Cobra 2000 GTL meters again

[Deleted]

I got a Cobra 2000 with meter issues. Works fine other than the meters. It appears neither is responsive. I know these have problems with sticky meters, but am wondering is there is a diode or cap that goes bad in it. The schematic shows a cap in series with the meters.

[Sandbagger]

Aug 29, 2009 11:39:49 GMT -5 @vinnies said:

I got a Cobra 2000 with meter issues. Works fine other than the meters. It appears neither is responsive. I know these have problems with sticky meters, but am wondering is there is a diode or cap that goes bad in it. The schematic shows a cap in series with the meters.

So are you asking if there is something other than the meter movements themselves which may cause this problem? You can test the meter movements by measuring them with a VOM. Older style analog VOM's put out enough voltage that they will usually peg a meter on the RX1 scale, and give a slight deflection on the RX10 scale.

The Cobra 2000 is notorious for meter movement problems, but you should see some movement from at least one of the meters. If not then look at the common ground lead and trace the wiring. You can always use a "test" meter scavanged from a junk radio as a substitute to test the circuit out.

[2600]

It's usually a mechanical problem inside the meter movement. The pivot just gets stiff. If you pick up the radio and spin it 45 or 90 degrees around the pivot axis of the meters, you'll see the needles move if they are free.

Loosening the pivot-tension adjusting screw through the hole in the rear of the meter will sometimes free them up. Trouble is, there's a dab of clear enamel on that screw and its tiny locknut. I have destroyed more than my share of jeweler's screwdrivers trying to turn one of those.

The only fix being offered for hire seems to be from folks who have a compatible NOS replacement meter with the wrong scale. They remove the plastic scale from the 'new' old-stock meter, and replace it with the scale from your old, dead meter.

Besides, if I had ready-to-install replacement meters for the Cobra 2000, I'd hold out for all the money I could get on Ebay or some such. They are THAT rare. On the other hand, if they didn't generally go bad, replacements would be a lot easier to find, I suspect.

The meter used for the Drake R-7 and TR-7 is close. The window is about a sixteenth of an inch shorter. Requires a tiny bit of trimming to the scale removed from the Cobra meter to make it fit. Once it's in place, you can't readily tell that it's different from the exact original.

It's possible that an electrical problem would keep one of them from moving, but not both. The seized pivot is by far the most-common cause.

73

[Joe]

If you find the meters are stuck using the VOM and you can't get them unstuck, you can always purchase new ones here. They are not cheap but they are not going to cost any less in the future. Both are available, this is just the link to one of them.
I bought a Robyn watt meter for the three meters in it to use as replacements. Just need to swap the scales and they are perfect replacements. I like the meter though so I am hoping mine don't go bad and I can use the watt/swr/mod meter for awhile.

stores.goldeneagleradios.com/-strse-694/Cobra-2000-GTL-1000/Detail.bok

[**GRUMPY**]

R&R Communications in Wilmington,Delaware also has them. You're not that far from them Tick, you could drive there and pick them up.

R&R Communications

Just scroll down to near the bottom of the page, price is $30.00 each!

[Deleted]

Thanks. I am like 2 minutes from them. $30 is about the going rate. Barket has them, too.

However, I was given permission to tear the old ones up, on the assumption that they are shot, so there is no loss in ruining them.

[Tombstone (R.I.P.)]

If you use your soldering iron and SLIGHTLY heat the slug that 2600 talked about you can usually turn it SLIGHTLY and back it off. I've loosened the stuck meters like this.

Tombstone

[Deleted]

I think I have figured out a way to free the meters. I tried the screw adjustment. Didn't work (did in past, not this time). So opened the meter and removed the cover. I took a needle nose plier and pulled on the bracket that the spindle sits in. I seem to have broken the seize. Both meters were frozen and both came loose. In the picture, put the needle nose on the straight part of the bracket (where the blue dots are) and pull. After I freed the seize, I tighted the screw until the meter stuck again, then I back off slightly until it freed.

You remove the scotch tape at the bottom of the cover, and the cover flips up. I used new scotch tape to close the meter. I also added a drop of WD-40 using a surgical needle witha dull tip. I did that more as a preventive measure for seizing in the future.