Fluke 123 Scopemeter and battery replacement

[Dbldutch]

Be aware of the Cameron Sino battery packs.

I have one, the CS-FBP120SL, and it simply does not work in my 123. It comes with the yellow NTC lead connected to a normally unused pin (1 or 5) on the connector and that is the only position the scope will boot. If you connect the NTC lead to the proper pin 6, the boot procedure is terminated, and the scope will not work, not even with the wall wart connected.

You can identify this battery pack by the lack of the second black wire, instead, there is a yellow one, which is used for the NTC connection. Although it says on the battery pack that it uses NiMH cells, there is no resistor in the identification link, so the scope treats it as a NiCAD pack. The bad part is that with the NTC lead going to an unused pin, the scope will not charge this pack. I have modded the pack and added the 825 Ohm resistor, but without success.

If you have a working pack, better yet an original one, can you please measure the NTC resistance at room temperature, or identify the partnumber?


I just ordered another pack, from another supplier, and from the picture, it seems to have the proper wiring.

[Dbldutch]

I have a follow-up on my previous post.

After looking long and hard to find a pack that was not coming from the apparently unreliable Cameron Sino stables, I found one that I ordered from 123accu.nl in the Netherlands.

From the pictures, it was clearly not coming from CS, and judging from what I could see of the connector, it had two black wires, so I ordered it. It just arrived, so I quickly got my DMM switched on and measured the resistance of the NTC and the ID wires against ground. The ID showed the presence of the 825 resistor, and the NTC showed about 12K (the pack was still cold from the transport). The voltage was about 5.1V, so I smelled success.

Although the connector had another (red) wire going to the unused pin 5, I installed it in my 123, and it switched on perfectly with only the battery connected.

Unfortunately, there is no manufacturing information on the pack, only a part number : B11483
It is a NiMH pack, with 4.8V, 3000mAh/14.4Wh, just as it supposed to be.

In the box I even found two black foam strips to replace the two already in the 123, which is a nice touch.
On the 123accu.nl provided box, it clearly states this is a Fluke BP120MH / B11483 / BP120 accu.
Of course these 123's are made in the Netherlands, but in any case, they have the right product.

The version number of my 123 readws V01.08, and is from 2000.
This also means that the refresh rate is still showing 12 hours, but at least is recognizes the pack as a valid one.

Now I need to build me an optical cable and see if I can update the firmware to the latest version that my hardware version will support.

I'm happy, and I hope you can use this information to get your 123 up-and-running as well.

[umkumiut]

Now I need to build me an optical cable and see if I can update the firmware to the latest version that my hardware version will support.

From Fluke's website: "Instruments with firmware version V1.0x cannot be upgraded to V2.03"
V1.08 is the latest from the 1.xx family, so there is no further update.
The foam strips are indeed a nice addition, mines already started to decompose (my instrument is from 1998)...

http://en-us.fluke.com/support/software-downloads/fluke-scopemeter-123-124-series-version-2-firmware-upgrade.html

[Dbldutch]

Hi Umkumiut,

1998?, you must have one of the earliest models!
My version is already at V01.08, so no chance to update the firmware, thanks for the hint.
I am building an optical interface anyway to connect the 123 to a computer and get access to the data.

Regards,

Paul

[abid0011]

 i buy individual battery cells each cell is 4000mah 1.2v
 the battery pack with the fluke 123 is 2000mah.
 
when open the original battery pack i remove the top covered pvc to copy the wiring connection i saw some two thing connected.

can i remove  the old wiring and solder to the new battery cells as on the fluke battery pack.

need suggestion .

thank u

[mucek]

Here's my mod for LiIon battery (based on info in this forum) as well as replacing CCFL lamp with LED backlight. The difference is enormous! Now F123 is easily readable in every condition! There is plenty of images with description ...

http://iksor.si/en/2017/04/03/fluke-123-modifikacija-na-liion-in-led-osvetlitev/

Regards,
Gregor

p.s. We are still working on our webpage, especially english one is pretty "lonely" ... Don't look too much around

[abid0011]

thanks for reply.

as u say this unit is pretty old.
what do u think fluke 123 vs the fluke 87v or 88v multimeters.

does the fluke 123 better than these two millimeters

thank u

[mucek]

You can't compare those two! F123 is Scopemeter, which is an oscilloscope and digital multimeter in one unit, when 87 (and similar) are "only" multimeters. I do owe also F279 and I try to avoid it, as it takes quite some time to startup. I use F179 instead usually.

Regards,
Gregor

[rsivan]

Here's my mod for LiIon battery (based on info in this forum) as well as replacing CCFL lamp with LED backlight. The difference is enormous! Now F123 is easily readable in every condition! There is plenty of images with description ...

http://iksor.si/en/2017/04/03/fluke-123-modifikacija-na-liion-in-led-osvetlitev/

Regards,
Gregor

p.s. We are still working on our webpage, especially english one is pretty "lonely" ... Don't look too much around

very interested the led mod!... also  for nice schematic with my mod,unfortunately cannot try led mod because selled my F123 6 months ago to a friend which very happy with,
I got a discount from supplier for F125B (colors model) and I could not resist....I'm very happy with, this time no need hack (for now), battery life is good and already li-ion

[abid0011]

hi i replace the fluke 2000 mah with the 4000 mah battery.
what i did is i remove the wired connection from the original battery pack and installed on the 4000 mah 1.2 volts 4 cells.

now the problem is after charging the battery the battery drains very quickly.
does the battery need completer refresh .
when select the refresh option it shows 12 hours.

any suggestion.

thank u

[carl_lab]

Is your 4000mAh battery NiMH type? NiMH has a significant self discharge.

Which time does it take to completely self discharge?

[abid0011]

suppose I put the scope for charge 5 hours.

yes the battery type is 4000 mah Nimh
when I power on the scope the battery will discharge with in 30min and the x sign shows on the batter icon.

[carl_lab]

I don't know, if there's a timeout limit for charging time, or not, but if it is, your batteries will not full charged.
5 hours charging at 400mA will charge your battery only 2000mAh (or 50% of 4000mAh).

Here's a link to mod charge current from 400mA to 800mA to overcome possible timeout limit:
http://iksor.si/en/2017/04/03/fluke-123-modifikacija-na-liion-in-led-osvetlitev/

Can you charge your battery externally from a laboratory power supply, RC charger or similar to 8,4V?
Then test operating time of your scope to shut down.

[abid0011]

thank u for reply.

need one suggestion.
i am a electrician and now i start learning electronics as hobbyist.

fluke 123 is a scope meter dual multi meter with scope.

the fluke have black line on display and also facing problem with the battery.

i am thinking to sell this unit or keep it in my storage. and buy a fluke 28-2 or 87 - v multi meters.

question is  that fluke 123 worth to spend time to make it perfect and what u think as we know its old unit still better in  functionality then the above mentioned meters.


thank u

[carl_lab]

Fluke 123 (or 99) is a scopemeter, not only a simple multimeter as the others you mentioned.
It is a portable, isolated (!) oscilloscope, that also can be used as a multimeter.
A multimeter only is useless if you have to watch waveforms.

Keep the scopemeter and buy an additional multimeter, if you need more accuracy or functions as continuity beeper, capacitance, temperature etc.

PS: additional static lines on LCD is probably a contact problem between PCB and LCD. Can you show a photo?

[none]

I have an 123 on FW 1.08 (earlier model, late nineties, 20 yrs old!) and rebuilt the battery pack with Sanyo NiCd batteries (KR-1800SCE) once, but that did not last very long and I have since been running the scope on power adapter only. I'm digging this up because I've always been interested in fixing this, and now I need to be able to use the scope on batteries. This will either be a DIY NiMH pack or maybe even Lithium. I'll try to recap and add more info in the hope it may help others.

There used to be a forum/discussion on http://www.flukecommunity.com/forums/showpost.php?p=6844 "123 battery pack, difference BP120 <-> BP120MH?" with some information on the battery pack by someone looking for the NiMH ID resistor. They seem to mix up their links regularly, the new forums are now called "Fluke Nation" and seem to be outsourced to http://flukecorp-cx.custhelp.com/app/utils/login_form - however, this now seems to be inaccessible without registration/login. The thread now is at http://flukenation.com/posts/9d37b58388. Another, more recent one, "BP130 battery" at http://flukenation.com/posts/32b879babc.

Back to the charging:

The charging circuit and procedure are very well described in the ScopeMeter Service Manual. There are a few different versions of the manual, but the power/charging section overview seems to be mostly identical. The 2003 version has added information about the battery packs and ID resistors:

Two different battery packs are possible: as a standard Fluke 123 is equipped with a Ni-
Cd battery, Fluke 124 has a Ni-MH battery that allows a longer operation time. Both
instruments will also function on a battery pack different from the standard type. The
installed battery type is read by the D-ASIC via BATIDENT/BATIDGAR (pin B5): for
Ni-Cd there is 0 ? between BATIDENT and – of battery, for Ni-MH this is 825 ?.

Battery pack models:
BP120 - original NiCd -obsolete-
BP130 - Battery Pack NiMH for ScopeMeter 124 -obsolete-
BP120MH - NiMH Battery Park for Fluke 123, Fluke 43 and 43B - The BP120MH replaces the earlier models BP120 and BP130 alike. SKU 2544081: $129.99 (https://www.flukeonlinestore.com/products/batteries-and-chargers/battery/bp120mh-rechargeable-battery-pack-for-43-43b-123)

No mention of the 123 V1 with last FW 1.08 supporting/using the NiMh ID-resistor so far.

Firmware Upgrades
http://www.fluke.com/fluke/uyes/support/software/ScopeMeter_Firmware_Upgrades.htm
http://en-us.fluke.com/support/software-downloads/fluke-scopeMeter-123-series-version-1-firmware-upgrade.html

V1.08 changes do not mention battery support, I can't find changelogs for earlier firmwares.

How the charging works (see service manual):

Nominal battery voltage: 4*1.2 V = 4.8 V ("If no battery pack is installed, VBAT is approximately +15V.")

The power/charge supply is a 100 kHz switch mode regulator in the P(ower)-ASIC, which in turn is controlled by D(igital)-ASIC.
Charge conditions/cycle:

• Battery Voltage (VBAT, via BATVOLT) <5.2V (is this a typo and it should be 4.2 V?), Battery temperature 10..45 °C
• 500 mA until dV/dt, up to 6 h (fast charge)
• 200 mA 2 h (top off)
• 60 mA trickle up to 48 h

The lower limit seems to be 4.0 V, the instrument then enters OFF mode (see "3.2.5 Start-up Sequence, Operating Modes").

Safety measures:

• both ASICs monitor temperature, bimetal switch shuts off at 70°C.
• "The P-ASIC limits the voltage VBAT to 7.4V via its internal Control circuit.  This situation arises in case no battery or a defective battery (open) is present." This voltage is probably set by R513 / VBTHIGH.

Thoughts on the Lithium battery hack

Regarding user rsivan's mod starting at https://www.eevblog.com/forum/testgear/fluke-123-scopemeter-and-battery-replacement/msg279033/#msg279033
They modified VBTHIGH to 8.2 V, doubled the charging current by halving IBAT sense shunt resistor, and modifying the voltage feedback BATVOLT.

Lithium batteries are charged constant current followed by constant voltage, determined by absolute cell voltage:
https://www.digikey.com/en/articles/techzone/2016/sep/a-designer-guide-fast-lithium-ion-battery-charging

Without modifications, a single lithium battery cell (3 ... 4.2 V) would be overcharged, but 2 in series might not have that problem, as the charger hardware supposedly limits the voltage to 7.4 V (just about the nominal 2*3.7 V, so quite a lot of headroom, but not using the full battery capacity [by far]).
However, they would be discharged down to 4 V (2V)!

Can the lower level be modified, too?
 
User rsivan has determined threshold levels for the battery voltage with regard to battery indicator and shutdown, though the theory does not seem to match their value:
  0.95 V for battery X icon ((0.95/0.67)+3.27 = 4.687)
  0.8 V for shutdown threshold ((0.80/0.67)+3.27 = 4.464)

rsivan gives 5.9V for their battery warning threshold, so (5.9-3.27)*0.67 = 1,7621.

The calculation is derived from service manual section "7.5.3 Slow ADC"
"BATVOLT (N501 pin 78), must be {0.67 x (VBAT-3.27)} Volt.", (Measure VBAT on TP504 = N501 pin 3), so:
  (7.4-3.27)*0.67 = 2.7671
  (4.8-3.27)*0.67 = 1.0251
  (4.0-3.27)*0.67 = 0.4891

Something is off!

Regardless of the 4V shutoff treshold, the  +3V3GAR linear regulator is always on, draining the battery (slowly). Assuming a 0.65V V drop by the transistor, we're also at just below 4 Volts minimum (there still might be current drawn by the regulator and/or other parts that are constantly connected).

So for lithium batteries it seems one would need to rely on the charger's overvoltage cutoff (instead of dV/dt), but also on the batteries protection circuit's shut-down function to disconnect the battery at undervoltage, though I don't know how the charger circuit reacts to that and how the protection circuit would "recover":
  Overvoltage -> Battery protection disconnects -> Vbat rises to 15 Volts (?) as power control assumes there is no battery
  Undervoltage -> same if battery appears to be disconnected.

Any input on this appreciated.

The battery types on Wikipedia :
https://en.wikipedia.org/wiki/Nickel%E2%80%93cadmium_battery
https://en.wikipedia.org/wiki/Nickel%E2%80%93metal_hydride_battery
https://en.wikipedia.org/wiki/Lithium-ion_battery

[gowniak13]

i will keep updating this post from time to time.

I just purchased old fluke 123 with original ni-cd batteries in.. and im looking to upgrade them, monitoring this thread, any update or progress for ultimate solution Mr. noone ?

my 123 has 1.04 software... upgrading to 1.08 wont change anything, anyway;

from my research for now the best Ni-Cd cells to use are; Sanyo n-3000cr, i havent seen Ni-MH yet but i still dont understand some things, like for example charging circuit inside the scopemeter, i have already read some post saying that putting Ni-MH cells inside f123 are not doing the job, is that because f123 is not designed to use Ni-MH cells ? i mean 'using' as also process of recharging them inside scopemeter, charging current between Ni-Cd and Ni-MH should be different, right ?, yes i know, i will read service manual later on..., the problem is that i dont want to modify pcb yet cause it doesnt seems to be stable enough for a long run(?).

No mention of the 123 V1 with last FW 1.08 supporting/using the NiMh ID-resistor so far.

[Dr. Ka]

Not sure if this still interests somebody. Nevertheless, I have just completed the LiIon-Mod. It had a NiCd battery before that was empty, whenever I needed it...

Here are my thoughts: 

Charging

User none has mentioned the charging process:

500 mA until dV/dt, up to 6 h (fast charge)
200 mA 2 h (top off)
60 mA trickle up to 48 h

A LiIon battery does not show a dV/dt dip, therefore the charging process reduces to constant current charging for up to 6h (with a limited maximum voltage).

I have measured the charging current, in my device it is 480mA. My LiIon cells should be fully charged within 6 hours, but I wanted to reduce charging time...
As user rsivan suggests, I have added 3x1R  resistors (1206 SMD) in parallel to R504/R506/R507 to double the charging current.

"If no battery pack is installed, VBAT is approximately +15V."

I read that too in the manual, but elsewhere it says: "The P-ASIC limits the voltage VBAT to 7.4V via its internal Control circuit. This situation arises in case no battery or a defective battery (open) is
present."  The measured value in my device was 7.58V. This is the highest voltage, the charger provides to the circuit and battery (independent if battery is installed or not). In no case, the Vbat voltage rises to 15V!

As user rsivan suggests, the value can be modified by altering the value of R513. I desoldered the original 26.1k resistor and replaced it with a 28.7k one (0805 SMD). In my case the charging voltage (VBAT) is now limited to 8.3V.

I use 2 LiIon cells. with these two modifications, I have constant current charging (960mA), but the charger limits the battery voltage to 8.3V (4.15V per Cell). Should be OK for my Lithium cells! In case something happens, I still have the battery protection circuit to prevent overcharging.


Discharging

The P-ASIC converts the battery voltage into the signal BATVOLT, which is digitized by the SlowADC. The conversion is given in the manual (as user none mentioned): BATVOLT= 0.67 x (VBAT-3.27)

After some experiments, I discovered the following behavior with my device:

• If the battery voltage drops below 4.54V (BATVOLT 0.85V), the battery empty symbol (x) appears in the display.
• If the battery voltage drops below 4.00V (BATVOLT 0.49), the device can be switched on (display goes on), but immediately powers-down again.
• If the battery voltage drops below 3.10V, the device cannot be switched on.

The observed values are different from the values stated by user rsivan, but my observations seem reasonable. For the original 4Cell NiCd battery-pack, battery low is displayed at cell voltage 1.135V and and the device is powered down at cell voltage 1.0V.

User none states:

Regardless of the 4V shutoff treshold, the  +3V3GAR linear regulator is always on, draining the battery (slowly). Assuming a 0.65V V drop by the transistor, we're also at just below 4 Volts minimum.

The linear regulator is a low-dropout regulator, and does not need much voltage overhead! That's why my observations show the 3.10V limit, below which the device cannot be switched on. But the general observation is correct, it is slowly draining the battery. That  is probably the reason why my NiCd batteriy is always empty...

As suggested by user rsivan, I added a voltage divider to the BATVOLT signal path, to adapt the voltage limits. The output impedance of the P-ASIC was measured with about 15kOhm. I thus used a 100kOhm to 68kOhm divider to modify the voltage seen by the slow ADC. The measured voltage is thereby scaled by a factor 68/(68+100+15). With this modification, the battery low signal is now displayed at about 6.66V and the device is powered off at about 5.24V. I have a 2 cell LiIon configuration, the device is thus switched off at a cell voltage of 2.62V.

However, the +3V3GAR linear regulator keeps draining the battery with some mA... In this case I rely on the battery protection circuit, which disconnects the battery if a cell voltage drops below 2.5V. From this time on, the battery protection circuit only allows charging of the cells, but no further discharging.

When the charger is connected, it starts charging the LiIon pack with a maximum voltage of 8.3V. When the cell voltages of my battery pack reach 3V, the battery protection circuit returns to normal operation (charging and discharging allowed).


Until now, my modifications seem to work as expected!

[DMM123]

Guys, I've been trying to get the thermistor part number and the part number for the "fuse" for the BP120 battery pack (NiCad).  Not able to find the part numbers or the values listed in the Fluke service manual.

Anyone know the value of the thermistor or the "fuse"?

I am building a NiCad pack for my 123 and have no info to work with.  Any help appreciated - thanks!

[none]

@ Dr. Ka
Yes, thanks for sharing. I have two LIS1441 in the SM123 and just dug out this thread to see what I did last time around. I have a 2S balancer/protection board (https://github.com/megasaturnv/HX-2S-JH20-JH10-reverse-engineered_aka-2S-10A-Balance-Li-ion-Protection-PCB/) that I want to add, since last time I noticed the batteries becoming unbalanced. I'll have to see how this works out, since the batteries appear to have an integrated protection already.
I have currently not planned to modify the ScopeMeter, at the cost of wasting battery capacity and slow charging, of course.

@ DMM123
I think the information about thermistor and fuse is somewhere in this thread, or on the Fluke forums (try the links I posted previously) - I've seen it before.

EDIT:
These threads might be of interest:
https://www.eevblog.com/forum/testgear/usb-powered-fluke-123/
https://www.eevblog.com/forum/testgear/fluke-123/ (power supply)

[DMM123]

@ DMM123
I think the information about thermistor and fuse is somewhere in this thread, or on the Fluke forums (try the links I posted previously) - I've seen it before.

EDIT:
These threads might be of interest:
https://www.eevblog.com/forum/testgear/usb-powered-fluke-123/
https://www.eevblog.com/forum/testgear/fluke-123/ (power supply)

Thank you, but I still don't see the thermistor value (beta), the part number, or the range of the thermistor in temperature.  I have contacted a thermistor manufacturer and given them 40 measured values at different temperatures with the kOhm readings on the old battery.  I will post what they say.

[Jcm05]

Hello,

My Scopemeter does not work after battery exchange.
After seeing verified I found a polarity reversal of + and - on the battery.

This has caused a short internal circuit to my scopemeter and it does not work even connected to the power supply.
The 3 resistors R504, R506 and R507 have burned.
I replaced them but he still does not work.

Have you ever encountered the same problem and what is the solution?

Thanks for your help.

[DMM123]

@ DMM123
I think the information about thermistor and fuse is somewhere in this thread, or on the Fluke forums (try the links I posted previously) - I've seen it before.

EDIT:
These threads might be of interest:
https://www.eevblog.com/forum/testgear/usb-powered-fluke-123/
https://www.eevblog.com/forum/testgear/fluke-123/ (power supply)

Thank you, but I still don't see the thermistor value (beta), the part number, or the range of the thermistor in temperature.  I have contacted a thermistor manufacturer and given them 40 measured values at different temperatures with the kOhm readings on the old battery.  I will post what they say.

Well, so far no answer.  I've emailed a couple of times but no response.  Initially they said they would have an answer in a couple of weeks.  Patience, I hope, is the key.

[iurius]

Thank you very very much!

[alwanuel]

Hi, would you please consider a YouTube video, what you did is really useful, please consider to share it properly. Cheers.