Sharpe LCD TV LC60E77UN

**dick_barton** · 11-18-2020, 01:08 PM

Re: Sharpe LCD TV LC60E77UN

I couldn't find a picture in which you could read the chip part number but did you mean IC7905 on the power board,

**budm** · 11-18-2020, 11:39 PM

Re: Sharpe LCD TV LC60E77UN

Must be IC7905.
Per shopjimmy pictures, it looks like TNY264PN by Power Integration.
Some one on the web sell the IC and the 2.2 Ohms resistor R7914 that will be blown too when the IC7905 blew up.
TNY spec:
Here is the link to one of the kit: https://www.yoycart.com/Product/566813822866/

**BruceGilbert** · 11-21-2020, 12:07 PM

Re: Sharpe LCD TV LC60E77UN

Thank you so much everyone that has responded that is exactly the IC that I was referring to. Also the comments made regarding the resistor this must be a known problem. Any additional information would be greatly appreciated.
Thanks Again everyone

Bruce

**budm** · 11-21-2020, 02:52 PM

Re: Sharpe LCD TV LC60E77UN

TNY IC does blow up a lot, it is used in many power supplies. The 2.2 Ohms fusible resistor is there to stop further damage when the TNY shorted out.

**BruceGilbert** · 12-16-2020, 04:22 AM

Re: Sharpe LCD TV LC60E77UN

Finally got IC7905 replaced and the fusible resistor R7914. Tried to power up the board with still no success. Here are some of my findings.
I still do not get any standby 5 volts on the low side of the power supply. It seems that I am getting 28 volts AC all over the low side of the power supply board.
Does anyone know where I can find the source of the 5 volt standby voltage on this power supply board? This is a DPS 343AP-A. Any suggestions as to where I should look would be greatly appreciated.

**dick_barton** · 12-16-2020, 06:21 AM

Re: Sharpe LCD TV LC60E77UN

What dc voltage do you have between the legs of C7830.
Do you have 5.8V dc on the BP pin of the Tny IC with the negative meter lead connected to the negative leg of C7830. Be carefull when measuring that the prove does not slip.

**BruceGilbert** · 12-16-2020, 10:37 AM

Re: Sharpe LCD TV LC60E77UN

Hi Dick
Thankyou so much for the advice I will check this afternoon. I do know that with the board plugged in on my bench. When I probe between the center securing screw for the board that has a terminal lug on it and the legs of the TNY IC I read 30 volts AC on all the legs with the exception of one which reads 60 volts. However I will do the test you are recommending and get back to you. Thanks again

**dick_barton** · 12-16-2020, 10:56 AM

Re: Sharpe LCD TV LC60E77UN

When taking measurements on the high voltage supply side of the power supply (HOT) you do not use the chassis as ground which is why you are getting AC readings. All measurement on the HOT side are always referenced to HOT ground which in this case, the negative leg of C7830 is a suitable point.

Measurements on the COLD side are referenced to chassis. COLD is the secondary supplies side of the power supply.

**BruceGilbert** · 12-16-2020, 04:03 PM

Re: Sharpe LCD TV LC60E77UN

Hi Dick
I was able to take the voltage measurements that you asked. Between the legs of C7830 I read 163.5 volts DC and between the negative leg of C7830 and BP of IC 7905 I read 5.95 volts DC.
With regards to the above comment I should read standby voltage between the pin on the connector and the chassis ground correct. I do not believe I am seeing that.

**dick_barton** · 12-16-2020, 05:10 PM

Re: Sharpe LCD TV LC60E77UN

The 5.95V measurement for BP is what was to be expected so I think that IC is probably working OK. It's the 5.8V regulated output derived from the supply at the drain and charges up the capacitor connected to BP pin.

Without the circuit diagram I can only guess that the 163.5V means that the PFC circuit is not operational.

Are you seeing any dc voltage on at the pins of PL, PD, LA1

**BruceGilbert** · 12-17-2020, 05:15 AM

Re: Sharpe LCD TV LC60E77UN

Thanks I will look later today possibly Snow storm here in Nova Scotia today. Not completely sure what these letters mean. PL,PD and LA1 but will do some digging.
Thanks again.

**dick_barton** · 12-17-2020, 07:33 AM

Re: Sharpe LCD TV LC60E77UN

That's why photo's of your circuit boards are helpful when posted.
I'm not 100% certain but if this is your power supply then PL, PD and LA1 are the connector names.
Photo from Shopjimmy

Attached Files

**BruceGilbert** · 12-17-2020, 04:52 PM

Re: Sharpe LCD TV LC60E77UN

Dick you are sharp yes this is my board.
With the power to the board and I use the chassis connection point as my ground and I measure any of these pins I do not see any voltages. Perhaps I am not connected correctly to see the voltage.
For your information I did find the 5.93 volts on pin one of IC7905 I believe. These are I believe opto couplers PC123. There are 6 of these between the hi and low side of the board and only IC7905 is upside down it is the very top one by the connectors you are referring to. I think I should see the 5.93 volts on pin 2 as well and if this coupler is not working would this prevent the 5.93 volts from getting to the low side of the board and on to the connector. Hope this makes some sense to you.

Bruce

**dick_barton** · 12-18-2020, 07:33 AM

Re: Sharpe LCD TV LC60E77UN

The board is sitting on my bench and connected to 115 volts AC. I can measure the high side as you have pointed out. The low side I am connecting one lead to the mounting connector with the metal connector and the other lead to any of the pins on the recommended connectors and I don't see a voltage. On IC7905 the first of 6 opto couplers which is mounted opposite to the remaining 5 on pin 1 I do see 5.93 volts which is on the high side of the board. Should I not see this voltage on pins 3 and 4 of this opto coupler?

To check the voltage on the LOW side ie secondary, you can generally connect the black meter lead to the metal chassis (back of led panel) or use any of the GND (ground) pins of the output connectors. The voltages will be DC set set your meter accordingly.

Can you post sharp well focused pictures since I have no information on your power supply other than what you posted. For example I can see the opto's in the picture I posted but have no Idea which one is which.

**dick_barton** · 12-18-2020, 07:58 AM

Re: Sharpe LCD TV LC60E77UN

IC7905 is a PFC control IC and not an opto-coupler.

What dc voltage do you have on pin 4 (EN/UV) of IC7905 with the black meter lead connected to negative leg of capacitor C7830.

Repair kit looks quite comprehensive.
https://www.shopjimmy.com/sharp-rden...ly-repair-kit/

Here is the information on IC7905

Attached Files

TNY263_268 SMPS IC.pdf (760.2 KB, 12 views)

**dick_barton** · 12-18-2020, 08:53 AM

Re: Sharpe LCD TV LC60E77UN

Carry out the same tests as done in this thread which is the same power supply as yours
https://www.badcaps.net/forum/showth...t=24435&page=2

**BruceGilbert** · 12-18-2020, 11:47 AM

Re: Sharpe LCD TV LC60E77UN

Thank you once again for all your help. Thank goodness that you have patience with us armatures. I will take some pictures and carefully review the information provided and get back to you.