LF501EM5F No Power, Chirping/Beeping Transformer

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

I did change the capacitor out but it didn't help the situation

[SLK001]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

That is a ceramic cap, not a electrolytic. ESR depends also with what frequency you test. You don't test ESR on a ceramic cap.

Sure you do. ESR is just as important for a ceramic cap as it is for an electrolytic cap. However, the ESR of a ceramic cap is usually <<0.1 ohms.

Measuring 17 ohms on any cap, especially a ceramic, indicates either 1) serious problems, or 2) measurement error.

[CapLeaker]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

WAAAY too high. ESR of a ceramic should be less than 0.1 ohms.

That is a ceramic cap, not a electrolytic. ESR depends also with what frequency you test. You don't test ESR on a ceramic cap.

[SLK001]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

c611 is measuring 17 ohms with esr meter. Seems high but I'm not at all familiar with ceramic caps.

WAAAY too high. ESR of a ceramic should be less than 0.1 ohms.

[CapLeaker]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Not smart. You don't lift a pin on an IC. Either you take it off or leave it on. VCC isn't produced there. That is the input voltage required for the IC to work properly. So we got to follow the line back. VCC has to have at least 14V in order for the IC to turn on.

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Is it possible that IC601 is just bad? Can I lift just the one leg of the IC601 and see if 20volts is being produced or is that not smart?

[CapLeaker]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Only the electrolytic ones.

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

c611 is measuring 17 ohms with esr meter. Seems high but I'm not at all familiar with ceramic caps. I'm going to try and find a parts board from a different TV and try find one with the same value and change them out.

[CapLeaker]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

VCC on IC601 is low. Check esr c620 and c616

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

checked c602 with a esr meter and it checked good.

[SLK001]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

D614 is hooked directly to pin 6 of IC601.

Should be thru a resistor (R634).

If those three diodes are really good, then check C602. It is a 0.1uF, 310V cap. If you can't test it, then just replace it with a comparable part.

You need to focus on why your booster isn't boosting.

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Lifted one leg of D605, D606, and D607 and they were all in good shape. Since it was so damn fun I did every diode on the board. All diodes tested good. As far as the voltage on pin 6 of IC601 it is the same as it was the last time. Still 11.33 volts as is D614. D614 is hooked directly to pin 6 of IC601. D614 also checked good. And as long as I was checking I check as many of the surface mount diodes I could find and they all measured fine.

[SLK001]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

slk001 I'm assuming you are talking about the surface mounted caps on the back side?

Sorry, I meant D605, D606 and D607. These are your booster diodes, which should boost your voltage to ~300VDC.

The Vcc pin on IC601 (PIN 6) is right at cut-off voltage (11V). This means that your driver IC is probably going in and out of shutdown. The voltage on PIN 6 should be in the 20V range.

Check the voltage on D614 (a zener diode).

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

The Main board is disconnected and there is a resistor soldered from the All+3.3volts to the p-on. Budm was stating that 3.3vdc isn't present so we were trying to figure out why that was. He had me start with ic601 and there voltages.

[CapLeaker]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

is that with the main board disconnected? If not, unhook everything from that PSU and measure those pins again.

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Pins 1-8 all 0 vdc
Pins 15-18 Are 8.15 vdc
Pins 20-23 Are 13.8 vdc

[CapLeaker]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Measure all pin outs on the PSU, post pin name with voltages measured. TV on and TV off, so we have a start point. I went back, but that isn't your thread. Use GND pins 9-14 as your GND reference.

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

amp +13 is 8.136 and p on+21v is 13.81

This is the measurements of IC601
1 8.9 mv
2 291.4 mv
3 27mv
4 Gnd
5 22mv
6 11.33vdc
7 42mv
8 166vdc

[budm]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

BTW, what DCV do you have on the AMP+13V and PON+21V jumpers? Notes: just the power supply board by itself.

[budm]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

OK, we need to find out what dcv you have on the SMD SMPS IC601 (FA5640N please verify that is the P/N as printed on top of the IC) in the primary side, we need the DCV readings of all the pin with ref to the GND pin pin 4 (or use the negative leg of the main filter cap as the GND ref point).
Be real careful not to touch anything since you are working in the primary side of the circuit.