Dead Sammy - LE26B450C4W

[AlbertRoss]

Hi Guys,

T.V. has no power indicator light, no clicking noise, no sound, no picture, just dead! Both fuses o.k. Have 240VAC across fuse FS801S, what kind of voltage should I expect to have on the second fuse FM802S? What would the next step be to check? Apart from throwing it the dumpster! Have included some photos, can take some more if required.

[selldoor]

Re: Dead Sammy - LE26B450C4W

I would go for testing the at the BIG Cap. With it plugged in and switched on, Meter on volts 600 DC put red lead on positive leg and black lead on negative leg - polarity is important CARE high voltage & do not touch any heatsinks.

[tom66]

Re: Dead Sammy - LE26B450C4W

Check to see if you have good standby voltage. If unsure post a closer picture of the connector going from PSU to mainboard.

[AlbertRoss]

Re: Dead Sammy - LE26B450C4W

326.3 Vdc on BIG Cap (CP815)

Pin configuration PSU to Main Board (1 to 15)

1. PWR_ON/OFF
2. STBY 5.3V
3. GND
4. 13V (s)
5. GND
6. GND
7. 5.3V
8. 5.3V
9. GND
10. 13.5V (m)
11. 13V (m)
12. Inv_ON/OFF
13. E-PWM
14. DET_5V
15. N.C

Except for the GND pins, I have unstable readings on all others (fluctuating voltage)

[tom66]

Re: Dead Sammy - LE26B450C4W

This points to a bad startup capacitor, or shorted output diode.

This power supply looks like it combines standby and main supplies. Inverters are run off the +400V bus.

My suggestion: Replace CM808, the yellow and brown caps, and the other small brown cap near the blue capacitor.

[AlbertRoss]

Re: Dead Sammy - LE26B450C4W

Found the CM808 as in the enclosed picture but having trouble finding the other one's you've mentioned without the numbers? I have a capacitance meter to check when I find the others.

[tom66]

Re: Dead Sammy - LE26B450C4W

These.

Cap meter might not show bad ones (ESR meter necessary), but give it a go.

[AlbertRoss]

Re: Dead Sammy - LE26B450C4W

CM808 is a 50V 22uF, when checked on board: 23uF
CP809 : : 50V 47uF : : : : 38.5uF
CB804 : : : : : : : : 3.8uF (yellow cap)
CM804 : : : : : : : : 50.2uF

Looks as if I have some bad capacitors? Is it worth checking off of the board? Who would you suggest I purchase the caps from in the UK?

[tom66]

Re: Dead Sammy - LE26B450C4W

Looks like it. Farnell is a good source. And for small caps, eBay can work.

[AlbertRoss]

Re: Dead Sammy - LE26B450C4W

Thanks for your time and help, just having a look around e-Bay and Farnell.

[tom66]

Re: Dead Sammy - LE26B450C4W

Thanks for your time and help, just having a look around e-Bay and Farnell.

Let me know if you need any help, may be able to order them cheaper via contract pricing.

[AlbertRoss]

Re: Dead Sammy - LE26B450C4W

Now I'm not to sure as I've removed CB804 from the board and checked it on my capacitance meter. On the board it read 3.8uF, off the board it's reading 51.0uF?

[tom66]

Re: Dead Sammy - LE26B450C4W

With high ESR, cap will sometimes read much larger. Your meter is optimised for caps with near zero ESR. I would say that it is a clear sign something is wrong.

[AlbertRoss]

Re: Dead Sammy - LE26B450C4W

So the $64,000 question is, do I just go and replace most of the electrolytic caps which should only cost a few pounds anyway? At least they will be taken out of the equation.

[tom66]

Re: Dead Sammy - LE26B450C4W

So the $64,000 question is, do I just go and replace most of the electrolytic caps which should only cost a few pounds anyway? At least they will be taken out of the equation.

If you like. Use decent quality caps, like Panasonic FC/FM/FR.

[AlbertRoss]

Re: Dead Sammy - LE26B450C4W

Awaiting delivery of the capacitors, will keep you posted.

[AlbertRoss]

Re: Dead Sammy - LE26B450C4W

Have replaced the caps as circled in the previous reply/picture. I've not replaced any other components, The standby light flashes on/off which I would say, looks a bit dim? No picture, no sound, no clicking sounds and no response from the on/off switch or remote. I have some spare caps the same as I've replaced but not the 1200uF 25V or 1200uF 10V.

I'm a bit stuck now as what to check next?

[selldoor]

Re: Dead Sammy - LE26B450C4W

Check that you put them in the right way round then re test the voltages on the out socket. When doing the poweron cycle the on/off switch

[AlbertRoss]

Re: Dead Sammy - LE26B450C4W

The caps are installed correctly. I'm checking on the 1st pin of the 15 pin socket, which is PWR-ON/OFF, no voltage change when on/off switch operated. As before, I have fluctuating voltage on the remaining 14 pins (except gnd) Makes no difference voltage wise if the 15 pin is connected/disconnected.

[ben7]

Re: Dead Sammy - LE26B450C4W

The caps are installed correctly. I'm checking on the 1st pin of the 15 pin socket, which is PWR-ON/OFF, no voltage change when on/off switch operated. As before, I have fluctuating voltage on the remaining 14 pins (except gnd) Makes no difference voltage wise if the 15 pin is connected/disconnected.

Sounds like either the mainboard is dead, or there is no standby supply going to the mainboard.