Pipo M8 pro power cable

[StoneTheKiwis]

My M8 pro has just arrived and the supplied charger, with a choke filter on the cable, charges it up as expected. However, I normally use a USB cable with a power jack on one end to charge with, and this does not work.

The screen gets ghost touches, it flickers, and the charging level stays unchanging. In short, it behaves just as devices do with cheap chargers that don't regulate or filter the power properly.

Has anyone else experienced this? Is it just my unit? I rather suspect that Pipo have put filters on all supplied cables for good reason, and this demonstrates that reason for the power cable.

I have ordered a ferrite choke filter off **** and will try that on my USB charging cable when it arrives, but it would be nice to see what others have experienced.

[StoneTheKiwis]

Update:

the choke filter arrived along with a new cable with a higher amperage rating. The new cable alone makes a big difference - the charger for my Galaxy Note 2 now charges the Pipo without problem. However the 2port charger, which I had thought was well filtered, still gives ghost touches. And the USB battery also gives ghost touches (these are actually 3.7v bumped up to 5.07v at the port). The **** choke filter doesn't make any discernible difference - I expect it has to be the right type and in the right place along the cable length and this one is apparently not. My solar charger, 24v dropped down to 5.2v, seems OK but today is so cloudy that the battery level is going down despite the charge going in, so this may not be a fair test.

In summary, only the Samsung USB charger will charge the Pipo properly without using a specially choked cable, and only the cable supplied by Pipo will choke anything else properly (without endless poncing around testing this and that filter ...). So I will now splice a USB jack and socket into Pipo's cable so I have a filtered USB cable that's usable with other USB power sources.

[pipomall.com]

M8 pro must use the standard AC adapter for charging, not USB cable. Because the electronic current is not stable without using standard adapter. be careful, it is easy to damaged if using USB for a long time.
I just bought a M6 from http://pipomall.com and the custom server told me that.

[pr0xZen]

Update:

the choke filter arrived along with a new cable with a higher amperage rating. The new cable alone makes a big difference - the charger for my Galaxy Note 2 now charges the Pipo without problem. However the 2port charger, which I had thought was well filtered, still gives ghost touches. And the USB battery also gives ghost touches (these are actually 3.7v bumped up to 5.07v at the port). The **** choke filter doesn't make any discernible difference - I expect it has to be the right type and in the right place along the cable length and this one is apparently not. My solar charger, 24v dropped down to 5.2v, seems OK but today is so cloudy that the battery level is going down despite the charge going in, so this may not be a fair test.

In summary, only the Samsung USB charger will charge the Pipo properly without using a specially choked cable, and only the cable supplied by Pipo will choke anything else properly (without endless poncing around testing this and that filter ...). So I will now splice a USB jack and socket into Pipo's cable so I have a filtered USB cable that's usable with other USB power sources.

I believe that besides the quality of components, and power/voltage regulation - the 2.1A samsung chargers (and tablets/phones) have a built-in circuit to assure that the unit doesn't try to draw more than 500mAh from any source that doesn't "check out'". The purpose of this should be obvious.

It could very well be that the M8pro and/or its charger has a similar, or same circuit. The circuit itself isn't that complicated - can be mocked together in a few minutes as a Female-> male USB adapter, if you have plugs, a 10k and 30k ohm resistor, soldering iron, snippets and some tape. Could be worth a shot, but DON'T USE THIS WHEN CHARGING OFF A COMPUTER! If the circuitry works the same way as the samsung, the tablet will attempt to draw max current - and fry your usb controller.

A step-by-step guide for the adapter is available here. Hopefully noone gets mad for referring to another forum (XDA-Developers), but no way I'll rewrite it

Beware though - there's no guarantee that the curcuitry is the same. And it can be a tad difficult to measure because of the very small round connector. Anyway, if it DOES work - you should be able to draw max current from any charger, including the cheapo 2.5A ones - with any micro-usb cable (that fits the deep M8pro slot).

Ps. Don't use this with a charger that supplies a higher amperage than the original one. And keep in mind, that this will not regulate the supplied voltage any better. A crap charger can still damage the tablet.

[StoneTheKiwis]

I believe that besides the quality of components, and power/voltage regulation - the 2.1A samsung chargers (and tablets/phones) have a built-in circuit to assure that the unit doesn't try to draw more than 500mAh from any source that doesn't "check out'". The purpose of this should be obvious.

It could very well be that the M8pro and/or its charger has a similar, or same circuit. The circuit itself isn't that complicated - can be mocked together in a few minutes as a Female-> male USB adapter, if you have plugs, a 10k and 30k ohm resistor, soldering iron, snippets and some tape. Could be worth a shot, but DON'T USE THIS WHEN CHARGING OFF A COMPUTER! If the circuitry works the same way as the samsung, the tablet will attempt to draw max current - and fry your usb controller.

A step-by-step guide for the adapter is available here. Hopefully noone gets mad for referring to another forum (XDA-Developers), but no way I'll rewrite it

Beware though - there's no guarantee that the curcuitry is the same. And it can be a tad difficult to measure because of the very small round connector. Anyway, if it DOES work - you should be able to draw max current from any charger, including the cheapo 2.5A ones - with any micro-usb cable (that fits the deep M8pro slot).

Ps. Don't use this with a charger that supplies a higher amperage than the original one. And keep in mind, that this will not regulate the supplied voltage any better. A crap charger can still damage the tablet.

Interesting. Certainly I would expect the Samsung charger for the Galaxy Note 2 to have better quality regulation than most. I had always believed that simply shorting the two usb data wires was the usual way to extract maximum currrent from a charger. My solar panel supplies 24v and came without a regulator, so I bought a good regulator, put it into a weatherproof box, and wired USB sockets to it with the data wires shorted. It's charging the Pipo now as I write this on it, but again the day is so cloudy that that the nett charge is going down. Just plugged the Note 2 into it and it won't even register a charge, so this is not a fair test. Though there is no sign of the ghost touches etc you normally get with a badly regulated charger. I'll try all this on a sunny day before splicing the USB plug and socket into the Pipo charger lead.

Cheer

[StoneTheKiwis]

Quick update. Today was sunny enough that the solar charger had enough power to charge up a usb battery (though not enough to trigger the Galaxy Note into accepting a charge) so I tried the Pipo. Alas it again exhibited ghost touches etc.

However, my Ployer Momo8 came back from repair today so I tried the charger for that - amazingly it worked and charged the Pipo right up with absolutely no trace of these errors. I then measured the voltage and found it was 5.30v - the same as the Galaxy charger which also works and only a little more than the 5.23v of the Pipo charger. All the other chargers that give this problem only put out less than 5.2v.

So it seems that it's the voltage, not the ripple smoothing / regulation that is the key factor. This is rather a big surprise to be honest - it's not at all what you would normally expect. Somewhere in my box of bits I should have an adjustable regulator - when I find it I will add a usb socket and plug and put it inline with these usb chargers and then wind the output voltage up and down to see if it's really this that makes the difference.

[StoneTheKiwis]

Well I couldn't find an adjustable voltage regulator so I bought one which arrived today. Tried it on the USB battery, boosting the voltage from 5.07 to 5.27 (the Pipo charger is 5.23v, the Samsung and Ployer both work on the Pipo at 5.30v). Bad news, it still gets ghost touches. Worse, it freezes to my touch and has to be reset. Varying the voltage between 5.20 and 5.30 gives the same result.

So it's not just the voltage after all - it would have been a little strange if it had been to be honest. I'm a bit stumped now. The only sensible way forward is to break the Pipo charger apart and see what is in their regulator circuit, though there may not be enough visible to be of real help. I see Pipomall have spare chargers.

I need a tablet which can be taken out hill walking and charged off a solar charger and usb batteries - this M8 now seems useless to me. My Ployer Momo8 has been repaired and returned (a broken charging socket), so I may just sell the Pipo. A pity, it seems to me that Pipo are going to be one of the better Chinese tablet manufacturers but this gremlin is a deal breaker for me. I might just sell this now while it's still good and buy a spare charger to break apart - I want to know what is going on here.

[pr0xZen]

These are quite informative news indeed Question: How much current can the usb battery and voltage regulator setup push through? The tablet might still go bonkers if it gets to low a current if charging with the tablet on, even though the voltage is good. Both chargers you have /working/, are pushing atleast 2 amps...?. And - have you measured any resistance? Should probably compare resistance across the lines with stock charger and your voltage-regulated setup. maye they put in a resistor, them sneaky bastards.

Just to be safe here: did you measure the output voltages under load? "all" psu's show high voltages with no load - that measurement is irrelevant really.

[pr0xZen]

I'm leaning more and more on attempting to charge while the tablet is off... If it does charge, it would probably indicate a current issue...

[StoneTheKiwis]

I'm leaning more and more on attempting to charge while the tablet is off... If it does charge, it would probably indicate a current issue...

A very good thought, and I've just run a check. Turned it off and plugged in the USB battery (from the 2.1Amp port). The boot logo (but not the animation) came on and then a battery charging animation, then the screen turned off. After an hour I booted it and found that the screen was frozen and it needed a hard reset. Checked the battery stats and it had charged up from 49% to 50% in one hour. So it's misbehaving whether powered up or down. Damn.

I'll think more about this in the morning

[pr0xZen]

Damnit... any ideas on how much current the usb battery actually can serve? (not its rating, but actual supply current). I guess a multimeter connected in-line, while "charging" would be needed. You'd still probably have to do another hard reset afterwards - but if we find out that the usb battery/voltage regulator combo delivers less than 2A, i would think that could be the issue. How much can the Momo8 charger deliver?

Guess wire guage is also a factor. If using a cable designed for data transfer, these really aren't rated for more than 5-700mA. If pushing 2.1-2.5A through them, there will be a remarkable resistance (and thus voltage drop). Maybe its not that important for now, with your voltage regulator setup - but if this project proves fruitful, its noteworthy for a "finished product".

[pr0xZen]

Got my 3m extension today, same experience as you. While off, it looks like its charging - but after 1 hour there was no increased charge. AND, the touchscreen froze up.
I think the original charger delivers a high enough current - but there's a significant voltage drop when pushing 2.5A thorugh that extra 3m of wire. I could try to measure, but I'd need to wait for my spare original pipo charger to get here first. Don't want to risk breaking the only fuctioning charger I have that works with this.

UPDATE: I did some calculations, and if we're to use this cable it looks like we're going to need a ~5.5v power source.

I did some preliminary calculations. The cable is branded 18AWG (0.8mm). With a 3 meter length with this cable, pushing the required 2.5A - we get a voltage drop of 0.2v if its copper, and almost 0.4v if its aluminium. To be able to get close to zero voltage drop, we need to go down to 2A.

The voltage is low already, so there WILL be a noticable drop normally. So if to use an extension, and get ~5.3v - we ned AT LEAST a 5.5v source.

How far can you go with that regulator of yours?

[StoneTheKiwis]

22v

I also ran some tests with a meter in line with the power from my USB sources (battery, Samsung charger, Vanson 2 port charger). Found that all three gave about 1 amp to the Ployer Momo8, and the same to an old cheap 7" tablet. But to the Pipo the current fluctuated wildly - 0/0.15/0.5 - never above 0.6 that I saw. Exactly the same from all three sources. And putting the regulator inline to boost the voltage to 5.3 made no difference except that the battery switched off internally when connected to the Pipo and would not give power again until put on charge briefly.

I checked the Samsung charger again on the Pipo and it charges up nicely, but the screen froze this time. A nuisance as I had just ordered one of those off **** (supposedly genuine) with the intention of breaking it apart to look for clues. So I have now just ordered a spare charger off pipomall - this will take a couple of weeks to get here but as my Ployer charger works well on the Pipo I will break the Pipo one apart tomorrow.

If I can't get this to work off batteries and solar chargers then, reluctantly, it will have to be sold.

[pr0xZen]

We're not there yet, but these are productive results Damn pipo for complicating this so much :@ I don't know what they did, but I can't really see a chinese tablet manifacturer - even pipo - doing this just to make sure proprietary (their) chargers were used.

[StoneTheKiwis]

Some progress. I broke the charger up today and found the key factor is probably the very large capacitors in there. It's a 2 diode setup, meaning it takes voltage off a centre-tap in the transformer. It's a very long time since I played around with practical electronics, and while trying to find the centre-tap I slipped with the meter prong and blew it ... oops I had been thinking of just applying 5v DC from my USB source to that side of the transformer, but no longer ...

The two capacitors on the output side are 1000mF each, so tomorrow I'll get some from Maplins and put them across the usb socket in my test rig. Here are some pictures:


The second photo shows the end cut off - the PCB inside is *very* close and the cut needs to be right up against the end. The third is with just one side broken off - the PCB is sitting on sponge rubber to jam it against the top of the case. The manufacturer is powwt.com, whose website indicates that they are probably a solid enough player in their field. This not a fancy charger, but it's helpful to us to see what the main components are.

Maybe we'll be lucky and the extra smoothing from these large capacitors will do the trick ...