Vizio M420SL PS Issue

[Jsikora]

Hi all,

I have a Vizio M420SL that I am not getting 24V output from PS to LED driver. I am getting other voltages like 3V and proper voltage at main cap C612, however, on the cold side I have no voltage at any caps. C301 C302 C503 c504 C506 and C508. I have not yet checked C501, 505, C305, 307. All fuses check good, just trying to get an idea of where to start. Any ideas welcome. Thanks and here are pics.

[Jsikora]

Re: Vizio M420SL PS Issue

Also Diodes D601, 601A and D603 all testing no good in circuit.

[CapLeaker]

Re: Vizio M420SL PS Issue

Check the PFC on the PSU. If the PFC isn't working, there won't be any 24V. What voltage are you getting on the main filter cap of the PSU with the PSU running? Also check the BLon to see if its getting the turn on signal.

[budm]

Re: Vizio M420SL PS Issue

Are you getting ALL the control Voltage?
The connector of the power supply board to the main board has pin labels, you need to report all the reading for each pin when TV is off and when power switch is activated.

[Jsikora]

Re: Vizio M420SL PS Issue

CN103 only plugged in nothing. When power applied 3.28 @ BL-ON
CN102 On 1-14 5.15, 5.15, 5.15, .002, .002, .003, .002, .004, .004, .004, 3.28, 3.28, 0,0
Main Cap 170.5

[budm]

Re: Vizio M420SL PS Issue

CN103 only plugged in nothing. When power applied 3.28 @ BL-ON
CN102 On 1-14 5.15, 5.15, 5.15, .002, .002, .003, .002, .004, .004, .004, 3.28, 3.28, 0,0
Main Cap 170.5

Each pin has name so you need to put down the pin name follow by the reading so we can easily what it has or does not have.

[nomoresonys]

Re: Vizio M420SL PS Issue

When you have a questionable reading on a diode, next you lift one leg out of circuit and retest diode.

[Jsikora]

Re: Vizio M420SL PS Issue

Pin 1 5.15
#2 5.15
#3 5.15
#4 .002
#5 .002
#6 .003
#7 .002
#8 .004
#9 .004
#10 .004
#11 3.28
#12 3.28
#13 0.00
#14 0.00

[budm]

Re: Vizio M420SL PS Issue

Pin names needed.

[Jsikora]

Re: Vizio M420SL PS Issue

I will check themout of circuit, but I guess what my question is, would something else be causing these to show bad in circuit before these diodes. Just seems wierd that only those 3 in the same area show bad, but I'm desoldering them to check now.

[Jsikora]

Re: Vizio M420SL PS Issue

Pin 1-14 down they are as posted on CN102

[Jsikora]

Re: Vizio M420SL PS Issue

Connectors

[nomoresonys]

Re: Vizio M420SL PS Issue

Appears to be this one: https://www.shopjimmy.com/vizio-0500...upply-unit.htm

[Jsikora]

Re: Vizio M420SL PS Issue

Yep, getting ready to test these diodes.

[budm]

Re: Vizio M420SL PS Issue

Also Diodes D601, 601A and D603 all testing no good in circuit.

No good in which way?

[budm]

Re: Vizio M420SL PS Issue

"Main Cap 170.5" that should be about 360 ~ 400VDC if PS-ON (PWR-ON) is present.
No PFC boosted Voltage = no switched 12V, 24V.

[budm]

Re: Vizio M420SL PS Issue

Connectors

Sorry, I do not flip back and forth between pictures and the reported Voltage, that is not the format we are asking for. we are asking to type out the pin name and follow by the Voltage reading for each pin.
See post #3 & 4 on how OP reports the readings in the format as requested: https://www.badcaps.net/forum/showth...nector+voltage

[Jsikora]

Re: Vizio M420SL PS Issue

D601 & D601A both test good out but D603 seems to be the culprit. Going to look and see if I have a replacement and will update.

[budm]

Re: Vizio M420SL PS Issue

D601, 601A, 603 are the PFC Diodes.
https://assets.shopjimmy.com/media/c...0-bottom_3.jpg

[nomoresonys]

Re: Vizio M420SL PS Issue

pins 1-3 5,2vsb
pins 4-7 gnd
pins 8-10 12v
pin 11 pwr_on
pin 12 bl_on
pin 13 A
pin 14 c_dimming