Re: Help to diagnose SMPS issue

Have a little bit more time to do more troubleshooting

Component circled red is good... its a diode, just got coated with heavy browning flux..

Fusable resistor are all good..

Under the heatsink is NTC. 2x 5Ohm for a total 10Ohm NTC. Seems a bit low for my liking to limit inrush current...

So.. testing the M51995AFP again off board shows they are good with pulse out from the Vout pin. Placed on board and it goes quiet. I have a similar lambda power supply (24V instead of 3.3V output) laying...

Re: Help to diagnose SMPS issue

Thanks for the suggestion. I couldn't trace the ground fault current. As said, ramping up with variac does not trip the ELCB. Another info : I disconnected the ground cable to the main (from PSU to variac), and it still trigger ELCB whenever I start it with >80VAC. Slowly ramping up doesn't trigger ELCB, The trk trk sound I believe is coming from the PFC circuitry charging up the main cap to 385V. Sounds right ? Or is it more of the M51995 trying to start up but bogged down by some OVP/OCP etc protection ? I probed the OVP, OCP (CLM pin) and got...

Re: Help to diagnose SMPS issue

No voltage at all at the output terminal. I did check the secondary portion and they seem to be doing ok. Injecting voltage at the output terminal light up the led and feedback through the optocoupler is going up and down according to the injected voltage.

Now I'm waiting for ebay replacement IC... this IC is EOL and only ebay has some... anyone knows of any direct replacement for M51995AFP ?

Re: Help to diagnose SMPS issue

Attached front and back picture of the PSU. It's a Densei-Lamda JWS100-3/RA. 3.3V 20A power supply. The grey wire is just connecting the V+ to Sense+ and V- to Sense-.


Main switcher IC : M51995AFP (Mitsubishi/Renesas)
PFC IC : 5331M (Fuji Electric)

BTW confirmed that the switcher IC is dead, no pulse output. Testing method : Connect VC (Output collector) to Vcc and VCC to + Supply , GND to gnd. Based on test of the working unit, if you monitor the Vout, it should start pulsing once the VCC hits slightly more...

Hi guys,

Is there any easy way to test newer design SMPS IC that has all kind of over voltage, over current limit ? e.g. : M51995AFP.

I have a power supply using this IC with no output. Fuse is good, secondary diode are good, switchers are good. Supply will trip ELCB if powered on with full AC input (>100VAC), ramping input up shows that the PSU suddenly draw high current at about 80VAC (about 2-3A) from mains, and there is trkk trkkk sound for half a second or less and after that it does not pull current anymore. Increasing VAC beyond 100V is fine this way and...

Re: Delta DPS 320 EB missing power good signal

Picture of the PSU. Replaced capacitor is highlighted with red square. Additional note : This is PSU for B2600 HP Workstation, after replacing these bad capacitor workstation boots up and running for 3 days straight without issue. I also have a second workstation that I have replaced it with normal ATX power supply (swapping the pin around to match B2600 pin) and that is also running fine.

Next plan is to blindly replace every single electrolytic cap for both secondary and primary side to see if that brings the PG signal...

Re: Delta DPS 320 EB missing power good signal

Output capacitor are all tested good (surprisingly...). Primary cap is also tested good. Bad capacitor are mostly on the control path and bypass cap for the IC. 47uf and 4.7uf type.
Capacitor testing is using oscilloscope and function gen set at 125khz square wave 250mVp for onboard testing, if it shows some high ESR then taken out and replaced ( for a 250mV signal i define it as questionable if it still shows a 5mV signal after connected to the cap ). Did a test adding 2200uF parallel cap on all the output cap and it does not...

Hi all,

I'm troubleshooting this delta DPS 320 EB. Problem : PG Signal is at 0V. Leaky capacitor has all been replaced and could not help to think that the problem lies in the DNA1002 chip which from what I read is a custom IC by delta.

I'm using the following schematic as it looks quite similar (not the same at all in terms of component value but more or less similar) : [url]https://cdn.badcaps-static.com/pdfs/1917ea682c489c8dcbb3ba2cdd095645.pdf[/url]

Measurement at the output :
5V : 5.15
12V : 11.7
-12V : -12.08
3.3V :...

Re: New Members - please post your introductions here

Hi, new in this forum trying to fix delta DPS320EB PSU