E470VA with a PLHH-Y009A - no power

[primuspaul]

I have a E470VA with a PLHH-Y009A power board. No power, nothing when cord is plugged in and power button is pushed. I opened the case and saw one of the capacitors was swollen and the legs has some substance on them, so I assumed this was the problem (later I tested it and it came up as having 8uF which seems pretty bad given its nominal rating). I replaced that, but still no power.

Checked the fuses and one of the two fuses I saw was blown (no continuity). Fortunately I had an old power board with what appeared to be an identical fuse that was NOT blown when it was on the old board, but as soon as I connected it to this board using some alligator clips, it also blew, so whatever problem there was with the power supply board must still be there.

Can someone advise what to test next? Also, for troubleshooting, I don't have anymore 3.15 fast blow fuses. Is it OK to use a 5A car fuse?

[dick_barton]

Re: E470VA with a PLHH-Y009A - no power

Do not replace the fuse and definately not a 5A. Fuses blow because there's a fault so until you have done some checking as to why the fuse is blowing, for example find what component(s) have gone faulty then they will blow every time and damage your board beyond repair.

The photo's are to dark and out of focus. Could you post brighter sharper images of your board.

Start by checking all the mosfets/diodes to see if any have gone short circuit or appear to be damaged.

Any components fitted on the underside of the board that may look damaged?

What is the part number on the IC mounted on the heatsink?

Has the 5A main fuse also blown?

[primuspaul]

Re: E470VA with a PLHH-Y009A - no power

Do not replace the fuse and definately not a 5A. Fuses blow because there's a fault so until you have done some checking as to why the fuse is blowing, for example find what component(s) have gone faulty then they will blow every time and damage your board beyond repair.

I guess I thought it was the bad capacitor that was causing the faults. I guess there's something else wrong somewhere, too.

The photo's are to dark and out of focus. Could you post brighter sharper images of your board.

See attached. Should be better.

Start by checking all the mosfets/diodes to see if any have gone short circuit or appear to be damaged.

Could you explain how to test these? I only have multimeters. Do I need to test with the power board on the TV and plugged in, or off the TV and unpowered?

Any components fitted on the underside of the board that may look damaged?

I didn't notice anything like that. Just the bad swollen capacitor I replaced.

What is the part number on the IC mounted on the heatsink?

Attached a picture of what I think you wanted. If not, could you point it out on the board and I will take a picture of that part close up.

Has the 5A main fuse also blown?

The 5A fuse near the power plug has NOT blown, it still shows continuity.

[dick_barton]

Re: E470VA with a PLHH-Y009A - no power

The easiest way to quickly learn how to check the diodes/mosfets is to search Youtube where there are plenty of example videos and very much easier than trying to explain to someone. A multimeter is all you need to carry out thoses tests which is carried out with the power disconnected from the wall socket.

The 5A fuse hasn't blown so it looks like it may well be a problem with the mosfets/diodes or IC that drive the inverter transformers. They are the two black transformers with B on top.

You didn't say what that IC in the red box part number was?

[primuspaul]

Re: E470VA with a PLHH-Y009A - no power

The easiest way to quickly learn how to check the diodes/mosfets is to search Youtube where there are plenty of example videos and very much easier than trying to explain to someone. A multimeter is all you need to carry out thoses tests which is carried out with the power disconnected from the wall socket.

The 5A fuse hasn't blown so it looks like it may well be a problem with the mosfets/diodes or IC that drive the inverter transformers. They are the two black transformers with B on top.

You didn't say what that IC in the red box part number was?

Red box part number? You mean these two? (see attached, I put arrows next to the ones I think you mean; please verify and I will get closeup info)

[primuspaul]

Re: E470VA with a PLHH-Y009A - no power

By the way, here is the underside of the board. Nothing special besides one part's solder connection appearing rusted.

[dick_barton]

Re: E470VA with a PLHH-Y009A - no power

Placed an arrow showing the IC

[primuspaul]

Re: E470VA with a PLHH-Y009A - no power

Placed an arrow showing the IC

STR
W6053N
1313K

Also, it looks like there are two ways of testing the diodes/MOSFETS - on the board AS IS or desoldered from the board THEN tested. Which one should I do?

[dick_barton]

Re: E470VA with a PLHH-Y009A - no power

And what is the IC part nuber next to the arrow?

[dick_barton]

Re: E470VA with a PLHH-Y009A - no power

Also, it looks like there are two ways of testing the diodes/MOSFETS - on the board AS IS or desoldered from the board THEN tested. Which one should I do?

Initially test on the board and remove to test if you find an anomaly.

[dick_barton]

Re: E470VA with a PLHH-Y009A - no power

Can you check with the power to the set disconnected and using your meter set to ohms, what the resistance is between pin1 and pin3 of the STRW6053N

[primuspaul]

Re: E470VA with a PLHH-Y009A - no power

And what is the IC part nuber next to the arrow?

Very hard to see. Looks like:

HS01
PQ0W

Also, so far I checked the following 7 diodes and all read between 0.4 to 0.6 while on the board, so I assume that's all I need to do for the diodes, or did I miss some diodes? Want to check one part type at a time make it simpler.

[R_J]

Re: E470VA with a PLHH-Y009A - no power

.

[primuspaul]

Re: E470VA with a PLHH-Y009A - no power

Can you check with the power to the set disconnected and using your meter set to ohms, what the resistance is between pin1 and pin3 of the STRW6053N

Getting 0.9 and a beep. See what I tested and what mode I used.

[dick_barton]

Re: E470VA with a PLHH-Y009A - no power

That would indicate that the IC has shorted and needs to be replaced. You also need to test the resistors and any diodes that connect to the IC especially any resistor that may be connected to pin 3.

[primuspaul]

Re: E470VA with a PLHH-Y009A - no power

That would indicate that the IC has shorted and needs to be replaced. You also need to test the resistors and any diodes that connect to the IC especially any resistor that may be connected to pin 3.

In the same multimeter mode, I am getting 0.2 and a beep on that resistor you pointed out. It displays the same value, but no beep, if I push the select button to go from continuity testing to resistance testing.

Did I miss any diodes? (see attached image).

For the other resistors you want me to test (I assume all of them?), what am I looking for in the resistance test?

Updated test so far with resistance values. I think that's all of them. The two on the bottom right tested 0.00.

But the way, I did find one more 3.15A fuse from another power board that is still OK, so I guess that will serve as a test once repairs are made.

[primuspaul]

Re: E470VA with a PLHH-Y009A - no power

Attached my shopping list so far. Getting those fuses just for testing so I don't break my last solderable 3.15A fuse. Let me know if I need to do any other tests or if I am good to order.

[dick_barton]

Re: E470VA with a PLHH-Y009A - no power

The 5K resistor would be correct if the three 15K ohm resistors are connected in parallel.

The 0.2 is probably OK and is an 0.33 ohm resistor.

I don't like glass fuses since they can explode when a short circuit occurs which is why ceramic fuses are normanlly used in sets.

You can buy the 3.15A fuses with the wire already connected to them for soldering into the circuit board.

I would also replace the 82uF capacitor back to the 68uF 450V

Normally when the STRW iC shorts, it does tend to damage other components connected to it so hopefully you have made a good inspection of the parts fitted to that IC


https://tinyurl.com/y89yyyfl

[primuspaul]

Re: E470VA with a PLHH-Y009A - no power

The 5K resistor would be correct if the three 15K ohm resistors are connected in parallel.

The 0.2 is probably OK and is an 0.33 ohm resistor.

I don't like glass fuses since they can explode when a short circuit occurs which is why ceramic fuses are normanlly used in sets.

You can buy the 3.15A fuses with the wire already connected to them for soldering into the circuit board.

I would also replace the 82uF capacitor back to the 68uF 450V

Normally when the STRW iC shorts, it does tend to damage other components connected to it so hopefully you have made a good inspection of the parts fitted to that IC


https://tinyurl.com/y89yyyfl

I already have an identical fuse on a different board that I will scrap to fix this one (the other board is from a totally different TV I no longer have). Only reason I'm getting the glass fuses is to test out the circuit - don't want to blow the expensive fuse, will install it later once I know the TV works without blowing fuses.

Updated shopping list attached. Can you confirm? Also, please recommend any adjustments if you think these can be bought for less somewhere.

[dick_barton]

Re: E470VA with a PLHH-Y009A - no power

I would order more than one STRWxxxx in the event that the replacement blows again.

If you go ahead using glass fuses then slide a sleeve over it in the event that if it ruptures it does'nt spray glass everywhere.

I would have thought you could obtain these items from US suppliers or on Ebay.