Konica DR-BC-K4 Battery Charger

[Per Hansson]

Story is like this, I buy a known dead LCD for almost nothing, fire it up and it starts to flimmer, I wanna take some pics of it and my camera says "no more power" so I put the battery in the charger but it wont charge... (sorry for the off topic bit)

Anyway, I measure 230v up to the black small component on the back marked BD1 on the silkscreen, on the other side of it, where also a 400v 10uF Fuhjyyu MH cap is (brown on pic) I do not measure AC, I measure 300VDC!!!

The trace leading forward has some burned solder it looks like, and if you follow that trace till it ends you end up at a leg of the transformer; that solder leg also looks burned (or reflowed from very high heat...)

I would have thought that up untill now all I was going to measure was AC voltage, and on the other side of the transformer I would have seen low DC voltage... Well, on the other side of the transformer there is no voltage to speak of, just a couple mv... I measure 0.000v on the 3 terminal legs for the battery...

[linuxguru]

Re: Konica DR-BC-K4 Battery Charger

It has Fuhjyyu caps, but that's probably not the reason it failed - the likely failure is the primary HV switching device, probably a TOPswitch or similar.

[Per Hansson]

Re: Konica DR-BC-K4 Battery Charger

Ok, over the "gap" which signifies the AC>DC side there is a chip "PC817 SHARP"

On the AC side there is another chip "DH565"

The sharp seems to be a photocoupler, whatever that is...?

The other chip google is not my friend on

And I agree on you with the Fuhjyyu caps, it's not like the charger has seen more (total) use than like max a week or so...

[Rainbow]

Re: Konica DR-BC-K4 Battery Charger

Photocouplers are used for feedback from the secondary side back to the primary side.
I'd check the zener diodes - some of them might be shorted.

[japlytic]

Re: Konica DR-BC-K4 Battery Charger

The "DH565" is a FSDH565 (it is abbreviated, because there is not enough space). This is obviously a unit from a Chinese manufacturer because of the Chinese characters on the PCB (better be careful with outsorcing!). Also, a Playstation 2 power supply was made by Hipro, which was involved in a recall.

[Per Hansson]

Re: Konica DR-BC-K4 Battery Charger

Photocouplers are used for feedback from the secondary side back to the primary side.
I'd check the zener diodes - some of them might be shorted.

I desoldered one of the legs on every diode, with a DMM Diode test I read 700 on the small red diodes (Silicon Diodes?)

On the two large black diodes (Zener Diodes?) I measure ca 160 on one and 180 on the other with the diode test.

All diodes are "open"; no reading the other way around so they seem to be ok...

The "DH565" is a FSDH565 (it is abbreviated, because there is not enough space). This is obviously a unit from a Chinese manufacturer because of the Chinese characters on the PCB (better be careful with outsorcing!). Also, a Playstation 2 power supply was made by Hipro, which was involved in a recall.

Ok, thnx, found the datasheet, did not make me very much wiser though

What was that about the Playstation 2 huh?

[Per Hansson]

Re: Konica DR-BC-K4 Battery Charger

Small update: the 16v cap is being slowly charged, after about a minute it is up at 0.73v... So seems something is letting power through but not much enough?

And it still stumps me how I can be reading 320VDC on that "big" capacitor right after the small black chip marked "BD1" on the silkcreen, has UA80 and 0324 (datecode?) written on it... It is also marked for + and -

[Per Hansson]

Re: Konica DR-BC-K4 Battery Charger

small update 2: that FSDH565 chip gets pretty warm at 80°C so I think it is faulty...

[VILE DISRUPTION]

Re: Konica DR-BC-K4 Battery Charger

forward voltage drop of 700 is great across silicon diodes

if it takes that long to get to 0.73volts it might be something like a failed resistor but i dont really have much of an idea.

as for the chip if it is that hot it most certanily is faulty.

[Rainbow]

Re: Konica DR-BC-K4 Battery Charger

Common failure mode for zener diodes (the ones with ZD marking on the PCB) is short - so if they're not shorted, look elsewhere. That hot FSDH565 looks like prime candidate.

[PeteS in CA]

Re: Konica DR-BC-K4 Battery Charger

If the FSDH565 is the PWM and is driving a MOSFET with a gate-source short, it would get pretty warm.

[Per Hansson]

Re: Konica DR-BC-K4 Battery Charger

Yea, the FSDH565 is the PWM...

Description
The FSDH565 is specially designed for an off-line SMPS with
minimal external components. The FSDH565 is a monolithic
high voltage power switching regulator that combine the
SenseFET(LDMOS) with voltage mode PWM control block.
Included PWM controller features integrated fixed oscillator,
under voltage lock out, leading edge blanking, optimized gate
turn-on/turn-off driver, thermal shut down protection and
temperature compensated precision current sources for loop
compensation and fault protection circuitry. compared to
discrete MOSFET and controller or RCC switching converter
solution, a FSDH565 can reduce total component count, design
size, weight and at the same time increase efficiency,
productivity, and system reliability. It has a basic platform well
suited for cost effective design in a flyback converter.

[Rainbow]

Re: Konica DR-BC-K4 Battery Charger

Of course, testing power components like MOSFETs for shorts never hurts.

[Per Hansson]

Re: Konica DR-BC-K4 Battery Charger

I have unsoldered the Mosfet but my DMM only provides 1.8v on the diode test and most "Mosfet test" articles I found on the webster say that you need 3-4 volt...

Any other tests I can do with it?

[Per Hansson]

Re: Konica DR-BC-K4 Battery Charger

I dug up an old LM317, on it I read 830 with the diode test, I followed this guide:

http://www.4qd.co.uk/serv/mostest.html

However I do not have to do the gate part, i.e. I measure 830 if I directly touch source and drain... And it does not drop to zero if I touch the legs when measuring...

So is my multimeter unable to do the test or am I doing something wrong? (or is this mosfet dead too?)

This is the Mosfet on the charger, I can't read anything across any leg on it...

[starfury1]

Re: Konica DR-BC-K4 Battery Charger

Per, if I follow correctly BD1 is a dip package bridge rectifier the 400v cap is the smoothing cap for the pulsating DC just like a normal linear PSU except no transformer to step down and isolate from the mains "we have Direct Rectification of the Mains to DC"
340 (odd) Volts DC is what should be on the cap (1.414 X 230 Volts ac if you use a bridge rectifier)
The "High frequency transformer" along with the "optcoupler" provide "Isolation" of the mains primary side from the secondary.
Now tranformers only work with AC so therefore we need to convert the HV DC to a high frequency AC (so we can use a much smaller tranformer)
This from the circuit above is done with the FSDH565 and from a quick squizz seems it does the all on the primary side.
If it getting el stinko hot then I would agree it may be the fault.
But when you have feedback you can have a chicken and egg thing happening.
As to the mosfet not sure but its not TO220 case style so may be different pinout
Tried to find some data on it and the IC on the underside ....no luck really
ok not much help again, its late I am sleepy so will have to leave it for now

BTW an LM317 is a linear variable regulator IC so it a bit like comparing apples with oranges....different kettle of fish

[gonzo0815]

Re: Konica DR-BC-K4 Battery Charger

This mosfet isn`t there for the switching of the smps. The smps consists only of this smal chip, the input and output rectifier. And of coursr usually on or two input caps and some op caps should be there. The rest of your circuit is probably the current regulation part, for loading the cells. If no volltage is there, you should check the smps alone, e.g reading the app note and make sure that it isn`t disabled by the charge controler on the downside.
I have some of those simple tiny switchers in several switches, the design is realy simple, but in my units the smps chip is cooled by a piece of sheet metal, soldered on the pcb next to the chip.
As the chip contains the switching device already, it intensionally is getting warm or even hot.
The 320v is fine and is same by my units.

[starfury1]

Re: Konica DR-BC-K4 Battery Charger

Thanks gonzo0815 for ponting that out clearly, I didnt in my post, never even got to the secondary side of things
your explaination of the secondary side makes sence since it is a battery charger,you would put the smarts onboard

That "mosfet" on the secondary side of things is from what I can work out a PNP transistor type number HT772
From the pdf I grabbed its use's are output for 1Watt audio amp ,Votage regulator, DC DC converter, Relay driver.
package type TO 126
(I really should have known the package type but couldn't recall it at the time I did the reply above...brain getting old and rusty LOL)

Pin out from you pic above is (L2R) Emitter Collector Base
(looking at the numbers on the back)

D2 appears to be a high speed rectifier diode and along with that 16 Volt cap would be the AC secondary to secondary DC (rec, filter part of the circuit)
(half wave by the looks of it) You say you have no DC there
I'll stand to be corrected on this thought.

Next a question you say the DH565 gets really hot, is the transformer or any other components getting really hot? Err make sure you unplug it OK.
If its not doing any work I would expect nothing to be getting overly hot

I dont know how likely it is for the DH565 to fail internally but if static tests of components are not showing up a dud then possibly it is the fault

Again I know its not the answer your looking for but hope it helps

[gonzo0815]

Re: Konica DR-BC-K4 Battery Charger

May be i should pointing out why i have opend my switches . One of both won`t power on all the times, and with time the reliability drops. So i opend the case and cheked for badcaps. Guess what i found? the ugliest crap cap GSC even the high voltage caps are GSC, and had been failed (without signs of bulging.) So i replaced those 10uf 400v caps with some Elna 4,7uf/350v (had them laying around and spekulating of the +20% specs )and the o/p caps with some Rubycon mcz and it now is working fine since several months.
So, don`t wory about that, replace the hv caps or ad some know good cap and chek if it will powering on.
And yes, there are 320 to 340v on the caps.

[starfury1]

Re: Konica DR-BC-K4 Battery Charger

Since these seem the most likely candidate, I thought he might have already tried that by now
but yes