XVT3D554SV - Blinking Amber / White - PS Damage

[budm]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

What is printed on ZD4 body? What does it look like? And what resistance do you read between the two empty pads of the ZD4?
I'm also expecting pin 2 of the IC will be connected to a resistor beside the Cathode of the ZD4.
BTW, I see that the Rectifier D18 which provides VCC to run the SMPS IC was also shorted out, I am beginning to wonder if the OPTO Couple IC6 may be damaged (pin E and C) also.

[jason123]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

regular glass through hole part - NZ 158
I don't see another resistor connected to pin 2
Pin E and C are not shorted on IC6 - Not to say it's not damaged. Do you suggest I replace?

[budm]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

Based on the spec sheet of the IC, if pin 2 (LATCH/PLIMIT) is >4V the SMP IC will go into shutdown, so I would think the ZD can be around 6.2V. I would replace OPTO at this point since that sections has so many shorted/blown parts already when the board blew up.

[jason123]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

thanks budm. I happened to have exactly a 6.2V Zener, 0.5W glass body zener diode
Haven't replaced the Opto (on order) but I wanted to see what would happen when I power it up.
Good new is no explosions or violent events. Large Caps have 164V DC. on CN202, I tied REMOTE On/OFF, BL On/OFF and LD ON/OFF to 5.1 VSB (present and measures 5.12V) - nothing happens. Opto measures 0.6 on one leg and 0.01 on the other (hot side) Large caps still 164V, and 12 V never comes on. Expected behavior due to Opto?

[budm]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

If REMOTE -ON/OFF (PS-ON) is present then you should have the PFC Boosted Voltage around 380 ~ 400 VDC between the two legs of the main filter caps, that power section needs the boosted Voltage to run, so you need to check and see why you are not getting the Bootsed Voltage when PS-ON is present.
Are you testing the power supply by itself? If you do then you will need to force on the power supply using force on resistors to test the power supply board by itself.
Get the P/N and spec sheet of the PFC IC1.
Check the RESISTANCE of PFC Diode D5, D6.

[jason123]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

I'm testing power supply by itself. Yes, REMOTE-On/OFF has 5V (direct-no resistor- connection to 5V)
PFC is SC2101 labeled (I think that's the datasheet attached)
Measuring in-circuit Resistance:
D5: 77.8k & 1.5 Meg (and going up)
D6: 13.8 k & 4.4 Meg (and going up)

[budm]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

The PFC diodes are fine.
Now you need to check and see PFC VCC pin 4 has Voltage (11.6V typ. per spec sheet), you will use the negative leg of the main filter cap as gnd ref for the meter.

[jason123]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

Pin 1 0.16v
Pin 2. 1.040v
Pin 3. 0.996
Pin 4. 0.577v
Pin 5. 0.33 v
Pin 6. 0.000 v
Pin 7. 0.32 v
Pin 8. 0.00 v

[budm]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

Pin 1 0.16v
Pin 2. 1.040v
Pin 3. 0.996
Pin 4. 0.577v
Pin 5. 0.33 v
Pin 6. 0.000 v
Pin 7. 0.32 v
Pin 8. 0.00 v

You did use the negative leg of the main filter as the gnd ref, correct? If that is true then you need to do more in-depth troubleshooting to see where the pin 4 VCC goes to, it should go to the switched Transistor that supplies the switched VCC for the PFC IC to run.
Also check the resistance between GND and VCC pin 4 to see what it shows.
The VCC for running the PFC IC and other SMPS IC is generated by the standby SMPS section.

[jason123]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

Yes, all measurements referenced to hot gnd (negative terminal of large caps)

The standby 5.x V is on. Is it a different circuit that generates the VCC for the PFC circuit?

[budm]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

There is auxiliary winding on the Standby power transformer this is used for generating the power to run the PFC IC through the switch that is turned on when PS-ON is present. Right now it is a matter of tracing the VCC pin of the PFC IC back to the power source.
"Also check the resistance between GND and VCC pin 4 to see what it shows." What is the result?

[jason123]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

resistance between Pin 4 (VCC) and Pin 6 (GND) is 2.924 kOhm.

Attached is the path - Not sure what pin of the L6599AD is actually generating the VCC for PFC.

[budm]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

https://www.badcaps.net/forum/attach...4&d=1569159308
So you found another shorted out diode, that is not good, so many damaged parts in may section of the boards.

[budm]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

I traced out D15 Anode, it looks like it goes to the Collector of Q5 in the Standby power supply section, I cannot see much based on shopjimmy pictures.

[jason123]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

Anything specific you need me to trace or better photos of?

[budm]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

Trace to see if D15 Anode goes to Q5as shown in the picture.
https://www.badcaps.net/forum/attach...5&d=1569213118

[jason123]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

Yes, it does. See pic in #35

[budm]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

https://www.badcaps.net/forum/attach...8&d=1569504979
Us C35 Negative leg as the GDN for the meter, then check the Voltage on Base, Emitter, and Collector of Q5 when PS-ON is present.

[jason123]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

Here are the pin voltage measurements, referenced to neg lead of C35

[budm]

Re: XVT3D554SV - Blinking Amber / White - PS Damage

Per your picture in post #39, top left is EMITTER (E), top right is Base (B), and bottom pin is Collector (C). It is a PNP Transistor.
Put meter in diode mode and check E and B pins, then C and B pins