Yamaha T-7 tuner - replacement memory battery

[radine]

I recently took delivery of a T-7 and it needs a new battery for the station presets.

I opened the case and I think that it is an Ni-Cd AA battery with solder tags. It is marked 1.2v 450 mAh.

Could someone please confirm if it is indeed soldered in place rather than just a standard battery clipped in position. I didn't want to force it.

Would this Ni-Cd battery be a suitable replacement or would I be better off using a Ni-Mh replacement instead?

Thanks in advance.
Paul

 

[N8Nagel]

Theoretically a LSD NiMH is better but it may not last as long because of the slight difference in ideal charging curves. NiCD is the safe choice. Either should work fine for years so just flip a coin

 

[radine]

Thanks much appreciated. So it is soldered in place. Glad I didn't apply any force. Can I presume that there is no problem in replacing a 450mAh with a 1000mAh battery?

 

[Dingman]

As long as the voltage and fit is the same, it will be OK. It's not a standard battery, like a CR2023?

It's bitch to get the new battery soldered in, the case doesn't want to adhere to the solder.

 

[N8Nagel]

going larger in capacity should not be an issue. It might take longer to charge up to 100% but not a big deal.

 

[radine]

be aware there is usually a cap that keeps the presets and it can fail, causing loss of presets, even when the battery is still good.

.

Thanks for your replies. Much appreciated.

With regard to the cap for the memory, my presets work fine as long as the unit is powered on. Is this an indication that the cap is still functioning as intended?

 

[Dingman]

.

Thanks for your replies. Much appreciated.

With regard to the cap for the memory, my presets work fine as long as the unit is powered on. Is this an indication that the cap is still functioning as intended?

EDITED

 

[Blue Shadow]

@Dingman was the cap you needed to replace after changing the battery in a Yamaha T-7? Did you install a freshly recharged battery when you did that step?

I have seen units that use a cap, usually a low voltage say 5V and high capacity like 0.22F (notice no µ in front of the F), yes .22 Farad which is 220,000µF. And I have seen units that use a battery. I didn't see a large capacity battery in the circuit for the T-7 but the schematic isn't from Stereomanuals.com and was free on the web so it isn't as clear as it needs to be.

Can you fill us in on the cap that needs replacement if the battery repair in the T-7 does not fix the station memory?

 

[dksp]

Hi radine, I used this NiCd Battery in my T-7 (found at a local battery/electronics shop). As you can see it's a 940 mAh, and it works fine. I didn't have to change a cap. When installing the new battery, don't forget to respect the right polarity. The + is pointing towards the transistor with the little heatsink..

 

[Dingman]

Nope, it wasn't a T7, it was a Sony tuner that I had to replace the cap.

 

[Blue Shadow]

nicely done dksp. Good shot of the install and info for polarity.

 

[Dingman]

yes, I shouldn't have commented without knowing the cap\battery setup for this unit. I edited my post.

Battery it is!

 

[BuddhaBob]

I put 1.2V NiMH in my T7 and it's been working well for over a year. I clipped the old one away carefully, leaving the leads soldered to the board, then soldered a new one in place between the old leads. Silicone rubber compound to hold the battery in there firmly.

 

[Blue Shadow]

Silicone rubber compound to hold the battery in there firmly.

Hope the unit does not receive the kind of treatment needed to warrant that hold down clamp. Something is needed and that seems like a good solution.

 

[dksp]

So, radine, any luck ?

 

[radine]

So, radine, any luck ?

Yes. I decided that this job was beyond my limited skill set. I got my tech to put in a battery holder and a new high capacity battery. In future a battery change will be much more straightforward. Very happy with the sq of the tuner and loving the presets.

 

[dksp]

Fine, that's a very good idea. Do you have a photo of the battery holder installed?

And thanks

 

[radine]

Sorry I don't. When I take the Yammies out of rotation in a couple of months, I will open it up and post back with pics.

 

[Blue Shadow]

This one is not hard. Install a battery holder wherever you want and attach wires to the proper locations where the old battery was installed. Positive on the battery holder to the positive location where the old battery was. Same with negative to negative. Location of the battery holder is not critical. It can be glued, double stick taped, wire tied, or bolted in place. But WAIT there IS MORE...a site with PICTURES that has done this already!!! Can't get much better than that other than maybe it could be in English but google translate will take care of that to some degree.

http://www.riric.jp/electronics/repair/T7.html

HTH

 

[radine]

Finally I got around to taking a picture of the battery holder in situ.