the meter, that would indicate a mechanical fault in the meter movement.

Now, how that mechanical fault happened to have happened, well, that may involve other electrical components such as those diodes if the meter needle was slammed into that kind of stuck position.

On the other hand, if the needle only does its dirty deed when you are applying RF to the input, with a proper load on the output, then the finger points squarely at electronic component(s) failure only provided the needle returns to proper position when RF is not applied.


73

K4ZOT
06-12-2013, 12:15 AM
The needle has fallen to below the screw position when power was applied while tuning and it stays there with no power.

K4ZOT
06-17-2013, 05:43 PM
Solution - I took the case off and everything checked out OK. I then had a thought - I turned the tuner upside down and shook it and guess what the needle came out from underneath the screw it had fallen under. It now works fine. Why the needle collapsed with such force that it fell underneath the screw, I do not know. But, it works great now and the needles do not suddenly collaspe they just fall down slowly when RF is released.

KE3WD
06-17-2013, 08:47 PM
There ya go.

The old joke about the fellow who called the TV Tech in for an emergency house call right before the big game. The tech walks in, takes a look at the garbled picture for a second, then bends over and hits the set a good whack. And the picture is perfect.

Tech presents the customer with a $35.00 envoice.

"What? All you did was hit it!" stammers the customer.

"Let me break that down for you, sir." says our intrepid technician.

Hit Set --------------- $1.00

Knowing WHERE to hit set ---------- $34.00


Sounds like you performed a good repair there to me.


73