Lithium Battery CMT 64Kb
09-10-2018, 12:12 PM (This post was last modified: 09-10-2018 03:15 PM by KimH.)
Post: #1
 KimH Member Posts: 150 Joined: Jul 2018
Lithium Battery CMT 64Kb
Hello all 71B friends

Recently returning here to see what is there for the 71B, which is my favorite when it comes to Mods - I have a stack of working "gutted" 71's (it almost always start with a battery acid clean up) traces resoldered and so forth (no pun on FORTH).

I play with the signals/bus to make the unit do things it wasn't really planned to do. The most obvious to Daisy chain modules on breadboards, just for fun, learning how the bus handles.

Next project is to build a sort of mini I/O - a mini 82166 with 8 bits through a latch - simple, but fun.

BUT

I have one of the great CMT 64KR Memory Modules, the one with the tiny Lithium BackUp battery.

Amazingly it still carries a charge of 3,2 Volt, but for how long.

Does anyone know where this battery can be found - purchased?

Best regards

KimH
09-10-2018, 04:49 PM (This post was last modified: 09-10-2018 04:51 PM by Zaphod.)
Post: #2
 Zaphod Member Posts: 270 Joined: Apr 2018
RE: Lithium Battery CMT 64Kb
Is a primary (non-rechargeable/single use) or secondary (rechargeable) cell do you know ?

This is rather crucial.

If you can give the dimensions also, there are many tag batteries you could use (with the proviso above)
Example of a small secondary type (which you could wrap) :
https://uk.farnell.com/seiko-instruments...0001322136
09-10-2018, 04:56 PM
Post: #3
 KimH Member Posts: 150 Joined: Jul 2018
RE: Lithium Battery CMT 64Kb
Hi Zaphod,

Thanks for your response, I have been rumaging on various sites to find something, but to no avail.

It is 16*34mm and about 2mm think (can't use the calipper, it would short-circuit the battery).

Any help/direction is appreciated

Best regards

Kim

(09-10-2018 04:49 PM)Zaphod Wrote:  Is a primary (non-rechargeable/single use) or secondary (rechargeable) cell do you know ?

This is rather crucial.

If you can give the dimensions also, there are many tag batteries you could use (with the proviso above)
Example of a small secondary type (which you could wrap) :
https://uk.farnell.com/seiko-instruments...0001322136
09-10-2018, 05:03 PM
Post: #4
 KimH Member Posts: 150 Joined: Jul 2018
RE: Lithium Battery CMT 64Kb
Forgot - Single use

(09-10-2018 04:49 PM)Zaphod Wrote:  Is a primary (non-rechargeable/single use) or secondary (rechargeable) cell do you know ?

This is rather crucial.

If you can give the dimensions also, there are many tag batteries you could use (with the proviso above)
Example of a small secondary type (which you could wrap) :
https://uk.farnell.com/seiko-instruments...0001322136
09-11-2018, 12:21 AM
Post: #5
 rprosperi Super Moderator Posts: 5,197 Joined: Dec 2013
RE: Lithium Battery CMT 64Kb
This topic comes up about once per year; sadly sources for these batteries have never been found. They have no writing on them, no manufacturer's makers, etc.

I even contacted CMT (they are still in (a very different) business); they could offer no help except to say it's likely they are available on eBay or Amazon. While I can understand this is generic advice which is most often true, did they really think one would not look there before tracking down an obscure small company in Oregon... but I digress?

Have you come up with some kind of replacement for the zebra connector inside a 71B? If so, I'd say there is very real market demand here as lots of machines have been damaged by leaks and can be found on eBay, etc. for not too much (unlike the real ugly listed now for $1299 LOL). --Bob Prosperi 09-11-2018, 08:21 AM Post: #6  KimH Member Posts: 150 Joined: Jul 2018 RE: Lithium Battery CMT 64Kb Hi Bob, thanks a lot for that insight - it helps me to not bother finding the "Perfect" solution, but to get creative.. Let's see what I find out. Regarding the ZEBRA, I simply use thin WireWrap, soldered onto the PCB pads. Not elegant, but it works - I have yet to experience one that broke. I am not sure I have seen the$1299 version you mention, is there a link to something, which you can share?

/Kim

(09-11-2018 12:21 AM)rprosperi Wrote:  This topic comes up about once per year; sadly sources for these batteries have never been found. They have no writing on them, no manufacturer's makers, etc.

I even contacted CMT (they are still in (a very different) business); they could offer no help except to say it's likely they are available on eBay or Amazon. While I can understand this is generic advice which is most often true, did they really think one would not look there before tracking down an obscure small company in Oregon... but I digress?

Have you come up with some kind of replacement for the zebra connector inside a 71B? If so, I'd say there is very real market demand here as lots of machines have been damaged by leaks and can be found on eBay, etc. for not too much (unlike the real ugly listed now for $1299 LOL). 09-11-2018, 12:57 PM Post: #7  rprosperi Super Moderator Posts: 5,197 Joined: Dec 2013 RE: Lithium Battery CMT 64Kb (09-11-2018 08:21 AM)KimH Wrote: Hi Bob, thanks a lot for that insight - it helps me to not bother finding the "Perfect" solution, but to get creative.. Let's see what I find out. Regarding the ZEBRA, I simply use thin WireWrap, soldered onto the PCB pads. Not elegant, but it works - I have yet to experience one that broke. I am not sure I have seen the$1299 version you mention, is there a link to something, which you can share?

Thanks. I have seen using wirewrapping all the leads individually, and know a couple folks that have done that, but many (most?) of us don't have those skills and am always looking for a solution that 'normal' folks (i.e. without excellent soldering skills) can use.

If you would be willing to do that repair as a (paid) service for other users, I'd say there are probably at least a few takers here...

The ugly 71b that has suffered quite serious battery spill damage I mentioned is here:

https://www.ebay.com/itm/HEWLETT-PACKARD-71B/192653679533

Why it's priced at $1299 is anyone's guess, though the seller will find out soon enough that won't work, despite it having a naked CMT Card Reader port memory module installed. Pics and description don't reveal what is in the front ports, but pretty unlikely they could bring the value up that much, whatever they are. --Bob Prosperi 09-11-2018, 01:13 PM Post: #8  KimH Member Posts: 150 Joined: Jul 2018 RE: Lithium Battery CMT 64Kb (09-11-2018 12:57 PM)rprosperi Wrote: (09-11-2018 08:21 AM)KimH Wrote: Hi Bob, thanks a lot for that insight - it helps me to not bother finding the "Perfect" solution, but to get creative.. Let's see what I find out. Regarding the ZEBRA, I simply use thin WireWrap, soldered onto the PCB pads. Not elegant, but it works - I have yet to experience one that broke. I am not sure I have seen the$1299 version you mention, is there a link to something, which you can share?

Thanks. I have seen using wirewrapping all the leads individually, and know a couple folks that have done that, but many (most?) of us don't have those skills and am always looking for a solution that 'normal' folks (i.e. without excellent soldering skills) can use.

If you would be willing to do that repair as a (paid) service for other users, I'd say there are probably at least a few takers here...

The ugly 71b that has suffered quite serious battery spill damage I mentioned is here:

https://www.ebay.com/itm/HEWLETT-PACKARD-71B/192653679533

Why it's priced at $1299 is anyone's guess, though the seller will find out soon enough that won't work, despite it having a naked CMT Card Reader port memory module installed. Pics and description don't reveal what is in the front ports, but pretty unlikely they could bring the value up that much, whatever they are. Wauv... I don't think even I could wake this one up looks like it was run over by a truck as well. Interesting what is posted. This one is another good example: https://www.ebay.com/itm/Rare-HP-71B-3-C...Sw3opbVgVs I would be delighted to offer my service, but since I don't live in the US, there would be extensive shipping and even customs/duties to deal with - the Germans are quite particular on anything with more than "nominal Value". /KimH 09-11-2018, 03:42 PM Post: #9  Zaphod Member Posts: 270 Joined: Apr 2018 RE: Lithium Battery CMT 64Kb (09-10-2018 04:56 PM)KimH Wrote: Hi Zaphod, Thanks for your response, I have been rumaging on various sites to find something, but to no avail. It is 16*34mm and about 2mm think (can't use the calipper, it would short-circuit the battery). Any help/direction is appreciated If you’re sure it’s a single use (primary) cell , then you just need to source a tagged lithium battery of suitable size. (Don’t try and solder to a non-tagged battery) A ~3V lithium battery is a ~3V lithium battery. (The only difference is the capacity , a bigger battery will last longer) If you didn’t know, the Battery number of a CR style lithium battery gives you the dimensions: So a CR2032 is 20mm diameter and 3.2mm thick , a CR1620 is 16mm diameter and 2mm thick etc etc Although I can only see a 20mm diameter in primary (tagged) cells , maybe I’m not looking hard enough. The only other option is buy a non-tagged one, fit it in a holder , then wrap it to insulate it. http://www.smallbattery.company.org.uk/s...alogue.htm If it was rechargeable , there’s an even smaller one (12mm diameter and 2mm thick) https://cellpacksolutions.co.uk/products...d-battery/ 09-11-2018, 04:37 PM Post: #10  ijabbott Senior Member Posts: 1,091 Joined: Jul 2015 RE: Lithium Battery CMT 64Kb (09-11-2018 03:42 PM)Zaphod Wrote: (09-10-2018 04:56 PM)KimH Wrote: Hi Zaphod, Thanks for your response, I have been rumaging on various sites to find something, but to no avail. It is 16*34mm and about 2mm think (can't use the calipper, it would short-circuit the battery). Any help/direction is appreciated If you’re sure it’s a single use (primary) cell , then you just need to source a tagged lithium battery of suitable size. (Don’t try and solder to a non-tagged battery) A ~3V lithium battery is a ~3V lithium battery. (The only difference is the capacity , a bigger battery will last longer) If you didn’t know, the Battery number of a CR style lithium battery gives you the dimensions: So a CR2032 is 20mm diameter and 3.2mm thick , a CR1620 is 16mm diameter and 2mm thick etc etc Although I can only see a 20mm diameter in primary (tagged) cells , maybe I’m not looking hard enough. The only other option is buy a non-tagged one, fit it in a holder , then wrap it to insulate it. http://www.smallbattery.company.org.uk/s...alogue.htm If it was rechargeable , there’s an even smaller one (12mm diameter and 2mm thick) https://cellpacksolutions.co.uk/products...d-battery/ It may also be worth looking on Alibaba for something that has the tabs in the right place: https://www.alibaba.com/showroom/cr1620-...-tabs.html — Ian Abbott 09-11-2018, 05:25 PM Post: #11  rprosperi Super Moderator Posts: 5,197 Joined: Dec 2013 RE: Lithium Battery CMT 64Kb (09-11-2018 01:13 PM)KimH Wrote: Wauv... I don't think even I could wake this one up looks like it was run over by a truck as well. Interesting what is posted. This one is another good example: https://www.ebay.com/itm/Rare-HP-71B-3-C...Sw3opbVgVs That same listing has been around literally for years, with price ranging between$1999 and \$5999. Seller just keeps fishing for the right buyer. Must be a patient guy....

(09-11-2018 01:13 PM)KimH Wrote:  I would be delighted to offer my service, but since I don't live in the US, there would be extensive shipping and even customs/duties to deal with - the Germans are quite particular on anything with more than "nominal Value".

OK, good point for non-Europe-based folks, but there could be folks in Europe seeking repairs too.

Also, I've been quite lucky shipping things to/from Germany for repair with no customs fees at all. Maybe I just got lucky... I just mark them as they are - "No Commercial Value".

Thanks

--Bob Prosperi
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