Modify the Baofeng T1 to fix the very loud audio even at its lowest setting by adding a 15K, 20k or 22k resistor across the end pins 4 & 5 of the LN4890 chip. The datasheet www.natlinear.c...
I hope this video is of some use to somebody. The mod of the LN4890 itself begins at 4:50 after the radio has been taken apart. The circuit diagram for the example circuit is at 1:15 Thank you for watching.
Thanks for this video! I'm thinking of doing the same with my T1. Any thoughts on extending / stretching the antenna a bit for slightly improved performance while I'm in there? Saw someone else do that. Thanks again.
Hi Marc, Thanks for your comment. It's quite an easy mod really, and the radio goes back together easily. The beauty of the radio itself is how compact it is. It's neat. There are other chinese radios that have better antennas. So I'm not sure if it would be worth modifying this, although it's quite tempting to try isn't it!?
You could do that yes, but you'd have more hiss/noise. Turning down the gain (amplification) earlier on in the circuit results in less noise. A very good question - and thanks for your comment.
The battery would have still been disconnected before putting the screws in? Double-check for solder bridges first. They sell the ln4890 on AliExpress.
Thank you for your comment. That could be a good idea! It could also be done by putting another SMD on top 'piggy back' of the existing SMD (if it can be found) to try to avoid damaging the PCB in removing the original one.
Michael, well that got me thinking! Right so I've now opened up an unmodified Baofeng T1 and found that the resistance between the 4 and 5 pin of the IC is 117k. The SMD resistor that is 117k is one that is in view in 5:55 at the bottom-centre of the screen. It's the one nearest the unsoldered lead in the video, and nearest the blue blob of 'blu tack'. It's as if when they designed it they put in a resistor that was a decade too big, so installed a 116k resistor instead of 16k resistor.
Trystan, job done. I found yesterday evening the correct resistor > 120k close to OpAmp in its feedback loop to be replaced with 15-47k. I used 18k and it works fine. Simply I removed this 120k and replaced it with 18k / 405 SMD size resistor on the PCB. Nothing additionally added, nothing to cut, nobody can see anything after that mod job :) I am preparing the manual for it including the pictures.
Recently i brought 2 pcs baofeng T1 ftom Aliexpress.com but Unfortunately 1 of them is won't be able to be charging. Can you show me how to fixed it? Thanks you sir
The Baofeng T1 lacks any gaskets so it's not going to be waterproof unless you seal it in a plastic bag. a waterproofing spray isn't going to do anything to stop the water going in.
