# A4Tech Bloody RT7 Repair report (lazy sunday)



## silentbogo (Jan 7, 2018)

Hi everyone!
I figured I'd start sharing some random repair logs from my workshop, cause I have no other hobbies, and someone might find this useful (maybe not today, but decades from now).
I'm too lazy to do extensive youtube videos, so we'll go with some mundane stuff like pictures, diagrams and text 
_Plus, I don't have a good camera..._

Maybe this info will be useful or at least interesting to someone, so don't throw any rotten tomatoes, and just enjoy some boring reading materials.

Today on my surgical desk I found a brand new Bloody RT7 wireless gaming mouse with an unusual factory defect: it did not properly sense the charge of the internal battery and always reported it as empty.
It worked fine when hooked up to the charger, but once disconnected - the indicator drops to 0%, the mouse starts to blink fast (indicating low charge), and shuts down within a minute.

This is what it does when connected to PC:



Here's the mouse, already disassembled:


It's a fairly standard layout for a "slightly-above-average" wireless  mouse. It has the same old NRF24L01 controller for wireless communication (used in anything from cheap $2 laptop mice to high-end Logitech G-series wireless mice), also has an entry-level AVAGO A3050 optical sensor and a SONIX USB HID controller. Brief initial inspection showed that everything on the PCB is powered from a built-in 2.8V step-down converter, which made my life easier in finding the sensing circuit (should be the only part besides charging IC that is connected directly to the battery).

My first suspect was a faulty battery, but my multimeter said otherwise: it was almost fully charged and did not show any signs of malfunctioning.
After a wasted minute of poking and prodding random stuff with my multimeter I finally found the sensing part.
I say "wasted", because afterwards I found an ADC testpoint on the flipside of the PCB, made specifically for dumbassess like me... 
 
_Also, notice my contraption for holding a probe on a ground pin  I was using my other hand to hold the phone..._

Basically,  it uses a voltage divider to sense the current from the battery and keep this signal under 2.8V:


As you can see, R30 and R31 form a voltage divider, and for some reason engineers at A4Tech added a bypass capacitor, which is totally pointless cause there should be no significant voltage spikes or jitter on this line (there are already too many caps near the battery and charging circuit to take care of this problem).

From the high-school physics class you should know that our at 4.1V should give approximately 2.6V on the sense pin, so something is pulling that value lower than it should be (only 2.2V is there), which can be a bad resistor, bad cap, bad soldering etc.

My measurements confirmed that both resistors are OK, so the only remaining suspect was that bypass cap. After removing it, I tested the mouse and... oh miracle.... it came back to life! 



Now I finally have something more intimidating than a semi-working-sparkly-white-mini-wireless-mouse-for-kids to use in my workshop.

Thank you for your attention, and if you want more stuff like this, or more complex repair logs - let me know.


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## jsfitz54 (Jan 7, 2018)

I liked the write up.


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## SKBARON (Jan 7, 2018)

I love repair logs! Keep them coming


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## infrared (Jan 7, 2018)

Nicely done


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## Lachy (Jul 29, 2018)

Greetings, I made this account to post this comment and hopefully you can help me out with a couple questions. 
I love the R30 Wireless, has the exact same issue. I've tested the battery and it's fine, I just need to know which cap specifically to remove and how to go about removing it. Not wanting to venture in to the unknown and potentially ruin the entire thing. Cheers!


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## micropage7 (Jul 29, 2018)

I was nearly bought it


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## silentbogo (Jul 29, 2018)

Lachy said:


> Greetings, I made this account to post this comment and hopefully you can help me out with a couple questions.
> I love the R30 Wireless, has the exact same issue. I've tested the battery and it's fine, I just need to know which cap specifically to remove and how to go about removing it. Not wanting to venture in to the unknown and potentially ruin the entire thing. Cheers!



It's hard to tell for sure without poking and prodding around w/ multimeter. If you are not familiar with basic electronics, then it's probably better to find someone more experienced.
Otherwise, here's what I see:


I am not 100% sure, but it looks quite close. In order to confirm it you'll need a multimeter w/ continuity test function and some steady hands. One of those resistors must be directly connected to the battery's "+" terminal (probably the one marked _"104"_). The second one (_"124"_) should go to the ground. The other two pins of both are connected together and the trace will go to one of the pins of that SONIX microcontroller. A nearby cap should be on the same circuit. Also, you may want to flip the board and find a test pad marked "ADC". If you have it - it'll help you to locate the voltage sensing ciruit (our target capacitor is connected to it on one end, and to ground on the other).
In order to remove this cap you'll need a hot air rework station. There are some crude ways of de-soldering it with a regular soldering iron (which you can find on Youtube) but you can damage nearby traces or accidentally remove something else along with the cap, so you have to be very-very careful. Breaking it off the board is also a bad idea.


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## Solaris17 (Jul 29, 2018)

Man look at this guy making an account with the same issue (allegedly) that you just wrote a guide for, and you here picking it apart. Jesus this is why I love TPU god I miss this kind of stuff. I encourage anyone with any kind of talent or training in a specific field and an unbias heart to contribute guides or writeups like this.

This is the kind of shit that benefits people, not AMD and Intel buyers picking apart each others mothers over a damn platform. great GREAT work @silentbogo


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## DeVolf (Feb 24, 2019)

Hey ho! Recently my R30 stoped working. I have found this post and checked my VbatRef, it was 2.4V. But according to my calculations should be 2.64V. I have checked everything, values and traces, but no luck. Mice didn't wakes up from clicks and shows only "charging" status (according led)
The most funny thins is that actually mice lost connection from a dongle. Not because hardware. RMC to tray icon of Bloody -> Pairing (Or how it called on your language) , after finishing onscreen instructions every thing works as it was.


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## silentbogo (Feb 24, 2019)

DeVolf said:


> The most funny thins is that actually mice lost connection from a dongle. Not because hardware. RMC to tray icon of Bloody -> Pairing (Or how it called on your language) , after finishing onscreen instructions every thing works as it was.


Yep, also had a few with pairing issues. Just needed to follow the factory reset and pairing procedure, and that was it.
Also, what I like about this series is that receivers are interchangeable, just like on Logitech mice. 
Regarding voltage: your battery might've been discharged a bit, hence the lower voltage. 2.4V on the feedback pin is an equivalent of ~50-60% charge, so it wasn't a power issue.


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## psyko12 (Feb 24, 2019)

I miss this kinds of things, nowadays everything is just a video with a bit explanation. I like pictures and walls of text to explain how to fix this and that.

It's just much easier for me to understand.

Keep up the good work!


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## DeVolf (Feb 24, 2019)

Fun fact about receiver. PCB of my one dated 2008y



*silentbogo, can you say more about factory reset, please?*


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## silentbogo (Feb 24, 2019)

DeVolf said:


> @silentbogo, can you say more about factory reset, please?


Once paired, just chose another "Core" mode and then switch back (in Bloody software). E.g. if you are on Core 1, switch to Core 2, wait for settings to update, and then switch back to Core 1 and wait for it to finish. If you want to do a full reset, you can "soft-brick" the mouse on purpose by disconnecting it from PC while switching profiles (e.g. unplug the receiver before progress bar reaches the end). Then, plug in the USB cable and the software will restore the firmware, then do the pairing again. This is dangerous, but that's the way I've recovered a few RT7 and R70 mice with pairing issues.


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## Darvos (Apr 20, 2019)

silentbogo said:


> Once paired, just chose another "Core" mode and then switch back (in Bloody software). E.g. if you are on Core 1, switch to Core 2, wait for settings to update, and then switch back to Core 1 and wait for it to finish. If you want to do a full reset, you can "soft-brick" the mouse on purpose by disconnecting it from PC while switching profiles (e.g. unplug the receiver before progress bar reaches the end). Then, plug in the USB cable and the software will restore the firmware, then do the pairing again. This is dangerous, but that's the way I've recovered a few RT7 and R70 mice with pairing issues.




Hey SilentBogo, thank you for your post, I have a R80 mouse and I simply LOVE this bastard, I love it so much  this is my second one, cuz in less than a year my previous one just broke, so I got a new one, but not after trying every damn possible thing to fix its board. the problem with my previous item was the pointer simply stop working out of the suddently.
But lucky me, my new mouse,  from a little more than 1 year of use, also presented the SAME EXACTLY ISSUE. I never open this one but since the warranty is out of dated i'm gonna try removing this piece of garbage of a bypass cap. I noticed a problem with my battery, the inconsistency, by battery goes from 96% to 56% every damn time a reconnect the dongle.

And brother let me tell you, I made the account on this forum for this post and if your solution fix my mouse I would be mode than happy to give you a tip over pay pal. 

again, Wonderful work, as soon as I have a result I'm gonna give you the feedback


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## silentbogo (Apr 20, 2019)

Darvos said:


> again, Wonderful work, as soon as I have a result I'm gonna give you the feedback


Thx, dude. Let me know how it goes. 

Regarding a "jumpy" cursor - that's usually the receiver issue. Gotta play with RX/TX power settings, or with receiver positioning (absolutely gotta use that USB extension cable).
I have the exact same problem on my new Logitech G603, which works fine on the full battery charge, but once it gets past 50% I have to unpack the cable.
I don't have any Bloody mice left, but before selling them off I had an idea about adding external antennas to the receiver and the mouse. I think you can add one by removing one small SMD inductor near NRF24L01 chip, and soldering a wire or a laptop wifi antenna-sticker onto the input side (similar to old wireless mouse range boost hack).


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## Darvos (Apr 21, 2019)

Thank you for the quick answer SilentBogo, unfortunately ripping of the cap didn't solve my problem, I even tried to reset the dongle, even Open the dongle up but no success, I re solder the main optic chip and the mouse came back to life but for only 30 minutes, just like the last one, all other function of the mouse works properly and flawlessly, but the mouse is not moving anymore, I though my first one was a bad of mine, but after spending hours with my multi-meter trying to get any bad component was prob blocking the signal wave of the optical sensor and no success I might just buy another Wireless mouse.

Anyway thank you for the tips Silentbogo, and I'm not done yet, so if u have any schematics of any bloody mouse for me or a got indication of an good wireless rechargeable mouse, I would be thanking you for ever my friend.

EDIT:
I just realize it has to be some kind of a capacitor connected to the ground in between the output of the chip and the input of the ADC, on the first though I was assuming the heat of the solder iron was taking the mouse back to life, but know I think I just discharged the bastard! damn I think I might save this one!!

EDIT 2: Hooooly ***** its an SPI interface, Some clock frequency as an arduino but no capacitors in the middle of the data lines! damn, new plan, gonna try to manualy discharge the caps until I find the right one to take carefully out .

Results:

Well, I made it and you not gonna believe it, i'm just gonna run a few test to see if everything is actually working fine, but first let me tell u this, the problem was on the LED pin of the 3050 Microchip, yes, the LED pin which control the led brightness. I will do a full report as soon as I'm 100% confident Is fully working and functional.


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## drejtori69 (Mar 5, 2021)

Hello,

I am sorry for reopening this old thread but as the author @silentbogo said: "someone might find this useful (maybe not today, but decades from now)." 
I have a Bloody R80, and it randomly disconnects for 1 sec maybe 4-5 times a day. When this happens the mouse does not work to any command and shuts down its lights(for 1 sec) and then turns on. Even when i am not using it.
I tried with different computers and the problems still persists.
I know that the thread is not about this issue but this is the only thread in the internet for bloody mouse that has a lot of discussion in it.
Any Help would be appreciated.

Thanks


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## silentbogo (Mar 5, 2021)

That's common on their wireless mice. I had quite a few units with that same problem, basically it loses signal from base station if there's too much interference. 
What I found to be the most effective solution is:
1) Use the bundled receiver stand (USB extension cord). Those puny receivers are too weak, so they can lose signal even when plugged into the front panel USB less than a meter away from the mouse.
2) In Bloody software you need to drop the polling rate to 500Hz (or lower). 1kHz is super-unstable.
3) Do RF calibration(under "Zero frequency offset")
4) Try playing around with transmission boost (sometimes it can make things worse, but in few cases it helped a lot)
Basically your goal is to make sure that RF signal always stays at 100%. Even at 90% it's gonna lose packets occasionally or fall asleep.

If nothing helps, just RMA it. I've tried to boost the signal on one of my R70's back in a day, and even with decent external antennas it was buggy as hell. They are using generic NRF24L01 chips (same ones used in cheap Arduino 2.4GHz 6-channel tranceivers), and without an amp they are total garbage. Still have a box of dead electronics projects based on those(tried to make a remote for my friend's "RC bait boat" for his fishing trips)


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## drejtori69 (Mar 5, 2021)

Thanx for the reply. So basically no more Bloody wireless mouse . I thought for the price they were really good mice but this problem its kind of boring.
It happens when i play FPS games, and i usually end up dead . I tried in the past solution 1 and 4 from your list and it kind of helped.
I am gonna try 2 and 3 because i tend to let the frequency to max (max for my model is 500Hz). and i have turned off RF Calibration.
I will report again with the results but as you said i got what i paid for i think.
Kudos for "RC bait boat"


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## McTommy (Dec 30, 2021)

Hey I've got the very same mouse with a very similar issue, the difference is that on my mouse it shows varying % of battery. If I unplug and plug the mouse the battery % will change. Do you by any chance have a picture that shows the exact position of the bypass capacitor. I would've went to someone who does this professionally but I am a college student and I kind of need it right now. Thanks in advance.


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## silentbogo (Dec 30, 2021)

McTommy said:


> Hey I've got the very same mouse with a very similar issue, the difference is that on my mouse it shows varying % of battery.


Pretty sure it's a sign of a dying battery. Fortunately it can be replaced with pretty much any Li-Ion battery, all you need is to transplant the +/- wires, or find one with the same connector/pinout.
Something like this:





						Lithium Ion Battery - 400mAh - PRT-13851 - SparkFun Electronics
					

This is a very small, extremely lightweight battery based on Lithium Ion chemistry, with the highest energy density currently in production. Each cell outp




					www.sparkfun.com
				




...or maybe a 16340 cell(it might fit in that compartment).
The original one is 600mA.

I no longer have that mouse, but you can see that capacitor in my first post. Highlighted with green rectangle is a sensing circuit. Two resistors at the top, and cap right below.
But I'd start with the battery - it's the most likely suspect.

BTW, found a video with 16340 replacement procedure. Come to find out, the stock battery is actually two cheap-ass 300mAh cells wrapped together w/ common protection board. No wonder they died...


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## McTommy (Dec 30, 2021)

Thank you for the response although I don't think it is the battery dying. I bought this mouse 2 days ago brand new, besides that and my mouse isn't shutting off, it just starts blinking even though I use it for hours on end. I just charge it regularly regardless of what the indicator is showing, but still I would rather like if it were correct. It said 7% 4 hours ago it is still going.


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## silentbogo (Dec 30, 2021)

Ok, but before you do anything drastic, why not just take it back to the seller? If it really was brand new, it should still have 12mo warranty...
The reason I mention battery, is because RT7/R70 is a 2015-2016 model and definitely EoL by now. Regular Li-Ion batteries have a typical shelf life of 5-6 years, and with two shitty cells in parallel you can easily cut it in half. Could've been sitting on the shelf in some warehouse all these years.
If you still want to fix it on your own - you can try removing that capacitor. It doesn't really do anything anyways)))
But if it doesn't help - at least you know what to do next.


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## McTommy (Dec 30, 2021)

Alright I'll check if the battery is the issue if it is I'll just replace it. Thanks for the quick and helpful responses cheers.


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## aliaksandr (Nov 6, 2022)

I replaced the original battery by "602248 3.7V 600mAh Lithium Polymer Rechargeable Battery" 2.2$
from aliexpress


Spoiler: ba


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