Canon T90 Back up Battery.

[theo_bern]

<p>Hello,</p>

<p>Can anyone please inform me where the f..k :) is that back up battery located?<br>

I've been through the complete service manual three ... yes three times !<br>

I came to a point that I think I am STUPID. I am having ISO 100 BLINKING and its definately from that little battery that keeps hiding herself from me .... LOL<br>

Here's the test: I put film in the camera and check the ISO to see if it is correct (manually set to ISO200, not DX coded film), then I removed the AA batteries for a few minutes and put them back in.<br>

Re-check the ISO, ISO changed and ISO 100 BLINKS. <br>

Any help would be VERY much appreciated. I know the camera performs OK BUT IT GETS TO MY NERVOUS SYSTEM :)<br>

Just for your info ALL that happened because I was not storing her with batteries on.<br>

This is the backup body, the one I use regularly never had a problem because I am keeping her loaded with fresh alkaline batteries always, both of them was serviced back in 2002.<br>

Thanks a lot.</p>

[User_502260]

<p>The back-up battery is mentioned on Page 108 of the manual. It is supposed to last five years and is not user interchangeable. If you contact Ken Oikawa or someone else who services T90s you might get some guidance. If I did not need the shutter speeds higher than 1/1000 or a built in motor I would be just as happy using a Canon FTb/N or EF. With the FTb/N I have all mechanical shutter speeds and the excellent 12 degree metering. The EF gives me the faster silicon meter cells and shutter priority automation. If I do need the higher shutter speeds and TTL flash metering I think I would just use a Nikon FE2. It seems to have aged better than the T90. I handled the T90 a few times and it has a nice feature set but I don't think I will want to get one. </p>

[JDMvW]

<p>In my T90 manual, the reference is on page 87, but here it is:</p>

<blockquote>

<p>2, Back-up Battery<br />The T90 has a built-in back-up battery which<br />memorizes the display panel data, such as<br />the frame counter number and the ISO film<br />speed, when the AA-size batteries are being<br />changed. Battery life is about 5 years. When<br />voltage becomes insufficient, "ISO 100" will<br />blink (at 2 Hz) on the display panel after loading<br />batteries for normal camera operations, If<br />the back-Up battery IS removed, the memory<br />will be erased. In this case, reset the film<br />speed.<br />Take your camera to the nearest Canon Service<br />facility for the replacement of the liquid crystal or<br />the back-up battery, (Replacement will be at<br />owner's expense.)</p>

</blockquote>

[Farkle-Mpls]

<p>It would be interesting to know what type of battery technology was used in the T90. I'm sure many others have the same experience, but my display has never blinked indicating the backup battery is dead. On one hand, I wonder if it still has some life in it but I also must admit a certain amount of disbelief that the battery could last 25 years.</p>

[jeffrey_winn]

<p>I bought a Canon T-70 in the mid 1980's. I needed to replace the internal battery after about two years. The new battery has been in my camera ever since, or about 24 years! I realize that the T-90 is a different camera, but these batteries last a very long time.</p>

<p>Jeff</p>

[JDMvW]

<p>On my T90, the display shows nothing at all without the 4 AA batteries in the body. With a freshly charged set of batteries, the display comes to life when turned on.</p>

<p>Now I am wondering whether one ought to leave batteries in this? Will the built-in back up battery drain if there are no regular batteries in it? Hmm.</p>

<p>In some of the discussion on-line, it is mentioned that the battery is soldered in in the wiring above the prism? I wonder.</p>

[Farkle-Mpls]

<p>John and Jeff,</p>

<p>I just tested my two T90s. I turned them on, set different Tv values, set ISO to 160 and pulled the battery tray out. Left it out for several seconds, then replaced the tray. The Tv value was retained as was the ISO setting. <br>

I'm not electronics expert but I assume there is either a capacitor holding a small charge for several seconds/minutes between battery changes or there is some life left in the back-up battery. Dunno. Interesting and an impressive design feature nonetheless.</p>

[thomas_goehler]

<p>My T90 back up battery has also been in use for 20 years now without ever being changed. It is as far as I know a Lithium CR25, that is used. It is only needed to save the settings, it is not needed for the proper workflow of the camera.</p>

[rob_van_straten1]

<p>Reading a servicemanual several times finaly found the battery located on the flexboard above the prism. According to another document it's supposed to be an BR-1225 or CR-1220.</p>

<p> </p>

[JDMvW]

<p>Thanks Rob, that was what I had seen, but couldn't remember where.</p>

[theo_bern]

<p>Thanks Rob,<br>

Finally nailed that WELL KEPT Canon secret. It is a BR-1225.<br>

Soooo happy. Problem resolved but it was a bit tricky as this little thing was soldered.<br>

Thank you so much for all your responses.<br>

Photonet ROCKS !</p>

[barryreid]

The T90 is a great camera. Makes me think it's time I put a roll through mine again.

[mark_stephan2]

<p>I know I'm a little late with this reply but I asked the same question about my nFD 28 f/2 and this was the discussion. <a href="00OOd9">http://www.photo.net/canon-fd-camera-forum/00OOd9</a></p>

[User_4136860]

<p>It's about twenty five years since the T90 was made, it's amazing that so many of these batteries have lasted so long when they were supposed to last five years.</p>