Soon after I got him this nice walkie-talkie, my brother Nenad (YU1TTL) quickly found out how to overcome missing feature of UV-B5: LCD background light is turned on only when some keys are pressed and stays on far a very short time. He managed to use flash switch which is used in UV-B6 version but in UV-B5 has no function.
He decided to put up instructions on my blog so others can benefit of this modification. So here it is:
How to use Baofeng UV-B5 flash light switch for LCD background light
by Nenad Supurović YU1TTL
These are instructions for disassembling Baofeng UV-B5 walkie-talkie and also how to modify it to enable the third (Flash light) button to switch the LCD and keyboard back-light on/off
1. To disassemble UV-B5, first remove the battery, unscrew the antenna and pull off Volume and Chanel selector caps.
2. Undo four visible screws on the back side of unit. (Needs thorax and PH1.)
3. Undo two brass nuts located below Volume and Chanel selector caps. (Needs two small screw drivers.)
4. Carefully lift the lower part of aluminium frame and then push Chanel selector shaft. This will set frame with main board free, but it will stay connected to front panel by flat cable and speaker wires. Be carefull!
5. Disconnect the flat cable (latched connector!) and desolder the speaker wires. Now you have front panel and main board separated.
In order to make the third (Flash light) button on UV-B5 usefull to switch the LCD and keyboard backlight on/off, you will have to connect point „A“ on the front panel PCB and point „B“ on the main board, using flexible wire and a diode:
1. On front panel board, peel off insulation from PCB lead connected to SMD transistor (point marked „A“). You can simply continue scratching it with a sharp needle until the whole copper surface is clearly exposed.
2. Prepare the surface for soldering using flux and soldering iron. Avoid soldering directly to the SMD transistor because it can be destroyed easily! These preparations are critical.
3. Prepare a flexible wire, long enough (7-8cm), with blank soldered ends. Take really the thinnest and the most flexible wire you can get! Solder one end of the wire to the prepared surface at point „A“. Warning: it is extreemly small and delicate, a stiff wire will get disconneced easily!
4. Prepare a small diode (1N4148 or any similar) cut it short and solder it’s cathode (-) to point „B“ located on main board.
5. Solder the other end of the wire to the anode (+).
6. Check mechanical stability of soldering points, check for short circuits.. and you are done!
Solder the speaker wires back to where these belong, reconnect the flat cable (latch it correctly!) and assemble everything backwards as disassembled.
Now, if everything is done well, while LCD and keyboard backlight is timed-out to OFF, you can toggle it permanently ON/OFF using the third rubber button (located below PTT and Monitor buttons). Backlight uses only about 10mA from battery, means if constantly lit it will reduse your stand-by time by 30% only. So, no need to worry about it!
Thanks for your description, it works great on my UV-B5 :-)
Only difference was that my UV-B5 had an extra resistor near solderpoint A.
73 de Patrick, PD3RR
I think I have the same condition, did this work for you? My LCD backlight is now always on.
pozdrav, neki osnovni utisci o ovom radiju i mane , pre svega malo mo je bolja osetljivost prijemnika nego li kod 5r ali i dalje ima pauze kad se prelazi izmedju tx na rx pa ne cuje dovolno kratke repove repetitora ili sagovornika ne cuje prvih dva slova ako je neko brz na tasteru mikrofona , drugo sam enkoder nije nesto preskace ako se okrece brze, sum na prijemu posle predaje je neko vreme sa odsustvom visokih tonova i posle par sekundi oped dobija i visoke tonove u modulaciji, trece gornja dva srafa kojima se i pricvrscuje snsla zakacka ako se ne stegnu dovolno jako nema glavnog kontakta od baterije i uredjaj nece da se upali , znao je i par puta da se zaglupi prilikom pljenja ili posle programiranja jednostavno zabaguje nista ne prihvata ili sve na displeju izadju 0 pozdrav i 73 YT1PRM Milan
Thank you VERY much for sharing this „hack“.
I was almost about to give up my UV-B5, when i found this site.
Now one big disadvantage of this HT is gone. :-)
All the best, oz5es Ebbe
I just bought an anonymous purchaser a brand new radio Baofeng UV-B5 which came directly from China, but not power!
I have a friend who is electronics and I wonder if it would be possible to send me your company product the electronic scheme or else give me any help?
Heard a lot of good radio, so would love to fix it!
I am not manufacturer not I am in any way related to manufacturer. From your description I am not sure what is that you are missing.
If you do not have power supply but do have charger base, then any power supply of 10V will do the job.
If you do not have charger then it should work with any charger for 7.2V LiIon battery. Rady made such charger modules can be found for few bucks. However, more problem is how to connect charger to the battery. You can easily find UV-B5 replacement charger for about 10 USD.
This would be a great fix if it worked for me, but it doesn’t. My new UV-B5 also has another resistor in area A.
After applying this modification, my LCD background is now always on. It only turns off when I turn off the radio.Have I done something wrong? I think I followed your directions here pretty good.
Is there a way to upload one more details picture of that soldering area A after the wire is in place? Perhaps I’m missing something here.
Thank you for posting this.
Tomaas, the resistor in area „A“ doesn’t change much. You can solder to the very similar area marked in red color. If your LCD backlight is always ON, then you are having a short circuit between the wire and GND (or you have overheated/toasted the small black transistor). Desolder the wire and investigate.
By now, everybody resolved this issue simply by resoldering the wire again – clean and carefull.
I also have the slightly updated board with a resistor in the area of the transistor. Rather than removing any of the green solder mask, I simply soldered the wire onto the side of the resistor which was connected to the transistor’s circuit trace. Works like a champ! Thanks!!!!!
Thak You for sharing this. Works great. LZ1TDJ
I’m glad it worked for all of you.
But please avoid soldering to the resistor or to transistor directly, somebody reported that he managed to accidentally desolder and lose the resistor.
Chance for this to happen is quite big.
I don’t know if they have changed the UV-B5, but I couldn’t remove the internals.
I removed the aerial, took the battery off and undid the two top and two bottom screws off.
I lifted the board out a bit from the bottom end, and tried to push it out. I tried giving the tuning and on/off stalks a good old push to get the board out.
But it wouldn’t budge and I felt I was going to break something, so I put the radio back together again.
I don’t have brass screws under the volume and tuner knobs, they are more like circlips and would need something other than a screwdriver to remove them.
Usually it is a brass nut with two notches which can be undone with TWO screwdrivers used simultaneously. If you do have circlips (really?), you need to remove it somehow.
Please post your outcome here.
Nope, different board, I managed to undo the washers.
The speaker board has very little circuitry on it, almost bare and certainly not as pictured.
Also, the other board pointing to the two holes, has a very small surface mount IC mounted right below the holes.
So, no where to solder on the first (sub) board, I guess they’ve moved it to the underside.
On the main board it is fairly close to the holes, you could probably solder it, but without the other end to connect to, it was pointless for me.
My radio is only a few weeks old and only comes with a #27 menu, with both Comp and TAXB missed off.
I’ve emailed both Baofeng China and my UK supplier (who emailed his supplier) and both say that the #27 menu is correct.
Alastair, sorry but I can’t help further with this because I never saw this new type of board.
But, if you understand electronics then you can search yourself for a pull-down transistor which activates backlight LEDs by pulling it’s collector down to GND. The similar circuit (the second transistor) does the same with missing flashlight LED. My mod actually connects these two collectors using a simple diode – to ensure that voltage dilivered to backlight is correct (light intensity). It is as simple as that. Schematic for UV-5R would be helpfull and it can be easily found on the net. If you are succesfull – let us know!
However it is good to know that Baofeng keeps working (improving?) on their old products!
I attempted this mod and my radio will not turn on any longer. When I opened the case the diode has been blown into two. Any ideas? Thanks.
I believe you made a short circuit while assembling the case, or you soldered something to a wrong spot.
I did the mod successful with 2 of my transceivers, but today I received a new one with a complete different layout of the circuit board that holds the keyboard unit. Do you know about this version of the UV-B5? The mod is very useful and I would like to add it to the new one as well…
I found out that with the new type of B5 the Monitor button (the button just below the PTT button) can be used to switch the backlight on. A short press switches the backlight on, another short press switches it off again. A long press activates the monitor function (opens the squelch)
The third button has no function at all as far I know.
It is reported that new versions have different firmware. Thanks to you, now we also know hardware changes.
Pay attention, it seems like new options you have are lost if you factory reset device.
Werner, thanks for info, it is good to know that a forced backlight is finaly implemented in UV-B5 software! The third button is probably still used for activation of flashlight (UV-B6).
I have to add that the new backlight feature with the monitor button does not activate the backlight permanently like the flashlight mod. It is switched off automatically after the usual timeout.