Ryobi 12v Li-Ion Battery Charger dead

[sambul83]

Hi guys,

My Ryobi CH120L Li-Ion Battery Charger suddenly died after sitting in the closet for some time without being used. No lights at all, doesn't charge any battery, no voltage btw Battery Charging Terminals. It measures 0.06V btw Battery Control Terminals. The fuse checks OK for continuity. Here's its Manual.

I suspect its the same Bad Caps saga again, may be more.

Can you suggest how to pinpoint the failing parts? I don't have any electronic components stocked, so can't try freely which replacement will do.

[kc8adu]

Re: Ryobi 12v Li-Ion Battery Charger dead

get rid of the yellowish brown glue.esp on the primary side.see the mess around that 33k resistor? a leak to ground stops your startup.

[sambul83]

Re: Ryobi 12v Li-Ion Battery Charger dead

Not sure where exactly, can you circle the right places? Also, it was working well like that for 3 years, I never opened it before, then it suddenly doesn't work anymore without being used. As I read, they glue the parts on one side so they don't fall out from hits in transportation.

[stj]

Re: Ryobi 12v Li-Ion Battery Charger dead

c106 is my primary suspect.

[electronicsurplus]

Re: Ryobi 12v Li-Ion Battery Charger dead

Also test D106 to make sure it is not shorted

[sambul83]

Re: Ryobi 12v Li-Ion Battery Charger dead

c106 is CapXon 47uF 50V Vent P828 GL 105C. As I understand, reliable checking it is only by replacing with the same value cap - correct?

I also read somewhere that c201 cap CapXon 1000uF 50V was the problem, but in their case there were some lights working on the charger. Can this cap be a problem here with no lights and no voltage on battery terminals?

d106 I checked for continuity on the board like a fuse in both directions under power, and its not shorted in one direction, and shorted in the opposite. Was that a correct method? It looks like a diode should work like this?

What's position of "33k resistor under glue", or position near it?

[budm]

Re: Ryobi 12v Li-Ion Battery Charger dead

When you resistance testing or Diode mode testing, no power to the unit.
Check the DCV between the two leg of C106 with power applied, since you will be working in the primary (deadly side) side of the circuit, you must be real careful not to touch anything with your hands or body, you should at least plug this unit into GFCI outlet for some protection.

[sambul83]

Re: Ryobi 12v Li-Ion Battery Charger dead

Hi budm,

Glad to meet you again. I checked DCV, and its 0V on c106, and respectively 0v on c102 and c103. Its 14.3V on c201. I checked the diod d106 with power off, and it shows no continuity in both directions.

[newtothis]

Re: Ryobi 12v Li-Ion Battery Charger dead

Ok thats a bad reading on the diode... Remove from circuit and test

[sambul83]

Re: Ryobi 12v Li-Ion Battery Charger dead

Ops... my error. When I checked the diode on the board, I only listen for multimeter beep. Now I looked at the display, and it shows OL in one direction, and 540 mV in opposite direction. Does it mean the diode is OK?

[stj]

Re: Ryobi 12v Li-Ion Battery Charger dead

yes, a good diode is around 450-550 usually.

[sambul83]

Re: Ryobi 12v Li-Ion Battery Charger dead

How about the caps measurements? Should I replace c106 now? Only that one?

[kc8adu]

Re: Ryobi 12v Li-Ion Battery Charger dead

whats the voltage at the primary caps?
thats the 2 big ones side by side.
edit...
0v at 102 103 means problem between the wall and there.

[sambul83]

Re: Ryobi 12v Li-Ion Battery Charger dead

Sorry again, it was too late yesterday night, I was sleeping. Measured it today again, and the accurate voltages are:
6.65V on c106 (CapXon 47uF 50V), and respectively 181.7v on c102 and c103 (both are CapXon 100uF 200V). Its 16V on c201 (CapXon 1000uF 50V). All these voltages are stable. Wall outlet is at 116ACV.

[budm]

Re: Ryobi 12v Li-Ion Battery Charger dead

What is P/N on that multi-leg SMPS IC? 6.65V for the start-up/running Voltage is too low, we need the spec sheet of the SMPS IC.
181Vdc on the main filter caps do not look right either, higher than it should be based on only 116Vac input.

[newtothis]

Re: Ryobi 12v Li-Ion Battery Charger dead

Please check your meter/battery just to make sure

[sambul83]

Re: Ryobi 12v Li-Ion Battery Charger dead

My meter VC9808 had a fuse open after an error in Temperature measurement. I changed the fuse, but it may need some calibration now. Though it measures 9v batteries at 9.8 to 10.2v, and 1.5v batteries at 1.5-1.6v, so DCV seems to be accurate, when compared to a battery tester measurements. But for wall outlet AC it shows 136ACV, while UPS shows 118ACV, so the meter's AC circuit may need calibration now. Not sure, how to calibrate it?

As to the charger parts, the controller P/N is Atmel TBGA-FEB AU0820 - on the back
The board P/N 260111007 REVO0.21/070817 UL94VO ROHS - on the back
On the front side: WAN NIEN 03VO (A) E88653 94V-0

Other parts:
sfh617a optocoupler next to D106 diode
fbh42 fod 17p06 mosfets on the back

[budm]

Re: Ryobi 12v Li-Ion Battery Charger dead

The SMPS IC is mounted on the heatsink, it has 4 or 5 pins on it.
https://www.badcaps.net/forum/attach...9&d=1429058201

[sambul83]

Re: Ryobi 12v Li-Ion Battery Charger dead

That one SMPS IC on the larger heatsink is H826 TOP245YN, and the other one on a smaller heatsink is hidden behind the transformer, but it looks and feels exactly like the 1st one.

[budm]

Re: Ryobi 12v Li-Ion Battery Charger dead

OK, here is the spec sheet, and per page 5 the control pin needs to have 5.8V to start the circuit:

The CONTROL pin is a low impedance node that is capable
of receiving a combined supply and feedback current. During
normal operation, a shunt regulator is used to separate the
feedback signal from the supply current. CONTROL pin voltage
VC is the supply voltage for the control circuitry including the
MOSFET gate driver. An external bypass capacitor closely
connected between the CONTROL and SOURCE pins is required
to supply the instantaneous gate drive current. The total amount
of capacitance connected to this pin also sets the auto-restart
timing as well as control loop compensation.
When rectified DC high voltage is applied to the DRAIN
pin during start-up, the MOSFET is initially off, and the
CONTROL pin capacitor is charged through a switched high
voltage current source connected internally between the DRAIN
and CONTROL pins. When the CONTROL pin voltage VC
reaches approximately 5.8 V, the control circuitry is activated
and the soft-start begins. The soft-start circuit gradually
increases the duty cycle of the MOSFET from zero to the
maximum value over approximately 10 ms. If no external
feedback/supply current is fed into the CONTROL pin by the
end of the soft-start, the high voltage current source is turned
off and the CONTROL pin will start discharging in response
to the supply current drawn by the control circuitry. If the
power supply is designed properly, and no fault condition
such as open loop or shorted output exists, the feedback loop
will close, providing external CONTROL pin current, before
the CONTROL pin voltage has had a chance to discharge to
the lower threshold voltage of approximately 4.8 V (internal
supply under-voltage lockout threshold). When the externally
fed current charges the CONTROL pin to the shunt regulator
voltage of 5.8 V, current in excess of the consumption of the
chip is shunted to SOURCE through resistor RE as shown in
Figure 2. This current flowing through RE controls the duty cycle
of the power MOSFET to provide closed loop regulation. The
shunt regulator has a finite low output impedance ZC that sets
the gain of the error amplifier when used in a primary feedback
configuration. The dynamic impedance ZC of the CONTROL
pin together with the external CONTROL pin capacitance sets
the dominant pole for the control loop.
When a fault condition such as an open loop or shorted output
prevents the flow of an external current into the CONTROL
pin, the capacitor on the CONTROL pin discharges towards
4.8 V. At 4.8 V, auto-restart is activated which turns the output
MOSFET off and puts the control circuitry in a low current
standby mode. The high-voltage current source turns on and
charges the external capacitance again. A hysteretic internal
supply under-voltage comparator keeps VC within a window
of typically 4.8 V to 5.8 V by turning the high-voltage current
source on and off as shown in Figure 8. The auto-restart
circuit has a divide-by-eight counter which prevents the output
MOSFET from turning on again until eight discharge/charge
cycles have elapsed. This is accomplished by enabling the
output MOSFET only when the divide-by-eight counter reaches
full count (S7). The counter effectively limits TOPSwitch-GX
power dissipation by reducing the auto-restart duty cycle
to typically 4%. Auto-restart mode continues until output
voltage regulation is again achieved through closure of the
feedback loop.