Aura H2O tps65185_int_func under-voltage on DCDC1 detected ! - Page 3

DomesticExtremis · 10-13-2019, 10:11 PM

DCDC2 (part application circuit attached below) is checked first as it needs to be up and running before DCDC1 is powered up, so any faults here might be preventing DCDC1 from working.
Pins 24,25 and 26 are directly connected to the DCDC2 subsystem, in addition pins 4 and 16 are linked by an external rail and their attached support components need to be checked also. Pin numbers and component identifiers have been added in red.

Code:

Pin#    Pin name        Components
----  -----------     -------------------
24       VIN_P         C315
25       VN_SW         D49, L31, C320 (+C321)
25       VN            output to pins 4 and 16
   
4        VNEG_IN       C317       

16       VCOM_PWR     C323 (+C316 +C324)

Capacitors in brackets are additional to those on the circuit diagram and are extra capacitors in parallel to the one shown.

DomesticExtremis · 10-13-2019, 10:21 PM

DCDC1 uses pins 40, 41 and 42 and also is connected to pin 43 exterrnally.

Code:

Pin#   Pin name     Components
----   --------     ----------
40     VB_SW        D48, L33, C224, C319 (+C269)
41     PGND1        to ground
42     VB           to pin 43

43     VPOS_IN      C271 (+C319)

DomesticExtremis · 10-13-2019, 10:29 PM

All of the components were in good visual condition - not charred or discoloured.
The inductors should have resistance in the milliOhms range and measured a short i.e good.
The capaciotrs all measured as open loop, i.e. were not short.
The diodes measured as open loop in one polarity and gave a forward voltage in the other.
Despite the caveats about in-circuit measurement, both diodes had a forward voltage of~190mV, which is about right for a Schottky diode.

As far as can be ascertained, noe of the external components have failed, though it was not possible to determine that the capacitor and inductor values were correct relative to the typical application circuit.
Bear in mind that this was done using otoo large multimeter probes, 3.0 diopter reading glasses and a powerful head torch.
Nevertheless, that would appear to confirm that the TPS 65185 chip is the culprit for my broken e-reader.
Now I have to set about finding a replacement chip, replacing it and seeing if that fixes it. I am aware that I may need to set VCOM (the flat flax cable is marked -1.83, presumably volts) but I will cross that bridge if I ever reach it.

DomesticExtremis · 10-22-2019, 09:25 PM

Another hiatus - I have obtained a hot air rework station and have been practising on some scrap electronics the removal and resoldering of various chips. Now I have the hang of it (kinda, sorta) I will set about trying to source a replacement chip. Life is about to get in the way of this endeavour once more, so it may take some time until I am reagy to attempt replacing the PMIC.
Stay tuned...

DomesticExtremis · 12-02-2019, 10:46 PM

Once more real life has intervened to slow down this escapade.
I have considered giving up, but the faulty chip costs only ~£1.80 compared to the £180 cost of the original e-reader (the person that gave it to me bought it in 2017).

Just to avoid confusion, there are three different models of chip available:

Code:

PART NUMBER     PACKAGE       BODY SIZE (NOM)      MARKING ( | = newline)
TPS65185        RGZ (48)      7.00 mm × 7.00 mm    E INK | TPS65185
                RSL (48)      6.00 mm × 6.00 mm    TPS | 65185           <------

TPS651851       RSL (48)      6.00 mm × 6.00 mm    TPS | 651851

The Aura H2O has the chip marked on the second row.
The next problem is finding a supplier.
EBay does have some vendors in China offering them, however it was unclear to me whether the part they claimed was actually what they would send as the pictures did not match the description. In addition the delivery times were long and not all free postage.

The mainstream component suppliers (e.g Mouser, Farnell etc) need an account and some have a minimum order size plus delivery charges.

I was pointed to LCSC, an asian supplier, which had the exact item I need and reasonable delivery time plus delivery charges no higher than from more local suppliers. I decided to go with these as I wanted to get some other bits and also wished to test out their service,

The parts are winging or bobbing their way to me as I write, so the next set of updates will follow as soon as they arrive and I attempt to fit them.

DomesticExtremis · 12-14-2019, 02:17 PM

OK, so the chips arrived - 8 days from deepest China.
I got a spare just in case I mess up with the swap over (highly likely) but I'm not sure I will find time to make an attempt before Christmas.
Either way, watch this space

GuustFlater89 · 02-16-2024, 03:13 PM

Quote:

Originally Posted by DomesticExtremis

OK, so the chips arrived - 8 days from deepest China.
I got a spare just in case I mess up with the swap over (highly likely) but I'm not sure I will find time to make an attempt before Christmas.
Either way, watch this space

Sorry for kicking this old thread, but i do have the same issue. Did swapping the chip fix the problem?

DomesticExtremis · 02-23-2024, 04:28 PM

Quote:

Originally Posted by GuustFlater89

Sorry for kicking this old thread, but i do have the same issue. Did swapping the chip fix the problem?

No, it did not - sadly. :-(
I moved house shortly after trying (and failing), so it lies unloved in a box in the attic.
Bought a Clara instead which is very good apart from avoiding e-waste.

GuustFlater89 · 02-25-2024, 03:31 PM

Thnx for your reply. Too bad....
My new tps651851 chip is on its way. So i will try anyhow.
(I've got a Clara HD waiting to be rescued...)

GuustFlater89 · 02-26-2024, 03:25 PM

Do you think the screen was cracked? Or another electronic problem?

10-13-2019, 10:11 PM	#31
DomesticExtremis Addict Posts: 243 Karma: 359054 Join Date: Nov 2012 Device: default	DCDC2 DCDC2 (part application circuit attached below) is checked first as it needs to be up and running before DCDC1 is powered up, so any faults here might be preventing DCDC1 from working. Pins 24,25 and 26 are directly connected to the DCDC2 subsystem, in addition pins 4 and 16 are linked by an external rail and their attached support components need to be checked also. Pin numbers and component identifiers have been added in red. Code: Pin# Pin name Components ---- ----------- ------------------- 24 VIN_P C315 25 VN_SW D49, L31, C320 (+C321) 25 VN output to pins 4 and 16 4 VNEG_IN C317 16 VCOM_PWR C323 (+C316 +C324) Capacitors in brackets are additional to those on the circuit diagram and are extra capacitors in parallel to the one shown. Attached Thumbnails Last edited by DomesticExtremis; 10-13-2019 at 10:15 PM.

10-13-2019, 10:21 PM	#32
DomesticExtremis Addict Posts: 243 Karma: 359054 Join Date: Nov 2012 Device: default	DCDC1 DCDC1 uses pins 40, 41 and 42 and also is connected to pin 43 exterrnally. Code: Pin# Pin name Components ---- -------- ---------- 40 VB_SW D48, L33, C224, C319 (+C269) 41 PGND1 to ground 42 VB to pin 43 43 VPOS_IN C271 (+C319) Attached Thumbnails

12-02-2019, 10:46 PM	#35
DomesticExtremis Addict Posts: 243 Karma: 359054 Join Date: Nov 2012 Device: default	Obtaining a new chip Once more real life has intervened to slow down this escapade. I have considered giving up, but the faulty chip costs only ~£1.80 compared to the £180 cost of the original e-reader (the person that gave it to me bought it in 2017). Just to avoid confusion, there are three different models of chip available: Code: PART NUMBER PACKAGE BODY SIZE (NOM) MARKING ( \| = newline) TPS65185 RGZ (48) 7.00 mm × 7.00 mm E INK \| TPS65185 RSL (48) 6.00 mm × 6.00 mm TPS \| 65185 <------ TPS651851 RSL (48) 6.00 mm × 6.00 mm TPS \| 651851 The Aura H2O has the chip marked on the second row. The next problem is finding a supplier. EBay does have some vendors in China offering them, however it was unclear to me whether the part they claimed was actually what they would send as the pictures did not match the description. In addition the delivery times were long and not all free postage. The mainstream component suppliers (e.g Mouser, Farnell etc) need an account and some have a minimum order size plus delivery charges. I was pointed to LCSC, an asian supplier, which had the exact item I need and reasonable delivery time plus delivery charges no higher than from more local suppliers. I decided to go with these as I wanted to get some other bits and also wished to test out their service, The parts are winging or bobbing their way to me as I write, so the next set of updates will follow as soon as they arrive and I attempt to fit them. Last edited by DomesticExtremis; 12-02-2019 at 10:48 PM.

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10-13-2019, 10:29 PM	#33
DomesticExtremis Addict Posts: 243 Karma: 359054 Join Date: Nov 2012 Device: default	All of the components were in good visual condition - not charred or discoloured. The inductors should have resistance in the milliOhms range and measured a short i.e good. The capaciotrs all measured as open loop, i.e. were not short. The diodes measured as open loop in one polarity and gave a forward voltage in the other. Despite the caveats about in-circuit measurement, both diodes had a forward voltage of~190mV, which is about right for a Schottky diode. As far as can be ascertained, noe of the external components have failed, though it was not possible to determine that the capacitor and inductor values were correct relative to the typical application circuit. Bear in mind that this was done using otoo large multimeter probes, 3.0 diopter reading glasses and a powerful head torch. Nevertheless, that would appear to confirm that the TPS 65185 chip is the culprit for my broken e-reader. Now I have to set about finding a replacement chip, replacing it and seeing if that fixes it. I am aware that I may need to set VCOM (the flat flax cable is marked -1.83, presumably volts) but I will cross that bridge if I ever reach it.

10-22-2019, 09:25 PM	#34
DomesticExtremis Addict Posts: 243 Karma: 359054 Join Date: Nov 2012 Device: default	Another hiatus - I have obtained a hot air rework station and have been practising on some scrap electronics the removal and resoldering of various chips. Now I have the hang of it (kinda, sorta) I will set about trying to source a replacement chip. Life is about to get in the way of this endeavour once more, so it may take some time until I am reagy to attempt replacing the PMIC. Stay tuned...

12-14-2019, 02:17 PM	#36
DomesticExtremis Addict Posts: 243 Karma: 359054 Join Date: Nov 2012 Device: default	OK, so the chips arrived - 8 days from deepest China. I got a spare just in case I mess up with the swap over (highly likely) but I'm not sure I will find time to make an attempt before Christmas. Either way, watch this space

02-25-2024, 03:31 PM	#39
GuustFlater89 Junior Member Posts: 7 Karma: 10 Join Date: Feb 2024 Device: Kobo Clara HD	Thnx for your reply. Too bad.... My new tps651851 chip is on its way. So i will try anyhow. (I've got a Clara HD waiting to be rescued...)

02-26-2024, 03:25 PM	#40
GuustFlater89 Junior Member Posts: 7 Karma: 10 Join Date: Feb 2024 Device: Kobo Clara HD	Do you think the screen was cracked? Or another electronic problem?

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