Doremi IMB battery

[Bob Ezra]

I'm preparing for the scheduled 5 yr. replacement of the IMB battery.
I have been studying the instructions and have one question.
The instructions say, " Check that the IMB has a valid identity".
I'm sure it does but I'm wondering where to find it.
The answer to this and any other tips would be appreciated.

I have a ShowVault server

Thanks

[Jim Cassedy]

I've done DoreMi battery replacements on several DCP-2000's , including
one personally own. I sort of recall that line in the instructions, and I just
assumed that if the IMB was working before the battery replacement, then
it most likely had "a valid identity"

[Leo Enticknap]

It just means to check that it didn't lose its certificate during the battery swapout. If you don't see any red ink in diagnostic tool > media block after the swapout and remarriage, you're good.

I believe that the official manual says that you have three minutes to do the battery swapout, but keep in mind that some of these units are now nudging a decade old, and therefore I wouldn't rely on the capacitor to last that long. I'd suggest preparing everything on the bench first, and without rushing and taking great care not to short the contacts during the swapout (place a drinking straw over the upper, spring loaded terminal) do the swap as quickly as you can.

[Dave Macaulay]

IMB on a Bench? I just undo the screws (and they are not the Barco captive screws, you have to screw them most of the way out), have the battery ready to do on top of the projector with a piece of plastic straw and plastic tool ready, switch power off, slide the IMB out a bit, take the slimy cover off, and switch batteries. Then clean the slime off with alcohol and replace the cover, slide the board back in and get the screws back in. Then power it up and see if it still works.
For DCP2000 with Dolphin, I do it with the server running. A tissue laid under the battery catches a dropped battery, then I change it.

[Bob Ezra]

Dave,
slimy cover?
the instructions make no mention of a cover.
I have a Barco DCP2k-12C with Doremi IMB and Showvault server ( which I assume should be off during the change)

you're scaring me with "and see if it still works"

[Leo Enticknap]

When they leave the factory, the battery holder has a plastic cover on top of it that often has some slimy goo on it: I've no idea what the substance is or why the cover is coated with it.

you're scaring me with "and see if it still works"

I'm afraid that there is always an element of risk in this procedure. If you do lose the certificate, the IMB will have to go back to Doremi for repair. The good news is that the Doremi IMB is one of the less risky for battery swapouts: I've never lost one. Anecdotally, it seems that the Dolby cat745 is the most risky.

[Marco Giustini]

Bob,
As Leo says, it's a process that unfortunately involves some risks. You can either leave the old battery in place and lose the certificates 100% after a while, or service the battery and have a x% chance of losing the certificates during the process - with x < 100.

I would definitely check with the manufacturer what the turnaround for re-serialising the board is before you attempt the swap.

[Carsten Kurz]

The Doremi IMB can still be reserialised. Yes, there usually is a rubber/silicone-type cover over the cell, but that is easy to remove and reapply. Make sure you let the projector run full power (obviously, bulb power not required) for half an hour or so while you prepare tools and have a whiskey before. After switching off, start the swap immediately.
Using a high gauge plastic straw over the top battery contact is indeed a good idea, and yes, you may leave the IMB half-way slid out in the card cage performing the operation, as the battery is towards the front right. However, I still recommend putting it on a bench (isolated surface), at least for the first/only time you do it.

Something very useful is to wear a now ubiquitous non-powdered rubber/latex glove on your good hand. It will give you a much better grip on the coin cell while moving it out and in, and it will prevent hand grease or sweat on the cell surface. As this is a rather thin coin cell, it is comparatively easy to slide it out and in, though.


Here are updated instructions by Dolby:

https://kb.dolby.com/CinemaKnowledge...ment-Procedure

[Bob Ezra]

I watched when the battery was first changed by a seasoned tech in 2017 . There was no " cover or slime" .
He popped the old battery out and put the new one in.
The straw is an interesting idea but it seems like it could complicate the short time frame.
Can someone elaborate on the straw procedure?

Carsten, thanks for the updated instructions, they are the exact same as the ones I'm using, except Dolby branded.
No mention or image of a cover or slime.

All of the feedback is much appreciated.

thanks

[Leo Enticknap]

I'm guessing that the cover was lost from your unit during a previous battery swapout if it isn't there now.

Starting from basic principles. Per DCI security rules, a decryption certificate unique to the IMB has to be stored in volatile (i.e. it needs an electric charge to maintain it) memory. When the IMB is powered down, the battery is what maintains that memory. If the certificate is lost, the IMB will not work, and again, per DCI rules, the certificate cannot be replaced in the field: the IMB has to be returned to a FIPS-certified facility for reprogramming. Some IMBs use rechargeable batteries that receive a charge while the unit has mains power, and then discharges when it is powered down. You never need to replace them, but you do need to make sure that they are powered up regularly. The Doremi IMB, however, does not: it uses a one-time battery, which therefore has to be replaced periodically.

The Doremi IMB contains a capacitor that maintains the memory for the short period of time when there is no battery present, while you are changing it. This means that there are two things you have to be careful about during the replacement process. 1 - not taking too long about it, or the capacitor will drain and you'll lose the certificate, and 2 - not shorting the two contacts in the battery holder, because doing that will discharge the capacitor instantly, with the same result. 2 is why it's a good idea to place a drinking straw over the positive (spring-loaded, upper) contact before sliding the old battery out, and then pulling it out once you have the new one seated. It removes the risk that the two contacts in the battery holder will accidentally touch each other, thereby shorting the circuit, once the battery is out.

[Marcel Birgelen]

The straw-procedure is made increasingly difficult by the fact that straws seem to be universally banned. I recently was looking for a bunch of straws, as the wife had a problem drinking cold drinks, that hit a sensitive spot inside her mouth. I guess I gave up after shop #5, no straws of any kind to be found, no plastic ones and also none of those horrible paper ones... Maybe it's a supply-chain problem or maybe it's because someone put straws on the blacklist, I don't know...

I ended up buying paper straws in bulk from the PCO Group...

[Leo Enticknap]

Ostensibly to reduce plastic waste pollution, California cracked down on them a few years ago, by making it illegal for restaurants to give you a straw unless you actively ask for one. You can still buy them in supermarkets, though. Or at least you could when I bought a packet of 50 or 100 quite a while ago for battery terminal insulation. I've now used, worn out and discarded around three of them, meaning that I should be six feet under by the time I run out!

Many years ago, I saw a tech looking for something to insulate a contactor temporarily during a troubleshooting process. He eventually went to the little boys' room, bought a packet of condoms from the machine, and used one of those.

[Carsten Kurz]

It is forbidden in the EU to introduce 'new plastic' to the market, but remaining stock can still be sold. Guess it's the same elsewhere.
But yes, you may be unlucky finding them now.
Fortunately, we have a bag of large gauge plastic straws left, enough for my remaining days in this business. It's not a strict necessity for this procedure, but, eveything that helps does help. Using the straw is a matter of a few seconds, it doesn't add much time.

[Bob Ezra]

Update

Changed the battery today.
The silicon cap was in fact there.
Did not use straw but needed 2 spudgers to get battery out.
After booting up and marriage, Diagnostic tool had lots of red and media block tab lots of empty spaces
Tried rebooting and, thank goodness, everything worked!

5 yr old battery measured 2.943v new battery 3.404v

thanks for the input

[Leo Enticknap]

Congrats - you were just in the nick of time. I can recall breakdown calls that I diagnosed as a Doremi IMB with a lost certificate, where I measured 2.91 and 2.89; and also one I successfully swapped out that measured 2.87. So yours was definitely on the borderline.