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Author Topic: HELP!!!! Replacing the memory battery on FT-757GX  (Read 902 times)
WY4J
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Posts: 112




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« on: February 12, 2007, 05:51:00 PM »

I'm not sure this is a fix but someone suggested a battery replacement might correct the problem. The rig transmits and apparently receives as the needle in the S meter moves as the frequency is changed but the audio is totally DEAD. I have owned this rig for the last 22 years so I am familiar with its operation.

For sure the lithium memory battery on my Yaesu FT-757GX has died as the display will not save any previous info. I have already opened the rig and taken the battery out and left the pins in place so I would not have to take the rig completely apart. Radio Shack sells the CR-1/3N Lithium replacement battery, but my problem is finding the battery holder or even a battery that has the leads so I can solder it to the pins coming out of the pc board.  I have searched the Web and have not been successful in finding any place that sells the battery holder. I know is old but so am I. Still, this is a nice little radio. Any help would be appreciated.
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KC8VWM
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Posts: 3121




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« Reply #1 on: February 12, 2007, 06:03:45 PM »


Replacement coin battery holder for lithium batteries.

http://www.eemb.com/PDF/Holder.pdf


Is this what you are looking to replace inside your radio?

Hopefully, I am not missing some other relevant point you are attempting to make in your question.

73 de Charles - KC8VWM
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W6VPS
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Posts: 369




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« Reply #2 on: February 12, 2007, 06:20:43 PM »

You got 90% of the solution from Charles. The rest of the swap will probably requite wire from the PC board battery pins to allow for placement of the battery holder in a convenient spot inside the rig. Wrap the battery holder in some foam rubber and you can just lay it inside the rig.
Paul/W6VPS
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KC8VWM
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Posts: 3121




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« Reply #3 on: February 12, 2007, 06:58:38 PM »

Incidentally I wouldn't worry much about the particular battery part number you are currently using inside the rig when replacing the coin battery holder. I would focus on getting one that would function as it's voltage equivalent. For example, I would installed a more common coin battery holder that would perhaps accomodate the same one they use in computers such as a 3 volt CR2025 coin battery.

The battery inside your rig (CR-1/3N) is also rated a 3 volts however it seems the battery design is quite "beefy" in size (160 mAh) to the thinner CR2025 (170 mAh) coin battery. However it seems the mAh ratings are higher in the smaller battery despite the difference in physical size for some reason. The CR 2025 is probobly newer battery technology.

However it may be less specialized, cheaper to purchase ($5.99 compared to $4.99 "Radio Shack"), more common to find and easier to replace.  

For example, I think if I were reinstalling the battery holder, I would probobly rewire it and glue a new coin battery holder (#BH1001) permanently in place to an open space on the back of the rig so I wouldn't have to take the rig apart for easier battery replacement in the future.

However, Paul's earlier suggestion is just as valid and just as fuctional.

73 de Charles - KC8VWM
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WY4J
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Posts: 112




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« Reply #4 on: February 13, 2007, 01:58:18 PM »

Thank you very much for all the info. Now waiting for the mail to arrive with the goodies. I guess that I got so caught up in finding an exact holder for the original battery that I did not think of a 3 volt cell button replacement.

73's de WY4J
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N6AJR
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Posts: 9910




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« Reply #5 on: February 13, 2007, 02:21:16 PM »

on some of the older computers we used to have  this was a common problem, so we put a plastic rat shack battery holder in the back of the computer ( velcro or double sided sticky tape) and put in 4 alkaline batteries ( looking for 5 volts) and ran the wires inside. you could probably stick a 2 hole'r back there and run 2 aa's and find them easy to replace..
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WB6BYU
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Posts: 13336




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« Reply #6 on: February 13, 2007, 09:12:56 PM »

The button cells like the CR2025 typically have a much higher internal
resistance than the CR1/3 type.  Many lithium cells have a maximum
rated current draw and it may be only 1ma for the button-type cells.
That may or may not be an issue here, depending on what the peak
current draw is.

I think I got holders for the CR1/3 type from Mouser.  Actually I think
I ended up getting a single AA holder and trying to put two CR123
cells in it, but they didn't QUITE fit.  However I can cut the holder in
half and mount both pieces to a board to get 6V in the space of a single
AA cell.  You may find some AA holders they will fit in.
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