TNPA4250 Board Repair

[canadaboy25]

I've been trying to fix a Panasonic TH-42PZ77U with a broken SC board. The board number is TNPA4250.

I have lifted the legs of the transistors and tested them. A few of them read shorted so I took them off the board. But whenever i test them again different ones say shorted and then other times they may read good. Is there an easy way to test them and know if they are good or not?

I was thinking of just replacing all of them because there are only 14. But my main concern is the numbers on the transistors. There is one group of 6 transistors that have the 5N2307 and underneath have a 7 F4. But the group of 8 on the right have the numbers 5N2307 and underneath have a 6 M1. I have attached pictures of the different kinds. When I am ordering these do I need to worry about the 3 different numbers and are there different ways to test the two?

If they need replaced can I get these transistors from mouser or digi-key? I have searched on their sites but I really such at looking for transistors.

Any help on finding sources and testing methods will be appreciated.

[R_J]

Re: TNPA4250 Board Repair

Try posting in: "Troubleshooting TVs and Video Sources" you may get an answer

[momaka]

Re: TNPA4250 Board Repair

I can't find a proper datasheet for these, but I'm going to make a guess they are N-channel MOSFETs. In any case, this can be confirmed with the following test below.

MOSFETs in these type of cases have 3 pins. The Gate (G), Drain (D), and Source (S). Assuming you are looking at the MOSFET as if it was in the picture above, Gate is connected to the leftmost pin, Drain to the middle pin and also the large metal tab, and Source is connected to the right leg.

With the MOSFET removed from the board, touch all pins at the same time with your finger. If this is a MOSFET, this will discharge the Gate (required for proper measurement). Next, set multimeter to diode test, place black (- / COM) probe on D, and the red (+) probe on S. You should see a reading on the meter of about 0.2 to 0.7V (or 200 to 700 mV, depending on the multimeter). Now reverse the probes so that black probe is on S and red probe is on D and check again. You should see open-circuit... i.e. either a "1" on the left of the screen (typical for manual multimeters) or "OL" (typical for auto-ranging multimeters). This indicates that the S-D path on the MOSFET is not shorted. If not, try shorting all of the pins on the MOSFET again. Perhaps use something metal. Then check again.

Next, check if either S or D have resistance or continuity to G. If none, the MOSFET should be okay. If YES, the MOSFET is bad.

If the last two tests above pass, you may even be able to test the MOSFET's function. On a non-metal, isolated surface, set multimeter to diode test, put your red probe on G and black probe on S. Now move the red probe from G to D. You should see a small voltage drop (maybe 0.1 V or 100 mV, although this value can vary quite a bit with different MOSFETs) or perhaps none at all (i.e. the MOSFET's S-D path may appear like a short circuit). In this case, this is good, because you charged the Gate when you had the red probe on G and black probe on S, which means the S-D path should be shorted. If you touch all of the MOSFET's pins again with your finger, and measure S-D, the short should be gone. This generally concludes that the MOSFET is overall okay and not shorted.

I hope I didn't word this in a confusing way. Let me know if you need something explained better.

[canadaboy25]

Re: TNPA4250 Board Repair

I have removed all but two of the mosfets with 6 m1 on them thinking they were bad before posting this topic.

The mosfets with the 7 F4 on them all tested exactly as you described (other than 1 or 2 that I desoldered. May have been from heat.) But the mosfets with the 6 m1 that were left on the board all tested odd.

When I have my multimeter set on diode test with the red lead on source and the black lead on drain I get about 0.2 volts. When I have my red lead on the drain and my black lead on the source I get around 0.5 volts? And I also have resistance between the gate and drain and also the gate and source.

Now my next wtf moment is about where I took these mosfets off of. In the picture you can see 2 groups of mosfets. One with 6 and one with 8. There are two missing from the top row and those were gone from the factory. The set of 6 mosfets are the ones that have the 6 m1 numbers on them. The group of 8 are the ones with the 7 f4 numbers on them. I have a handful of 7 mosfets that i removed. 3 of them are 6 m1's and 4 are 7 f4's. So that being I have 1 extra 7 f4 that would have to be from the other group?

These two groups must be different so I don't know how I am going to go about ordering replacements.

This is all very confusing and I hope that you can somehow understand my madness. If you could explain to me what the heck is going on here that would be very nice. If you don't understand some of the crap that I wrote don't hesitate to call me out on it.

[capkid]

Re: TNPA4250 Board Repair

In my experience working on the TH-42PZ700U, one or more of the 5N2307 components fails in these TVs. I found some notes I'd kept from another forum that mention the transistor at Q6641 as a common point of failure. Did you have the 7 blinks of death?

https://www.badcaps.net/forum/showthread.php?t=24894

http://www.avsforum.com/t/1001318/ma...#post_17876879

[canadaboy25]

Re: TNPA4250 Board Repair

In my experience working on the TH-42PZ700U, one or more of the 5N2307 components fails in these TVs. I found some notes I'd kept from another forum that mention the transistor at Q6641 as a common point of failure. Did you have the 7 blinks of death?

Yes I did have a 7 blinks of death.

As long as I can get the right parts from a reliable source they are all being replaced so I can play my ps4

[momaka]

Re: TNPA4250 Board Repair

I have removed all but two of the mosfets with 6 m1 on them thinking they were bad before posting this topic.

The mosfets with the 7 F4 on them all tested exactly as you described (other than 1 or 2 that I desoldered. May have been from heat.) But the mosfets with the 6 m1 that were left on the board all tested odd.

When I have my multimeter set on diode test with the red lead on source and the black lead on drain I get about 0.2 volts. When I have my red lead on the drain and my black lead on the source I get around 0.5 volts? And I also have resistance between the gate and drain and also the gate and source.

Can't really test these on the board without having a bit more thorough knowledge of what is going in on in that circuit. For that reason, I encourage you to take off all MOSFETs and test them individually out of the board.

As for the 7 F4 and 6 m1 numbers - I don't think that really matters. The 5N2307 is the real part number IMO and the other numbers are probably just date or batch codes. All the info I could find on these 5N2307 MOSFETs is that they are rated for 230V 25A, N-channel type in a TO-252 case. I couldn't really find a datasheet, though. This is where I got the above info:
http://www.ohmsupplies.co.uk/5N2307-MOSFET-N-CH-TO252

My guess is other MOSFETs could be used too, as long as they are N-type (which is what the majority of power MOSFETs is, anyways) and same or better specs.

May also be worthwhile to check the dual common-cathode diodes on the top row (20LC30). You can do that while they are on the board though. Just check the resistaince or voltage drop between one of the pins and the tab. They all appear to be in parallel, so just checking one diode will tell you if any of them are shorted or not.
With the red multimeter probe on one of the pins and the black multimeter probe on the tap, what you are (ideally) looking for is about 0.3 to 0.7 V (or 300-700 mV) on the diode test function. That is with the MOSFETs out of the circuit as I'm not sure how they can affect the readings. Also check the resistaince. Any reading less than 100 Ohms between the diode pins and the tab is highly suspicious.

[capkid]

Re: TNPA4250 Board Repair

I've used this seller many times:http://pages.ebay.com/link/?nav=item...043848&alt=web

Lifting a leg should be sufficient to test each MOSFET.

[canadaboy25]

Re: TNPA4250 Board Repair

Ok then I will remove all of the mosfets.

The reason I was (and still am) wondering about the numbers is because they all (except for 1 or 2 that I probably blew up with my soldering iron) are testing the same as each other but in a different manor than the other numbered mosfets.

I suppose trying different ones wont hurt because the board is basically good for parts as it sits.

I will post back when they are removed.

[canadaboy25]

Re: TNPA4250 Board Repair

Well I took all of the MOSFET's off of the board and tested them using the method you described in post #3. Seven of the MOSFET's checked out fine and the other ones were shorted in some way. I lost one MOSFET between taking them off and testing them so whatever.

Now what other transistors or diodes on the board should I test? There is another row of transistor diode things that alternate between components and there are also 2 heatsinks with components on them. If the transistor diode things on the heatsinks can be tested without removal from the board then I will test them but if not I think I may just order new MOSFET's and see if it works. To get the components off of the heatsinks I will need to remove capacitors and screws which would be a pain in the neck.

Would these be available on mouser or digikey or any equivelent MOSFET's? I try my hardest to get parts from there vs Ebay because I know they are reliable sources.

I have uploaded two pictures of the rows of transistors on the heatsinks and of the ones on the board.

In the picture with all of the blue capacitors there are nine RF001's and three RJP6065's and three 2PG001 and one F20L60U.

In the other picture on the heatsink there are five 2PG001's and five RJP6065's and three F20L60U's and the two large ones on each ends are toshiba K3880's

In the same picture there is another row of transistors soldered on the board there are seven 20LC30's and five 5n2307's.

Let me know what you think.

Thanks

[momaka]

Re: TNPA4250 Board Repair

Now what other transistors or diodes on the board should I test?

Not sure as I've never done plasma board repairs myself. But I guess anything that looks discolored or darkened from heat. Mostly semiconductors (diodes, MOSFETs, etc.) and resistors.

There is another row of transistor diode things that alternate between components and there are also 2 heatsinks with components on them. If the transistor diode things on the heatsinks can be tested without removal from the board then I will test them...

Now that the MOSFETs are gone, I think you can.

The "transistor diode things", I'm assuming, are the 20LC30. 300V, 20A dual common cathode diodes. See last paragraph in my previous post to see how to test them.

Would these be available on mouser or digikey or any equivelent MOSFET's? I try my hardest to get parts from there vs Ebay because I know they are reliable sources.

The 5n2307 I don't see available on Digikey or Mouser. However, I did a search on Digikey and Mouser and refined the result to select only SMD MOSFETs rated for at least 230V and at least 25A in a TO-252 case/package.
IPD600N25N3 came up as the only reasonable suitable replacement that I could find on Digikey and Mouser. Not sure if the specs are more superior or inferior to what you have, but probably very close to try if you can't find exact replacements.

In the picture with all of the blue capacitors there are nine RF001's and three RJP6065's and three 2PG001 and one F20L60U.

I can't find any info on the RF001.

Same with the RJP6055. The RJP6065 is a 630V, 30A (100A peak) N-channel IGBT in a TO-3PFM case, though. Seeing how the pins for the 6065 are labeled G, C, and E (Gate, Collector, and Emitter), this is indeed an IGBT, and probably very similar to the 6065 (I just hope it's not the P-channel equivalent because that will make things confusing when testing). To test the 6055, check for short circuit between any of its pins. Also note if there is any resistance less than 100 Ohms between any of the pins and see if the other IGBTs have it too.

The 2PG001 is also an N-channel IGBT. Rated for 300V, 30A (120A peak). Same testing procedure as above.

Finally, the F20L60U is a 600V, 20A fast recovery diode. Test like a normal diode. First check for short between the two leads. If none, check the forward and reverse voltage using diode test function on your multimeter.

The Toshiba K3880 is actually a 2SK3880. N-channel MOSFET, 800V Vds, 6.5A Drain current (19.5A pulsed). Test like the other N-channel MOSFETs (i.e. the 5n2307).

[canadaboy25]

Re: TNPA4250 Board Repair

Well everything seems to check out just fine so now all I need to do is to get some replacement transistors.

[canadaboy25]

Re: TNPA4250 Board Repair

Well the transistors fianally arrived from China and I put them on the board. I even tested them after I soldered the back. They all tested fine and the TV still doesn't work.

I am really puzzled now. If you have any other ideas I will try them, otherwise I'm tossing it out the window.

[momaka]

Re: TNPA4250 Board Repair

You can find the service manual here:

The block diagram SC board is on page 119-120 and the schematic on page 122-125. I already looked at them, but I must admit this is a bit over my head. Usually tom66 is the go-to guy when it comes to plasma TV repair.

I guess my best advice would be to send a PM either TC, c_hegge, or one of the other moderators to move this thread into the TV section so that it can get more attention by the more experienced TV repair people. The issue may be simple too - I'm just not familiar at all with plasma TV sets, so I can't help with much other than how to test components.

[ratdude747]

Re: TNPA4250 Board Repair

I guess my best advice would be to send a PM either TC, c_hegge, or one of the other moderators to move this thread into the TV section so that it can get more attention by the more experienced TV repair people. The issue may be simple too - I'm just not familiar at all with plasma TV sets, so I can't help with much other than how to test components.

Or simply report the first post since this is a legitmate move request... done. Reported.

[capkid]

Re: TNPA4250 Board Repair

Same symptoms?

[canadaboy25]

Re: TNPA4250 Board Repair

I already posted in that section months ago and got no results.

[tom66]

Re: TNPA4250 Board Repair

With both buffer boards removed does the TV still do 7 blinks?

[canadaboy25]

Re: TNPA4250 Board Repair

Yup, With the SU and SD boards disconnected it still dies.

When I dissconnect the board I am working on the TV keeps running

[tom66]

Re: TNPA4250 Board Repair

I would try testing VAD, VSCN and VSET - they can cause 7 blinks error.