Ryobi 12v Li-Ion Battery Charger dead

[sambul83]

Re: Ryobi 12v Li-Ion Battery Charger dead

So which voltage should I measure now - btw SMPS IC C and D pins? C106 cap stays fixed at 6.65V -what does it say to you?

[budm]

Re: Ryobi 12v Li-Ion Battery Charger dead

S pin (which is connected to the primary circuit GND) and the C pin.
I do not know how C106 is connected in that board, it may be the same cap (C5) as shown in the circuit example on page 21, you will have to trace that out.
It can also be due to the OV/UV condition (due to bad sensing resistors), you should read the operation of the IC to get more details.

[sambul83]

Re: Ryobi 12v Li-Ion Battery Charger dead

C106 cap is connected by one leg through R110 to the line (x) pin - c105 - ISO optocoupler, by another leg to the line (c) pin - r106 - another leg of ISO optocoupler and possibly to d106, which is connected by another leg to big transformer (though d106 connections are hardly visible). So c106 is hooked basically to (x) and (c) IC pins. Voltage btw (c) and (x), and (c) and (s) is the same 6.6V stable, no variations in time. See the pc (read F instead of E).

Which particular sensing resistors you're talking about? Does it mean, due to very small sensing resistors and caps size this thing can't be diagnosed or repaired at home?

Given the nature of how the charger stopped working without being used for 3 months, it looks like a bigger cap failure like c106 - correct? Can any other than an electrolytic capacitor component from this board die without being used?

[redwire]

Re: Ryobi 12v Li-Ion Battery Charger dead

The TOP245YN may be working fine? (datasheet) It likes around 5.8V on the Control (c) pin which is close to what you have.
Measure voltage (on the secondary) C201, see if you have power there.

That PCB shows a lot of factory rework for crappy soldering and messy flux on Q204 (by the Test pad). I would resolder the almost fractured-looking joints and clean some flux off the board.

[kc8adu]

Re: Ryobi 12v Li-Ion Battery Charger dead

with 16v on the 1000uf its running.
bet the battery is overdischarged and possibly locked out.

[sambul83]

Re: Ryobi 12v Li-Ion Battery Charger dead

C201 is 16V. Just measured the battery, its 12.8V, and another one is 12.2V. Also, red led must light up when the charger is connected to wall outlet without battery present. It worked always like this, and that's what Manual says too. But there are no lights at all now, and no voltage on battery terminals. And voltage on C106 should periodically fluctuate as per IC spec, but it stays the same - or it only fluctuates when battery is charging?

[sambul83]

Re: Ryobi 12v Li-Ion Battery Charger dead

Regarding the red led, since it should light up when the charger is hooked to the wall with or without battery present, I assume its not controlled by the SMPS IC - correct? Its basically just a "power presence" indicator. So what component can block it?

[budm]

Re: Ryobi 12v Li-Ion Battery Charger dead

If the power supply is working but still no RED Power light as shown in the manual, then it is something else is wrong in the controller circuit some where.
First I would check and see if there is any DCV between the two legs of the LED first, if not, then need to locate the drop down Voltage regulator to convert 16VDC output of the power supply down to may be 5V to run the controller IC.

[sambul83]

Re: Ryobi 12v Li-Ion Battery Charger dead

On red led voltage is 0.35V, and on green led its 0.25V, so its probably not enough to light up any of them. It looks like the leds (and also device on/off and standby mode when applicable like in printers) are controlled by Atmel microcontroller communicating with SMPS IC via ISO optocoupler and IC (X) leg. Voltage btw (c) and (x) legs is 6.6V and on c201 is 16V, so it seems to be around working voltage for "Ready". So Atmel microcontroller should light up at least red led - correct?

And if Atmel's control circuitry doesn't work as it should, there will be no ANY voltage on battery terminals either - correct? Here we go again with a "time bomb" Ryobi conspiracy theory.

[budm]

Re: Ryobi 12v Li-Ion Battery Charger dead

I would check the VCC pin of the ATMEL, I also do not know if the output pin drives the RED power LED directly or not, this is not going to be easy to troubleshoot without the diagram.

[sambul83]

Re: Ryobi 12v Li-Ion Battery Charger dead

Here're some more pics. Which pins to check? May be the other caps are the culprit on output side?

I can't seems to find any remotely closed by complexity charger repair instructions on the web, only very simplistic ones.

I checked diode d203 that seemingly passes control current from the optocoupler to Atmel for continuity, and it shows 660mV in one direction, and 1990mV in the opposite. Is it normal, or it must be always open in one direction with wall power off?

[budm]

Re: Ryobi 12v Li-Ion Battery Charger dead

Can you read the P/N of that ATMEL? We need the spec sheet to get the pinout. It looks to be pin 3 for the VCC, needs verification.

[redwire]

Re: Ryobi 12v Li-Ion Battery Charger dead

MCU power needs a voltage regulator, I'm guessing it's IC203 with a 3.3V or 5VDC output. Can you measure the voltages on it, and the part #.
There is also Q209 (TO-92) and its zener ZD2? as a switch or pre-regulator.
Somewhere , the 16V gets down-regulated for the MCU.

[sambul83]

Re: Ryobi 12v Li-Ion Battery Charger dead

More Parts:

Controller P/N is Atmel TBGA-FEB AU0820 (IC202)
IC203 - C3E H62, voltages near 0 btw any pins
IC201 - LM358 Pamya voltage amplifier - that one? Its 6V growing to 7.5 V btw Gnd and 1Out, and 0.25V btw Gnd and 2Out
Transistor c1815 gr8e (Q209) What should I measure here?
Zener unknown (ZD203). Its 750mV in one direction, and 790mV continuity in the other with power off
Optocoupler sfh617a (ISO)
Mosfets fbh42 fod 17p06 (Q201 and Q208)

I also have 16.8mV on C203, 0.3v on C205 and C215, 4.5v on C202. And D202 checks OL & 505mV

[budm]

Re: Ryobi 12v Li-Ion Battery Charger dead

OK, use the negative leg of the C201 (secondary side main filter cap) as the GND ref and probe all 4 pins of the IC 203 and report the readings.

[sambul83]

Re: Ryobi 12v Li-Ion Battery Charger dead

And the readings are: 15.7, 16, 16, 16V (out)

I then measured voltages btw IC203 in and out, they were all around 0. Then I measured voltages 2nd time btw C201 and IC203 legs, and this time it was .25, 0, 0, 0V . Why is that - can such measurement fry it?

[budm]

Re: Ryobi 12v Li-Ion Battery Charger dead

OK, the IC203 is the one with tab on top and 3 small pins on the bottom, not the 8-pin one you have measured.
BTW, great pictures.

[sambul83]

Re: Ryobi 12v Li-Ion Battery Charger dead

I know, that one was giving 16V, but now it gives near 0v btw any pin and c201 ground.

[budm]

Re: Ryobi 12v Li-Ion Battery Charger dead

All 4 legs/pin of that IC against the negative leg of cap C201 is the secondary side circuit GND ref point (I will have to trace the board to make sure unless the secondary has two power supplies).. so put the meter's black probe on the negative leg of C201
you can report the readings like this: looking at it with tab up:
Left pin = xxxx VDC
Center pin = xxxx VDC
Right pin = xxxx VDC
Tab = xxxxVDC

[budm]

Re: Ryobi 12v Li-Ion Battery Charger dead

OK, I just look at the board layout, there are two power supplies:
D201 and filter cap C201 is the 16V power supply.
D202 and filter cap C202 is the second power supply (4.5V) which is more likely for running the Controller circuit.