Battery Charger / switch Mode PSU Diode ID?

[tw2005]

Hi guys,


Need some help identifying a diode sitting on the FETs. It's sitting off the gate of each 13N50 FET.

I've been pretty lucky working these SMD markings in the past but I'm stuck with this one. Could these be Zeners?


I've been out of the loop here for ages now but I'm currently working on a Projecta IC5000 intelligent battery charger. In the construction process they've used this cheap crappy glue that breaks down and / or corrodes resulting in both track damage and shorts.

I had already patched this up for someone but in hindsight should have stripped it down to clean the rest of the glue off.

It's had a rather big meltdown, still hoping to get it going again as these sell for $650 -800 AUD. The quality inside does not reflect this though.

G]

[budm]

Re: Battery Charger / switch Mode PSU Diode ID?

https://cdn.badcaps-static.com/pdfs/...d53b4b217a.pdf

[R_J]

Re: Battery Charger / switch Mode PSU Diode ID?

Could be a MMSZ5230B 4.7v zener

There are other diodes with the G5 marking, like SS1040 schottky barrier diode but they only have the product code and not the date code along side like the zener has

[tw2005]

Re: Battery Charger / switch Mode PSU Diode ID?

https://cdn.badcaps-static.com/pdfs/...d53b4b217a.pdf

awesome, was hoping you were still around. How do I decipher that sheet?

G5 on that = 3V zener

Could be a MMSZ5230B 4.7v zener

There are other diodes with the G5 marking, like SS1040 schottky barrier diode but they only have the product code and not the date code along side like the zener has

thanks also, this is the one I ordered and have. But again how do we know?

So the general take is it is a zener just the voltage I need to get right.

These do feed off into windings of a small transformer

[tw2005]

Re: Battery Charger / switch Mode PSU Diode ID?

actually, just remembered I have another problem, the thermistor it blew a hole in it it took the part number off.

Not sure what would help but it's a 50amp battery charger and a 12amp fuse on the mains

25mm in diameter approx

[R_J]

Re: Battery Charger / switch Mode PSU Diode ID?

All I can make out is the Agency Approvals. Where is it in the circuit? The printing does look like a Vishay VDRUS Series

[redwire]

Re: Battery Charger / switch Mode PSU Diode ID?

I doubt it's a zener as the 13N50 needs over 10V on the gate.
It looks like a (gate) turn-off diode, as anode goes to gate.
Consider SOD-123, Taitron TSD14W Schottky diode 40V 1A.

The 2****50M numbering on the NTC thermistor, guessing Joyin 20 or 25mm dia. +/-20% and ending in 50M it is either 15R "150" or 5R "050" resistance at 25C. 205+ is date code and RoHS. I was matching the text style.

I would take a dental pick and scrape between some component's pads, they look like extra solder or flux is there, not great for high voltage.

[tw2005]

Re: Battery Charger / switch Mode PSU Diode ID?

All I can make out is the Agency Approvals. Where is it in the circuit? The printing does look like a Vishay VDRUS Series

On the mains power in. mains in, fuse on active side, then on neutral passes through a choke, varistor across the A/N on other side then the neutral routes through the thermistor (in series) then to the 600v 25a bridge input.

VDRUS? I thought this was a thermistor being in series and varistor was across mains? There's one of them too

R55 is the thermistor location

[tw2005]

Re: Battery Charger / switch Mode PSU Diode ID?

I doubt it's a zener as the 13N50 needs over 10V on the gate.
It looks like a (gate) turn-off diode, as anode goes to gate.
Consider SOD-123, Taitron TSD14W Schottky diode 40V 1A.

The 2****50M numbering on the NTC thermistor, guessing Joyin 20 or 25mm dia. +/-20% and ending in 50M it is either 15R "150" or 5R "050" resistance at 25C. 205+ is date code and RoHS. I was matching the text style.

I would take a dental pick and scrape between some component's pads, they look like extra solder or flux is there, not great for high voltage.

Nice Some good heads in here. I think you're pretty right with that thermistor. Although it's had an explosion I did meter it out and was about 5.5 ohms with lead resistance 5.2. So I was working on 5 ohms and 25mm diamater to get close, but no luck.

Datasheet says o50M is 11amps and that rings true with the 12A fuse.

yes it is a mess inside now for sure.

as for that diode, I was originally thinking fast switching schottky but when I got hits for G5 as a zener, that's when I thought I better get some extra eyes on. I have no idea, that's why I was hoping someone who knew what a typical cct would have could confirm typical type of diode then maybe try hunting the code

[budm]

Re: Battery Charger / switch Mode PSU Diode ID?

The Diode D66 and D161 which each one is connected to the GATE on N-CH MOSFET 13N50, since the Anode of the diode is connected to the Gate and there is no parallel Gate resistor, diode will be reverse bias so there will be no Gate drive Voltage which is positive withe ref to the Source pin.
The Gate discharge will have resistor connected in parallel which I do not see in the pictures. You can see Gate to Source resistors (R19, R20) but no Gate drive resistor directly connected to the Gtae, only the Diode.
The Gate drive will have to be higher than the 3V + Vgth.
So the MOSFET's are still good?
You can easily verify if the diode is Zener or not by using power supply and resistor.
Can we see the straight shot pictures of the whole top and bottom side of the board, using attachment instead of inline pictures?

[redwire]

Re: Battery Charger / switch Mode PSU Diode ID?

If this battery charger uses a gate-drive transformer, we should step back, it could be a Schottky or a zener.
I drew this crude schematic based on what I can see, I think I had the mosfet GDS backwards on the underside of the PCB view.
Wildly guessing Q13, Q14 are PNP with CBE pinout.

Also attaching what I would expect for a (1/2 of) gate-drive if a transformer is used.

[tw2005]

Re: Battery Charger / switch Mode PSU Diode ID?

The Diode D66 and D161 which each one is connected to the GATE on N-CH MOSFET 13N50, since the Anode of the diode is connected to the Gate and there is no parallel Gate resistor, diode will be reverse bias so there will be no Gate drive Voltage which is positive withe ref to the Source pin.
The Gate discharge will have resistor connected in parallel which I do not see in the pictures. You can see Gate to Source resistors (R19, R20) but no Gate drive resistor directly connected to the Gtae, only the Diode.
The Gate drive will have to be higher than the 3V + Vgth.
So the MOSFET's are still good?
You can easily verify if the diode is Zener or not by using power supply and resistor.
Can we see the straight shot pictures of the whole top and bottom side of the board, using attachment instead of inline pictures?

I had a feeling you'd suggest a power supply and resistor to test, just hoping not to have to do that.

MOSFETS are toast as are all the supporting components underneath .

basically I got this going but used an underated Bridge (15A) in place of the 25A as a quick test while I waited for the correct one to arrive.

The charger turned on as normal but no output, it needs to sense a load to activate.

being impatient I selected 6Amps output and hooked a battery up expecting to stay within the bridges rating.

It went fine , but went to Boost which I am assuming is max current, not thinking, I let it run for about a minute when it popped.

MAy have been that or something else missed , anyway, my LAD comes out and says power is out. The charger is still connected and turned on. The fuse must have been still ok.

He flicked the breaker on before I knew what was going on, and the next explosion and noise sounded gruesome.

I think this is why I have more damage this time around. These part survived originally

[tw2005]

Re: Battery Charger / switch Mode PSU Diode ID?

I doubt it's a zener as the 13N50 needs over 10V on the gate.
It looks like a (gate) turn-off diode, as anode goes to gate.
Consider SOD-123, Taitron TSD14W Schottky diode 40V 1A.

The 2****50M numbering on the NTC thermistor, guessing Joyin 20 or 25mm dia. +/-20% and ending in 50M it is either 15R "150" or 5R "050" resistance at 25C. 205+ is date code and RoHS. I was matching the text style.

I would take a dental pick and scrape between some component's pads, they look like extra solder or flux is there, not great for high voltage.

I just tried reverse bias with a 1k resistor and at 10V and 19V it did not conduct. Forward it behaved like a std diode and had a V drop of 0.28V

[tw2005]

Re: Battery Charger / switch Mode PSU Diode ID?

I doubt it's a zener as the 13N50 needs over 10V on the gate.
It looks like a (gate) turn-off diode, as anode goes to gate.
Consider SOD-123, Taitron TSD14W Schottky diode 40V 1A.

The 2****50M numbering on the NTC thermistor, guessing Joyin 20 or 25mm dia. +/-20% and ending in 50M it is either 15R "150" or 5R "050" resistance at 25C. 205+ is date code and RoHS. I was matching the text style.

I would take a dental pick and scrape between some component's pads, they look like extra solder or flux is there, not great for high voltage.

Well I found this with G5. Just so happens to be 40V 1A

[tw2005]

Re: Battery Charger / switch Mode PSU Diode ID?

and this was that thermistor, got the diameter wrong, was in fact 20mm

20S050M

[tw2005]

Re: Battery Charger / switch Mode PSU Diode ID?

all fixed and running again using the schottky diodes.

Thanks for all the help fellas