Mean Well PT-65-R13VAI with a short.

[GLInick]

This looks to be the product page of the unit I am working with:
https://www.meanwell.com/webapp/prod...spx?prod=PT-65

The PS was working until an accidental short caused a white puff of smoke and the fuse to blow. An uninsulated ground mains wire was pushed under the right edge of the board (all along the edge of RTH1, C36, C16, ... SHR1).

The device supplies 240V input to the PS board, and the fuse is 250V/4A.

How do I isolate what blew? Nothing looks burned.

[R_J]

Re: Mean Well PT-65-R13VAI with a short.

Start by checking the resistance across the + & - of BD1 bridge rectifier, then check each of the 4 diodes in the bridge, then check Q1 mosfet for shorts, if it is shorted, I suspect the drive ic u1 may have also been damaged, also check R6, it should be a low ohm resistor
as for the secondary side, check the parts around shr1 (likely a tl341 reference) and zd2 zener as well as the other diodes in that area
Looks like it's only worth $21.00, likely cost more in parts to repair it.
https://www.digikey.com/products/en?...866-3929-ND%20 Just need to get the correct voltage output version

[stj]

Re: Mean Well PT-65-R13VAI with a short.

check c33 and all the gray resistors.

[GLInick]

Re: Mean Well PT-65-R13VAI with a short.

Looks like it's only worth $21.00, likely cost more in parts to repair it.
https://www.digikey.com/products/en?...866-3929-ND%20 Just need to get the correct voltage output version

Thank you for this link. Can you go over my logic to confirm the board I need to order?

The PS board has the following marking: PT-65-R13VAI. The data sheet doesn't list that exact one.

The PS output header has pins labelled -V, GND, +5V, +V

A couple of boards later, I found that the +V goes into a small linux board, which has a 3-pin power input, labelled GND, +15V, and +5V. I checked continuity on all pins, and it seems the +15V labelled pin is fed from the +V on the PS output.

So, per datasheet, I think I need PT-65C. Is this correct?

As an aside, while checking a few board components, i noticed a red stain under the transformer. I'll need to desolder it to check for shorts.

[R_J]

Re: Mean Well PT-65-R13VAI with a short.

That looks correct pt-65C Digikey 1866-3930-ND $21.01, Like said, hard to beat the price.
As for the transformer, its likely ok, usually its the toughest part on the board.

[eccerr0r]

Re: Mean Well PT-65-R13VAI with a short.

Is the PSU actually shorted now, tried just replacing the fuse and seeing if there's life? Use a DBT instead of the fuse?

The fuse did what it it was meant to do, maybe you got lucky and there's no additional damage.

[GLInick]

Re: Mean Well PT-65-R13VAI with a short.

I ordered a replacement board.

I already tried another fuse. Can I use a 120v DBT on a 240v circuit? The PSU is rated at 65 watts.

[R_J]

Re: Mean Well PT-65-R13VAI with a short.

No, If there is a dead short in the power supply, the 120v lamp will light really bright for about .5 sec. and go open. You would need to use two 120 volt lamps in series.

[GLInick]

Re: Mean Well PT-65-R13VAI with a short.

for the sake of learning, is there a relationship between wattage of the DBT, and the rating of the PSU? If say a PSU with 240VAC input was rated at 65W (full load), what would be an appropriate wattage for the each of the two 120VAC incand. bulbs?

[R_J]

Re: Mean Well PT-65-R13VAI with a short.

The lamp wattage is not important, you can use 60 watt lamps, the ps rating is what it is capable of producing the 65 watts. this setup is for testing, it is not going to be used when the ps is working and under load. it is used to limit the current and drop the voltage into the power supply if there is a problem, ie: short