Li-ion power mod

upsss
Posts: 15
Joined: Wed Sep 27, 2017 7:05 am

Re: Li-ion power mod

Post by upsss »

I am curious why JYE did this crazy encoder daughter board in the first place. If not for the reverse direction of the encoder leads it looks like it was originally designed NOT to use the daughter board at all.

My guess would be that originally the plan was to obtain the encoder with the leads bent in the opposite direction and for some reason the manufacturer of these encoders couldn't or didn't want to supply it that way. The other possibility is that originally they planed to do exactly as you suggested, simply bend the leads backwards. The only problem with this idea is that these leads are very flat and thin, bending these the leads backwards you almost are guarantee to snap them right at the crease which is exactly what happened to a couple of my the leads. I simply soldered a piece of resistor wire in place of the broken lead which fixed the problem. I guess they didn't want to deal with such a problem and having to replace encoders for too many customers.

If anyone is planing to mount the encoder without the daughter board by bending the encoder leads backwards, I would first straighten the leads carefully with a small long nose pliers and then bend the leads with the pliers slightly closer to the body of the encoder. This way you will prevent these leads bending exactly at the same location as the original bend and prevent it from snapping at the crease.
lps
Posts: 1
Joined: Mon Oct 09, 2017 8:15 pm

Re: Li-ion power mod

Post by lps »

Hello upsss or anybody else who can answer.

Appreciate the description and photos of your implementation. I've ordered the parts, now for a 1 month wait to arrive.

I could use some help as to which SMD feedback resistor on the step up converter board needs to be changed and from what value to what value ? If you could possibly add a more zoomed-in photo of the step-up converter and info as to what modification you did. i assume the Ground of the step-up converter is connected to any ground point of the original main board.

thanks in advance for any help,

Len
upsss
Posts: 15
Joined: Wed Sep 27, 2017 7:05 am

Re: Li-ion power mod

Post by upsss »

Most of these step up converters use either FP6291 or SX1308, both of these chips are almost identical and both use the same feedback arrangement and programing resistors. Some of these converters come with a small trim pot where you can adjust the output voltage to the desired output. Some of these converters come with fixed resistors for a specific output voltage. If your converter has fixed resistors all you have to change is one of the resistors for your desired output voltage. Google the data sheets for these chips and they have a very simple formula to calculate these feedback resistors.
hvorfordetda
Posts: 8
Joined: Fri Oct 20, 2017 3:49 pm

Re: Li-ion power mod

Post by hvorfordetda »

lps wrote:Hello upsss or anybody else who can answer.

Appreciate the description and photos of your implementation. I've ordered the parts, now for a 1 month wait to arrive.

I could use some help as to which SMD feedback resistor on the step up converter board needs to be changed and from what value to what value ? If you could possibly add a more zoomed-in photo of the step-up converter and info as to what modification you did. i assume the Ground of the step-up converter is connected to any ground point of the original main board.

thanks in advance for any help,

Len
For the stepup:
(Click for larger image)
B6286_mod.jpg
Measure R1 and R2 with ohm meter. Notice that R1 will be slow to settle because of capaictors.
Calcultate Vout, and see that you get 5V. Test for 5V out with voltmeter to make sure.

I measured R1 to be about 8.2 kohm and R1 to be about 1.1 kohm. If I add one resitor of 1.5 kohm in parallel to R2 I will get about 8.35V out.
Check with voltmeter to be sure.


For the charger:
(Click for larger image)
TP4056_current.jpg
Change R3 so you get the charging current you want. Initial value seems to be 1.2 kohm which gives a current of 1A.

Edit: It should read R2 is about 1.1 kohm
hvorfordetda
Posts: 8
Joined: Fri Oct 20, 2017 3:49 pm

Re: Li-ion power mod

Post by hvorfordetda »

Some pictures of my implementation inspired by the previous posters.
Battery is Motorola BH6X and charger / stepup as shown in my prevous post.

The stepup is lifted about 0..5 mm above the PCB to avoid shorts and the charger is held in place by some strong double-sided tape. I have added some foam both ends of the battery and some ontop of it. This holds it in place without placing any strain on it. The foam ontop of it allows for some expansion, so hopefully no "Samsung moment" here.

I changed the charging current to about 300 mA (R3 = 3k9)

I found that the hole for the barrel connector was a pefect fit for a 5 mm red / green LED, so I used it for charging staus. It's not that beautiful, but better than just an emty hole. The LED is actually a 5 mm RGB common anode type.

Click on images for larger version.
FINISHED.jpg
COMPLETE.jpg
SCHEMATICS.jpg
PCB-MOD.jpg
DETAIL.jpg
CHARGER.jpg
STEPUP.jpg
upsss
Posts: 15
Joined: Wed Sep 27, 2017 7:05 am

Re: Li-ion power mod

Post by upsss »

@hvorfordetda, perfect description and very nice pictures.
Wilcoyote
Posts: 2
Joined: Tue Oct 24, 2017 11:54 am

Re: Li-ion power mod

Post by Wilcoyote »

Hi MorganFlint,
I modded my DSO according your suggestions but I dont' understand why you had to change the charge/booster. In my opinion to avoid quiescent current to drain the battery when not in use it's enough to switch the battery.
I have encountered great difficulty in removing the encoder and daugheter board without damage them. At first I used https://goo.gl/umptpq but I realized that it was less precise than the original one so I had to unsolder it and I had to reassemble the original one and I didn't have to reduce the length of encoder shaft at all.

Thanks in advance for any help.
MorganFlint
Posts: 56
Joined: Sat Jun 06, 2015 9:06 am

Re: Li-ion power mod

Post by MorganFlint »

Wilcoyote wrote:... I dont' understand why you had to change the charge/booster. In my opinion to avoid quiescent current to drain the battery when not in use it's enough to switch the battery...
Hi, Wilcoyote,
Of course, switching the battery would avoid quiescent current to drain the battery, but it'd also prevent the possibility to charge it with the scope turned off (if I'm understanding correctly what you mean).

Regarding encoder shaft, maybe I didn't push it all the way in, but before I trimmed it, the knob wasn't close enough to the case.
Wilcoyote
Posts: 2
Joined: Tue Oct 24, 2017 11:54 am

Re: Li-ion power mod

Post by Wilcoyote »

MorganFlint wrote: Of course, switching the battery would avoid quiescent current to drain the battery, but it'd also prevent the possibility to charge it with the scope turned off (if I'm understanding correctly what you mean)
I was referring to the fact that you have to unsolded C2, cut the tracks and resolded C2 to the pads for battery connection.
vcpinto
Posts: 3
Joined: Mon Dec 11, 2017 1:27 am

Re: Li-ion power mod

Post by vcpinto »

Hi,

How do you know when the battery is low?
Has anyone made a circuit to show the battery level?
Attachments
DSO150_BATMOD.jpg
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