# Back from the grave: Casio BM-100WJ (long post)



## vrolok (Oct 23, 2007)

Among digital watches, one of my all-time favorites is Casio BM-100WJ (or BM-100J for the US market), i.e. the ancestor of ABC watches. This milestone is dated February 1989 in the Casio website:










It has a pressure sensor, which -as usual nowadays, and a real novelty back then- can work as altimeter and provide weather forecast. Importantly, the sensor is here used also as a depthmeter. Correct me if I am wrong, Casio has never used this combo (alti/depth) again. There were a few versions: all black (the first one); black w/ yellow pushers; black w/ yellow front mask and pushers (Japan market); dark green w/ black pushers.

On July 1990, I bought my all-black BM-100WJ and I was as happy as a clam! I have enjoyed that "magical" nerd watch till '94 or '95, that is when I enrolled into College and I have got to know a wee bit of the physics of semiconductors. And&#8230; curiosity killed the cat&#8230; I had to have a closer look at that pressure sensor&#8230; and after taking it out and playing with it&#8230; broke down, and forever gone. Damn it o| I remember I threw the sensor away. So sorry :-(

For 15+ long years, I had my watch hiding in a drawer. In the meantime, the batteries died and the strap decomposed. End of story? Naahhh :roll:

I did want it back, not just another BM-100WJ. It had to be that one and only, and fully working. First, I tried replacing (actually, installing) the sensor using another one I got from a (similar) BM-610. It is really amazing how ubiquitous these sensors are&#8230; but no&#8230; They actually share the same package but characteristics do differ. I then contacted Casio Support without success (of course, this watch is too old), and Fujikura Technical Service, i.e. the company which produces and provides (even nowadays) solid-state pressure sensors (and more) to Casio. I directly wrote to the Japanese headquarters, and in less than 24 hr I got an informative reply from a very competent and friendly engineer. Unfortunately there is not much they can do, he wrote: "I suppose you can not repair your watch by yourself even if you could change sensor part. Because each sensor needs the calibration process to match the sensor performance for LSI in the watch." &#8230;and the engineer ended up writing: "I believe you are good CASIO's customer and your watch is so happily that it was used for long time." He is a great guy! 

FYI, here's a picture and technical scheme of the sensor I was looking for:









Oh well, let us start again and use another approach. :think: I was lucky enough to find another old BM-100WJ having a working module (at least presumably, because the batteries died long time ago), and got it for a very cheap price. Furthermore, I bought a (hard-to-find) original NOS strap from an ebay US seller, and luckily also its NOS back gasket from a Casio shop in my city, together with new batteries. Yes&#8230; life is so beautiful! :-!

Here's the show, for you guys.




























Look at the four little springs in the bottom-front face of the module, which are the current-voltage contacts for the sensor:










Ok, let's swap the sensor(s)&#8230;










Removed the sensor holder:









Both naked:










Between the sensor and the watch case, there is a small circular seal gasket. I took it out to find that it was/is in very good condition. After a wee of silicon grease, I did put it back in. And after adding the sensor, the other module, and sealing the watch with the back plate and the new gasket&#8230;

YES, IT WORKS |>










Finally, the new-old-stock shoes&#8230;










Let me take from the drawer its original box, user manual, warranty card, tag&#8230;










Great, isn't it? 

Since this is an ABC forum, a picture of my "new" shining BM-100WJ together with my other fantastic and fully working ATC-1000, i.e. first triple-sensor, that I bought in 1994 (here I did not mess up with the sensors ;-) ):










Finally, it is just my opinion but&#8230; pressure sensors have not changed much in 20+ years. All basic functions were and still are there. My "modern" GW-9200 Riseman seems to happily agree:










Thanks for reading :thanks


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## Beau8 (May 24, 2008)

Pretty interesting renovation~Great job! ;-)


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## under-wear-taker (Feb 15, 2009)

vrolok said:


> Among digital watches, one of my all-time favorites is Casio BM-100WJ (or BM-100J for the US market), i.e. the ancestor of ABC watches. This milestone is dated February 1989 in the Casio website:
> 
> 
> 
> ...


are they calibrated? theres a difference between them :think:


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## vrolok (Oct 23, 2007)

under-wear-taker said:


> are they calibrated? theres a difference between them :think:


I would have been surprised if there were no differences :-d
Nope, no other calibration than the factory default.
Anyhow, you better look at the relative readings /trends, that I can assure you they are identical.


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## under-wear-taker (Feb 15, 2009)

vrolok said:


> I would have been surprised if there were no differences :-d
> Nope, no other calibration than the factory default.
> Anyhow, you better look at the relative readings /trends, that I can assure you they are identical.


I´d love to see a comparison with the modern ABC watches since thermoconpensation is a know problem in PROTREK family and very discussed ;-)


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## vrolok (Oct 23, 2007)

under-wear-taker said:


> I´d love to see a comparison with the modern ABC watches since thermoconpensation is a know problem in PROTREK family and very discussed ;-)


Dude, this has nothing to do with thermocompensation! Besides, there's no thermometry in this model ;-)

As far as thermocompensation concerns... some time ago, I did my own very simple "test", with a few Casio ABC watches as well as the Riseman, from the ATC-1000 to a PRG-80. Test was very simple: room-temperature reading, followed by another reading rigth after keeping the watches for a couple of hours in a fridge! I've got some funny results... And speaking of old guys... the ATC-1000 did not change the altimetry reading at all :-!


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## MandoBear (Apr 7, 2010)

I'm really pleased you got your BM-100WJ working again. I have one which I got new in 1989 - all black. It still works pretty well and I love the look of it. I used it in the mountains for quite a few years - it was (still is) a fantastic alti. 

One thing to be aware of though is that the silver oxide button cells can leak and damage the watch (when they're run down) - they're more prone to this than the lithium cells in later watches. I noticed this when I was taking the old batteries out of my BM-100WJ - they had just started to "sweat" a little. No damage done, but if I'd left them a month or two longer, I think it would have been a different story. I've also got the ALT-6000 which is a pretty cool early twin-sensor watch too - and still has better log book functions than almost all of the modern Pro-Treks.

Enjoy your BM-100WJ!


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## ThomAsio (Feb 26, 2010)

MandoBear said:


> I've also got the ALT-6000 which is a pretty cool early twin-sensor watch too - and still has better log book functions than almost all of the modern Pro-Treks.


I got an ALT-6000, and YES, the logging is great - I mis that on my Riseman, along with the easy-to-access-steel-buttons ! The Riseman got other advantages, though. But to be honest, I thought it was time for retirement of my ALT-6000, when I got the Riseman back in january - but now I think I'll restore the ALT-6000 someday... It has something, partial sentiment, which makes me want to keep it in good shape.

And the story about this Casio BM-100WJ, is inspiring - thanks b-)


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## ThomAsio (Feb 26, 2010)

vrolok - great work, creative too  Thanks for sharing, you've almost got me started for restoring my previously mentioned ALT-6000 :-!

Yeah, the alti/depth combo aint so usual - here's the only other I know of: SPF-60-1AVER - CASIO Sport - Watch - Products - CASIO


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## vrolok (Oct 23, 2007)

ThomAsio said:


> Yeah, the alti/depth combo aint so usual - here's the only other I know of: SPF-60-1AVER - CASIO Sport - Watch - Products - CASIO


Thank you ;-)


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## Ron5555 (Jan 2, 2011)

Hi Vrolok,

I also have this watch
is still oke but the strap is gone.
Looked on the internet but can't find one...

Any advice where i can find an original?


Thanks
Ron


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## Yang1815 (Aug 4, 2008)

Sure brings back memories. I had an ATC-1000 just like that!


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## srf52 (Nov 23, 2009)

Very well done! An excellent post with superlative text and pics. Congratulations!!


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## DragonJade (May 14, 2007)

Wow. I've got one of those, too. Also with a busted sensor. I'd love to get it up and running again. It's still fully functional otherwise. It was the second Casio watch I've ever owned, and I've had this for absolutely years. I had to beg my dad for ages before he'd buy it for me. It was really expensive, I remember. Something like £50 or £60. Not a small amount of money for when the watch first came out.


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## Tommygunn (Jun 20, 2008)

Vrolok,
Very nice restore job, congratulations. Really like the vertical gauge on this watch.

You mentioned in your opening statement that you had not come across another Casio that combined an Altimeter with a Depth meter. My BM-500W does indeed have those features but I think it may be the last of the line because the ALT-6000, which I believed followed very soon after, and as we know, does not have a depth gauge feature.










Cheers,
Tom.


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## isometrus (Apr 29, 2010)

A great warrior.RESPECTWHERE CAN I BUY THE ATC-1000 AND BM-500:think::-s


Tommygunn said:


> Vrolok,
> Very nice restore job, congratulations. Really like the vertical gauge on this watch.
> 
> You mentioned in your opening statement that you had not come across another Casio that combined an Altimeter with a Depth meter. My BM-500W does indeed have those features but I think it may be the last of the line because the ALT-6000, which I believed followed very soon after, and as we know, does not have a depth gauge feature.
> ...


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## wolw (Jan 1, 2012)

My BM-100WJ has been without a battery for quite some time, never wore it very much either. I bought it together with a ALT-6000 in '92, finding the ALT-6000 much nicer (read cooler b-)) I never used it more than when I dived.
I though it was about time to get it going again, everything worked with a new battery. A OEM band is expensive and hard to find, but I wanted it to look stock. So I took a look at the BM-500 band, looks are close to identical only it used 20mm springs instead of 18mm. Only needed a little trim, ~0.8mm each side and a small cut to access the spring

It would seem the BM-500 is thicker, I had to put in a bit of the old band to make the band stand out and be more comfortable to wear.

Peter


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## Silverstreak09 (Oct 5, 2011)

That is a thing of beauty. Nerd heaven. I want one.


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## vrolok (Oct 23, 2007)

For those looking for a new original vintage strap... few available here:
VINTAGE CASIO ORIGINAL STRAP BM-100 NOS | eBay 
cheers


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## jerseydan31 (Sep 27, 2015)

(bump on this thread...)

....anyone can confirm the the BM-500 strap will work on the BM-100W(J)? Need to give mine a good and matching tuxedo!

THX!


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## Lawer (Dec 29, 2017)

Great pictures!


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## Zzdudaka (Feb 16, 2020)

do you have instructions on how you removed the internal workings/module from the case? I'm have trouble getting it to come out and don't want to break it.

thank you.



vrolok said:


> Dude, this has nothing to do with thermocompensation! Besides, there's no thermometry in this model ;-)
> 
> As far as thermocompensation concerns... some time ago, I did my own very simple "test", with a few Casio ABC watches as well as the Riseman, from the ATC-1000 to a PRG-80. Test was very simple: room-temperature reading, followed by another reading rigth after keeping the watches for a couple of hours in a fridge! I've got some funny results... And speaking of old guys... the ATC-1000 did not change the altimetry reading at all :-!


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## Nemo_Sandman (Oct 28, 2014)

Zzdudaka said:


> do you have instructions on how you removed the internal workings/module from the case? I'm have trouble getting it to come out and don't want to break it.
> 
> thank you.


Do you know what a zombie thread is ?


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## vrolok (Oct 23, 2007)

Zzdudaka said:


> do you have instructions on how you removed the internal workings/module from the case? I'm have trouble getting it to come out and don't want to break it.
> 
> thank you.


Sorry for my slow reply... Hope you didn't break anything! Anyhow, can't really remember. But I don't think I used any special trick. Cheers

Enviado desde mi POCOPHONE F1 mediante Tapatalk


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## vrolok (Oct 23, 2007)

Nemo_Sandman said:


> Do you know what a zombie thread is ?


I am still alive 

Enviado desde mi POCOPHONE F1 mediante Tapatalk


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## Radiolarian (Oct 18, 2017)

Great post! I came across your Casio's journey while searching for the odd shaped gasket for this watch.

I just pulled my BM-100W out of the drawer and plan to get it running again. Years ago, I remember opening the caseback and taking the movement module out. When I put it back in, something was flashing, so I thought I bent one of the 4 springs. This was probably 20 years ago.

The original strap isn't in the drawer. Can't remember if it was shot or simply misplaced. I still have the original gasket, separate from the watch case, so I'll just reuse it since it seems to be in one piece.

I discovered the batteries (Energizer 395) were still there. Popped them out and luckily saw no visible signs of corrosion. I'm off to the store for a couple 395 batteries. I'll try the all clear reset procedure and hope for the best.

Turns out, I forgot to get some batteries so I'll have to tinker with this watch later this week, but here's a pic of the parts.


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## Radiolarian (Oct 18, 2017)

Fresh 395 batteries but it has ERROR flashing. That's what the issue was years ago. ?

Does anyone know how to fix this ERROR?

Thanks!


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## acinr_PL (Oct 11, 2018)

I have got the same watch. I bought

new original front bezel
original bm100 watch band
new original sensor
I moved the sensor and all module to a new front Casio bezel. I reset module at point AC with + from battery. Barometer and altimeter doesn't works. The watch displays "FULL". Does anyone have any idea how can I clear the watch memory?


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## bagel_byte (Dec 14, 2020)

@vrolok Do you remember the part number for the Fujikura sensor, there are two options FPBS-04A or the FPBS-82A? Thank you


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## vrolok (Oct 23, 2007)

bagel_byte said:


> @vrolok Do you remember the part number for the Fujikura sensor, there are two options FPBS-04A or the FPBS-82A? Thank you


Sorry cant help you, can't remember and don't have any note left anymore. Cheers


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## Gabort (May 9, 2021)

vrolok said:


> Among digital watches, one of my all-time favorites is Casio BM-100WJ (or BM-100J for the US market), i.e. the ancestor of ABC watches. This milestone is dated February 1989 in the Casio website:
> 
> 
> 
> ...


Hello, I have a Casio BM100 WJ and the sensor is not working. Do you think a Casio BM500 module 943 sensor can serve? They have the same user manual.


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## Gabort (May 9, 2021)

bagel_byte said:


> @vrolok Do you remember the part number for the Fujikura sensor, there are two options FPBS-04A or the FPBS-82A? Thank you


I think the correct sensor is FPBS-04A, its measurement range is: 62.1 to 434.7 kPa
The pressure measurement range of this watch is: 61 to 105 kPa
I have searched for this sensor on the internet but I cannot find it


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## Fabrizio Calaresu (Feb 11, 2015)

Is there a compatible casio bm-100 strap? The BM-500 strap is too large and does not fit well.
I tried the strap of the MRW-200 it is perfect but it does not touch the caseback and having a small wrist is not good ... do you have any ideas?


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## danielsacristanpolo (9 mo ago)

acinr_PL said:


> Tengo el mismo reloj. yo compré
> 
> nuevo bisel frontal original
> correa de reloj original bm100
> ...


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