Sony ST-JX520 not keeping presets

[Jim H B]

I have a Sony ST-JX520 tuner, mid or early 80's I believe. Not a bad tuner, but won't keep memorized stations memorized.

It has a main power button, and below it a green stand by button. The idea is that you don't turn the main power off, you just put it on stand by, and that is how the memorized stations are maintained.

But, even on stand by, it will lose the memorized stations after a few hours.

What would cause this?

Thanks for any help!

Jim

 

[qboneus]

there's a small rechargeable battery in there that needs to be replaced.
Tal

 

[Jim H B]

Thanks Tal.

Any idea where to get a replacement battery?

I know I'll need the specific information for this battery, but I was wondering, in general, where to find this kind of battery.

Jeweler; ie, someone who has watch batteries?

Jim

 

[qboneus]

I just picked the one I replaced in the Yammie R-2000 -a 3.6 v 65ma nicad up at a local electronics supply, odds a RS has them as well the yammie originally had a 3.6 50ma but I couldn't find the 50ma locally so I upsized to the 65ma.
No biggie, pretty easy fix-odds are that your old one has all the neccesary specs printed right on it.
Good luck.
Tal

Didn't even think of it when I needed one but I bet if you have a batteries plus they'll have one.

 

[Punker X]

Sometimes tuners use a super cap to hold a charge for a long time and supply the voltage to keep the memory. If a batter isn't visible with you open it up, you may have to find a manual.

X

 

[Jim H B]

Thanks guys, I'll open it up and see. Hopefully, a battery. I imagine those super caps are probably more expensive.

Jim

 

[qboneus]

yeah looks like mouser has supercaps for about 5 times as much as I paid for the nicad.
Tal

 

[Jim H B]

It's always something...

Well, I took the cover off, and sure enough there was the battery, lying face up. 3 volt lithium battery, a little bigger around than a nickel, but not as thick.

But it's held in by a little metal clip, almost like someone holding a cd between their thumb and forefinger. The battery is bonded to the clip. I don't see a bead of glue, but it is somehow bonded very tightly to that clip.

I barely got a razor blade between the top clip and the battery, but couldn't get it in very far.

Am I SOL? It seems like I have to replace the clip and the battery together, after somehow detaching them from the pcb.

What a crappy design. My analog tuners are looking better all the time...

Jim

 

[PMik]

I have owned a Sony tuner ...same batt. with weldered attachment. :thumbsdn:

I did locate a defect PC Motherboard and de-soldered the BU-batt. socket and mounted the socket in the tuner...the BU-batt. was by little effort become end-user serviceble :thmbsp:

 

[Jim H B]

Thanks, Pmik

 

[sky_tech]

Replacing battery on Sony ST-JX520

If you are still watching this post (you asked way back in 2004), I can help. I just replaced the same battery on my ST-JX520. There are a few approaches. First off, yes, it's soldered in, so first you will want to unsolder the old one. If you work carefully you don't have to remove the PCB. Just remove the front panel unit (3 screws) and fold it over the top of the tuner. Do be careful, though, that the sharp heatsinks don't scratch the top of the front bezel as you lay it back over the unit.
Use a good soldering iron with a moderate sized tip (the pad on the bottom of the board are big and the battery tabs also draw away a lot of heat). Heat the edge tab (the one that starts on the top of the battery and wraps around) while lifting that edge of the battery until the tab is free from the PCB. They heat the other tab and remove the battery. Now use solderwick or a vacuum-plunger solder-removal tool to remove the solder that's blocking the hole (you can use the vacuum-plunger removal tool from the top while heating the bottom. Then, to install a new battery your options are:
1) Buy an exact replacement with tabs (available from various suppliers - search for CR-2025 tabs or see below).
2) Add a battery holder along with a standard 2025 or 2032 battery (either will do). I went this route, but mounting the battery holder took a little bit of creativity for the holder I had. You can get ones with wires and just tape it up and set it somewhere.

CR2025 with tabs:
Renata 614-CR2025FH-LF from Mouser Electronics:
http://www.mouser.com/Search/ProductDetail.aspx?qs=%2bJ68kkgkfTrYGMMNh4BxJg==
or other suppliers
http://www.weisd.com/store2/DANCOMP-31-1.html

CR2032 with tabs for vertical mount. This actually looks like it will fit the mounting holes better and vertical mount is fine:
http://www.mouser.com/search/ProductDetail.aspx?qs=5D6tm72Z2%2bnF72f6fy0RlQ==