Emerson LC401EM2F no standby light or power

[CapLeaker]

Re: Emerson LC401EM2F no standby light or power

Ok I'm understanding it more now.
I thought I would mention this before I continue, when checking the dc voltage on the main filter capacitor, it's only reading out 1.90~V with both probes on each lead. That's already a problem right?

Not convinced on that yet. I think you measured that big capacitor in AC mode. Before the bridge rectifier is AC, after that everything is measured in DC. That big cap should have roughly 170V DC on it.

[dick_barton]

Re: Emerson LC401EM2F no standby light or power

+1
I also find it odd that there is mains being applied to the rectifiers but no DC on the cap.

[Beef_Ramen]

Re: Emerson LC401EM2F no standby light or power

Ignore that test for now.
You said you had 119V ac from the earlier measurement. There are 4 diodes that rectify the AC and apply it as DC to the capacitor C1612.
Measure once again across C1612, one probe on either pin with meter set to => 600V DC.

I have an innova 3320, it auto ranges since there's no fine tuning options. But yeah ill probe one lead from the capacitor and probe the diodes and see what I get

[vinceroger69]

Re: Emerson LC401EM2F no standby light or power

I have an innova 3320, it auto ranges since there's no fine tuning options. But yeah ill probe one lead from the capacitor and probe the diodes and see what I get

just to clarify when your testing the capacitor set your meter on 600v then test across both legs of the capacitor and let us know what it reads.

[cliff_hootarski]

Re: Emerson LC401EM2F no standby light or power

Also, Never measure resistance with Power applied to the set, or with the TV connected to your AC outlet.

[budm]

Re: Emerson LC401EM2F no standby light or power

If you trace out the board layout you will see that you have two sets of the bridge rectifier circuits, you will see that you are not going to have any DC on the main filter cap C1612 until the power supply board gets the PS-ON signal from the main board to turn on the power relay RL1201 which will then supplies 120VAC to the bridge rectifier diodes D1607, 1608, 1609, 1610.
D1201, 1202, 1203, 1204 are for the standby power supply feeding filter cap C1201 to run STBY SMPS IC 1201.
It is the Standby power supply section that you need to get it running first.

[dick_barton]

Re: Emerson LC401EM2F no standby light or power

Nice on Budm. I couldn't trace the circuit with the photo's provided.

[budm]

Re: Emerson LC401EM2F no standby light or power

Nice on Budm. I couldn't trace the circuit with the photo's provided.

Yes, the pictures have lots of glares so it was not easy to trace.
PCBA P/N per sticker is A17PC-MPW.
PCB P/M BA01P0F0103-3

[Beef_Ramen]

Re: Emerson LC401EM2F no standby light or power

Not convinced on that yet. I think you measured that big capacitor in AC mode. Before the bridge rectifier is AC, after that everything is measured in DC. That big cap should have roughly 170V DC on it.

I will double check thanks for pointing that out.

just to clarify when your testing the capacitor set your meter on 600v then test across both legs of the capacitor and let us know what it reads.

Mine doesn't have fine tuning, the innova 3320 is pretty basic.

Also, Never measure resistance with Power applied to the set, or with the TV connected to your AC outlet.

Thanks, I will remember this.

If you trace out the board layout you will see that you have two sets of the bridge rectifier circuits, you will see that you are not going to have any DC on the main filter cap C1612 until the power supply board gets the PS-ON signal from the main board to turn on the power relay RL1201 which will then supplies 120VAC to the bridge rectifier diodes D1607, 1608, 1609, 1610.
D1201, 1202, 1203, 1204 are for the standby power supply feeding filter cap C1201 to run STBY SMPS IC 1201.
It is the Standby power supply section that you need to get it running first.

Ok I will test the diodes as soon as I have time, is there a specific reading I should be looking for? As posted in the video above, I replaced 2 of them already because they were reading 0 and had continuity.

[budm]

Re: Emerson LC401EM2F no standby light or power

A this point you need to find out if you have 160VDC between the two legs of the standby power supply filter cap C1201 or not, that is the section you need to concentrate on first.

[Beef_Ramen]

Re: Emerson LC401EM2F no standby light or power

A this point you need to find out if you have 160VDC between the two legs of the standby power supply filter cap C1201 or not, that is the section you need to concentrate on first.

Ok great, I'll check that as soon as I get home tonight and will reply back promptly

[Beef_Ramen]

Re: Emerson LC401EM2F no standby light or power

A this point you need to find out if you have 160VDC between the two legs of the standby power supply filter cap C1201 or not, that is the section you need to concentrate on first.

Sorry for the delay, I'm getting 165DCV on that C1201

[budm]

Re: Emerson LC401EM2F no standby light or power

Good, so we do have the main DC to run the standby power supply section, now we need to find out why you are not getting the standby Voltage, more board tracing required.

[Beef_Ramen]

Re: Emerson LC401EM2F no standby light or power

Good, so we do have the main DC to run the standby power supply section, now we need to find out why you are not getting the standby Voltage, more board tracing required.

Ok, I guess that is good news to some extent. Let me know when you find another potentially problematic area and I will check it. Thank you.

[budm]

Re: Emerson LC401EM2F no standby light or power

OK, you need to check the fusible resistor R1201 fusible resistor which feeds the main DCV to the SMPS IC1201 (we need P/N of this IC as well) to see if the resistor is OK, looks to be 1 Ohm resistor.
The pcitures attached is the closest one I can find at SJ, there are many PCBA using this PCB BA01P0F0103-3, your PCBA is A17PCMPW.

BA01P0F0103-3
Pictures provided by shopjimmy.

[Beef_Ramen]

Re: Emerson LC401EM2F no standby light or power

OK, you need to check the fusible resistor R1201 fusible resistor which feeds the main DCV to the SMPS IC1201 (we need P/N of this IC as well) to see if the resistor is OK, looks to be 1 Ohm resistor.
The pcitures attached is the closest one I can find at SJ, there are many PCBA using this PCB BA01P0F0103-3, your PCBA is A17PCMPW.

BA01P0F0103-3
Pictures provided by shopjimmy.

Ok that resistor gives me 1 ohm resistance and has continuity with pin 5 of the IC chip

[vinceroger69]

Re: Emerson LC401EM2F no standby light or power

whats the part number of the ic so we can look at a data sheet.

[Beef_Ramen]

Re: Emerson LC401EM2F no standby light or power

whats the part number of the ic so we can look at a data sheet.

It's IC201, MIP2F3

[CapLeaker]

Re: Emerson LC401EM2F no standby light or power

Check what voltage you get on pin 4 (VCC) of that IC.

[budm]

Re: Emerson LC401EM2F no standby light or power

So just to be sure, you do not have the DCV at ALL+4.3V jumper for sure?