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Author Topic: FT757GX PROBLEMS  (Read 4158 times)
VE7ABC
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Posts: 29




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« on: August 14, 2010, 07:21:58 AM »

I was recently became the owner of a Yaesu FT757GX.  There are two problems with the radio, and I was wondering if help might be on board here.
Problem 1:  When you turn the rig on the display shows 7000.0.  Not a big deal I thought as I moved the VFO up frequency. Everything seemed normal, except for the 2nd problem.  I checked out the other functions of the rig, and all seems well.  Now, here is my problem.  When you shut the radio off, and then turn it back on, the rig returns to 7000.0, not the frequency it was on before you shut it down.
Problem 2:  The VFO is extremely stiff to move.  I loosed the adjustment screw on the bottom, but that did not make any difference.  I thought that the VFO shaft/bearing?? might need a drop of lube, but how does the VFO knob come off?  I took off the rubber ring and looked for a hole for a set screw but couldn't' find one.
Other than these two issues, the rig seems to work fine.  Any suggestions as to what the issues might be?
Thanks a bunch
Graham
VE7ABC
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KB3KWJ
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Posts: 8




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« Reply #1 on: August 14, 2010, 07:31:08 AM »

Dear Graham,

I have a 757 and on problem 1, the reason that the 757 returns to 7000.0 is that there is a flat button battery that needs to be replaced.  If you remove the top cover, your can see the battery(near the middle, towards the right side looking down).  The only pain is that the battery tabs are somehow attached to the button battery, in that I used an Xacto knife to get the tabs off the battery.

I hope that this helps.

John
KB3KWJ
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VE7ABC
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Posts: 29




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« Reply #2 on: August 14, 2010, 09:51:21 AM »

Thanks for the hint John.  I thought this might be the problem, as I had to do that for a Ten Tec Omni V I once owned.

I've just popped the top off, and see that there is a circuit board that is screwed on to it, and in the bottom half of the rig, there is of course another board you can see, underneath a perforated screen.  As I don't have the service manual, I want to tread slowly before unscrewing anything.  Which board is this battery on.
Thanks for your help.
Graham
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K7AAT
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Posts: 414




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« Reply #3 on: August 14, 2010, 09:53:04 AM »

  KB3KWJ is correct.  There is a "soldered in" memory battery in the FT757GX and it is probably dead.  The preferable replacement method would be to get a new battery from Yaesu  ( if still available )  and remove the old one.    The 'tabs' on those batteries are spot welded on.  I had not heard before of KB3KWJ's  suggestion of prying those spot welded tabs off the old battery and simply re soldering them to a new one, but it might be easier since otherwise you would have to remove the PC board to access the bottom to unsolder the old battery.

  Regarding your second problem,  this rings a dim bell .... I seem to recall VFO mechanism failures in some Yaesu radios in the past....  I would be strongly hesitant to put any kind of lubricant on that shaft .... I don't think it would help the problem, and it might make things worse if the lubricant worked its way into the opto-isolator tuning mechanism at the end of the shaft.  The best thing would be to replace the mechanism.... but may not be possible, or parts may no longer be available.   If I were you I'd Google and search for this specific problem in the FT-757.... there might be better help available out there on this specific issue.

  Good Luck  That's a nice radio ... I had one for several years long ago.

  Ed   K7AAT
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VA3GML
Member

Posts: 59




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« Reply #4 on: August 14, 2010, 12:22:37 PM »

Hi,

I have a 757GXII and had the same #2 problem.  Here is the fix:

http://www.eham.net/ehamforum/smf/index.php/topic,40565.0.html

Hope this helps.

ps - the knob is a press fit so I used 2 screwdrivers on opposite sides and 'popped' the knob off.
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KB3KWJ
Member

Posts: 8




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« Reply #5 on: August 14, 2010, 01:04:47 PM »

Graham,

I did exactly what Ed (K7AAT) stated.  After I got those tabs off I soldered those tabs to the new battery.  I remember it being hard to do and it was a sloppy job on my part.

Also, I forgot, I have the 757 Mark 2 so that might make a difference.

John
KB3KWJ
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VE7ABC
Member

Posts: 29




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« Reply #6 on: August 17, 2010, 11:17:55 AM »

My thanks to John, Ed, and VA3GML for your help.
I've fixed the stiff VFO problem.  What it was, was dry grease on the plastic bushing that is used basically as a brake drum.  I removed it, cleaned up the bushing and the band that is applied when you adjust the vfo tension, and all is now OK.  I applied a slight amount of (and I mean slight) an industrial grease to the band and the bushing.  Now the VFO is nice and smooth.  Grin The VFO knob on this radio pulls off.  I just applied a gentle, but steady pull to it, and it came right off.
I took pictures of the tension bushing and band, so if anyone needs these, email me at home, and I'll be happy to send them to you.
I'm waiting for the photos from John on where the battery is actually located, and then I'll tackle that problem.
Thanks again
Graham  VE7ABC
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