Cobra 148 GTL PC-416A A Meter Malfunction

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thundir
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Cobra 148 GTL PC-416A A Meter Malfunction

Post by thundir » Sunday 15th Mar 2009, 4:45

Radio Make and Model: Cobra 148 GTL
PCB Number: PCB-416AA
PLL Number: MB8719
Test gear available: Astatic 600 3 way power meters, MFJ 1.5KW Dummy Load. Voltage Test volt meters.
Symptoms: Meter Malfunction. Non Responsive

What is working: Everything.

What has been tried: Removed meter and tried adjusting the Tiny meter set screws.

Did it suddenly happen ?: Was bought yesterday with this Malfunction.
The Problem is the meter does not function. It lights up but no movement at all even when she is keyed up. I noticed the meter was stuck about 3/4 of the way up and was able to bring her back down. Still nothing. Tried moving the fine tiny adjustment on the actual meter but still No response on transmit or receive. Other than that the radio works great. Any Ideas on what can be causing this Malfunction? Thanks Guys :banghead:

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The Defpom
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Re: Cobra 148 GTL PC-416A A Meter Malfunction

Post by The Defpom » Sunday 15th Mar 2009, 11:43

You need to find out if it is an electrical or mechanical issue, so measure the voltage that is feeding the meter when you TX, if there is voltage but no movement then the meter is stuck.

Usually undoing BOTH the tiny screws 1/2 a turn or so will free it, sometimes you need to go further than that, one trick is to TX whilst you do it, so the needle is trying to be moved as the same time, if unscrewing them does not get it moving, then you will probably need to install a new meter, also be careful, as the two little screws are the pivet points of the needle, if they are unscrewed too far the needle will become dislodged.

thundir
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Re: Cobra 148 GTL PC-416A A Meter Malfunction

Post by thundir » Sunday 15th Mar 2009, 11:56

Thank you. I will check this tonight. I'm going up the roof to install coax on my base antenna. Just finished the soldering. Thank you. Will keep you posted on my findings......................John.........

thundir
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Re: Cobra 148 GTL PC-416A A Meter Malfunction

Post by thundir » Monday 16th Mar 2009, 17:44

Hi,
Update. There is no voltage being supplied to the meter. Wires to meter are white and Black. No Volt reading . Please any Ideas................? :banghead:

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Re: Cobra 148 GTL PC-416A A Meter Malfunction

Post by The Defpom » Tuesday 17th Mar 2009, 14:21

Check to see if there is any voltage in the CAL mode, and the S/RF mode, it could be bad wire on the S/RF/CAL/SWR switch.

The S/RF and CAL functions get the feeds from different places, I would be surprised if they have both failed.

It may also be a good idea to use the earth track of the main PCB for the 0V pickup, just in case the 0V wire is broken to the meter.

thundir
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Re: Cobra 148 GTL PC-416A A Meter Malfunction

Post by thundir » Tuesday 17th Mar 2009, 15:34

Thanks Scott. I will check on it. Someone said that the voltage supplied to the meter is so little that my volt testers wont read the value. Nevertheless we are going to check on it. I have a new meter on its way. Best wishes to you and thank you for being with me on this. Will report back with any new findings...........................................Cheers................John.

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